Feline Congenital Hypotrichosis and Alopecia – NAVLE Study Guide

Overview and Clinical Importance

Congenital hypotrichosis and alopecia represent a group of inherited disorders characterized by reduced (hypotrichosis) or absent (alopecia) hair from birth or early in life. These conditions result from abnormal hair follicle development, structure, or function due to genetic mutations affecting ectodermal tissue differentiation. While relatively rare in the general feline population, these disorders are particularly important in certain breeds and have significant clinical and breeding implications.

In cats, congenital hypotrichosis ranges from the desirable breed characteristics seen in Sphynx and Devon Rex cats to pathological conditions such as Birman hypotrichosis with thymic aplasia, which carries a grave prognosis. Understanding the genetic basis, clinical presentation, and breed predispositions is essential for accurate diagnosis, appropriate client counseling, and responsible breeding recommendations.

Definitions and Terminology

Key Terms

Etiology and Pathophysiology

Normal Hair Follicle Structure

Understanding normal hair follicle anatomy is essential for comprehending the pathophysiology of hypotrichosis. The pilosebaceous unit consists of the hair follicle, sebaceous gland, and arrector pili muscle. The hair follicle has three main segments: the infundibulum (upper portion), isthmus (middle), and inferior segment/bulb (lower portion containing the dermal papilla and hair matrix).