Atopy in Cats – Definition
Atopy, also referred to as inhalant allergies and atopic dermatitis, is a condition in which an animal develops immune-mediated skin allergies, called hypersensitivities or hypersensitivity reactions, to one or more things that are normal in the environment but usually don’t cause a cat to suffer any problems.
These substances are known as “allergens.” The allergens that cause atopy typically are breathed in (inhaled) or absorbed through a cat’s skin. Some of the more common allergens that contribute to atopy in cats are pollen, dust, mold, fertilizers and household chemicals.
Unfortunately, it can be difficult to differentiate atopic dermatitis from other disorders that cause feline skin problems, such as food allergies and saliva from the bites of fleas or other insects. Atopic cats may have seasonal symptoms, almost always including itchiness, that come and go early-on in the course of the disease but later become more chronic.
Causes and Prevention of Atopy in Cats
How Cats Get Atopy
Feline atopy is an inflammatory, itchy (pruritic) and abnormal overreaction by the immune system that causes a cat to become hypersensitive to regular things in the environment, called allergens, that normally wouldn’t cause it to have any sort of allergic reaction. Atopy is widely considered to be influenced by genetics.
However, the mode of inheritance is not well-understood, and factors in addition to heredity undoubtedly influence development of the disorder. Common things that reportedly have been associated with causing feline atopy include pollen, grasses, weeds, trees and other plants, molds, fungi, household cleaners, dust, dust mites, fleas, ticks, lice, animal dander or dandruff, fertilizers, chemicals, kitty litter and countless other environmental allergens.
There is no definite gender or breed predisposition for feline atopy, although most affected cats develop symptoms between 3 months and 3 years of age. The condition can be seasonal or non-seasonal, depending on the prevalence and presence of whatever is causing skin allergies in the kitty.
Many cats – reportedly up to 20% or 30% of those with atopy – suffer from concurrent food allergies and/or flea bite dermatitis that contribute to their skin problems, including itchiness, inflammation, irritation, redness and hair loss.
Preventing Atopy in Cats
Allergic reactions caused by the immune system’s hypersensitivity or overreaction to something in the environment that usually doesn’t cause a cat to develop skin problems typically can be prevented by eliminating or at least minimizing the animal’s exposure to the offending allergen(s).
Most of the time, the allergens can be identified by a veterinarian through specialized allergy tests on the skin (intradermal skin tests) or blood (seriologic tests), if the cause of the cat’s condition is not otherwise obvious.
Other prevention techniques include avoiding anything that might cause the cat to be itchy, such as fleas, ticks, mites, lice and ingredients in food that cause the cat’s skin to become itchy, red and inflamed.
There is no one simple test for feline atopy. Instead, the diagnosis is made based on the nature of the cat’s symptoms, its history and its response to treatment. There are a number of things that can be done for cats with atopy, but the “right” treatment protocol depends on what caused the condition, the cat’s overall health and the severity and length of its symptoms.
Atopy in cats rarely can be cured. However, it normally can be well-controlled with medication, dietary management and life-style changes. Fortunately, atopy is not life-threatening, but it does require life-long medical management to ensure that the cat maintains a good quality of life.
Symptoms of Atopy in Cats
Atopy in Cats – From the Cat’s Point of View
Atopy, also known as inhalant allergies or atopic dermatitis, is an immune-mediated, itchy and inflammatory disorder that affects the skin of some cats. It also can affect their respiratory system, causing breathing difficulties (also known as dyspnea).
The symptoms of atopy normally show up between 3 months and 3 years of age and tend to worsen as the cat grows older. In cats that live in North America, atopy often waxes and wanes, getting worse during the spring and summer months.
In chronic cases, atopy can become non-seasonal, progressing to where the cat has symptoms all of the time. Cats with atopy almost always have intensely itchy, inflamed skin, which in medical circles is referred to as “pruritis.” Atopy is diagnosed less commonly in companion cats than in dogs, and the characteristic signs differ somewhat between those species.
Atopy in Cats – What Owners May See
Owners of cats with atopic dermatitis may notice one or more of the following signs that alert them to their cat’s condition. Unfortunately, these symptoms can mimic those of several other disorders that cause cats to have itchy, inflamed skin:
- Intense and chronic itchy skin is the hallmark of feline atopy; affected cats will scratch, lick, bite and chew at their skin, without getting any apparent relief from their efforts
- Hair loss (alopecia); often symmetrical; can come and go and be seasonal or non-seasonal; tends to affect the feet, face, ears, tail base and underbelly most commonly
- Skin redness, inflammation and irritation
- Skin abrasions, weeping wounds, sores and scabs from self-trauma; can lead to secondary bacterial or yeast skin infections, although this is less common in cats than in dogs
- Breathing and other respiratory difficulties (dyspnea); can mimic the symptoms of feline asthma
- Smelly ear infections (malodorous otitis); swollen inflamed ears with profuse amounts of ear wax; more frequent in atopic cats than in dogs with atopy; can be recurrent or chronic
- Miliary dermatitis or one of several eosinophilic granuloma complex lesions (these are eosinophilic plaques, eosinophilic granulomas and indolent ulcers, the description of which is beyond the scope of this article)
Cats at Increased Risk
There is no reported gender or breed predisposition for atopy in cats. Most symptoms of the disorder worsen with time. True immune-mediated atopy in cats can’t be cured, but it usually can be controlled with appropriate medical management and identification and removal of the inciting allergens.
How Atopy in Cats is Diagnosed
Atopy in cats is the result of an allergic overreaction by a cat’s immune system to something that it comes into contact with in the environment, which is called an “allergen.” Usually, the cat interacts with the allergen through physical contact or inhalation.
The most consistent signs of feline atopy are skin inflammation and intense itchiness (pruritis), which can lead to weeping sores, scabs and other self-trauma, as well as some dramatic behavioral changes. Unlike dogs, atopic cats often also develop breathing difficulties, symmetric hair loss and other skin (cutaneous) lesions, in addition to pruritis.
A veterinarian presented with a cat showing this constellation of symptoms will take a thorough history from its owner and conduct a comprehensive physical examination. This will include a detailed dermatological check-up for the presence of any obvious external parasites such as fleas, lice, mites or ticks.
The veterinarian may also take deep skin scrapings and samples of plucked hair to look for further evidence of parasites. Samples taken from the cat’s ears and from any oozing skin sores can be sent to a laboratory for microscopic examination, which can be quite helpful to determining the cause of the cat’s discomfort.
In a nutshell, to diagnose atopy, the veterinarian needs to systematically rule out all other possible causes of the cat’s condition.
Based on the results of the initial evaluation, the veterinarian will probably recommend taking blood and urine samples for routine assessment. The results of these tests will typically be fairly normal in cats whose symptoms are caused by immune-mediated atopy rather than by something else.
Advanced skin allergy testing is available for cats and is conducted by referral to a veterinary dermatological specialist. Animals that are taking oral, injectable or topical steroid medications should be weaned off of those treatments for 1 to 3 months before skin allergy tests are performed, because they can skew the test results and affect their reliability.
Other drugs and supplements can also interfere with the results of skin tests. Intradermal testing is the gold standard for atopy in cats. It does require sedation and substantial clipping of the kitty’s fur. Blood (serologic) tests are also available but are much less reliable.
Probably the best way to diagnose atopy in cats is to conduct both skin and serologic tests, but this certainly will increase the diagnostic expenses.
Treating Atopy in Cats
Goals of Treating Atopy in Cats
The goals of feline atopy are to eliminate or at least minimize the cat’s exposure to whatever in the environment is causing its condition and to enhance the animal’s comfort and quality of life. Most cats will need lifelong treatment for this chronic problem.
Treatment Options for Feline Atopy
The appropriate treatment protocol will depend on the underlying cause of the cat’s atopy. Key factors will be the nature and intensity of clinical signs, seasonality of symptoms, severity of skin lesions, patient acceptance of treatments, client compliance and cost considerations.
Most atopic cats can be treated at home. Owners need to know that this is a progressive disorder that rarely goes into remission and can’t be cured. The itchiness associated with atopy often can be managed with oral antihistamines and omega fatty acid supplements.
Antihistamines can cause drowsiness, lethargy, anorexia, vomiting, diarrhea and even nervousness, so owners should watch for these side effects. Antibiotics can help cats with sores and secondary bacterial skin infections. Shampoos and topical treatments are available to help control fungal, yeast and other infections as well.
In severe cases, corticosteroids can be quite effective in controlling the itchiness associated with atopy and breaking the itch-scratch cycle. Long-term steroid use can have adverse side effects, and steroids should be tapered to the lowest daily dosage necessary to manage the cat’s condition.
Steroids are best used to provide short-term relief until atopic symptoms are brought under control. A combination of corticosteroids and antihistamines may control itchiness more effectively than steroids or antihistamines alone, and at much lower doses.
Cyclosporine is another immunosuppressant drug available to help control symptoms of atopy in cats. It is expensive and can cause vomiting, diarrhea, gingival hyperplasia, excessive hair growth, acne and other skin problems. Sometimes, allergen-specific immunotherapy (called hyposensitization or desensitization) is beneficial.
This involves injecting gradually increasing doses of the offending allergens under a cat’s skin; the allergens must first be identified by the cat’s positive reactions on intradermal skin tests. Hyposensitization therapy is known to be helpful in atopic dogs. While its efficacy in cats hasn’t been as well-established, it probably is similar to that in dogs.
Hyposensitization is best used when an animal has non-seasonal atopy and when anti-inflammatory treatment isn’t effective, causes unacceptable side effects or doesn’t provide enough relief. Physical restraint with Elizabethan collars, foot bandages, T-shirts or sweat shirts can help reduce self-inflicted wounds, although they won’t reduce the underlying itchiness that makes atopic cats scratch and chew in the first place. A warm bath every few days can provide relief simply by rehydrating the cat’s skin.
Prognosis for Atopy in Cats
With good owner compliance and individualized treatment, most cases of feline atopy can be well-managed on a long-term basis. Routine veterinary examinations, at least twice a year, are important to life-long control of this condition, especially for cats on prolonged or protracted steroid therapy.