Small Animal Dermatology Q&A 15

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A dog was presented for weight gain, hair loss, polyuria, and polydipsia. The owner is also concerned about the loss of the dog’s ear tip. She reports the ear tip bleeds, becomes necrotic, heals, and then the cycle repeats. Physical examination of the ear tip revealed that approximately one-third of the right ear tip has been sloughed as a result of these cycles.

Question	Answer		Article
This dog is showing the classic clinical signs of which endocrine disorder?	This dog is showing classic signs of canine hyperadrenocorticism. Note the bilaterally symmetrical hair loss, pendulous abdomen and prepuce, and ‘rat tail’.		Link to Article
What are the possible pathophysiologies of ear tip necrosis in this dog?	Ear tip necrosis can be seen in cases of canine hyperadrenocorticism, particularly in breeds with small thin ear pinnae. The cause is unknown, but it may be related to micro thromboembolisms. Animals with hyperadrenocorticism bruise easily and the skin becomes thinner, possibly contributing to the development of these lesions. Finally, high concentrations of circulating glucocorticoids may affect healing of the lesions.		Link to Article
What other nonendocrine diseases can be characterized by ear tip necrosis?	Other causes of ear tip necrosis include vasculitis, lupus erythematosus, proliferative thrombovascular pinnal necrosis, cold agglutinin disease, feline auricular chondritis, and familial vasculopathy of the German shepherd dog. Feline auricular chondritis is characterized by swollen, erythematous ears that are usually curled and deformed. Familial vasculopathy has been reported in young German shepherd dogs. It is inherited via an autosomal recessive trait, and affected dogs develop alopecia, crusts, and ulceration of the ear tips. Depigmentation and crusting of the footpads may be seen along with lethargy and pyrexia (Ferguson, 2002).		Link to Article