Immune deficiency in a dog with distemper.

A 16-week-old dog developed distemper 3 weeks after the 2nd of 2 vaccinations for canine distemper (CD). Symptomatic treatment was without effect and the dog was euthanatized. Prior to euthanasia, a blood sample was obtained for serologic study. The dog was found to be hypogammaglobulinemic and to have a serum-neutralization antibody titer of 1:16 to CD virus, which is considerably lower than the average 28-day response to a single CD vaccination (1:312). Histologic examination revealed absence of germinal centers in spleen and lymph nodes, generalized lymphoid depletion, and thymic hypoplasia. Comparison with primary immunodeficiencies of man and domestic animals and with CD virus-induced immune suppression led to inconclusive interpretation of these data. Thorough immune function analysis was deemed mandatory for separating primary immunodeficiency from CD virus-induced immunosuppression in dogs.