Clinical and pathological observations in English cocker spaniels with primary metabolic vitamin E deficiency and retinal pigment epithelial dystrophy.

Fifteen English cocker spaniels with confirmed vitamin E deficiency were examined physically, ophthalmologically and neurologically. Eleven of them had clinical signs of neurological dysfunction which included ataxia, proprioceptive deficits, abnormal spinal reflexes and muscle weakness. In the two dogs examined histopathologically there was central neuronal fibre degeneration with prominent neuroaxonal dystrophy, particularly within the sensory relay nuclei of the brainstem, and one of the dogs had severe intestinal lipofuscinosis.

Vitamin E deficiency in dogs with retinal pigment epithelial dystrophy.

The role of vitamin E deficiency in the development of retinal pigment epithelial dystrophy was investigated in 11 cocker spaniels and four other dogs. The concentration of alpha-tocopherol was measured by high performance liquid chromatography in plasma samples obtained from the affected dogs and from 28 ophthalmoscopically normal, healthy control dogs. The mean (sd) plasma alpha-tocopherol concentration in the normal dogs was 20.2 (7.1) microg/ml, compared with 1.14 (0.67) microg/ml in the 11 affected cocker spaniels. The difference between the two groups remained highly significant when the alpha-tocopherol concentrations were expressed relative to the concentrations of the plasma lipids cholesterol and triglycerides. Low plasma concentrations of alpha-tocopherol were observed in the four affected dogs of other breeds, but the finding was not so consistent. The plasma lipid concentrations were normal in the affected dogs. The deficiency of alpha-tocopherol in the affected dogs appeared to be primary, because there was no clinical, biochemical or pathological evidence of underlying disease, or any indication of a dietary deficiency which might have contributed to the low concentrations of alpha-tocopherol.

Ultrasonographic findings in 50 dogs with retrobulbar disease.

Records of 50 dogs with signs of retrobulbar disease that had ultrasonography and diagnosis based on results of cytopathology or histopathology were reviewed retrospectively. Abnormalities were identified ultrasonographically in 43 (86%) dogs. Mass effect was identified in 42% of dogs with neoplasia and 30% of dogs with abscess. Ten of 11 (91%) orbital bone lesions were in dogs with retrobulbar neoplasia. A cavitary lesion was recognized ultrasonographically in 75% of dogs with salivary mucocele and 50% of dogs with retrobulbar abscess. Neoplasms occurred predominantly on the ventral or medial aspect of the orbit, or both, which reflects invasion by nasal or sinus neoplasms. Presence of orbital bone lesions or a mass on the medial aspect of the orbit suggests neoplasia; however, other ultrasonographic signs were nonspecific.

Conjunctival flora observed in 70 healthy domestic rabbits (Oryctolagus cuniculus).

Conjunctival swabs were taken from both eyes of 70 healthy domestic rabbits and cultured to determine the microbial population. Bacteria were recovered from 83 per cent of the specimens. DNase-negative Staphylococcus species (57 per cent) were the most commonly recovered organisms followed by Micrococcus species (25 per cent) and Bacillus species (19 per cent). Other organisms isolated included Stomatococcus species (8 per cent), Neisseria species (8 per cent), Pasteurella species (6 per cent), Corynebacterium species (6 per cent), Streptococcus species (6 per cent) and Moraxella species (4 per cent), and other bacteria were isolated less frequently. Statistical analysis showed that there appeared to be no significant difference between the bacterial isolation rates from different breeds of rabbit. Significantly more of the swabs taken from young rabbits yielded cultivable bacteria than did those taken from rabbits over 12 months of age.

Retinal degeneration associated with vitamin E deficiency in hunting dogs.

A group of Walker Hounds and Beagles that were fed a diet of table scraps were examined because of slow, progressive loss of vision. Clinical and microscopic features of the disease were correlated to the dogs' micronutrient status. Sensory retinal degeneration, predominantly in the central tapetal fundus, was found in all dogs, and severity of changes varied with age of the dog. Plasma, serum, and tissue concentrations of vitamin E were low in affected dogs (10 to 40% of control values). Lipofuscin accumulation was found on microscopic examination in retinal pigment epithelium, smooth muscle cells of the intestinal tract, and neurons of the CNS. Findings were consistent with nutritional vitamin E deficiency and oxidative injury to photoreceptors of the retina. Changes in these dogs were similar to those described for central progressive retinal atrophy and equine lower motor neuron disease, suggesting these diseases may share a common pathogenesis to vitamin E deficiency.

The cytoskeletal intermediate filaments of canine retinal pigment epithelial cells in vivo and in vitro.

The cytoskeletal intermediate filament characteristics of normal, freshly isolated and subcultured canine retinal pigment epithelial (RPE) cells were studied using immunocytochemistry and immunoblotting techniques. Commercially available primary antibodies recognising a broad range of cytokeratins and vimentin were selected. Cytokeratin reactivity was a constant feature of all canine RPE cells. The main cytokeratins expressed by cultured RPE cells included 8, 18 and 19. This finding is consistent with the published findings of work carried out in other mammalian species including man. Freshly isolated RPE cells stained positively with broad-spectrum antibodies to cytokeratins but generally did not stain with antibodies specific to cytokeratins 18 or 19 and did not stain with antibodies to vimentin, or stained only very weakly. After a short time in culture however, cells demonstrated intense positive staining for vimentin. This study demonstrated that cytokeratin immunoreactivity (in conjunction with vimentin immunoreactivity in vitro) is a useful and consistent marker for canine RPE cells.