Allergies in Dogs and Cats (Atopy)

Just like people, pets can suffer from a number of allergies. The main categories of allergies for dogs and cats include flea allergies, food allergies, and environmental allergies.

Both dogs and cats can suffer from environmental (also known as atopic dermatitis or atopy) allergies, defined as allergic reactions to environmental substances. In some cases, pet allergies are mild and only have unpleasant but not severe symptoms. Some allergies, however, can become very serious and even life-threatening, depending not only on the allergen but also on your pet’s size, age, and overall health.

Environmental allergies can develop in young and adult cats and dogs, so just because your pet wasn’t allergic before doesn’t mean he can’t develop a problem later on. It is crucial to understand that allergies are rarely cured, but if diagnosed and addressed early, they can be managed successfully. You should also know that managing allergies can be very frustrating, time-consuming, and expensive. The more you are committed to helping your pet and the sooner you seek assistance from a veterinarian in the course of the allergies, the more rewarding your efforts will be.

Common Causes of Allergies in Dogs and Cats

There are two main types of environmental allergies:

Contact Allergies. These rare allergies (also known as contact dermatitis allergies) happen when your pet’s skin comes in direct contact with something toxic or caustic. It’s important to remember that just because one of your pets doesn’t react to a certain substance doesn’t mean another pet will respond the same way. For example, some dogs and cats can develop allergies to the chemicals found in flea collars or certain shampoos, while other pets might be able to use them without any problem. Pets can also become allergic to plastic and rubber and have a reaction from eating out of plastic food bowls. If you suspect food allergy symptoms in dogs, contact us as soon as possible. Insecticides, paint, carpet cleaners, bedding material, and wood preservatives can also cause contact allergies.

Contact allergies can cause localized (in one area) or generalized (all over the body) reactions which most often occurs in areas where the skin is not well protected by hair, such as the feet, chin, nose, legs, and undersurface of the body. Irritant contact dermatitis most commonly produces itchy red bumps, crusts, hot spots (moist, weepy spots), and skin inflammation. Excessive scratching damages the skin and leads to a secondary skin infection called pyoderma.

Inhalant Allergies (Called Atopy). These are allergic reactions caused by something your pet inhales. The main inhalant allergens are tree, grass, weed pollens, molds, mildew, and house dust mites. While many of these types of allergies are seasonal allergies (a response to pollen from grasses, plants, and trees), they can undoubtedly be year-round (a reaction to chemicals, dust mites, molds, and mildew).

Although inhaled allergies can cause sneezing, coughing, and respiratory symptoms in pets, they are more likely to cause skin itchiness, especially in the feet, abdomen, and around the eyes. Pets are also prone to having ear problems when they’re allergic. You might see frequent ear infections, itchy ears with a discharge or debris, and often a foul-smelling odor.

Allergies in dogs and cats are often inherited and worsen with each generation; therefore, animals with known allergies should not be used as breeding animals.

Most pets with atopy usually have allergies to multiple allergens and typically begin showing signs around one to three years of age. Still, symptoms can start at any time in life, especially with a move to a new area or changes in the environment. This means that animals who are affected by allergies often suffer their entire lives, and it is very common for symptoms often become worse with age, especially if they are continuing to be exposed to the offending allergens or if the secondary symptoms are left untreated.

Symptoms of Allergies

Unfortunately, the list of symptoms connected to environmental allergies is very long. Not every pet develops the same symptoms or at the same intensity. That makes diagnosing an environmental allergy very difficult. Common signs and symptoms of an environmental allergy:

  • Constant itching and scratching in a pet that doesn’t have fleas or ticks.
  • Sneezing, reverse sneezing, wheezing, and/or coughing
  • Red, itchy, and watery eyes with or without discharge
  • Chewing, licking, or rubbing certain parts of the body constantly (especially the feet, face, ears, and sides)

Secondary signs will be crusts, scabs, pimples, and moist areas, which often occur when bacteria and/or yeast are introduced to damage skin from constant chewing, licking, and scratching.

Diagnostic Testing

When determining the cause of environmental allergies, it is vital to rule out additional allergies, such as food allergies and flea allergies, before doing allergy testing. It is also crucial to do a few basic skin tests to rule out secondary causes of your pet’s symptoms. These include combing the fur to look for fleas and lice, skin scraping to look for parasites (i.e., demodex or sarcoptes), skin cytology and ear cytology to look for yeast and/or bacterial infections on the skin and ears, respectively. These simple, painless, and inexpensive tests will also be used to determine the response to medications and likely will need to be repeated at most follow-up visits.

Should your pet’s environmental allergies become chronic, increasingly more frustrating for you and your pet, and difficult to control, then allergy testing is performed either with a blood test or intradermal skin test. We can perform blood tests here at Harmony, and this test is reasonably reliable for detecting airborne allergies but not for food or contact allergies. Skin testing, which is generally performed by a dermatologist, is considered more accurate and involves shaving a patch of hair on your pet’s side and then injecting small amounts of allergens under the skin. A positive test is diagnosed if the skin is reddening or welting after injection. Although there are potentially hundreds of different offending allergens, the tests are done with the most common allergens in the region where the pet resides and should be done at the height of their symptoms for best results. With either the blood or skin allergy testing, your pet must be off of all antihistamines, steroids, and immunosuppressive medications for several days to weeks before testing. This can be difficult for your pet to be off the medications. Bathing with medicated shampoos is often the best method to get your pet through this waiting period.

Treatment for Allergies in Dogs and Cats

The best way to treat environmental allergies is to eliminate the allergen from the surrounding environment. However, this is the tricky part because there can be many allergens causing the symptoms, and it is not always easy to determine all of them or to avoid contact with them completely. You can start by washing your pet’s bedding and any other linen they might be in regular contact with. Wash everything twice with hot water and avoid harsh detergents. If you know or suspect what might be causing the allergy (such as a flea collar or a particular chemical), immediately eliminate it from your pet’s life. If you have areas in or near your house that are moist or wet, have them evaluated and cleaned up for mold and mildew, as this can be harmful to people too, and these allergens cause year-round skin and possibly respiratory problems.

In this area of the country, it is highly recommended that all pets with any form of allergies and their housemates be protected with year-round flea and tick preventatives. There are topical products (i.e., Vectra, Frontline, Advantage), oral (i.e., Sentinel or Trifexis), and even effective collars (i.e., Seresto) available, and we are happy to discuss the pros and cons of each of these with you. Please understand that even if your pet is exclusively indoors and you do not see fleas, it is important to prevent fleas from entering your pet’s environment since they often worsen allergies and make your allergic pet much more miserable.

As mentioned above, most cases of environmental allergies (Atopy) in dogs and cats cannot be cured, but with commitment, continued diligence, and a team approach (your veterinary team, you, and your pet), we can often manage allergies and keep your pet comfortable. With many dog allergies, treatment is not difficult but requires commitment. The main goal of therapy is to control itching and eliminate all secondary infections. Typically prescription oral +/- topical medications, bathing, and nutraceuticals (i.e., fish oils and immune supportive supplements) are used to control the symptoms as a first line of therapy. In many cases where pets are self-mutilating, barrier methods are needed, such as an e-collar, t-shirts, or bandages, to prevent them from being able to chew and lick, which creates more damage to the skin and increases the chance of secondary infections.

To help your pet’s itchiness and discomfort, antihistamines (Benadryl, Zyrtec, Hydroxyzine), steroids (Prednisone), and/or immunosuppressive drugs (Cyclosporine) can be used. Antihistamines won’t cure allergies but can help with the symptoms so your pet feels better. They are best used at the earliest signs of itching and are most useful for mild to moderate flare ups. Steroids are often very effective in helping control the more moderate to severe symptoms caused by allergens in the body, but they can have serious side effects, so they should only be administered under the careful watch of a veterinarian. Cyclosporine immunosuppressive medication can be used in conjunction with or instead of steroids. While often very effective at controlling inflammation and itchiness, these too can have significant side effects and are quite costly, especially for larger breeds.

Antibiotics are always needed if there is a secondary bacterial infection, and anti-fungal medications are required if there is a secondary yeast infection. It is imperative that all secondary infections on the skin and within the ears are completely cleared up for all animals with underlying allergies. Until these secondary infections are addressed and resolved, even the most aggressive allergy treatment will yield poor results, and your pet will continue to be miserable.

Bathing is also recommended for many pets suffering from allergies. Bathing can help soothe itchy skin, remove topical bacteria and yeast, improve the skin barrier against allergens, and reduce the need for oral medications. Often medicated shampoos and cream rinses are recommended to help effectively alleviate the itchiness, inflammation, and infections. The best way to bathe your pet is to wet their coat with cool to lukewarm water (avoid hot water as this can make them itchier), apply a generous amount of the shampoo to their coat, massage the shampoo into all the affected areas while allowing the shampoo to remain in contact with the skin for a minimum of 10-20 minutes (the longer, the better), then rinse well. These steps can be repeated with medicated or oatmeal-based pet cream rinses or conditioners if your pet’s coat and skin are dried out by frequent bathing.

While all of the above treatments address the symptoms of allergies, the best therapy to address the underlying allergies is to use the results of the allergy testing (either blood or skin test) to diagnose the exact allergens your pet is reacting to. A laboratory can then mix together those allergens and either administer them as daily sub-lingual (under the tongue) drops or subcutaneous (under the skin) injections given weekly at home over several months to years. This immunotherapy can help diminish your pet’s reaction to the allergens over time. While many animals respond quite well to this therapy, it can take several months to a year to see optimal results. Most pets will also need additional treatments such as those mentioned above on a consistent or intermittent basis depending on the type of allergies, severity of the allergies, number of allergens the pet is allergic to, and the amount of exposure they have to the allergens.

If you see signs of allergies in your dog or cat, bring them in for a consultation as soon as possible, because the sooner we address the symptoms and causes of allergies, the more likely we will be able to control them long term.