What are the most common causes of chronic itching?

Itching in cats can involve not only scratching but also chewing, licking and rubbing. The common causes of itching in cats are a type of fungal infection called ringworm, external parasites such as fleas and mange, and allergies.

In itchy cats, we do some culture tests for ringworm, so we can be sure that is not the problem. We often recommend therapeutic trials for mange in chronically and severely itchy cats.  We always recommend stepped-up flea control and monitoring for fleas, as flea infestation can really make allergy worse!

What are allergies?

Allergies are a common cause of skin conditions in cats. People with allergies usually have hay fever (watery eyes, runny nose and sneezing) or asthma. Although cats with asthma can be allergic, most cats with allergies lick or chew their fur.

What are the major types of allergies in cats?

Flea Allergy

Flea allergic dermatitis is the most common skin disease in cats.  For the flea allergic patient, 100% flea control is essential for remaining symptom-free. 

“But doctor, I never see fleas on my pet.”  You may not see them, but that doesn’t mean they aren’t there!  Flea allergy is caused by the flea’s saliva, and it only takes a few bites to cause a problem.  Also, the itchy pet often scratches or licks so much that adult fleas are hard to find because they are removed from the body.

“If fleas are the problem, why is my pet still itchy in the winter?”  In warm climates or in our homes, fleas may survive in low numbers year-round.  Because flea allergy is so common, many veterinarians recommend instituting complete flea control before proceeding with test for itching. For most allergic pets, year-round flea treatment is an important part of reducing itch.

Food Allergy

Some pets develop hypersensitivities to foods. Various food proteins, carbohydrates, or even preservatives or dyes can all be potential food allergens. There is currently no accurate blood or skin test to determine if your cat has a food allergy. The only method of diagnosing a food allergy is by placing your pet on a carefully selected prescription or homemade hypoallergenic diet for several weeks, which is called a food trial. The diet only contains ingredients your pet has never eaten before. If the allergy signs resolve, a food challenge is performed by feeding the former diet and watching for a return of the itching.  If this occurs, a diagnosis of food allergy is confirmed.

Atopic Dermatitis

Atopic dermatitis (AD) is an inherited predisposition to developing skin problems from exposure to a variety of commonplace and otherwise harmless substances including the pollens of weeds, grasses and trees, as well as house dust mites and mold spores.  In cats that have been diagnosed with AD, allergy testing by intradermal skin testing or in vitro blood testing can identify what a pet is allergic to in the environment.  Evaluating the results of these tests helps us compile a list of allergens for a “vaccine” to decrease the pet’s sensitivity. 

Secondary Infections

Allergies are often the underlying cause of recurring skin and/or ear infections.  Bacterial and yeast infections, though secondary to the allergy, can increase your pet’s level of itching.

Can allergies be cured?

Unfortunately, there is no cure for allergy and it is usually a life-long problem. We seek to control allergies and improve the quality of life for both you and your cat.  We will formulate the best program of management that suits all involved with your cat’s care. 

Can itching be treated without the expense of diagnostic testing?

There are many anti-allergy medications to reduce itching.  These medications do not cure allergies but can help decrease the symptoms. However, without addressing the underlying cause of the allergy, the itching will return when the medication is stopped. 

Long-term use of some anti-allergy medications, such as steroids, can result in many health problems.  Working with your veterinarian to diagnose the underlying cause of the allergy and itching may reduce the need for medications or enable your veterinarian to use more specific and targeted allergy treatments.

In conjunctivitis those membranes become red and swollen. Dogs and cats with conjunctivitis normally have cloudy, yellow, or greenish discharge from the eyes; a lot of blinking or squinting; and redness and swelling around the eye. Green or yellow discharge often indicates a bacterial infection; clear or whitish discharge is more likely to be caused by allergies or a bit of debris in the eye. Usually both eyes are affected, but not always. Sometimes other signs are seen, such as itching, hairlessness around the eye, discharge from the nose, sneezing, or coughing.

What we normally call “pink eye” in people is a type of conjunctivitis. The condition can be caused by several reasons, such as bacteria, herpes virus or allergies.

Any breed of dog or cat may develop allergic conjunctivitis. All breeds predisposed to atopic dermatitis, a hypersensitivity or over-reaction to a variety of commonplace and otherwise harmless substances like pollen, are also predisposed to allergic conjunctivitis. Allergic conjunctivitis is most common in young adults but can occur at any age.

In this allergic condition, the following are frequent contributors:

• Allergies
• Atopy (genetic tendency towards allergies)
• Dust
• Food allergy
• House dust, molds

Treatment

Allergic conjunctivitis is most commonly treated with eyedrops or ointments containing corticosteroids, such as dexamethasone or hydrocortisone. Your veterinarian may check first for a scratch on the cornea (called a corneal ulcer) by instilling a yellow dye called fluorescein. If the eye has a scratch, medication without steroids is used, as steroids can delay healing of the scratch. Oral corticosteroids and/or antihistamines may also be helpful, especially in those pets with associated skin disease. Over-the-counter topical antihistamines may be beneficial, particularly in itchy dogs, but ask your veterinarian which one is best for your pet’s situation. However, topical mast cell stabilizers and antihistamines have variable clinical results.

A sterile saline eye wash can be used once or twice a day to clean the eyes and remove the accumulated discharge. Saline may also reduce surface irritation by flushing dirt, dust, debris, and pollens away from the eye.

Preventing damage to the eye is important as pets with allergic conjunctivitis may scratch at their eye with their paws or rub their face on furniture. This rubbing can lead to a corneal ulcer and associated pain and damage to the eye. Using an Elizabethan collar to prevent scratching may be part of the treatment plan from your veterinarian. This is especially important in short-faced breeds like pugs and shih-tzus, who are particularly prone to eye injuries. A recheck examination may be recommended by your veterinarian after treatment. If signs have not improved, your veterinarian may suggest sending your pet to a veterinary dermatologist or ophthalmologist for a work-up or recommending allergen testing to try and determine what your pet is allergic to. This step is usually reserved for dogs or cats with severe allergies.

Prevention

Allergic conjunctivitis is caused by allergies, so the best way to prevent it from happening again is to remove whatever your pet is allergic to from your home, if possible. Even if you can figure out what allergen they are reacting to and remove it or deal with it, you may not be able to eliminate it. If dust is found to be a cause, keep household dust to a minimum, and consider using an air purifier to filter out dust.

Allergic skin testing or food trials may be needed to find out the cause of the inflammation. In those cases, you may be able to determine if your dog or cat is reacting to something like dust or an ingredient in their food.

In many cases, allergic conjunctivitis can’t be cured, but with the help of your veterinarian (and perhaps a few steps taken around the house) it can be managed and you can make your pet more comfortable.