Right dorsal colitis.

The study explores a form of ulcerative colitis in horses, often resulting from the misuse of nonsteroidal anti-inflammatory drugs (NSAIDs), which typically presents as colic, diarrhea, or weight loss. The research also documents an experiment where these conclusions were tested by artificially inducing these conditions in horses.

Study Background and Purpose

• The researchers conducted clinical observations and exploratory investigations on 13 horses that showed pronounced signs of colic, diarrhea, or weight loss. The main goal was to understand the root causes of these ailments often diagnosed as moderate to severe ulcerative colitis, specifically in the right dorsal colon of the horse.

Clinical Observations

• In observed horses, this colitis presented in two main forms. One was an acute condition characterized by severe diarrhea (sometimes accompanied by fever), colic, dehydration, endotoxic shock, and in some cases, death. On the other hand, the condition also took a more chronic, long-term form, where mild, recurrent colic, weight loss, and occasional mild diarrhea were noticed.
• Interestingly, before developing these symptoms, these horses, in most cases, have either been hypovolemic or have been exposed to nonsteroidal anti-inflammatory drugs (NSAID) or large doses of phenylbutazone.

Experimental Procedure and Findings

• To substantiate their hypothesis about the linkage between NSAIDs and this specific form of colitis, the researchers conducted an experimental trial on two horses.
• These two horses were given high doses of a phenylbutazone oral paste (6 gm once daily for 5 days) and their water intake was reduced to half the maintenance requirement for the same period. The aim was to mimic conditions preceding the onset of the illness as noticed in the observation phase.
• Necropsy examinations conducted 11 and 15 days after initiating the drug use revealed ulcerative colitis limited only to the right dorsal colon, thereby reproducing the observed ailment under controlled conditions.

Conclusions

• Basing on both observational and experimental evidence, the researchers concluded that localized ulcerative lesions in the right dorsal colon could likely be a hitherto unreported side effect of NSAID administration in horses, leading to the observed signs of illness.
• This study is hence significant in shedding light on potential negative effects of NSAIDs and providing a direction for better administration guidelines of such drugs in veterinary practice.