Cerebellar abiotrophy diagnosed in 1 -year-old female cat
By Barbara C. Lewis, DVM, MS, DACVP
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A 7-year-old, spayed female DLH cat was obtained as a stray. She was noted to have mild hind limb dysmetria characterized by bunny hopping when sprinting. She could jump and was stable when standing still. The attending veterinarian tentatively diagnosed cerebellar hypoplasia, most likely due to in utero infection with feline parvovirus. The deficits progressed over the next seven years and consisted of truncal ataxia, front limb hypermetria, decreased ability to jump and loss of balance. She was otherwise apparently physically healthy, affectionate and continued to eat and drink. Two months later the cat suddenly became inappetant and jaundiced with bilirubinuria. She was diagnosed with liver failure and was euthanized and submitted to TVMDL for necropsy. Notable gross changes included icterus and a distended gall bladder full of mucus and inspissated, pasty green bile. The common bile duct was distended and tortuous. An approximately 3 mm diameter, hard black cholelith blocked the common bile duct at the major duodenal papilla. The liver had an accentuated lobular pattern. The cerebellum was well formed and approximately 2/3 normal size. Histologically, the cerebellar cortex exhibited neuronal degeneration and loss with reactive astrogliosis, most notably involving the Purkinje cells. Based on the histologic findings and progressive nature of the central nervous system signs, a diagnosis of cerebellar abiotrophy was made.
The majority of the neuronal abiotrophic diseases in animals involve the cerebellar cortex, especially the Purkinje cells. In medical terms, abiotrophy presumes that the premature neuronal degeneration is not acquired, but rather is the consequence of an intrinsic metabolic disorder. Neuronal abiotrophy is a generic classification, and often the underlying pathogenesis is unknown. An abiotrophic process occurs after the development of a full cellular complement. Cerebellar atrophy may be a correct description, but it lacks specificity. By contrast, cerebellar hypoplasia is the term reserved for intrinsic or extrinsic disease processes that alter the normal development of a group (or groups) of neurons. Examples of these processes include, but are not limited to, inherited disorders (generally autosomal recessive), nutritional deficiencies, teratogens and in utero viral infections (BVD, parvoviruses). Cerebellar abiotrophy has been most extensively studied in dogs and occurs in a variety of breeds. The disease is also reported to occur in cattle sheep, horses, swine, primates and rodents. Cerebellar cortical abiotrophies are reported to be exceptionally uncommon in the cat. The gross and histologic appearance of the cerebellar lesions in this cat are similar to those previously published and include decreased cerebellar size (by visual assessment), the near complete absence of the Purkinje cells with hyperplasia of the Bergman’s astrocytes and reduction in the number of granular cells. There is equivocal shrinkage of the molecular layer in an otherwise normal background of cerebellar parenchyma. No other areas of the brain were affected. The cat had no apparent visual deficits, but the eyes were not examined histologically. Because the cat was obtained as a young adult, a congenital or acquired insult to the cerebellum could not be completely ruled out; however, the slow, progressive nature of the disease process favors the diagnosis of abiotrophy.
Contact Dr. Barb Lewis, Veterinary Pathologist at the College Station laboratory to learn more about this case. To view TVMDL’s test catalog visit tvmdl.tamu.edu or call 1.888.646.5623.