EQUINE RHABDOMYLOSIS

Equine exertional rhabdomyolysis (ER, also known as tying up, azoturia, or Monday morning disease) is a syndrome that damages the muscle tissue in horses. 

Muscular problems are common in working horses and range from stiffness and mild cramps.

The basic mechanism for the condition remains unknown ,although a common history in many cases is several days without exercise while fed on grain followed by vigorous exercise.


Causes

• Occurs in horses in Rigorous training programs that are rested for a period of time while being maintained on the same high concentrate diet.
  
• The overfeeding of non-structural carbohydrates (grain and pellets, for example)
• Poor conditioning or fitness, sudden increase of workload
  
  
• Imbalance of hormones, including the reproductive hormones in nervous fillies and mares and thyroid hormones in horses with hypothyroidism
•  Wet, cold, or windy weather conditions
• A deficiency in selenium or vitamin E
• The work of a horse after a period of rest, if the concentrate ration was not reduced

The disease occurs once the horse returns to work,even after light exercise.
Two heritable syndromes have been recently described
1.Polysaccharide storage myopathy
2.Reccurent exertional rhabdomylosis


Clinical signs

• Horse walk with stiff
  
• Stilted gait
  
• Muscle fasciculation
  
•  Inability to move
• Muscles of back and hind limbs are tight and painful
  
• Horse is often Anxious,sweat profusely
  
• Myoglobinuria
  

Treatments


Treatment of the severly affected horse preventing further muscle damage,correcting metabolic abnormalities and dehydrations.
Fluids will increase the production of urine that will in turn help flush out the excess, and potentially damaging, myoglobin from the kidneys and will reduce NSAID-produced kidney damage
Analgesia in animals that are in extreme pain and reluctant to move.

Severe cases

Even walking back to barn is contraindicated.In those cases , transport to a stall should be arranged.
In severe dehydration or hypovolemia and electrolyte imbalances a balanced polyionic electrolyte solution should be administered iv or through nasogastric tube.
Myoglobin can be nephrotoxic, especially in dehyrated animals.
Vitamin E is an anti-oxidant, and so may help prevent further cell degeneration in the affected muscles.
NSAIDS such as phenylbutazone help to relieve pain.
Good nursing care is essential.
The horse is force to stand if it wishes to recumbent.
Prolonged recumbency in one position is detrimental .


References


The Equine manual by Andrew J. Higgins and Jack R.Snyder
Manual of Equine Practice Reuben J.Rose and David R.Hodgson