Image Quiz: External ear lesions in a dog

Images are courtesy of Judy Seltzer, BVetMed, MRCVS, DACVD.

A 2-year-old, neutered male Rhodesian ridgeback started losing hair at the tips of both pinnae. Over a 2-to 3-month period, the owner noticed erythema, crusting, and eventual ulceration and bleeding of the affected areas. Pruritus does not appear to be associated with the lesions. No other lesions are noted on the body, and the dog is not showing systemic signs of illness. The dog is up-to-date on vaccinations and parasite prevention, and has not been treated with any other medications. What is the likely diagnosis?

A. Sarcoptic mange

B. Cutaneous vasculitis

C. Dermatophytosis

D. Pemphigus foliaceus

B. Cutaneous vasculitis

Cutaneous vasculitis, a condition that involves inflammation of the blood vessels in the skin, is triggered by an abnormal immune system response that can lead to crusting and ulceration. Underlying causes include infections (bacterial, rickettsial, fungal, viral), medications, vaccines, foods, trauma, immune-mediated disease, and neoplasia. However, in 50% of cases, the underlying cause remains unknown and cutaneous vasculitis is considered idiopathic.

__________________________________________________________________________________________________

Besides the ear tips, in which other location would you most likely encounter cutaneous vasculitis in a dog?

A. Abdomen

B. Forelimbs

C. Footpads

D. Ventral neck

Answer: C. Footpads

Vasculitis can present in many ways, depending on the underlying cause and severity of the disease process, and the location of affected vessels. Lesions can start with erythema, alopecia, scaling, and depigmentation. As the disease progresses, plaques, ulcerations, and necrosis may become visible. Extremities, such as the ear tips, footpads, and tip of the tail, are often affected because there is less collateral circulation in these areas. Other common locations include the nose, elbows, and inside of the mouth.

__________________________________________________________________________________________________

Along with management of the underlying disease process, which of the following medications would be treatment options in dogs with cutaneous vasculitis?

A. Prednisone

B. Doxycycline or niacinamide

C. Pentoxifylline

D. Any of the above

D. Any of the above.

Although no single treatment protocol exists for cutaneous vasculitis, a variety of medications can be selected based on clinical signs and response to therapy.

Pentoxifylline is often selected as the first therapeutic option. This medication helps erythrocytes become more pliable, allowing them to travel easier through damaged blood vessels and restore blood flow. However, it may take 2 to 3 months to see the most beneficial effects.

Other immunomodulatory or immunosuppressive therapies, including doxycycline and niacinamide, steroids, cyclosporine, and mycophenolate, may be necessary. Multimodal therapy may be needed in dogs with more severe disease.

In patients that are refractory to medical therapy for cutaneous vasculitis of the ear tips, surgical intervention (e.g. partial pinnectomy) may be required.

Judy Seltzer, BVedMed, MRCVS, DACVD, graduated from the Royal Veterinary College in London and completed her residency in dermatology at the University of Florida. She has been working in her home state of New York since 2009, currently at BluePearl Veterinary Partners in New York City. She and her husband have a baby girl and four cats, and enjoy traveling, fall festivals, winter activities, and dining out.