Merck Manual

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Professional Version

Eosinophilic Lesions in Dogs


Karen A. Moriello

, DVM, DACVD, Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison

Reviewed/Revised Apr 2020 | Modified Oct 2022

In dogs, lesions histologically characterized as eosinophilic granulomas have been reported. These lesions are rare but have been noted in the oral cavity as ulcerated or vegetative masses or as raised plaques or nodules. These are most commonly associated with hypersensitivity reactions. Any breed may be affected, but Siberian Huskies and Cavalier King Charles Spaniels may be at greater risk.

Some lesions resolve without treatment. Oral prednisone or prednisolone (0.5–1 mg/kg/day until lesion remission and then gradually tapering the dose over several weeks) may be needed. Recurrence of lesions may indicate an underlying allergic trigger.

Canine nasal eosinophilic furunculosis can occur in any dog at any time. It is most often observed in the summer and may be associated with insect bites. The onset of lesions is rapid, and there is acute, proliferative, exudative, nasal/muzzle swelling and pain. In some dogs, similar lesions may be seen on the head, periocularly, and around the pinna. Impression smears show eosinophils. Diagnosis is most commonly based on clinical signs and cytology. If there is microbial overgrowth, topical therapy with antibiotics may be needed.

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