Atopic Dermatitis in Cats and Dogs

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Could my dog or cat have atopic dermatitis as a cause of itching and/or recurrent infections?

Atopic dermatitis is the most common cause of itching in pets in Minnesota, if your pet is on a good flea and tick prevention.  Especially in warmer areas of the United States, or if your pet goes outdoors without a flea and tick prevention, fleas and parasites are a more common cause for itching.   A consultation with a veterinarian is warranted to rule out parasites or other skin diseases prior to making the diagnosis of atopic dermatitis. 

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Why does my pet have atopic dermatitis?

Atopic dermatitis is a disease of the skin barrier and immune system which has a strong genetic predisposition, which means if parents or grandparents had similar issues, their offspring are predisposed to have the same issues. In pets predisposed to atopic dermatitis, the immune system makes the skin inflamed and itchy and also may over-react to allergens, which triggers more inflammation. A poor skin barrier, itchiness, and inflammation predispose to recurrent infections of the skin and ears. Dogs with folds of skin (bulldogs) often have more constant or severe signs.

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Symptoms of atopic dermatitis in dogs and cats

Dogs

The main symptoms of atopic dermatitis in dogs are itching and recurrent infections of the skin and ears.  Atopic dermatitis in dogs typically starts with symptoms between the ages of 1-6 years, but may start as puppies.  Symptoms can wax and wane, but in dogs symptoms typically worsen up to the age of 6.  As dogs with atopic dermatitis get older, they tend to get more frequent infections.  Dogs relieve itch by licking, chewing, scooting, rubbing, or scratching.  Dogs rarely perform these behaviors out of boredom or anxiety, although being bored or anxious makes things worse.       

 

Infections are typically yeast and/or bacterial infections of the skin and ears.  The ears may be the only affected area in some pets.  Another area typically affected is the feet.  If you look between the toes you may notice the skin there is red or your dog chews the feet or licks the legs.  Then the armpits, abdomen, chest, under the neck, and anal area are often affected- the skin may be red, greasy, smelly or itchy.  With long term issues, the skin becomes darker and thicker/rougher.  The hair may be missing or shorter due to infections and chewing.  Some terriers have their worst symptoms down their backs.  Some dogs lick huge sores on their lower legs.  Some dogs have red, runny eyes and may sneeze due to allergies.

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Many dogs with atopic dermatitis also have sensitive digestive tracts with chronic soft stools, diarrhea, or vomiting.

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Cats

Cats are usually over 1 year of age when symptoms start.  The main symptom of atopic dermatitis in cats is itching.  Cats will scratch, bite their skin, pull out hair, and overgroom to help relieve itch. Cats rarely perform these behaviors out of boredom or anxiety, although being bored or anxious makes things worse.  Cats with atopic dermatitis get skin and ear infections less often than dogs do, but they certainly occur.  Cats most often make bald patches on themselves, usually the lower abdomen is the worst area, and with progression, raw areas are created with the cat’s raspy tongue.  Cats often will scratch at the head with the hind leg and create scabs around the eyes and ears.  Cats can manifest allergies with asthma too, but it is not common to have asthma and skin symptoms at the same time.  Asthma causes coughing, and some people mistake this for "coughing up a hairball" but cats do not cough up hairballs, they vomit hairballs.

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Could my dog or cat have allergies?

Because there are immune system defects and skin barrier defects with atopic dermatitis, many pets with atopic dermatitis have allergies to things they are exposed to.  Pollens or other allergens in the environment or certain foods can cause a flare of skin symptoms. 

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Food allergies

If your pet had allergy symptoms start at younger than 1 year of age, the symptoms are year round, or there are any gastrointestinal signs like vomiting, loose stools, or having more than 2 bowel movements per day, food allergies are more likely.  Most pets with atopic dermatitis don’t have food allergies, only about 5-10% of dogs and perhaps 10% of cats do improve with diet change.  There is no diagnostic test for a food allergy other than an elimination diet trial where a prescription diet is fed exclusively for 4-8 weeks.

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Environmental allergies

Environmental allergies are reactions to allergens like pollens, dusts, and molds.  Environmental allergies may be seasonal with outdoor allergens, or year round with indoor allergens.  To determine what allergens in the environment are causing your pet to have symptoms, we can perform allergy testing.  There is no test for food allergy other than a dietary trial.

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Treatments for atopic dermatitis and allergies in dogs and cats

Treatment of atopic dermatitis involves: avoiding or desensitizing against allergies, infection control and prevention, keeping the skin clean and dry, and using medications (Apoquel, Cytopoint, Cyclosporine) to control atopic inflammation of the skin.  Medications and topicals help control itch and infections.

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What combination of therapies is best for your pet depends on your individual pet, their personality, type and locations of infections, seasonality, skin and hair type, and of course what they respond best to.  It often takes several visits with a dermatologist to find the perfect combination of treatments, especially with severe cases, but our goal is that your pet ultimately has less flare ups, infections, and vet visits.  Our whole team is here to help you and your pet, to make sure your pet gets relief and you have peace of mind.

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What else could be causing my pet’s itching and infections?

There are many other causes of itching, including parasites.  For example, if ear margins are affected, and the pet is minimally or not responding to glucocorticoid (steroid) and antibiotic treatments, then your pet has a much higher likelihood of having sarcoptic mites.  If the area of the back over your pet’s back legs to the tail is affected, then your pet has a higher chance of having fleas or a mite called Cheyletiella.  Skin infections with yeast and/or bacteria can be very itchy.  The underlying reason why your pet got an infection in the first place should be investigated- if your pet is young and has recurrent infections, the most likely cause is atopic dermatitis.  There are other diseases we would need to rule out if an older dog or cat suddenly develops itching or infections.  Sometimes dogs and cats focus on a particular area due to pain- like licking an arthritic paw, or licking the lower abdomen with bladder stones.  A thorough history, physical exam, diagnostics, and response to treatment help to confirm a diagnosis.

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