Page 774 - Veterinary Immunology, 10th Edition

immune globulin should be given to horses and cattle; at least 500
VetBooks.ir IU to calves, sheep, goats, and swine; and at least 250 IU to dogs.

The exact amount should vary with the amount of tissue damage,
the degree of wound contamination, and the time elapsed since

injury. Tetanus immune globulin, 300,000 IU intravenously has
been used successfully for the treatment of clinical disease in
horses.
Although immune globulins give immediate protection, some

problems are associated with their use. For instance, when horse
tetanus immune globulin is given to a cow or dog, the horse
proteins will be perceived as foreign, elicit an immune response,
and be rapidly eliminated (Fig. 24.3). To reduce antigenicity,

immune globulins are usually treated with pepsin to destroy their
Fc region and leave intact only the portion of the immunoglobulin
molecule required for toxin neutralization, the F(ab)′ fragment.
2

FIG. 24.3 The fate of passively administered equine immune
globulin when given to a homologous species (horse) or to a
heterologous species (dog).

If circulating horse antibody is still present by the time the
recipient animal mounts an immune response, the immune-

complexes formed may cause a type III hypersensitivity reaction
called serum sickness (Chapter 32). If repeated doses of horse
immune globulin are given to an animal of another species, this

may provoke immunoglobulin E (IgE) production and anaphylaxis
(Chapter 30). Finally, the presence of high levels of circulating horse

774