Page 1088 - Veterinary Immunology, 10th Edition

VetBooks.ir

FIG. 33.3 A section of guinea pig skin 18 hours after attachment of
a tick in an animal sensitized by prior infestation with tick larvae.
The skin is infiltrated with large numbers of basophils. (From McLaren
D, Worms MJ, Askenase PW: Cutaneous basophil associated resistance to
ectoparasites (ticks). Electron microscopy of Rhipicephalus appendiculatus larval
feeding sites in actively sensitised guinea pigs and recipients of immune serum, J
Pathol 139:289, 1983.)

Tuberculin Reactions in Cattle

Because a positive tuberculin reaction occurs only in animals that

have, or have had, tuberculosis, skin testing may be used to identify
animals affected by this disease. Indeed, the tuberculin test has
provided the basis for all tuberculosis eradication schemes that

involve the detection and subsequent elimination of infected
animals.
Skin testing of cattle may be performed in several ways (Table
33.1). The simplest is the single intradermal (SID) test. In this test,

1088