Page 829 - Veterinary Immunology, 10th Edition

These may cause intense local inflammation, or they may present as
VetBooks.ir a generalized vascular disturbance such as purpura. A type III

reaction can occur in the eyes of dogs vaccinated against infectious
canine hepatitis (see Fig. 27.8). Some rabies vaccines may induce a

local complement-mediated vasculitis leading to ischemic
dermatitis and local alopecia. This type of reaction is most often
seen in small dogs such as Dachshunds, Miniature Poodles, Bichon
Frises, and Terriers.

Type IV hypersensitivity reactions may occur in response to
vaccination, but a more common reaction is granuloma formation at
the site of inoculation. This may be a response to depot adjuvants
containing alum or oil. Vaccines containing a water-in-oil adjuvant

produce larger and more persistent lesions at injection sites than
vaccines containing alum and aluminum hydroxide. These lesions
can be granulomas or sterile abscesses. If the skin is dirty at the
injection site, these abscesses may become infected. For this reason,

it is inappropriate to administer vaccines intramuscularly to
animals used for human consumption.
Postvaccinal canine distemper virus encephalitis is a rare
complication that may develop after administration of a modified

live canine distemper vaccine. The affected animal may show
aggression, incoordination, and seizures or other neurological
signs. The pathogenesis of this condition is unknown, but it may be
due to residual virulence, increased susceptibility, or triggering of a

latent paramyxovirus by the vaccine.

Errors in Manufacture or Administration

Some problems associated with vaccine use may be due to poor
production or administration. Thus some modified live vaccines

may retain the ability to cause disease. For example, some modified
live herpes vaccines or calicivirus vaccines given intranasally may
spread to the oropharynx and result in persistent infection. Indeed,

such a virus vaccine may infect (and protect) other animals in
contact. Even if these vaccines do not cause overt disease, they may
reduce the rate of growth of farm animals with significant economic
consequences.
Some vaccines may trigger a mild immunosuppression. For

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