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Similar-looking conditions affect the muzzle in dogs

They require extensive detective work to properly diagnose

[From Tufts January 2011 Issue]

It’s easy to spot problems with the muzzle — the dog’s snout — because the signs are readily discernible. The skin or nose may exhibit depigmentation, ulcers, scaling, itchiness or redness.

The muzzle includes the nasal planum, or nose; the nasal cavity, or interior of the muzzle; and the skin and bone overlying the nasal cavity. Diseases of the nasal cavity are usually associated with sneezing, bleeding and discharge from the nostrils. Identifying their cause, however, can be daunting.

“The most important thing for owners to realize is that conditions affecting the muzzle may look similar but can have a variety of causes that often require some detective work to properly diagnose,” says dermatologist Lowell Ackerman, DVM, a member of Your Dog’s advisory board. “For some of the rarer conditions, a referral to a veterinary dermatologist may be recommended.”

The most common diseases of the nasal cavity are fungal infections and cancer. Common diseases of the skin and the nose include solar dermatitis and immune system disorders.

Fungal infections
A dog’s nasal cavity may become infected with the fungus aspergillus, which enters the nasal cavity by inhalation. The fungus is frequently found in compost piles and moldy hay, but in most cases, the source of the fungus can’t be identified with certainty. Many dogs who acquire the disease were never exposed to an obvious source.

The fungus causes swelling and irritation of the tissues inside the nasal cavity. Symptoms include chronic nasal discharge, bleeding from the nostrils and sneezing. To diagnose the infection, a veterinarian will take a biopsy from within the nasal cavity and may order X-rays to determine if any damage has occurred to the bone structure. Once a diagnosis is made, a topical antifungal agent is instilled into the nasal cavity under anesthesia to eliminate the fungus.

Nasal cancer
While a dog with a severe runny nose may have only a short-term bacterial or viral infection, the discharge can also be a sign of nasal cancer, especially if it progressively worsens and contains mucus, pus or blood. A facial deformity, such as a firm swelling overlying the nasal cavity, can also be indicative of cancer.

The diagnosis is based on a biopsy, and the veterinarian may also order X-rays or a CT scan to determine the extent of the disease. The primary mode of therapy is radiation therapy, which is sometimes combined with surgery. The quality of life afterward is excellent, although there is a significant risk of eventual tumor recurrence.

Skin and nose diseases
Just like people, dogs can suffer excessive exposure to the sun, causing sunburn and, eventually, skin damage. The condition is known as solar dermatitis. Signs may include hair loss, rough patches of skin and thickening and reddening of the nose. Left untreated, bacterial infections can develop, and antibiotics are needed to treat the condition. Solar dermatitis is most commonly seen in short-coated dogs such as bull terriers, boxers and Dalmatians.

Prevention is key. At least 15 minutes before your dog goes outside, apply a waterproof sunscreen (one made especially for dogs) with an SPF factor of 15 or higher. The sunscreen should be applied to the nose and other sensitive areas such as ears and underside of his belly.

Immune system disorders
Certain autoimmune diseases, such as lupus erythematosus, pemphigus erythematosus and systemic lupus erythematosus, can cause ulcers to form on the dog’s nose, face and mouth. Depigmentation is common. The ulcers are benign and are easily recognizable — they’re shaped like a butterfly. A veterinarian will draw blood and perform a skin biopsy to diagnose immune system disorders and will prescribe immunosuppressive drugs to treat the condition. Antibiotics may be prescribed if there is a secondary bacterial infection. Collies are more prone to contracting autoimmune disorders of the nose; females are at risk more than males.

Systemic lupus erythematosus is a more serious, and often, fatal form of lupus. Like the more common forms of lupus, the disease is characterized by butterfly-shaped ulcers. A dog will often exhibit joint stiffness, fever and pain. Kidney damage can occur, resulting in renal failure.

As with any disease, proper diagnosis and treatment can help produce a speedy recovery. “The main challenge with skin diseases involving the muzzle region is to make the correct diagnosis,” Dr. Ackerman says.

Karen Lee Stevens is a writer in
Santa Barbara, Calif.

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