FEAR IN HORSES

Fear is inherent in horses, with varying levels of intensity and behavioral reactions. Significant fear reactions—bolting and rearing, for example—can lead to horse and/or human injury and sometimes to material damage as well. Fear reactions can also determine how a horse will be used and who will ride it. Results from a survey of horse trainers showed that 56% of the dressage trainers considered fearfulness an unwanted characteristic in the horse, while only 29% of the show jumping trainers did. Furthermore, particularly fearful horses are more often ridden by elite or professional riders, whereas intermediate riders are considered safer with less fearful horses. If it’s severe or chronic, fear can even threaten an animal’s well-being.

The anatomy of a fear reaction

 As a prey animal, horses have evolved to be aware—and fearful—of sudden dangers, with a primary physical response of flight, which may or may not follow a short period of intense observation. They could show a startle reflex (body jerk) and stiffness. They might also make vocal noises, such as a snort, or defecate.At the start, fear can cause a horse to raise his head high, flare his nostrils, and show the whites of his eyes. The horse might also tremble and flick his tail. Knowing these early signs could help humans prevent or avoid injuries from the more dangerous reactions (bucking, rearing, and running off).

Fear reactions versus fearfulness 

While all horses might exhibit signs of fear in different situations or to various stimuli (opening umbrellas, fire, other livestock, plastic tarps, etc.), recent research results reveal that some horses are simply more or less fearful by nature. Scientists refer to this as the “fearfulness temperament,” which is consistent throughout the horse’s life. Owners and trainers can potentially detect a horse’s fearfulness temperament through behavior testing when the horse is as young as 8 months of age.Fearfulness is now recognized as one of the five core dimensions of a horse’s overall character. Researchers have designed various tests to evaluate horses’ fearfulness but have been challenged to find one that focuses purely on fear and not other traits, such as the horse’s particular social needs. However, a fearfulness test that Lea Lansade, PhD, developed in 2010 as part of an overall personality test for horses has been gaining acceptance among scientists. In 2014 this test was simplified to make it easier and faster to perform while still providing reliable results.5 Researchers do not yet know whether fearfulness is genetic. In the late 1990s scientists found that fear reactions were more similar among halfsibling horses than among unrelated horses.6 Today’s more reliable fearfulness testing should allow researchers to test for the heritability of fearfulness in the future.

Reducing Fear

 Regardless of a horse’s basic fearfulness temperament, handlers can help minimize a horse’s fear and fearful behaviors. Anecdotal evidence has suggested that imprinting makes horses less fearful, but recent research has shown that this early handling technique has no significant effects on fearfulness.Handling just after weaning, however, does—at least for a while. When foals were haltered and petted daily, separate from other foals, in the first 12 days after weaning, they were less fearful than control foals with the same handling three to four weeks after weaning. The foals handled just after weaning showed less prominent reactions when separated from their groups, approached by a human, exposed to a new object (pylon, plastic bags), and surprised by an opening umbrella.Young foals who saw their mothers accept frightening stimuli also had reduced fear reactions. Researchers exposed mares to several scary situations (opening umbrellas, plastic bags placed on them, etc.) for eight weeks starting at foaling. The foals were able to observe their mothers’ reactions. At 8 weeks and 5 months of age, the foals were exposed to the same stimuli, as well as new stimuli they had not seen before. Compared to control foals, they were calmer—even with the new stimuli—and had lower heart rates. Enriched environments—those with social companionship in shared pastures, frequent feedings, and regular sensory stimulation (objects and music)— appear to reduce fear reactions, too. Yearlings housed in enriched environments became less fearful after five weeks than controls living in individual housing with individual paddocks and fed three times a day.


Managing Fear Reactions

 When horses do show fear reactions, especially to frightening objects, it’s usually best to help them approach the object. While this might induce more stress initially, horses will habituate to objects faster than if they’re left to discover them on their own. That’s not recommended, though, if it puts the human or horse in significant danger. When there’s high risk, such as when treating a sick or injured animal, applying various learning theory techniques—overshadowing and gentle negative reinforcement, in particular—can result in rapid learning that allows the horse to accept frightening stimuli, even in a hospital environment.When time isn’t an issue, handlers can gradually introduce the source of fear into a horse’s daily environment to help reduce his reactions. If a horse is afraid of cows, for example, pasture him near cows and, eventually, in the same field as the cows to help him overcome the fear. A calm companion can be a useful training aid in frightening situations as well. Two-year-old stallions confronted with scary situations had lower heart rates and fewer fear reactions, compared to control horses, when they were accompanied by horses already habituated to the fear source.

Loving the Naturally Fearful Horse A naturally fearful horse learns better than a less fearful horse—as long as the fearful horse is free of external stress. Stress related to the actual learning task at hand won’t affect learning. This improved learning might be related to the finding that fearful horses are more habit-forming—for good and for bad.Horses with a stronger fearfulness temperament also learned better in Pavlovian-to-Instrumental-Transfer training, a kind of test in which horses learn to associate audiovisual cues with a task in order to get a reward.Show jumpers testing high on the fearfulness factor were more difficult to ride, but they had the fewest penalties in competition during a recent study. Generally though, jumpers are less fearful than eventing and dressage horses.Fearfulness isn’t necessarily a negative trait. As researchers are finding out, fear has many advantages. Provided the horse is trained and managed properly, with its fearfulness in mind, it can become a healthy, high-achieving horse.

Reference
thehorse.com

OMEGA- 3-FATTY ACID

• Omega 3 oils modulate cell wall flexibility, immune function, inflammatory responses and are a potent source of anti-oxidants
• Clinical investigations in man and animals have demonstrated a reduction in cholesterol, clotting abnormalities and blood pressure.
• Omega 3 oils have been shown to have an important role in the structure and formation of the wall of the red blood cells-conferring upon them increased suppleness and flexibility.
• Omega 3 deficiency is also involved in hoof problems such as shelly feet and in the incidence of allergic skin conditions.
• Other common deficiencies causing poor hoof quality include zinc, methionine and biotin, but if the problem is related to insufficient omega-3 oils in the diet, supplementation is necessary.
• Feeding Omega 3 oils for 6 weeks to horses with Queensland itch led to a reduction in the severity of the itch and inflammation.
• There are also benefits for horses at stud – after 6 weeks on an Omega 3 supplement, mares milk conferred increased immunity and resistance to infection
• For the breeding stallion, a study presented at the Convention of the American Association of Equine Practitioners in 2003 showed that raising the intake of specific Omega 3 fatty acids improved the motion characteristics of cooled-stored and frozen-thawed semen.
• Because animals are unable to synthesize omega 3 fatty acids, they must acquire them from the diet.
• Vegetable oils, such as corn and soybean oil, contain high levels of omega 6 fatty acids which favours the incorporation of omega-6 fatty acids over omega-3 fatty acids.
• The tissues of wild horses and wild plants contain higher amounts of Omega-3 fatty acids compared to domesticated or cultivated ones.

Reference
http://www.o3animalhealth.com/benefit.pdf

EXTRACORPOREAL SHOCK WAVE THERAPY

Extracorporeal Shock Wave Therapy

Extracorporeal shock wave therapy (ESWT) is a method of applying energy waves to hard or soft tissue in a particular area of the body.
Developed for human use in breaking up kidney stones, the technique has been adopted by veterinarians to reduce pain and stimulate healing in some types of injuries.
“Extracorporeal” refers to the fact that the treatment is given from outside the horse’s body, in contrast to oral medications, injections, or surgery that are considered more invasive.

 Two types of shock wave machines, focused and radial, are available.

Focused waves can be directed at a particular point and can penetrate further through soft tissue, while radial waves impact a larger but more shallow area. Because there is little tissue overlying most limb bones and joints, it is believed that radial waves have sufficient energy to reach many targeted areas, and the radial machine’s significantly smaller size makes it somewhat easier to transport and use.

How is the treatment administered?

While a veterinary clinic can administer ESWT to inpatients, most practitioners take the therapy to their equine clients.

The horse remains standing in his stall and is usually lightly sedated to keep him from moving excessively during the treatment. A veterinarian uses a portable unit to generate high-pressure acoustic (sound) waves. The apparatus is held against the injured area (bone, joint, tendon, or ligament) for about twenty minutes.

 A typical course of therapy involves three treatments at three-week intervals.
What happens to the tissues treated with this therapy?

While the exact mechanism is not yet known, ESWT commonly leads to improved circulation due to blood vessel dilation in and around the injured area. 

Growth of new blood vessels has also been recorded. Significant pain relief is almost immediately evident, although slight swelling and sensitivity may be noticed for a few days. ESWT also has a positive effect on the concentration of transforming growth factor beta 1, which stimulates cell activity. In addition, ESWT influences bone remodeling by thickening the outer layers and strengthening the cell network underlying joint cartilage.

What equine conditions are commonly treated by ESWT?

The best results have been seen in horses with hock problems and proximal suspensory ligament injuries. Stress fractures, ringbone, navicular syndrome, back pain, and tendon injuries have been treated with variable results.


 How successful is this treatment?

In a study at Iowa State University, horses with inflammation of the suspensory ligament were treated with ESWT. The treated animals had a decrease in lesion area, improved fiber alignment, and less swelling than animals in a control group. A similar study in Germany compared ESWT with conventional treatment (rest, cold treatment, blistering, application of anti-inflammatory and steroidal products). Of the conventionally treated group, 50% of the horses returned to full work within six months, while 71% of the ESWT group were able to resume full work in the same time period. In a third study group, horses with bone spavin (degenerative arthritis of the hock) were treated with ESWT. A decrease in lameness was seen in 80% of the treated horses. If ESWT is so useful, why is there controversy regarding its use? One effect of shock wave therapy is a transient numbing of the nerves in the treated area. The numbness begins almost immediately after treatment and subsides slowly during the next two to four days, with some loss of nerve conductivity still detectable up to three weeks later. Professionals worry that horses raced or shown during this pain-free period may suffer more serious injuries, possibly falling and endangering riders and other horses. Subtle movement changes caused by pain or injury are often a jockey’s clues that a horse needs to be eased or pulled up before the injury leads to breakdown. Jockeys have voiced serious concerns that horses racing within a day or two of ESWT may not exhibit these telltale gait changes. A number of states already have regulations banning racing within seven to fourteen days following ESWT, and Minnesota has completely disallowed its use. Enforcement is difficult, however, because horses show very little evidence that this therapy has been performed. While many tracks require trainers to register shock wave machines and report all treatments to the official track veterinarian, there is virtually no way to be certain of how much time has elapsed since therapy was performed on a particular horse. What’s the bottom line on extracorporeal shock wave therapy? ESWT seems to be a useful technique for treating some types of injury and lameness. As with any treatment or therapy, irresponsible use can lead to problems. A veterinarian can provide guidance about local regulations and the use of ESWT as a treatment option in a particular situation.

References

A publication of Kentucky Equine Research,  www.ker.com 

WIND SUCKING

Cribbing or crib biting is an abnormal, compulsive behaviour or stereotype seen in some horses.It is also called as wind sucking.
Horses grabbing solid object such as the stall door or fence.
Crib bitting is highly linked to stomach ulcers.

Causes

• Dietary deficiencies
• Boredom /Anxiety
• Stress
• Gastric inflammation/ colic

Treatment

• Antacid diet should be given.
• Higher roughages should be given.
• Reduce the level of concentrates.
• Collar like device can be applied to prevent wind sucking.
• Decrease stall confinement.
• Increase contact with other horses
• Bedding materials like straws can be used.

Hoof Abscesses in Horses

A hoof abscess is a localized bacterial infection in the sensitive structure of the hoof, or in layman’s terms, an abscess is the hoof’s way of getting rid of dead cells from a trauma. Truly, it is a pimple in the hoof. An abscess can develop for many reasons. Some common 

causes

• Introduction of a foreign body
• Shoeing nails hitting too close to the laminae, thus allowing bacteria to enter
• Some other kind of trauma to the sensitive layers of the hoof, such as going from shod to barefoot without proper preparation
• Reaction to bruising
• Laminitis
• Shoeing difficulties
• Navicular disease
• Contraction of the heels
• Going from dry to wet weather conditions

Symptoms 

• Swelling in the lower leg
• Heat is felt by touching the hoof wall.
• Increased digital arterial pulse in the hoof.
• If severe pain is there horse try to walk on the toe.

Detecting Abscesses

"Clinical signs depend on the severity of the infection; therefore, lameness could vary from mild, minimal lameness progressing to moderate, severe lameness

Clinical signs might include swelling, heat, draining tracts ,from the sole/coronary band), increased digital pulse, and evidence of hoof injuries (that can introduce bacteria into inner hoof structures, leading to abscesses)."

In severe cases deep within the hoof, the abscess pocket or its effects, such as deteriorating bone, are visible on a radiograph.

"A hoof tester exam  cam be for detection of pain in the hoof.

 Applying focal force is often vital to localizing an abscess within the confines of the foot," says Lyle. "As the pressure increases, so does the pain."

Also, when trimming the foot one might see a black spot on the sole or sole-wall junction where a crack or puncture is contaminated with muck. This stands out in contrast to the rest of the clean, trimmed sole. This contaminated tract might lead to an abscess (not all contaminated cracks will cause abscesses

 Treatment

 The basic abscess treatment strategy is to open it and let it drain. 
  Some will even pop on their own, often after traveling up the hoof to the coronary band or heel bulbs where the wall is thinner and easier to break through.

When possible, a veterinarian drains an abscess through the sole for two reasons: 
One, the crack or puncture that can lead to an abscess generally is in the sole, and it can be followed to the abscess. 
Two, this puts a hole beneath the abscess so gravity can help pull out the pus. Cleanliness is essential during and after the procedure.

"Treatment requires cleaning the foot, locating the entry wound , establishing drainage, softening the hoof capsule via foot soaks and poultices to encourage rupture/drainage, and keeping the foot wrapped and protected from further debris entering and causing further infection.  
Anti-inflammatory medication and antibiotics may also be given if needed. 
After drainage is obtained, progressive improvement should be expected on a daily basis." If drainage and lameness continue, perform other diagnostic procedures to determine the true cause.

Abscesses that have gone undetected can undermine a large portion of the sole, which might need to be pared away. In such cases the foot might require longer-term protection such as a pad or a plate.

Some veterinarians avoid foot soaks to prevent oversoftening the foot. Bras soaks feet only when abscesses appear ready to rupture .

Preventing Abscesses

"Good hoof care that leaves adequate sole for protection and develops a snug and uniform sole-wall junction is the best line of prevention," says Lyle.

Good hoof care includes frequent hoof cleaning to remove rocks/mud and routine farrier care to keep the feet balanced and address any problems.

"If a horse has thin soles or is prone to bruising ... protect them with shoes, etc., "Keep the feet trimmed so they don't get wall separations that can lead to white line disease and abscesses. Be proactive; don't wait for things to happen."

HORSE VISION

The equine eye is the largest of any land mammal. Its visual abilities are directly related to the animal's behmavior and the fact that the horse is a flight animal. Both the strengths and weaknesses of the horse's visual abilities should be taken into consideration when training the animal, as an understanding of the horse's eye can help to discover why the animal behaves the way it does in various situations.

How do horses see the world?

It’s a question horse owners may occasionally consider as they go about their daily lives, enjoying the benefits of their finely tuned binocular vision and the rich tapestry of reds, blues, greens and yellows we see in our world .A 1942 study observed that horses, like other ungulates, were active during the day, at dusk, dawn, and during the night. Their eyes, it was found, were designed to provide high sensitivity for vision in dim light and better vision still under higher light levels.

Eyes are believed to have started evolving some 540 million years ago. They have evolved in different ways to meet specialist needs throughout the animal kingdom.In insects, for example, we find compound eyes. Horses and humans have what could best be called a camera-type eye.

Light passes through the lens and focuses the image on the retina at the back of the eye – much like a camera lens throwing an image on to a piece of film.

The eye’s curved retina is linked to the optic nerve, which transmits information about the visual environment to the brain.

Not all cones are created equal. In humans there are three types of cone cells – each one is most sensitive to a different wavelength (colour) of light. Inside each cone is a photopigment, and it is this pigment that gives a particular cone its characteristic sensitivity.Retinas are lined with two types of light-sensing cells, called rods and cones. Rods look after vision in low light, and cones handle colour. This is why colours are barely, if at all, distinguishable to us in low light, as the cones are not sensitive enough in these conditions.

Horses – in common with pigs, goats, cows, sheep and deer – have only two different cone types on their retina, providing them with what scientists call dichromatic vision.

Primates, which include humans, are the only placental mammals to have three cone types at the back of their eyes, called trichromatic vision.

So, the way that humans and other primates see is fairly unique in the world of mammals. However, 1993 research revealed that birds go one better, having four cone types (tetrachromacy), as well as ultra violet (UV) sensitivity.

Dichromatic mammals such as horses have one type of cone most sensitive in the middle-to-long wavelength of the light spectrum and a second cone with maximum sensitivity to short wavelengths – either UV, as found in many rodents, or a more traditional short-wavelength-sensitive cone.

One of the most detailed studies into equine vision was carried out in 2000 by researchers based in Wisconsin, in the United States. Their findings were published the following year in the Journal of Vision.

The team used a flickerphotometric electroretinogram (ERG) in their study – a device not unlike an electrocardiogram (EKG) which measures the electrical activity of the heart to provide an assessment of its performance.

Six ponies, all with healthy eyes, were used in the trial.

The animals were first anaesthetised, then electrodes were placed gently on the eye and just beneath the skin as part of the monitoring process.

Different-coloured light was then shone into their eyes and the change in electrical response of the retina was measured. The stronger the response, the more sensitive the cones were to that colour.

The team found evidence, as previous researchers had, for two cone types in the horse that provide the basis for their dichromatic colour vision.

But by analysing the strength of the response to the different colours, the researchers, lad by Dr Joseph Carroll, of the Department of Ophthalmology at the Medical College of Wisconsin, were able to paint perhaps the best picture yet of how horses might see the world.

Behaviourial experiments by other researchers had already proved the ability of horses to discriminate colours. However, what colours were they actually seeing?

“People often wonder what the visual world is like for an animal whose eyes and nervous system are different from our own,” Dr Carroll says.

“Because of its special relationship with humans as a companion and a form of transportation, as well as a beast of burden and source of recreation, there are probably few animals that have more often been the subject of curiosity about alternate sensory worlds than the horse.”

Using data gathered in the study, the research team believe they derived a sense of what the daytime colour experience of the horse might be like.

People, with their trichromic vision, see four basic unique colours: red, green, blue, and yellow, as well as a range of intermediate hues.

The research showed that horses, with their dichromatic vision, cannot distinguish red.

“It’s not that they don’t ‘see’ red,” says Dr Carroll. “They just can’t discriminate in the red/green region of the spectrum. They are also slightly less sensitive to red light.”

Human dichromats who have inherited red-green colour vision defects – commonly referred to as colour blindness – indicate that instead of having four basic colors, they have only two hues, the ones most similar to blue and yellow.

“One of the most dramatic differences believed to differentiate the visual world of the dichromat from the trichromat is that, for dichromats, there are no intermediate hues,” Dr Carroll says.

Two colour wheels show the differences in colour perception between people, with their trichromic vision (left) and the dichromatic colour vision of horses. Dichromic vision sees a big reduction in the number of different colors seen.

“For a dichromat, when colours from the two ends of the spectrum are mixed, rather than getting an intermediate hue, the result is either achromatic (white or gray) or a desaturated version of one of the two basic hues – that is, a pastel blue or yellow.”

Using the information from the study, Dr Carroll’s team was able to produce a colour wheel showing how a horse’s eye perceives colour, compared with people.

Colour perception is, however, only part of the equation.

A 1992 study showed that horse vision is not as sharp as human sight. If good human vision is 20/20, a horse rates as 20/60. This means that details a person with 20/20 vision can see at 60m are only visible to a horse at 20m. The findings were obtained by measuring brain activity when horses saw different sets of lines on a television screen.

The series of lines in the accompanying illustration demonstrate the difference between 20/20 and 20/60.

Dr Carroll’s team combined both sets of findings and doctored two typical daytime scenes to give some insight into what a horse might be seeing.

It is not, however, an exact science.

There are many differences between the horse and human visual systems, Dr Carroll points out. These include the positioning and optics of the eye, as well as differences in the retina and the brain. All these factors would contribute to differences between horse sight and our own.

Many questions remain.

Dr Carroll sees scope for further measurement of equine colour discrimination, as well as other visual skills, such as motion, depth and spatial abilities.

Why then, have primates ended up with three cone-types and other mammals only two?

“This is pretty well known,” Dr Carroll says. “Old World primates, including humans, evolved trichromacy as a result of a gene duplication some 40 million to 60 million years ago in a primate ancestor.”

Why should red be the colour that horses have trouble distinguishing?

It probably had a lot to do with the environment in which the species evolved. “It bears thinking about how much long-wavelength light [the red end of the spectrum] that an animal is exposed to.”

Dr Carroll says identifying the cone pigments in any given species is an important first step toward understanding its colour-vision ability, but he cautions that it is an incomplete picture.

Research into horse vision has also been conducted in New Zealand. Tania Blackmore, when a graduate student in the Department of Psychology at the University of Waikato, designed a research study for her Masters thesis.

Her test was behavioural-based, involving four horses who were incentivised to distinguish between a colour and grey. They had to achieve an 85% success or better for a pass.

Her study found that horses could definitely see the difference between blue and grey, between yellow and grey and between green and grey. They could tell red from grey to some extent but they found this much more difficult, as would be expected when considered in tandem with Dr Carroll’s findings.

FOOTNOTE: Research led by Dr Joseph Carroll, entitled “Photopigment basis for dichromatic color vision in the horse” was published in the Journal of Vision in 2001. The other researchers involved in the study were Christopher J. Murphy, Maureen Neitz, James N. Ver Hoeve, and Jay Neitz.

PROUD FLESH IN HORSES

Exuberant granulation tissue, or proud flesh as it is more commonly known, is part of the normal wound healing response in the horse.

Granulation tissue is the pebbly or granular appearing tissue which develops in healing wounds anywhere on the horse's body.

Granulation tissue is composed of small blood vessels and fibroblasts, but has no nerve supply.

This healing tissue is beneficial within open wounds for several reasons:

1) Granulation tissue helps the open wound resist infection;

2) As it fills the healing wound, it provides a surface for the epithelial (skin) cells on the periphery of the wound to "crawl" over and help cover the wound;

3) Granulation tissue helps aid the wound in contracting or becoming smaller.

Granulation tissue is a very important and necessary part of wound healing in the horse. However, there can be problems when the horse develops too much granulation tissue.

Research has found that horses have the ability to produce granulation tissue in wounds quite rapidly when compared to other animals.

When granulation tissue grows out and protrudes from the wound, then the granulation tissue is known as proud flesh.
Proud flesh is not conducive to wound healing as it prevents the wound from epithelializing (the process of the skin cells covering the wound).

Proud flesh sometimes can take on a "life of its own" if the healing wound is not managed properly. The granulation tissue can become so large it appears to be a tumor, usually obliterating the original wound.

Granulation tissue in this excessively exuberant form usually occurs within wounds on the distal (lower) leg of the horse, such as wounds over the cannon bone or pastern area. Granulation tissue in this form can be very difficult to manage.

We believe excessive exuberant granulation tissue forms as a result of several different factors--excessive movement of the healing tissue, minimal soft tissue coverage around the wound, contamination (infection) of the wound, and a reduced blood supply.

Prevention of exuberant granulation tissue involves good wound management. Any significant wound should be evaluated and treated by a veterinarian as soon as possible.

Proper and timely management is crucial to a satisfactory outcome for any wound, but especially those of lower limbs.

Bandaging is very important in the prevention of exuberant granulation tissue and helps prevent bacteria from contaminating the wound.

It also helps maintain a healthy environment for optimum healing, and helps reduce motion of the tissue, again optimizing wound healing.

You should cover the wound with a non-stick pad and some type of conforming gauze bandage.

Depending on the wound location, that can be followed by a thick cotton bandage and an elastic bandage to prevent contamination of the wound from bedding and dirt.

The pressure from the bandage helps prevent the granulation tissue from becoming exuberant.

The treatment of wounds that have developed exuberant granulation tissue usually depends on the extent of the overgrowth.

Mild overgrowth of tissue--just protruding above the surface of the wound--might require only steroid ointment applied directly to the granulation tissue to inhibit the growth of the exuberant tissue, then bandaging of the wound to prevent further growth of the granulation tissue and to encourage wound epithelialization.

For additional reading see Equine Wound Management by Ted S. Stashak.

Disorders of the Foot in Horses

Bone Cyst in the Pedal Bone

A large cyst in the pedal bone (the distal phalanx) can cause longterm lameness that may be severe and unresponsive to anti-inflammatory medication. This uncommon condition, caused by trauma, may be seen in any foot but more often affects a hindfoot. The diagnosis may be confirmed by your veterinarian through the use of regional analgesia and x-rays. Progressive weakening of the pedal bone can lead to a secondary fracture. Because of the cyst's location and size, surgery is not always successful. However, some horses do return to performance status, while others may be used for less strenuous activity such as breeding.

Bruised Sole and Corns

Bruising on the sole of the foot usually is caused by direct injury from stones, irregular ground, or other trauma. Poor shoeing, especially in horses with flat feet or dropped soles, can increase the risk of bruising, usually around the outside edge of the sole. Bruising may or may not be associated with lameness, but if it becomes longterm, the affected area can become infected.

A corn is a type of bruise that appears in the sole at the buttress (that is, the angle between the wall and the bar). It is most common in the forefeet on the inner buttress. Corns may arise from pressure applied to the sole by the heel of a shoe improperly placed or left on too long. Shoes that have been fitted too closely at the quarters can also cause corns. Malformations of the feet, such as straight walls that tend to turn in at the quarters, increase a horse's vulnerability. Other causes include excess trimming of the sole (which exposes the sensitive tissue to injury) or neglect of the feet to the extent that they become long and irregular.

Corns may be dry, with only mild inflammation, or moist, with extensive inflammation. If infection sets in, they may discharge pus. The sole of the foot looks discolored, either red or reddish yellow, and lameness sometimes occurs in the supporting leg. Applying pressure may cause discomfort or pain. If not promptly treated, a corn may lead to the formation of a pus-filled tract that runs to where the horn of the hoof meets the skin (the coronet).

The outlook for recovery is favorable. In uncomplicated dry corns, the first step is to relieve pressure on the affected area. Shortening a too-long toe or using an appropriate type of bar shoe (such as a three-quarter-bar shoe) can relieve pressure. A corn that produces pus must be surgically drained, then bandaged to allow continued drainage. Hot foot baths and poultices may help, and the horse should be kept in a dry, clean box stall. After the infection is controlled, the cavity can be packed with sterile gauze and topical antibiotic ointment. A metal, rubber, or leather sole may be placed between the shoe and the foot.

Canker

Canker is an enlargement of the horn-producing tissues of the foot, involving the tough flexible pad in the middle of the sole (the frog) and the sole, with obvious production of pus. The cause is unknown. Primarily a disease of heavy draft horses, canker is seldom seen today, although it has been seen in certain stables of light horses in the southern United States.

Canker is most often found in the hindfeet and is frequently well advanced before detection. The frog may appear to be intact but has a ragged, oiled appearance. The horn tissue of the frog loosens easily and reveals a swollen, foul-smelling layer covered with dry, diseased, dead tissue. The disease may extend to the sole and even to the wall of the hoof and show no tendency to heal.

The outlook for recovery for canker is guarded. Treatment must be intensive. All loose horn and affected tissue should be removed, and an antiseptic or antibiotic dressing applied daily. A clean, dry wound environment must be maintained to allow healing, which may take weeks or months. If the horse is not lame, it may be able to return to work during the healing period by use of a special shoe to maintain the dressing.

Contracted Heels

Contracted heels are seen primarily in the forefeet of light horses. The condition may be caused by improper shoeing that draws in the quarters. This prevents hoof expansion and adequate frog pressure. Dry hooves, excess scraping of the wall, and trimming of the bars make a horse more prone to contracted heels. However, this condition may also occur after the use of a hoof-immobilizing shoe, such as that used for fracture of the third phalanx (pedal bone).

When the heel is contracted, the frog is narrow and shrunken, and the bars may be curved or almost parallel to each other. The quarters and heels are noticeably contracted and drawn in. The hoof horn is dry and hard, and heat may be noticed around the heels and quarters. If the horse is worked at speed, it may become lame, and its stride length will be shortened.

The outlook for recovery is guarded. In advanced cases, recovery can take 6 to 12 months. The most important factors in treatment are to moisturize the hooves and to promote expansion. This can be achieved by soaking the feet in water daily for 10 to 14 days followed by corrective shoeing. Hoof-moisturizing products that contain oils or waxy substances should be used with caution because they can keep water out of the hoof. Slipper shoes with no more than 3 nails in each branch promote hoof expansion. Quarter clips and the fourth shoe nail must be avoided.

A veterinarian can thin the wall of the quarters or groove the walls parallel to the coronet to aid in expanding the heels. As the quarters grow out, the procedure may need to be repeated until the heels and quarters are expanded normally.

Fracture of the Navicular Bone

The navicular bone may fracture as a result of trauma or a jarring injury to the foot. It may also break as a consequence of navicular disease (see Bone, Joint, and Muscle Disorders in Horses: Navicular Disease). Fracture of the navicular bone is much less common than that of the pedal bone, but it may be seen in either the fore- or hindfeet. Pain may vary, but a hoof tester usually can locate the general area of the fracture. Lameness is persistent. X-rays and regional analgesia can confirm the diagnosis.

Treatment is prolonged rest and corrective trimming, although the fracture seldom heals entirely. Surgical repair using lag screws is an option, but the outlook for recovery remains guarded to poor.

Fracture of the Pedal Bone

Pedal bone fractures (fracture of the third phalanx, os pedis, or distal phalanx) generally follow a jarring injury, producing a sudden onset of lameness during exercise or racing. Most fractures are through the wing (flat side) of the pedal bone and often extend up into the adjacent joint.

A horse that fractures its pedal bone immediately becomes lame. Compressing the foot with hoof testers causes pain. Lightly tapping the hoof with a hammer also may cause pain, and turning the horse or making it pivot on the affected leg worsens the lameness. Lameness may improve considerably after 48 hours of stall rest, unless the fracture extends into the joint.

Diagnosis is confirmed by regional analgesia and x-rays. X-ray confirmation may be difficult immediately after the injury because the fracture may be only a hairline at this stage. Repeating the x-ray 2 or 3 days later may be necessary for confirmation and to determine the extent of the fracture.

Conservative treatment of 6 to 9 months' rest is usually all that is required for fractures that do not involve the joint. The horse should return to soundness, although the fracture will remain visible on x-rays. It is usual to fit a plain bar shoe with a clip well back on each quarter to limit expansion and contraction of the heels. In young horses (less than 3 years old), fractures into the joint usually heal satisfactorily, provided a 12-month rest period is given. Horses older than 3 years have a much less favorable outlook for recovery, and insertion of a bone screw is recommended. However, infection is a frequent complication. Many fractures heal in the presence of infection, but the screw must be removed at a second surgery to restore the horse to complete working soundness.

Keratoma

A keratoma is a hard, thickened area of the horn, usually at the toe. It is believed to follow longterm inflammation caused by nail bind, which occurs when a horseshoe nail is driven close to, but not into, the soft tissue. A keratoma may also be caused by mechanical injury to the wall or coronet, or by hoof-grooving. The condition may be difficult to detect until the growth is well advanced. Examining the surface of the underside of the horse's forefoot shows that the growth has pushed the white line in toward the center of the sole. In severe cases, the pressure shrinks the pedal bone. Surgical removal of the mass is recommended. In mild cases, corrective shoeing may give some temporary relief. The outlook for recovery is guarded.

Laminitis (Founder)

A horse's foot has 2 types of laminae (tissue layers). The sensitive laminae are attached to the pedal bone. The insensitive laminae are the layers of tissue just inside the hard exterior of the hoof. The word laminitis means “inflammation of the laminae,” and it can refer to either a short-term (acute) inflammation or the disease caused by longterm or repeated (chronic) attacks of inflammation. Laminitis can develop in the forefeet, in all 4 feet, or in the hindfeet only. Biomechanical laminitis can be seen in a single foot, usually as a complication of a severe lameness or bone injury in the limb on the opposite side of the body.

Acute laminitis occurs when an inadequate supply of blood reaches the laminae. The reduced blood flow causes tissue to break down where the sensitive and insensitive laminae come together, eventually leading to a degeneration of the union between the layers of tissue. When treatment is unsuccessful, the pedal bone often rotates. If rotation progresses, a hole may form through the sole of the foot.

The most common causes of laminitis are ingestion of too much grain, grazing of lush pastures (especially in ponies), and excessive exercise or repetitive trauma. Other causes include generalized infections, colic, and treatment with corticosteroids and certain other medications. The risk is higher in ponies and in horses that are overweight and unfit. The number of cases of acute laminitis tends to increase whenever there is a flush of new grass.

Initially, the disturbances in the circulation to the foot are reversible. However, if the condition is severe or lasts for a long time, the outlook for recovery is poor. The pedal bone may rotate, or the hoof may alter its shape or separate from the underlying tissues. These changes may be irreversible, and secondary infection is common.

Signs and Diagnosis

In acute laminitis, the horse is depressed, has no appetite, and stands reluctantly. The horse resists exercise and attempts to shift weight off of the affected feet. If forced to walk, it has a slow, crouching, short-striding gait. Each foot, once lifted, is set down as quickly as possible.

Usually, heat is apparent in the whole hoof, especially near the coronary band. Pain can cause muscle trembling, and pressure reveals tenderness in the feet. If an effective treatment is not given quickly, the pedal bone may rotate. X-ray evidence of rotation can be present as early as the third day. Horses with laminitis typically have elevated vital signs, such as increased body temperature, heart rate, and respiration. In exceptionally severe cases, for which the outlook for recovery is unfavorable, a blood-stained discharge may seep from the coronary bands.

In less severe cases, the horse may exhibit any or all of the above signs but to a lesser degree. Often, there is only a mild change in stance, with reluctance to walk and some increased sensitivity in the soles of the affected feet. Episodes of acute laminitis tend to come back at varying intervals and may develop into a chronic condition.

Chronic laminitis is characterized by changes in the shape of the hoof and usually follows one or more acute attacks. Bands of irregular horn growth may appear in the hoof, and the hoof itself may narrow and become elongated, with the wall almost vertical at the heel and horizontal at the toe. As the condition progresses, the sole thickens and either flattens or begins to curve outward. When standing, the horse continually shifts its body weight from one foot to the other. X‑rays reveal rotation of the pedal bone, as well as a diseased state in which the bone has become very porous. The top of the bone is forced downward and presses on the sole. In severe cases, it may poke through the sole just in front of the point of the frog.

To diagnose laminitis, a medical history is taken, noting possible contributing factors such as a grain overload in the diet. The physical examination will pay close attention to the posture of the horse, any abnormalities of the hooves, and a reluctance to move. Mild cases with no visible hoof deformity can be identified by x‑rays of the affected feet.

Treatment and Outlook

Acute laminitis is considered a medical emergency because pedal rotation can occur quickly. If laminitis is suspected, your veterinarian should be contacted immediately.

In cases of grain overload, it is critical to prevent the absorption of toxic material from the gastrointestinal tract. Mineral oil is usually recommended—1 gallon (4 liters), by mouth. Purgation should not be performed on horses in the acute phase as they tend to be dehydrated.

Traditionally, cold packs or ice packs applied to the affected feet have been encouraged, but recent evidence suggests that hot packs used early in the course of the disease may be more beneficial.

Your veterinarian may prescribe certain nonsteroidal anti-inflammatory medications to lessen inflammation. Administration of corticosteroids is not recommended. Follow prescriptions exactly as described.

Heart-bar shoes have been used in acute cases of laminitis in an attempt to distribute sole pressure and avoid pedal rotation. Because an improperly fitted heart-bar shoe aggravates the pain, correct fitting is essential.

Treatments of chronic laminitis have attempted to restore the normal alignment of the rotated coffin bone and encourage frog pressure by lowering the heels, removing excess toe, and protecting the dropped sole. This requires corrective hoof trimming and the use of full leather pads or a heart-bar shoe. The hoof should be trimmed and the shoe reset at 4- to 6‑week intervals. This approach can be successful in selected cases but is expensive, labor intensive, and prolonged.

Surgical removal of the separated hoof wall may also be recommended and has been used in cases of both acute and chronic laminitis. This procedure carries risk and should follow consultation between the veterinarian and the person who makes and fits the horseshoes (farrier).

Despite prompt treatment, the outlook for recovery is guarded until recovery is complete and it is evident that the hoof structure is not altered.

Navicular Disease

Navicular disease is essentially a longterm, degenerative condition of the navicular bursa and navicular bone that involves damage to the surface of the bone and the flexor tendon with abnormal outgrowth of bone on the borders of the bone. Thus, it is a syndrome with a complex disease development. It is one of the most common causes of longterm forelimb lameness in horses. Navicular disease is essentially unknown in ponies and donkeys.

The exact cause is unknown, but many factors involving the navicular bone and its blood supply, as well as the nearby ligament, joint, bursa, and tendon, may contribute. It is most often a disease of the more mature riding horse, although it has been seen in 3-year-olds. Navicular disease may be partially hereditary. Defective shoeing that stops the action of the frog and the quarters may also be a contributing factor, as well as trauma or a jarring injury.

Usually, navicular disease is slowly and subtly harmful in onset. An early sign may be the way in which the horse relieves pressure on the painful area by pointing or advancing the affected foot with the heel off the ground. If both forefeet are affected, the horse points them alternately. Lameness tends to come and go early in the course of the disease. The stride is shortened, and the horse may tend to stumble. Turning the horse in a tight circle usually produces a short-term worsening of lameness. There may be soreness in the shoulder muscles after the changes in posture and gait, resulting in a common complaint of “shoulder lameness.”

Diagnosis is based on a complete history and careful physical examination. The lameness can be eliminated by the use of regional analgesia (see Bone, Joint, and Muscle Disorders in Horses: Regional Analgesia). X‑rays show degenerative changes involving the navicular bone, including some abnormal outgrowths of bone and bone reshaping.

Because the condition is both longterm and degenerative, it can be managed in some horses but not cured. With severe lameness, rest is recommended. Foot care includes trimming and shoeing that restores normal bone alignment and balance. Nonsteroidal anti-inflammatory drugs, along with proper foot management, extend serviceable soundness in some horses. The injection of corticosteroids into the bursa may relieve pain but is not curative.

Surgical removal of part of the palmar digital nerve (“denerving”) may provide relief from pain and prolong the usefulness of the horse, but this should not be considered curative. The surgical removal of nerves can be accompanied by severe complications such as a painful tumor formation.

The outlook for recovery is guarded to poor, but a carefully designed treatment plan can prolong the usefulness of most horses. Athletes may even temporarily return to competitive status. However, over months or years, all affected horses eventually stop responding to treatment.

Pedal Osteitis

Pedal osteitis is an inflammation of the sensitive structures of the soles of the forefeet, associated with inflammation of bony tissue and mineral loss from the coffin bone. Repeated jarring injuries, laminitis (see Bone, Joint, and Muscle Disorders in Horses: Laminitis (Founder)), persistent corns, and chronic bruised soles have been implicated as causes. Pedal osteitis is common in performance horses and usually is associated with work on hard tracks.

Lameness may not be obvious because usually both forelimbs are affected. There may be a stilted or shuffling action in front, with signs of discomfort in the hoof region. Tapping and pressure from hoof testers usually reveal tenderness over the entire sole. X-rays are helpful in diagnosis and can be used to help differentiate this condition from others with similar signs.

Treatment involves prolonged rest, anti-inflammatory medication, and careful shoeing to relieve sole pressure. The outlook for recovery is guarded, but the serviceable soundness of many horses can be extended by proper management.

Puncture Wounds of the Foot

Puncture wounds are usually the result of poor horse-shoeing technique but can occur when a horse steps on a penetrating foreign object. Nail bind implies that a nail has been driven close to the sensitive structures of the foot, causing severe pain and lameness. Nail prick means that the thick, sensitive layer of connective tissue beneath the outer layer of skin has been pierced.

When a foreign object penetrates the sole of the foot, it can introduce microorganisms that can cause infection. Lameness is usually severe following a puncture wound, especially when the foot bears weight; the degree of lameness may be similar to that produced by a fracture. The horse may stand and point the affected foot. The foot will show increased pain and may be warm to the touch. Infection may progress to the coronary band, and abscesses may form. Subsequently, the pastern and fetlock areas accumulate fluid and swell. Diagnosis requires confirming the site of pain by pulling the shoe, applying hoof testers, and paring down the suspect area to locate the foreign object or its path of entry.

Prompt treatment with disinfectants and poultices is important for nail bind and nail prick. Ensuring adequate wound drainage helps prevent the formation of abscesses. In pricked foot, the outlook for recovery is good, provided diagnosis is made and treatment begun early. If an abscess has developed below the sole of the foot, treatment may be prolonged, and the outlook for recovery is guarded. If infection spreads to the joints, the outlook for recovery is unfavorable.

Any foreign object must always be found and removed, and the infected area pared with a hoof knife to allow adequate drainage. The foot should then be kept in a rubber or plastic boot for 3 to 5 days with a cotton pad soaked in saturated magnesium sulfate solution or other suitable poultice. All horses with puncture wounds should be immunized against tetanus. If the pain is severe, regional analgesia provides temporary relief. Antibiotic treatment is not necessary, provided the infection is localized and good drainage has been achieved. Deep punctures of the foot that involve the deep digital flexor tendon, navicular bursa, navicular bone, or third phalanx require emergency surgery.

Pyramidal Disease (Buttress Foot)

Pyramidal disease, also called buttress foot, involves inflammation of the covering of connective tissue that surrounds the coffin bone. The disease may arise after trauma or from a separating fracture caused by excess tension on the tendon. Secondary arthritis is a likely complication. In early stages, the area will be hot and painful. The toe region above the coronet usually enlarges, creating the “buttress foot” appearance.

There is no specific treatment for pyramidal disease. Anti-inflammatory medication given by mouth or injection may be beneficial. Corrective shoeing can help minimize lameness. Surgery has been successful for the separating fractures. The outlook is guarded to poor for a return to soundness.

Quittor

Quittor is a chronic inflammation of the cartilage of the pedal bone characterized by death of the cartilage and one or more sinus tracts extending from the diseased cartilage through the skin. It is seldom encountered today but once was common in working draft horses.

In most cases, injury to the coronet or pastern introduces infection into the deep tissues, forming a pus-filled sore called an abscess. Quittor may also occur after a penetrating wound through the sole. The first sign is an inflammatory swelling over the cartilage, followed by the formation of abscesses. During the inflammatory stage, lameness occurs.

Surgery to remove the diseased tissue and cartilage is usually successful. Drug treatment without surgery is likely to fail. Without treatment and drainage the cartilage will die, and abscesses will recur and extend to deep structures, leading to longterm lameness. If damage is extensive and the distal phalangeal joint has been invaded, the outlook for recovery is unfavorable.

Sandcrack (Toe Crack, Quarter Crack, Heel Crack)

In sandcrack, cracks in the wall of the hoof begin at the coronet and run down the hoof. They are most common in racehorses. Excess drying of the hoof makes the hoof more prone to cracking, but trauma or structural factors are usually to blame. Extensive injury to the coronet may leave a crack in the wall characterized by an overlapping buildup in the wall at the site of injury. This latter condition is referred to as false quarter.

A crack in the horn coming from the coronet is the most obvious sign of sandcrack. Lameness varies depending on the site and extent of the injury; if infection is involved, lameness may be accompanied by a bloody or pus-filled discharge and signs of inflammation.

Treatment involves surgery and corrective shoeing to change the distribution of weight on the hoof. The use of bar shoes is often recommended. If the crack has become infected, an antiseptic pack may be used. The hoof is then bandaged until new horn formation is evident.

Scratches (Greasy Heel)

Scratches, sometimes referred to as greasy heel, is a longterm inflammation of the skin in which the rear surface of the pastern and fetlock enlarge and ooze discharge. It often is associated with poor stable hygiene, but no specific cause is known. Heavy horses are particularly susceptible, and the hindlimbs more commonly are affected. Standardbreds often are affected in the spring when tracks are wet. The common use of limestone on racetracks has been associated with scratches.

Scratches may go unnoticed if hidden by the “feather” at the back of the pastern. The skin is itchy, sensitive, and swollen during the early stages; later, it thickens and loses all but its shorter hairs, which stand in an upright position. The surface of the skin is soft, and the grayish discharge has a rotten odor. If the condition becomes chronic, small masses of tissue may appear. Lameness may or may not be present, but it can be severe if inflamed tissues beneath the skin of the limb become infected. As the condition progresses, the skin of the affected regions thickens and hardens.

Persistent and aggressive treatment is usually successful. This consists of removing the hair, regular washing and cleansing with warm water and soap to remove all soft discharge, drying, and applying an astringent dressing. If small masses appear, a veterinarian should remove them. Infection requires whole-body antibiotics and preventive treatment for tetanus.

Seedy Toe (Hollow Wall)

Seedy toe is a condition of the hoof wall in the toe region, characterized by changes in or loss of the tissue that makes up the horn. It is most often a consequence of mild, longterm laminitis (see Bone, Joint, and Muscle Disorders in Horses: Laminitis (Founder)). The outer surface of the wall appears sound, but the inner surface of the wall is mealy, and there may be a cavity due to loss of horn substance. Tapping on the outside of the wall at the toe produces a hollow sound over the affected portion. The disease may affect only a small area or nearly the entire width of the wall at the toe. Lameness is infrequent but may occur if infection or an abscess is also present.

The outlook for recovery is usually good. The diseased portion of the hoof wall should be cleaned and packed with juniper tar and oakum. In the absence of lameness, shoeing and work can continue. If the condition is extensive, the outer wall may need to be removed over the affected area.

Sheared Heels

In sheared heels, unevenness of the heels produces a severe imbalance of the foot. This results in one side of the heel contacting the ground before the other, creating a shearing force at the rounded parts of the heel, uneven growth of the toe, and severe overriding contraction of the heels. The heel develops longterm soreness similar to that of navicular disease (see Bone, Joint, and Muscle Disorders in Horses: Navicular Disease). Hoof cracks, deep cracks between the rounded parts of the heel, and an infection of the frog frequently accompany the problem. Navicular disease may occur at the same time.

Heel alignment and foot balance may be restored with corrective trimming and shoeing. A full bar shoe with a reinforcing diagonal bar to support the affected quarter and heel is used. Improvement will likely require several shoe resettings. The outlook for recovery is good in uncomplicated cases, if corrective measures are consistently applied until new hoof growth occurs.

Sidebone

Sidebone is the hardening (calcification) of the cartilage of the coffin or pedal bone. It is most common in the forefeet of heavy horses working on hard surfaces. It also is frequent in hunters and jumpers but is rare in racing Thoroughbreds. Repeated jarring injuries to the quarters of the feet are probably the most basic cause. Improper shoeing that stops normal movement of the quarters may also lead to sidebone. Other cases arise from direct trauma.

The hardened cartilage may stick out above the coronet. The presence of lameness depends on the stage of the hardening process, the amount of jarring injury sustained by the feet, and the type of terrain underfoot. Often, no lameness is noted. A narrow or contracted foot makes lameness more likely. Lameness also may occur if sidebone is accompanied by another condition such as navicular disease. The stride may be shortened, and walking the horse across a slope may exaggerate the soreness.

Sidebone may be diagnosed using examination and palpation (hands-on evaluation of the leg); however, x-rays are necessary for confirmation. When lameness is present, corrective shoeing to promote expansion of the quarters and to protect the foot from jarring injury often helps. Grooving the hooves also may promote expansion of the wall.

Thrush

Thrush is a degeneration of the frog with secondary bacterial infection. It results from poor management and hygiene, such as allowing the horse to stand too long in wet conditions and failing to clean the hooves regularly. The condition is more common in the hindfeet. The affected area is moist and contains a black, thick discharge with a characteristic foul odor. These signs alone are sufficient to make the diagnosis.

Treatment should begin by providing dry, clean material underfoot and cleaning out the hoof, including the removal of all softened horn. An astringent lotion, used with daily hoof cleaning, aids recovery after removal of the diseased tissue. Use of a bar shoe after the disease has been stopped may help the frog regenerate. The outlook for recovery is usually favorable, but if the connective tissue of the frog has been damaged, all diseased tissue must be removed.

Last full review/revision July 2011 by Russell R. Hanson, DVM, DACVS, DACVECC; Joerg A. Auer, DrMedVet, Dr h c, MS, DACVS, DECVS; Andrew P. Bathe, MA, VetMB, DACVS, DEO, MRCVS; Leo B. Jeffcott, MA, BVM, PhD, FRCVS, DVSc, VD; Svend E. Kold, DMV, MRCVS, RCVS Specialist in Equine Surgery (Orthopedics); C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, DACVS; Dale A. Moore, MS, DVM, MPVM, PhD; Sheldon Padgett, DVM, MS, DACVS; Tracy A. Turner, DVM, MS, DACVS, DABT; Stephanie J. Valberg, DVM, PhD, DACVIM; John F. Van Vleet, DVM, PhD