Cryptorchidism in horses

Cryptorchidism is the failure of one or both testes to descend into a normal scrotal position from the abdominal cavity after birth.

Horses with one descended testicle are usually fertile, while horses with both undescended testicle are generally sterile. The testes may be retained anywhere from the abdomen to the inguinal canal, the normal passage route into the scrotum.

Three different forms of cryptorchidism are observed in horses: under the skin in the inguinal area, in the inguinal canal and in the abdomen. In bilateral cryptorchids, most of the time both testes are abdominal.
Cryptorchidism may not be apparent at birth, as the testes do not drop from the abdominal space, through the inguinal canal and ring and into the scrotum – where they remain – until after birth. The time it takes before both testes have descended varies from horse to horse but both testes should be in the scrotum by two years of age. In all cases of one undescended testicle, the stallion will still be able to produce normal amounts of testosterone. Usually, the undescended testicle is much smaller than the descended one.

Symptoms and Types

Bilateral cryptorchids/Complete rig

Both testicles remain in the abdomen
Physically appears as a gelding (testes cannot be palpated)
Infertility
Stallion-like behavior

Unilateral cryptorchids

One testicle remains in abdomen
Will still be fertile from the one descended testicle


Causes

Cryptorchidism can be due to hereditary or developmental issues, whereby the testicles fail to drop into the scrotum after birth.

 Treatment

There is only one method of treatment for cryptorchidism in horses — surgical removal of both testes. This is to prevent the trait from being passed on to offspring. In cases where the undescended testicle is low in the abdomen, the castration can be performed on the farm and is generally uncomplicated. If both testicles have been retained and are high in the abdomen, your horse may require more complicated surgery and will be referred to an equine surgical facilit

Placentitis

Placentitis—an inflammation of the placenta—is often caused by an ascending infection that enters the mare's uterus through the cervix.Placentitis may be caused by bacteria, fungi or viral agents; however it is most commonly associated with bacterial infection.
This usually arises from faecal contamination with bacteria subsequently ascending through the vagina and cervix thus reaching the placenta
Signsvaginal discharge
premature udder development
Ascending infections may show one or both of these signs where as hematogenous and mucoid usually only show premature lactationA diagnosis usually can be determined using trans-rectal and/or trans-abdominal ultrasound in combination with a culture if a vaginal discharge is present.

Treatment

• Antibiotics
• Anti-inflammatory drugs
• Hormonal treatment

Hypocalcemia in mares

Hypocalcemia is the condition where there is low level of calcium in blood.Calcium is responsible for normal functioning of muscles and nerves.Hypocalcemia occurs frequently in lactating mares following prolonged transport.

Causes

• Lactating mares in high milk production results in hypocalcemia.
• Grazing of lush pastures
• Prolonged physical exercise
• After transport
• Stress
• Decrease calcium intake.

Signs

• Increased muscle tone
• Stiff gait
• Sweating
• Prolapse of third eyelid
• Excess salivation
• convulsion

Treatment
Intravenous infusion of calcium solution.

Prevention

• Calcium supplement are required
• Alfalfa or calcium containing mineral mixer should be provided.
• Stress should be minimized
• Avoid fasting

Abortion in horses

Abortion of the fetus before it reaches the 300 days of gestation period.
It may be due to infectious or non infectious.

Causes

1.Infectious

 a.Viral
EHV-Equine herpes virus/Equine rhinopnemonitis

EVA-Equine viral arteritis causes potential abortion in horses

b.Bacteria
Erlichiosis
Leptospirosis
Pseudomonas
E.coli
Pasteurella
c.Fungus
Aspergillus
Candida
2.Non infectious
Twinning ---  Birth of twins is unusual in horses.
Hormonal---Progesterone deficiency leads to abortion
Stress induced
Umblical cord torsion
Congenital
Symptoms
Coughing
Fever
Depression
Formation of milk
Swelling of mammary gland
Vaginal discharge
Bleeding from vagina
Treatment
Identification of causative agents and treat accordingly.
consult the veterinarian.

Orchitis

Orchitis is inflammation of horse testis.
Symptoms

• Hard swelling if scrotum
• Pain
• Warmness
• Increased temperature of testis
• Decreased semen quality and motility.

Causes

• Bacterial
• Virus
• Parasitic
• Auto immune

Prevention

Good horse management to prevent infections

Treatment

• Cold packs can be applied to reduce temperature
• NSAIDS can be used to reduce pain and swelling.
• Antibiotics can be given to control bacterial infections.

Afterbirth /Retained

Placenta is membranous vascular organ develops in mare during pregnancy.
Mostly expelled after birth but sometimes it may retain and causes various problems.
If it is retained for longer time, it leads to production of toxins and released in the blood stream.

Symptoms

• Fever
• Depression
• Dullness
• Metritis
• Laminitis
• Increased digital pulse
• Decreased appetite

Causes

• Mares with history of retained placenta will prone again for afterbirth
• Breeding should be delayed for atleast 25 days.

Treatment

• Antimicrobials should be given to contrl bacterial infections.
• Fluid therapy is required in severe cases.
• Oxytocin can be given to expell the retaine placenta.

Cryptorchidism in horses

• Cryptorchidism is a congenital condition in which one (unilateral) or both (bilateral) of the testes fail to descend into the scrotum.Generally, unilateral cryptorchids are usually fertile, while bilateral cryptorchids are generally sterile
• Cryptorchidism in the horse can occur with either the left or right testis or with both testes.
• Failure of one or both testes to descend into the scrotum may be due to genetic predisposition, insufficient androgen (i.e. testosterone) stimulation, and other factors.
• Cryptorchid testes are incapable of producing sperm due to the elevated temperature of the retained testes. If one or both testis remains in abdomen,the horse is called Rig.
• Consequently, a stallion would be sterile if both testes are cryptorchid. Libido and aggressive male behavior is present in cryptorchid stallions since testosterone is still produced by the retained testes

Causes
Hereditary


Symptoms and Types
Bilateral
Both testicles remain in abdomen
Infertility
Stallion like behaviour


Unilateral
One testicles remains in abdomen
still fertile from one testicles


Treatment
Surgical removal of both the testis is the only treatment.

Important parameters of Reproduction in Mare

Puberty Age      : 12-15 months

Types of oestrus : seasonally polyoestrus

Interval of cycle : 21-23 days

Oestrus length duration : 5-7 days

Average length of gestation : 340 +or-10days

Time of foal heat after foaling : 9-11 days

CONTAGIOUS EQUINE METRITIS

Contagious equine metritis (CEM) is an extremely contagious venereal disease that is acquired primarily via breeding. While this disease can be carried by either mares or stallions, it is the mare that suffers the ill effects of the infection. Stallions do not show any symptoms of CEM, but mares often will have a thick discharge from the vagina, and will be unable to conceive during the point at which the infection is active.

Etiology
The causative agent of CEM is a microaerophilic gram-negative coccobacillus Taylorella equigenitalis in the family Alcaligenaceae.

Symptoms

Stallions are asymptomatic (no symptoms), but may carry the bacterium on their external genitalia for years, and therefore be persistent carriers and transmitters of the disease.
In fact, to be technical, the stallion does not become "infected" with the CEMO, but rather harbours it in the manner of a commensal organism.

One of the first symptoms in a mare is likely to be that she is not pregnant after one or more breeding cycles. 
It should be noted that although failure to establish pregnancy is a common sequela of infection, abortion is rare.

There are three categories of infection in the mare:

The acutely infected mare: This mare will present with an actively inflamed uterus, with an obvious milky-mucoid (pus) discharge from the external genitalia when she returns to estrus (and the cervix relaxes) - and quite often that return to estrus is earlier than anticipated

The chronically infected mare: This mare shows a lesser level of uterine inflammation, and an associated lower level of vulval discharge. It is likely that mares in this category will be more difficult to treat in order to clear the organism.

The carrier mare: This mare shows no symptoms of the disease, but is harbouring the CEMO in the reproductive tract. This mare is more difficult yet to clear, and as a result of no obvious external signs represents a greater risk to the non-identified at-risk population

The incubation period in the mare from the time of exposure to the onset of active symptoms (or diagnostic ability) is 2-12 days.

Transmission
The following includes practices that may result in, or increase, the likelihood of transmission in the face of T. equigenitalis presence:

• Not using a disposable AV liner;
  
• Sharing AV's between stallions;
  
• Not cleaning AV's adequately between use;
  
• Not using a disposable protective barrier on the rear of the breeding mount (where the penis contacts) during collection and changing it between stallions;
  
• Not washing the breeding mount with a suitable agent (e.g. Chlorhexidine) between stallions;
  
• Not using an antibiotic extender (or an antibiotic to which the organism is not sensitive) - it should be noted that even with the use of a suitable antibiotic, transmission may still occur;
  
• Sharing of penis washing equipment without sterilization in between stallions or good aseptic technique (this includes hands - e.g. use of disposable latex gloves when washing and/or guiding the penis that are then discarded, or thorough scrubbing of the hands in between collections/breedings with a suitable bactericide);
  
• Other poor sterility or aseptic technique associated with the collection/breeding process.
  
  Treatment
  Treatment for both sexes is primarily topical with the intent of removing the offending organism and any smegma in which it may be located.
  Scrubbing the clitoral sinuses and fossa in the mare with a 4% solution of chlorhexidine for 5 consecutive days, following each daily treatment with packing of the area with a 0.2% nitrofurazone ointment (such as Furacin) is one protocol.
  An alternative treatment is 5 days of scrubbing with Betadine, followed by packing with Silvidine cream.
  Systemic antibiotic treatment may be provided in conjunction with the topical cleansing. It should be noted that until the acutely infected mare has resolved internal tract presence of T. equigenitalis, there is little point in implementing external treatment.
  Repeated treatment of the mare is often required to eradicate the bacterium, so the mare is tested again 28 days after the last treatment, and if still positive a repeat of the treatment and testing is performed until found to be clear.
  In rare cases of persistent infection in the mare, surgical removal of the clitoral sinuses may be necessary. This was once a common part of treatment of the infected mare, but is now only used in extreme cases.
  
  Treatment for the stallion is similar, consisting of thorough cleansing of the external genitalia, with the penis fully extended and erect. Additionally the urethral fossa and sinus are cleansed.
  A 2% Chlorhexidine solution is adequate for the stallion. It is recommended by some that following the Chlorhexidine wash, the penis be rinsed with sterile saline to avoid irritation, this is not however included in other protocol recommendations.
  Following this washing, the region is coated with 0.2% nitrofurazone cream or a similar ointment. Again, these treatments are continued for five consecutive days.
  Systemic antibiotics may also be used, oral Trimethoprim-Sulfa being suitable. Once treated and tested clear, a stallion that previously tested positive for presence of T. equigenitalis will be required to test-breed two mares that were confirmed clear of the pathogen prior to that breeding.
  The mares are subsequently tested following breeding as discussed above under "diagnosis" to confirm absence of a carrier state in the stallion.
  If a mare tests positive for T. equigenitalis during the post-breeding testing, treatment and further testing of the stallion is recommenced, as well as treatment of the test mare. Most stallions however typically respond favourably to a single course of treatment, and are found to be clear upon the post-treatment test breeding.
  

References

1: Eaglesome MD, Garcia MM (1979) Contagious Equine Metritis: A Review; Canadian Vet. J. 20:8 201-2062: Powell DG. Contagious Equine Metritis. (1978) Equine vet. J. 10: 1-43:O'Driscoll JG, Troy PT, Geoghan FJ. (1977) An epidemic of venereal infection in Thoroughbreds. Vet. Rec. 101: 359-3604: Taylor CED, Rosenthal RO, Brown DFJ, Lapage SP, Hill LR, Legros RM. (1978) The causative organism of contagious equine metritis 1977: proposal for a new species to be known as Haemophilus equigenitalis. Equine Vet. J. 10: 136-1445: Jang SS, Donahue JM, Arata AB, Goris J, Hansen LM, Earley DL, Vandamme PA, Timoney PJ, Hirsh DC. (2001) Taylorella asinigenitalis sp. nov., a bacterium isolated from the genital tract of male donkeys (Equus asinus); Int J. Syst. Evol. Microbiol. 51(Pt 3):971-66: Båveruda V, Nyströmb C, Johansson K-E. (2006) Isolation and identification of Taylorella asinigenitalis from the genital tract of a stallion, first case of a natural infection; Veterinary Microbiology 116:4, 294-3007: USDA-Aphis CEM Factsheet, 2005.8: Swerczek, T.W. 1979. Contagious equine metritis - - outbreak of the disease in Kentucky and laboratory methods for diagnosing the disease. J. Reprod. Fertil. (Suppl), 27:361-365.9: Simpson, D.J., and Eaton-Evans, W.E. 1978. Sites of CEM infection. Vet. Rec., 102:488.10: Swerczek, T.W. 1984. Unpublished data.11: Swerczek, T.W. 1978. The first occurrence of contagious metritis in the United States. J. Am. Vet. Med. Assoc., 173:405-407.12: Wakeley PR, Errington J, Hannon S, Roest HIJ, Carson T, Hunt B, Sawyer J, Heath P. (2006) Development of a real time PCR for the detection of Taylorella equigenitalis directly from genital swabs and discrimination from Taylorella asinigenitalis; Vet. Microbiology 118:3-4; 247 – 254,13: KY Department of Agriculture recommendations for CEM-exposed stallions. 12/19/0814: AclandHM, Kenney RM. (1983) Lesions of contagious equine metritis in mares. Vet. Pathol., 20:330-34115: Platt H, Atherton JG, Simpson DJ. (1978) The experimental infection of ponies with contagious equine metritis. Equine Vet. J., 10:153-15916: Timoney PJ. (2003) The Continuing Threat to the US Horse Population Posed by CEM; Proc. NIAA Annual Meeting Proceedings

ENDOMETRITIS

Endometritis is infection of the endometrium.
Endometritis is a common cause of poor fertility in the mare.It occurs following uterine contamination during covering, artificial insemination, reproductive examination, parturition and as a result of poor conformation.

History and signs

• Failure to concieve
• mucopurulent discharge from the vagina
• Early embroynic loss
• Short oestrus cycles

Clinical findings

• Signs of vulval discharge and in some cases failure to concieve.
• Definitive diagnosis is by collection of bacteriological swabs from the cervix or endometrium,which should be under taken under strict aceptic conditions.
• The mere presence of bacteria is not enough to diagnose infections.
• Examination with speculum is an important of the workup and can be performed when the bacteriologic and cytologic swabs are collected

Types

• Venereal Infectious Endometritis
• Non-venereal Infectious Endometritis
• Persistent Post-mating Endometritis
• Chronic Degenerative Endometritis
• Chronic Infectious Endometritis

Venereal Infectious Endometritis

Three major pathogens cause venereal endometritis in the mare:

• Taylorella equigenitalis - causing the notifiable Contagious Equine Metritis (CEM)
• Klebsiella pneumoniae - tests can be performed to identify capsule types 1, 2 and 5 which are sexually transmitted
• Pseudomonas aeruginosa - there is no available test to differentiate strains so all must be treated as pathogenic

The mare may present with vaginal discharge in anacute infection. However she may also present in acarrier state, in which case there may be no outward clinical signs. Stallions are usually sub-clinical carriers of disease. All three bacteria prevent conception.

Equine Viral Arteritis (EAV) and Equine Herpes Virus 3 (EHV-3) are also classified as venereal infections however they do not cause endometritis or prevent conception.

Detailed guidelines on the diagnosis, treatment and prevention of all these infections can be found in the of Practice which are followed by Thoroughbred breeders in the UK.

Non-venereal Infectious Endometritis

This occurs following infection during covering, reproductive examination or foaling. The mare will normally present with a history ofinfertility or early embryonic death and short cycles. There may also be evidence of vaginal discharge. Infection may be caused by:

• Bacterial Infection - Streptococcus zooepidemicus, Escherichia coli or Staphylococcus aureus
• Fungal Infection

Persistent Post-mating Endometritis

This is more common in older and multiparous mares. They present with a history of short cycling and often an vaginal discharge approximately two weeks post-cover.

A transient inflammatory response is normal in the mare post-cover, however a normal immunological response is mounted and the infection cleared before the embryo exits the fallopian tube. In the cases of persistent post-mating endometritis the inflammation persists longer than 72-96 hours so that when the embryo enters the uterus the environment is still unsuitable for embryonic development, resulting in early embryonic death.

Chronic Degenerative Endometritis

Chronic degenerative endometritis aka endometriosis is degenerative change that occurs in older mares or following repeated inflammation of the uterus. If the condition is severe it may result in delayed clearance of the uterus post-cover. Definitive diagnosis can only be achieved by biopsy, which will show degenerative change of the uterus histologically.

Chronic Infectious Endometritis

Normally an underlying conformational condition such as pneumovagina predisposes the mare to chronic infectious endometritis. Definitive diagnosis is again by biopsy which should show infiltration of the endometrium with lymphocytes and plasma cells. Infection may be:

• Bacterial - Streptococcus zooepidemicus, Escherichia coli
• Fungal - more common if there is a history of multiply intra-uterine antibiotic treatments

Prognosis is guarded due to the chronic nature of the infection and the anatomical faults predisposing to infection. Surgical correction of the conformational abnormalities may be attempted using Caslicks procedure.

Diagnosis

• Vaginal examination
• Ultrasound
• Clitoral and endometrial swabs
• Uterine flush
• Endometrial endoscopy
• Uterine biopsy diagnose

Treatment

(1) Uterine lavage with copious amounts of fluid. This is beneficial because it:

removes contaminants such as bacteria and purulent material

stimulates uterine contractions to aid clearance

causes mechanical irritation to the endometrium aiding healthy neutrophil recruitment

2-3 litres of saline or lactated ringers solution should be administered using a uterine flushing catheter and then drained back into the bag and inspected. Dilute Povidone iodine can also be used as a cheap alternative.

(2) Antibiotics (intrauterine or systemic). Antibiotic type should be guided by culture and sensitivity and activity of the drug in the uterus where possible. The length of the treatment should be proportional to the severity of infection.

(3) Administration of ecbolics to stimulate uterine contractility and clearance of infection - oxytocin and prostaglandin analogues

Reference

Manual of Equine Practice by Reuben J.Rose and David R.Hodgson

Pycock, JF (1997) Self-Assessment Colour Review Equine Reproduction and Stud Medicine Manson

Pycock, JF (2004) Pre-breeding checks for mares In Practice 2004 26: 78-85

Ricketts, S (1987) Vaginal discharge in the mare In Practice 1987 9: 117-123

RVC staff (2009) Urogenital system RVC Intergrated BVetMed Course, Royal Veterinary College