Stephen T. Simpson

Intervertebral Disc Disease

This article describes the functional anatomy of intervertebral discs and their relationship to the vertebrae and spinal cord. The pathologic events and clinical complications of intervertebral disc disease are described. A discussion of proper staging of disc disease and appropriate conservative management of degenerative disc disease is included.

Survival of a Suspected Case of Central Nervous System Cuterebrosis in a Dog: Clinical and Magnetic Resonance Imaging Findings

A 3-year-old, spayed female rat terrier was evaluated for acute onset of stupor, disorientation, and tetraparesis. Clinical signs progressed over 3 weeks to eventual right-sided hemiparesis and circling to the left. A Cuterebra spp. larva was discovered in the vomitus of the dog 2 weeks after the onset of clinical signs. Cerebrospinal fluid analysis showed chronic inflammation, and magnetic resonance imaging supported a diagnosis of a parasitic tract through the left cerebral hemisphere. Medical management included a tapering anti-inflammatory dose of prednisone. Clinical signs improved slowly over time. This is the first description of a presumptive antemortem diagnosis of canine cuterebrosis in the central nervous system.

Analysis of cat retina for dopamine, dihydroxyphenylacetic acid, 3-methoxytyramine and homovanillic acid

Twenty retinas from 10 cats were evaluted for dopamine (DA) and its metabolites dihydroxyphenylacetic acid (DOPAC), 3-methoxytyramine (3-MT) and homovanillic acid (HVA) by high pressure liquid chromatography and electrochemical detection. Dopamine was present in all 20 retinas at a mean concentration of 3.00±0.54 ng/mg protein. Dihydroxyphenylacetic acid, 3-MT and HVA were detected in 16, 14 and 9 retinas respectively.In retinas in which these metabolites were detectable, they were present in the following mean concentrations: DOPAC, 1.07±0.21 ng/mg protein; 3-MT, 3.44±0.97 ng/mg protein and HVA, 4.54±1.05 ng/mg protein. Significantly higher concentrations of 3-MT (p=0.0108, paired t test) and HVA (p=0.0166, paired t test) than DOPAC were present in cat retina. Linear correlation analysis between DA and its metabolites indicated that the 3-MT and DOPAC concentrations correlated well with each other and with the amount of DA in cat retina. The concentrations of the end product metabolite, HVA, had poor correlations with the concentrations of 3-MT, DOPAC or DA. These data indicated that once DA is released in cat retina it can be metabolized to 3-MT, DOPAC and HVA.