Necropsy of sheep and goats

In this article, diseases will be discussed by system. Common differential diagnoses that may be associated with gross lesions are pointed out, and practical laboratory tests are presented that may help establish a specific diagnosis.     

Radiculomeningomyelitis due to Halicephalobus gingivalis in a horse

An adult horse was euthanatized following a clinical diagnosis of cauda equina neuritis. Significant gross postmortem and histopathologic findings were limited to the sacral spinal cord and cauda equina. The sacral spinal cord, meninges, and spinal nerve roots were expanded and partially effaced by sclerosing granulomatous inflammation with necrosis. The lesion contained numerous nematode larvae and fewer adults with a rhabditiform esophagus having a corpus, isthmus, and valved bulb. Female nematodes were amphidelphic and didelphic with reflexed ovaries. These morphologic features confirm Halicephalobus gingivalis as a novel cause of clinical signs in this case of cauda equina neuritis.     

Diabetes mellitus in a domesticated Spanish mustang

An 18-year-old Spanish Mustang mare was referred for evaluation of progressive weight loss and persistent hyperglycemia. Clinicopathologic abnormalities included marked hyperglycemia and glycosuria. Serum cortisol concentration was appropriately decreased following administration of dexamethasone, indicating that the horse did not have pituitary pars intermedia dysfunction. Serum insulin and plasma C-peptide concentrations were low, suggesting that hyperglycemia was a result of decreased secretion of insulin by pancreatic beta cells. In addition, glucose concentration did not return to the baseline concentration until 5 hours after i.v. administration of a glucose bolus, suggesting that insulin secretion, insulin effect, or both were reduced. However, i.v. administration of insulin caused only a slight decrease in the plasma glucose concentration, giving the impression that the action of insulin was impaired. Within 5 hours after administration of a combination of glyburide and metformin, which is used to treat diabetes mellitus in humans, the glucose concentration was within reference limits. The horse was euthanized, and a postmortem examination was done. Immunohistochemical staining of sections of the pancreas revealed attenuation of the pancreatic islet beta-cell population, with beta cells that remained generally limited to the periphery of the islets. These findings indicate that, albeit rare, pancreatic beta-cell failure may contribute to the development of diabetes mellitus in horses.     

Canine von Willebrand's disease. A heterogeneous group of bleeding disorders

The term "von Willebrand's disease," refers to a group of inherited bleeding disorders, all of which are caused by a deficiency of the multimeric plasma glycoprotein, von Willebrand factor. The various forms of canine von Willebrand's disease can be categorized into one of three major types: in type I canine von Willebrand's disease, all sizes of von Willebrand factor multimers can be detected in the plasma; in type II canine von Willebrand's disease, only the smaller von Willebrand factor multimers are found in the plasma (larger multimers are absent); and in type III canine von Willebrand's disease, von Willebrand factor is completely absent from the plasma or present in only trace amounts. Von Willebrand's disease is common in dogs, but some forms of the disease are so mild that they are of questionable clinical significance.