Rabbits normally have a large thymus that is placed cranial to the heart and extends into the thoracic inlet. Thymoma, thymic lymphoma and thymic carcinoma have all been reported in rabbits. Thymic lymphoma and carcinoma are rare in rabbits.The overall incidence of thymoma in rabbits is low (around 7% of reported neoplasms in 55 colony rabbits) with no apparent sex predilection. The mean age at presentation is 6.7 years based on one survey of 19 cases. Rabbit thymomas are generally slow growing and are potentially locally invasive tumors that rarely metastasize. Continue reading →
Inflammatory disease is the second most common cause of hepatobiliary disease in cats. The histological classification of feline inflammatory liver disease is confusing. Terms used in the literature have included suppurative or acute cholangiohepatitis, chronic cholangiohepatitis, chronic lympocytic cholangitis, progressive lymphocytic cholangitis, sclerosing cholangitis, lymphoplasmacytic cholangitis/cholangiohepatitis, lymphocytic portal hepatitis, and biliary cirrhosis. This lack of consistency has made it difficult to compare reported cases. In 2004, the WSAVA Liver Disease and Pathology Standardization Research Group proposed a new classification scheme in order to provide consistency in terminology. Since the group felt that the inflammation was primarily centered on the biliary tree it defined three distinct histopathologic forms of feline cholangitis: 1.) neutrophilic cholangitis (acute and chronic) 2.) lymphocytic cholangitis and 3.) chronic cholangitis associated with biliary fluke infestation. Cats can get true chronic hepatitis but it is rare. Copper toxicity would be one to rule out.
Mesenchymal Stem Cell Therapy for Labrador Retriever Chronic Hepatitis
Labrador retrievers develop a breed-specific chronic hepatitis (CH) that progresses to cirrhosis and hepatic failure. Vague clinical signs include decreased appetite, lethargy, PU/PD and vomiting. Median age at diagnosis is between 6.4-9.3 years (range: 2-15 years). A female predominance is noted in some, but not all reports. Dogs typically have increases in serum ALT and AST with more modest and variable increases in ALP and GGT. Some dogs also have renal tubular disease manifested by the presence of normoglycemic glucosuria. Definitive diagnosis is by hepatic histopathology, which shows varying degrees of necrosis/apoptosis with centrolobular to periportal mononuclear inflammation (lymphocytes, plasma cells and histiocytes), regeneration and fibrosis (Fig 3). In some dogs cirrhosis is present at diagnosis. Median survival is 374 days (range:1-2,645 days).
Figure 3: Hepatic biospy from a 5-year-old spayed female Labrador that presented for anorexia, weight loss, and PU/PD. H and E stains (A, B) show marked portal inflammation consisting of lymphocytes, plasma cells and macrophages. Multifocal lipogranulomas are present. Siruis Red stains (C, D) highlight the abundant fibrosis with prominent bridging between portal areas. Low (A C, 100X)) and high (B, D 400X) power.
A 9-year-old intact male Labrador retriever presented to Tufts Foster Hospital for Small Animals for further evaluation of history of painful gait, chronic atopic dermatitis/pododermatitis (for years) and the recent discovery of of increased liver enzymes (ALT =422 U/L, ALP= 377 U/L, AST =73 U/L) with a normal albumin and bilirubin. The dog had failed to respond to consecutive 3 week courses of clindamycin and cefpodoxime. On physical examination the dog was normal except for extreme difficulty in getting up and walked gingerly. He would not permit full examination of the feet, but a moist dermatitis and areas of ulceration were appreciated (Fig 2 A).
Fig 2. Hepatocutaneous syndrome in a dog. A. Gross appearance of feet with hyperkeratosis and ulceration. B. Ultrasound of liver showing typical ‘honeycomb’ pattern consisting of variable-sized hypoechoic regions surrounded by hyperechoic borders. B. Skin biopsy (H&E) with 1: Marked parakeratotic hyperkeratosis; 2: Vacuolar change in the upper levels of the epidermis; 3. Hyperplastic epidermis with acanthosis. Images A and C courtesy of Dr Lluis Ferrer and B from Dr. Dominique Penninck.