Michel's medium as a preservative for immunofluorescent staining of cutaneous biopsy specimens in dogs and cats.

Paired 3-mm skin biopsy specimens from 24 dogs and 11 cats with suspected autoimmune dermatopathies were stained with fluorescein-conjugated antisera. In each case, 1 specimen was immediately embedded in optimum cutting temperature compound, quick frozen to -30 C, processed, stained, and examined. The other sample was placed in Michel's transport medium, held for 7 days, and then processed, stained, and examined. The location, quality, and intensity of immunofluorescent staining (when positive) were then compared in the 2 specimens. There were no differences in the staining patterns between the specimens processed immediately and those held in Michel's medium, thus demonstrating the validity of preserving canine and feline skin biopsy specimens in Michel's medium for immunofluorescent examination.