chapter 20 Dermatomyositis, Canine Familial..........................
DEFINITION/OVERVIEW
An inherited idiopathic inflammatory disorder of dogs that involves the skin and muscle
(rarely, blood vessels).
ETIOLOGY/PATHOPHYSIOLOGY
Exact pathogenesis unknown.
Although it is well accepted that there is a genetic predisposition, an infectious agent
(i.e., a virus) may act as a trigger for the development of clinical signs; an immune-
mediated or autoimmune process may be involved.Skin: variable dermatitis on the face, ears, tail tip, and over the bony prominences of
the distal extremities; may become more generalized.
Musculoskeletal: subtle to severe; temporal and masseter muscles initial; severe cases
exhibit generalized muscle disease, involvement of the esophageal muscles results in
megaesophagus.Typically, advanced dermatitis is associated with severe myositis.
Thought to be inherited as an autosomal dominant trait with variable expression in
collies, Shetland sheepdogs, and Beauceron shepherds.
SIGNALMENT/HISTORY
Breed Predilection
Collies, Shetland sheepdogs, Beauceron shepherds, and their cross-breeds.
Isolated reports: Australian cattle dogs, Welsh corgis, chow chows, German shep-
herds, and the kuvasz.
MEAN AGE AND RANGE
Cutaneous lesions usually develop between 7 weeks and 6 months of age.
Mild disease: lesions may resolve in 3 months.
Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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