Predictive factors for the regression of canine transmissible venereal tumor during vincristine therapy

Canine transmissible venereal tumor (CTVT) is a neoplasm transmitted by transplantation. Monochemotherapy with vincristine is considered to be effective, but treatment time until complete clinical remission may vary. The aim of this study was to determine which clinical data at diagnosis could predict the responsiveness of CTVT to vincristine chemotherapy. One hundred dogs with CTVT entered this prospective study. The animals were treated with vincristine sulfate (0.025 mg/kg) at weekly intervals until the tumor had macroscopically disappeared. The time to complete remission was recorded. A multivariate Cox regression model indicated that larger tumor mass, increased age and therapy during hot and rainy months were independent significant unfavorable predictive factors retarding remission, whereas sex, weight, status as owned dog or breed were of no predictive relevance. Further studies are necessary to investigate whether these results are due to changes in immunological response mechanisms in animals with a diminished immune surveillance, resulting in delays in tumor regression.     

Photodamage in feline skin: clinical and histomorphometric analysis

The purpose of this study was to investigate clinical and histomorphometric features of cat skin under long-term solar exposure. Ear skin of 34 Domestic Shorthair cats that were chronically exposed to sun was classified as follows: group 0, normal (n = 13); group 1, initial stage of photodamage (PD) (n = 10); group 2, advanced stage of PD (n = 11). Histologic sections were examined independently by 2 pathologists, and epidermal thickness, adnexal unit area, and dermal cellularity were assessed by morphometry. A positive correlation was obtained between age, degree of edema and sclerosis in the upper dermis, telangiectases, squamatization of basal keratinocytes, and epidermis thickness and the degree of PD. The area occupied by adnexal structures in the dermis diminished with increased PD. Dermal sclerosis and edema best separated the 3 groups. The results indicated a high level of skin hypersensitivity to sun rays in cats. The findings may be useful for clinical testing and in general veterinary pathology and dermatology.     

Immunohistochemical detection of rabies virus antigen in the cardiac ganglia of dogs in paraffin sections

The hearts of five naturally infected rabid dogs were studied by immunohistochemistry on paraffin sections using a monoclonal antibody and the peroxidase labelled streptavidin-biotin method to detect rabies ribonucleoprotein. In all cases distinct small granular and ring-shaped antigen deposits were found within the nerve cells of the cardiac ganglia thus reflecting the early centrifugal spread of virus along the pathway of the vagal nerve to the heart. Histologic findings consisted only of single small eosinophilic inclusions in some nerve cell bodies. These findings may be of diagnostic value.