Chronic salmonellosis has been isolated from horses with large chronic ulcerative lesions of the large colon, but their role in the cause of the ulcer is not clear. Weight loss results from loss of large amounts of protein from these large, open, ulcerated areas. All of these situations are marked by continued loss of plasma proteins, and in many cases by abnormal absorption as well. Laboratory data is not specific. Mild anemia may be present, and chronic inflammation can be reflected by a moderate leukocytosis.
Serum chemistries are unremarkable except for a low serum protein, especially albumin.
Chronic renal disease, which may be immune mediated, can lead to significant protein loss, and this proteinuria accounts for some of the weight loss encountered. In addition, affected horses are usually azotemic, depressed, and anorectic. Thus, they have an accelerated loss of nutrients in the urine and a markedly reduced intake. Peripheral limb and ventral edema can develop secondary to the marked hypoalbuminemia in advanced cases. These animals may also be anemic, hypochloremic, hyponatremic, and hypercalcemic.