Bacteria such as Salmonella or Clostridium can wreak havoc on a horse's gastrointestinal tract, causing massive losses of water, electrolytes, and proteins. The result? Diarrhea. A smelly, watery, life-threatening mess.
"In more than 60% of diarrhea cases, we never actually discover the inciting cause and testing for all the possibilities can be costly," said Kate Savage, BVSc, MS, PhD, Dipl. ACVIM, specialist in equine medicine and head of Equine Clinical Services at the University of Melbourne's Equine Centre in Australia. She presented on the topic at the 11th Congress of the World Equine Veterinary Association in Guarujá, Sao Paulo, Brazil.
Nonetheless, treating horses with diarrhea, even those in which the underlying cause remains elusive, can be a successful endeavor.
"It is important to identify cases of diarrhea as early as possible," advised Savage. This entails client education, including:
- Warning horse owners about the possibility for diarrhea when prescribing antimicrobials;
- Ensuring owners are able to properly take a rectal temperature; and
- Encouraging owners to examine oral mucous membranes and be able to assess a horse''s capillary refill time , which is a measure of hydration and blood perfusion.
It is then the veterinarian's job to obtain a detailed history, perform a complete physical examination, and institute an appropriate treatment plan that might or might not involve using antimicrobials.
Savage explained, "In adults, I rarely use antimicrobials unless (the diarrhea) is likely to be caused by Clostridium. In these cases, the diarrhea is often bloody and has a bad odor."
Veterinarians commonly use the antimicrobial metronidazole to treat horses with Clostridium-caused diarrhea.
Other cases in which antimicrobials are indicated include foals (neonates require antimicrobial treatment because the cause of the diarrhea is often an underlying sepsis, or blood infection); those diagnosed with Potomac horse fever (oxytetracycline); those with Lawsonia intracellularis (erythromycin and rifampicin or tetracyclines); and horses diagnosed as infected with Salmonella spp.
"Horses without any evidence of an infectious cause are managed with aggressive supportive therapy involving intravenous fluids for electrolyte and water replacement and to help keep water in blood vessels (colloids), replacing lost protein (especially a protein called albumin)," advised Savage. "We also need to consider the health of kidneys, as we often like to put these horses with diarrhea on NSAIDs (which can cause kidney damage).
"Using this common-sense approach to managing horses and foals with diarrhea will assist in early treatment and, therefore, better outcomes and less money spent in the long run," Savage said.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.