All horse owners should be very familiar with the signs and symptoms of colic – anyone in doubt should check out PonyGirl's extremely detailed and informative blog post on the subject. But how many of us would even think of peritonitis as the cause of our horse's distress?
Peritonitis can be very easily confused with colic. Signs indicative of peritonitis include rolling, watching the flanks and pawing at the ground. The horse may hold himself in a hunched, tucked up position; he may be breathing unusually heavily and his temperature could be elevated. Examination of his nostrils will show bright red mucous membranes rather than a healthy salmon pink. This could indicate toxic shock which his potentially fatal.
What is peritonitis?
The peritoneum is a thin protective membrane that covers the intestines. The peritoneum also lines the insides of the walls of the horse's abdominal cavity and provides a smooth surface along which the various pieces of bowel can slide without sticking together or becoming entangled. It also produces fluid to help lubricate the contents of the abdomen. Inflammation or irritation of the peritoneum is called peritonitis.
Peritonitis is not common but it is very serious and requires immediate veterinary intervention. Provided treatment is commenced early enough the prognosis for a full recovery is good. In cases of sudden, acute onset where the stomach has ruptured, the horse will usually be found dead or in an extremely poor state when euthanasia is the only option.
Bingo was a 12 year old thoroughbred gelding owned by a friend of mine.
He began showing classic colic signs one evening after a normal day out in the field and the vet was called. The vet referred Bingo as an emergency to the Equine Unit and on admission he was placed in intensive care.
Bingo stood quietly while he was examined; his tummy was tucked up and his demeanour was dull and depressed. He was clearly in considerable discomfort. The vet checked his heart and respiratory rates and listened to his gut sounds. He then carried out an abdominal ultrasound which showed an abnormally high amount of fluid around his intestines; a sign of infection. Bingo then underwent a rectal examination and a nasogastric intubation. During this procedure a tube is fed down the horse's throat and into its stomach to check for signs of reflux which could indicate a problem with the small intestine. Finally, a sample of the peritoneal fluid was taken.
Peritoneal fluid should be amber in colour. In cases of colic you would expect to see blood in the fluid. Bingo's sample was opaque and murky in colour. Tests revealed a high level of white blood cells in the fluid. Elevated levels of white corpuscles are indicative of bacterial or viral infection. These cells migrate from the blood to the area of the body which is under attack; in Bingo's case this was his abdomen. With the exception of the abnormal peritoneal fluid, all the other tests and examinations were normal. The vet therefore diagnosed not colic, but septic peritonitis.
Peritonitis sometimes has an obvious cause such as a penetrating injury to the abdomen, damage to the intestines caused by ulcers, abscess or a compromised immune system. Complications during foaling, damage caused by worms or a tumour are also possible causes. Most cases have no discernible cause however. Immediate treatment of the symptoms begins with a course of broad-spectrum antibiotics administered intravenously, orally and into the muscles to cover all bases.
Bingo remained on the cocktail of three antibiotics for a week until he showed signs of improvement. This was then reduced to just oral antibiotics and he was able to be turned out for short periods each day. After ten days he was finally able to come home and resumed his usual routine of being turned out during the day and stabled at night. The medication was continued for a further week and bute (phenylbutazone) was also given to combat any residual inflammation, fever or pain.
Happily, thanks to the prompt action of his owner's vet and the staff at the Equine Hospital, Bingo made a full recovery although the cause of his frightening illness remains a mystery.
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