There are a few different reasons why cats can lose hair. In older cats diagnosed with cancer , alopecia is common. Nervous disorders (., over-grooming) can also cause cats to lose their hair. Hormonal imbalances, specifically too much thyroid or increased levels of steroids in the body, may lead to hair loss. Some cats experience skin allergies, which can also cause hair loss to occur. Parasites that bring about mange , and fungal issues like ringworm, are also a common cause of alopecia. Another less common factor is heredity .
Mechanism of action: Topical immunotherapy acts by varied mechanisms of action. The most important mechanism is a decrease in CD4 to CD8 lymphocyte ratio which changes from 4:1 to 1:1 after contact immunotherapy. A decrease in the intra-bulbar CD6 lymphocytes and Langerhan cells is also noted. Happle et al, proposed the concept of ‘antigenic competition’, where an allergic reaction generates suppressor T cells that non-specifically inhibit the autoimmune reaction against a hair follicle constituent. Expression of class I and III MHC molecules, which are normally increased in areas affected by alopecia areata disappear after topical immunotherapy treatment 34 .A ‘cytokine inhibitor’ theory has also been postulated 34 .
The course of typical alopecia areata is not predictable with a high likelihood of spontaneous remission. The longer the period of time of hair loss and the larger the area involved, the less likely the hair will regrow spontaneously. Therefore, there are a variety of treatments, but none of these can confidently be predicted to impact the course of this disease. Steroid injections may be very helpful in restarting the hair growth cycle in treated areas. Steroid creams, lotions and shampoos have been used for many years but are of limited benefit at best.