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DIAGNOSIS OF ALOPECIA in dogs and cats
Figure 10. Follicular casts in a dog with sebaceous
Figure 11. Dystrophic bulbs in a dog with follicular dysplasia.
adenitis.
Abnormalities of the follicular bulb can be associated with inherited and congenital disorders as well as metabolic and nutritional diseases (Fig. 11). Animals with alopecia areata show some normal hairs in telogen phase, as well as other hairs with dystrophic bulbs and frayed, broken, and pigmented tips that taper towards the proximal end in the form of an exclamation mark (Fig. 12).
INFECTIOUS AND PARASITIC AGENTS Microscopic examination is useful for the diagnosis of demodicosis in very young or restless animals or in locations in which scrapings are difficult to obtain, such as the eyelid or interdigital space. Compared with skin scraping and exudate analysis, the trichogram is a less sensitive technique for the diagnosis of demodicosis. Sometimes this test can be negative, despite the presence of many mites. The use of mineral oil to collect the sample and visualise the parasite is recommended (Fig. 13).
Figure 13. Trichogram revealing the presence of a mite (Demodex canis).
Figure 12. Dystrophic bulbs in a dog with alopecia areata.