Page 1319 - Veterinary Immunology, 10th Edition

loss of T cells so that the puppies lacked a thymus, and the lymph
VetBooks.ir nodes and spleen were very small. The disease was inherited as an

autosomal recessive disease, and the parents of affected puppies
could be traced to one common ancestor. Because of its similarities

to trait A-46 of cattle, these dogs were treated with oral zinc. Very
high doses resulted in some clinical improvement, but this could
not be sustained.
German Shepherd pyoderma is, as its name implies, a chronic

skin disease that occurs in middle-aged German Shepherds and is
associated with infection with coagulase-positive staphylococci.
These cases do not respond well to antibiotic therapy, and it is
believed to reflect some form of underlying genetic or

immunological defect. Although affected dogs appeared to mount
normal humoral responses, limited studies have shown reduced
lymphocyte responses to mitogens, an imbalance of lymphocyte
subsets (CD4 cells are depressed, CD8 cells are increased), and a

+
decline in the level of CD21 B cells. (The complement receptor
+
CD21 plays a role in B cell activation.) When the number of CD3 T
cells and B cells were examined in normal dog skin and in the skin
of dogs with pyoderma, it was found that the B cell numbers were

similar, but the number of T cells infiltrating the lesions in German
Shepherds was significantly reduced, suggesting that T cell
dysfunction may play a role in the pathogenesis of pyoderma in
this breed.

Uncharacterized Immunodeficiencies

The veterinary literature contains several reports of dogs with
severe recurrent infections caused by organisms that are not
normally considered to be highly pathogenic. Protothecosis has

been recorded in dogs. One-third of the cases have been in Collies,
suggesting an inherited predisposition. Weimaraners are unusually
susceptible to some systemic bacterial infections; German

Shepherds are susceptible to generalized systemic Aspergillus
infections, whereas some Rottweiler and Doberman families are
unusually susceptible to parvovirus infection. None of these have
been shown to be due to primary immunodeficiencies, and all
require further investigation.

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