Why Your Cat Is Itchy and What You Can Do
“Pruritus” is the term veterinarians use for itchiness in pets, and it is among the most common presenting complaints in animal hospitals. In both dogs and cats, the majority of skin disease is pruritic. Unfortunately for itchy cats, direct treatment options are slightly more limited than in dogs.
The focus of treatment for pruritus is eliminating the underlying cause. Itchy skin in cats can be successfully managed in most cases once the main cause of the itch is identified, and they will be much more comfortable after treatment.
Here’s what you need to know about why your cat is itchy and what you can do about it.
What Causes Itchy Skin in Cats?
There are many causes of itchy skin in cats, but you can roughly divide them into three categories:
Infectious causes are often parasitic, although bacterial and fungal infections are common as well.
Allergic causes are usually inflammatory in nature. When your cat inhales, ingests, or otherwise comes in contact with an allergen, her immune system can overreact, so to speak, resulting in skin inflammation and itchiness.
The "everything else” category of feline pruritus is lengthy and diverse. Everything from inherited, genetic diseases to autoimmune disorders to cancers can generate an itching sensation in the skin of cats.
Once your veterinarian is able to determine the underlying cause of your cat’s itchy skin, the treatment is targeted at eliminating that cause (if possible) to minimize the itch and to improve your pet’s quality of life.
Infectious Causes Behind Itchiness in Cats
When a cat’s skin becomes infected—be it with bacteria, fungi, or parasites—itchiness is usually the result.
When an itchy cat comes into the animal hospital, testing for the most common skin infections is one of the first diagnostic steps in the workup.
“Dermatophytosis” is the medical word for a ringworm infection, and it’s among the most common infectious causes of feline pruritus. Dermatophytosis can be passed to people, so testing for ringworm, either by fungal culture or a more modern laboratory test called PCR, is an important step, even if pet owners don’t believe ringworm to be the cause.
More commonly, parasitic infections (sometimes referred to as parasitic infestations) can cause cats to become itchy.
Parasites that live on the skin are called ectoparasites, a term that includes fleas, ticks, mites, and other organisms.
Because many cats live exclusively indoors, administration of flea and tick preventatives is far less common in cats than in dogs. The reluctance of cat owners to administer these products in a consistent manner is due partly to the false perception that indoor cats cannot contract parasitic infections.
The owners of itchy indoor cats are almost always surprised when told that their cat has fleas, even though fleas are present in over 50% of itchy cat cases.
Cats who are itchy on the back half of the body, especially near the base of the tail, represent a classic case of flea infestation. Your veterinarian will visually inspect the skin and fur, often using a flea comb to check for flea dirt.
Additionally, skin scrapes are commonly performed to check for the presence of mites such as demodex. However, because flea and tick preventatives are very effective in killing fleas and numerous types of mites, some veterinarians will treat itchy cats with these products first, then continue with the workup only if the itchiness persists.
Inflammatory Causes of Itchiness in Cats
Different types of allergies constitute the inflammatory issues that can lead to itchiness in cats. The most common itch-causing allergies in cats are:
While rare, inflammatory itchiness can also be caused by contact allergies.
In cats, food allergies are usually caused by proteins like chicken or fish. Despite common wisdom, grain allergies are extremely rare. People will often switch their cat to a grain-free diet, a limited-ingredient diet, or other diets, thinking falsely that these diets are the best way to reduce their cat’s itchiness.
According to veterinary dermatologists, a food trial is one of the best, most cost-effective ways to evaluate whether food allergies are contributing to a cat’s itch. During a food trial, the cat is fed nothing but a hydrolyzed diet. Hydrolyzed diets are prescription pet foods that cannot elicit an allergic response because the proteins in the food have been broken up into such small pieces (amino acids) that the immune system cannot recognize them as foreign proteins, so they don’t trigger the allergic reaction.
Food trials typically last eight weeks (although there is emerging evidence that shorter food trials are possible with the aid of steroids, at least in dogs).
After eight weeks, the cat’s itch level is reassessed. If the itch is dramatically improved while on the hydrolyzed diet, but quickly returns when other diets are given, a food allergy is the primary culprit. These cats should be fed a hydrolyzed protein diet or a novel protein diet throughout their lives.
Environmental allergies are caused by allergens that are inhaled by cats, who then develop the allergic skin condition known as atopy.
These allergies can be strongly suspected based on factors like seasonality or regionality, but definitive diagnosis involves intradermal allergy testing. Allergy blood tests are readily available but are less reliable than intradermal testing.
As with people, intradermal allergy testing in cats involves the injection of small amounts of dozens of common potential allergens (done under sedation or anesthesia), then visually inspecting the skin’s reaction to each of the injections.
Since environmental allergens like dust and pollen are nearly impossible to avoid, allergy testing is most useful in cases where pet owners are interested in pursuing hyposensitization therapy (allergy shots).
Flea Bite Hypersensitivity
Flea bite hypersensitivity, also known as flea allergy dermatitis (FAD), is the number one cause of skin disease in both dogs and cats.
FAD is an allergy to flea saliva, resulting in a disproportionate immune response and severe itchiness after even a small number of flea bites. Itchiness in the rear half of a cat’s body is the classic clinical presentation of FAD.
Because so few fleas can cause such dramatic levels of itch, elimination of 100% of fleas is the goal, both in the environment and on the cat. Other insect bites, such as mosquito bites, can induce a similar but milder skin reaction and itch.
Contact allergies, while rare, can cause cats to become itchy after coming in contact with an allergen.
Reactions to cat litter are one common example, but certain fabrics, dyes, cleaning materials, plastics, and plants can also cause contact allergies.
Unlike environmental allergies, contact allergies are easily avoided once the offending agent is identified, so long-term therapy is usually focused on removing the allergen rather than treating the animal directly.
Everything Else That Can Cause Itchiness in Cats
As stated above, there are many reasons a cat can become itchy. If your pet’s itchiness is not attributable to one of the infectious or allergic causes above, the remaining list of causes is quite long.
Your regular veterinarian may recommend a referral to a veterinary dermatologist at this juncture. Further testing, especially biopsies of the skin, may also be performed in-house. If further testing or referral to a specialty practice is cost-prohibitive, treating symptoms alone is sometimes possible, although less ideal.
Why Is My Indoor Cat Itchy?
Many cat owners falsely believe that itchiness, especially due to fleas, is solely an affliction of cats that go outdoors. While going outdoors does increase a cat’s risk for parasites, ringworm, contact allergies, and environmental allergies, remaining indoors does not eliminate the risk.
The list of possible causes for your indoor cat’s itch is quite similar to the list if he were an outdoor cat, although the list ranked by likelihood may appear in a different order.
How Do Vets Determine Why a Cat Is Itchy?
Generally, the first step in a dermatologic workup for an itchy cat is to perform tests that look for skin infections.
Testing for Skin Infections
Your vet will likely perform these tests to see if your cat has a skin infection that is causing itchiness:
Cytology involves transferring material from the cat’s skin to a microscope slide, either directly, by pressing the slide to the skin, or by using transparent tape to pick up cells and deposit them onto the slide.
Skin scrapes are another routine test in which a small blade is scraped across a small patch of the cat’s skin. The cells collected from the scrape are also examined microscopically for mites such as demodex.
Hairs are generally plucked from the most-affected areas and submitted to a lab for ringworm testing.
Occasionally, veterinary clinics will perform fungal cultures in-house, but this practice is becoming increasingly rare.
Biopsies and Allergy Testing
Once infections have been ruled out or treated, cats that remain itchy will usually go through several other diagnostic tests to discover the cause.
Biopsies, in which small, circular punches of skin are removed and submitted to a pathologist for review, are among the most useful diagnostics for skin disease. The downside to skin biopsies is that cats must be sedated or anesthetized to collect the sample.
Intradermal allergy testing, which must also be done under sedation or general anesthesia, is useful for identifying the allergens that trigger your cat to itch. This can theoretically be done by your regular veterinarian but is almost always performed by veterinary dermatologists due to the importance of experience in interpreting the results.
"Response to Treatment" Approach
Often, a cat owner’s budget will be stretched too thin to pursue further testing. Therefore, “response to treatment” is often used as a diagnostic:
Cats with suspect food allergies can be fed a hydrolyzed diet. If they respond well to the diet and stop itching, but quickly resume itching when the diet is switched back, a diagnosis of food allergies has been achieved.
If administration of Bravecto or another flea/tick preventative takes away the itch, a parasite infection was probably the cause.
Similarly, if your cat seems to always do better after steroid administration, the problem is probably not infectious, and is more likely to be allergic.
What Can I Give My Cat for Itchy Skin?
You should always be wary of administering your own medications to your pets. Contact your veterinarian before pursuing at-home treatment for your itchy cat.
Generally speaking, a bath is probably the safest place to start when trying to reduce your cat’s itch at home.
Warm water itself soothes the skin by washing away scabs, dandruff, and environmental allergens like pollen or dust, as well as other debris on the skin that could be harboring infections or creating direct irritation.
Do not use human shampoo products.
Shampoos that are made especially for cats generally moisturize the skin, which reduces itchiness. Cat shampoos that contain colloidal oatmeal or phytosphingosine are generally the most useful in reducing your cat’s itchiness.
If no over-the-counter cat shampoos seem to alleviate the itch, consult with your veterinarian, as a medicated cat shampoo may provide better relief, depending on your cat’s specific condition.
Human Allergy Products
Pet owners with an itchy cat will commonly ask about antihistamines as an at-home treatment for itchiness in cats. Unfortunately, while these medications are safe to try, they are nowhere near as effective in dogs and cats as they are in people, since histamine is not the main inflammatory mediator in pets as it is with people.
For cats with skin disease that manifests as itchy flare-ups rather than a chronic, daily itch, antihistamines are probably not at all helpful for reducing feline itch, except in very mild cases.
However, for the more chronic cases, antihistamines are thought to provide some benefit, and given the relative safety of these drugs, many veterinarians will recommend at least trying these medications if owners are in search of a readily available, over-the-counter solution.
One source says that the chance of any single antihistamine reducing your cat’s itch is only about 15%, but that trying multiple antihistamines will improve your odds of finding an antihistamine that provides your cat relief.
Diphenhydramine (Benadryl), hydroxyzine (Atarax), chlorpheniramine (Chlor-Trimeton), loratadine (Claritin®), and cetirizine (Zyrtec®) can all be safely tried in cats, but you should always consult your veterinarian for dosing information.
Use a Cone to Prevent Scratching
As simple as it sounds (and as annoying as it is), putting an E-collar on your cat for a week or so is a safe method to try at home of reducing your cat’s itch, especially if the skin disease appears to be focal rather than generalized.
Using E-collars will simply prevent your cat from licking the affected skin. Excessive licking increases irritation and inflammation in the skin, worsening the itch. By preventing the lick, you reduce the itch.
This will not fix the underlying issue, but you can use an E-collar to buy time between noticing your cat’s itchiness and being able to make a veterinary appointment.
Application of steroid-containing creams is generally not recommended due to the potential side effects and possibility of worsening your cat’s condition. Infections will often become worse if the body’s immune response is dialed down.
Furthermore, cats are always grooming themselves, so any product applied to the skin has the potential to be ingested by your cat. Verify with your veterinarian that the products you have at home are safe and whether they think you should use them.
What's the Veterinary Treatment for Itchy Skin in Cats?
When possible, the veterinary treatment for itchy skin in cats is targeted at the underlying cause, whether you’re dealing with infections, allergies, or other causes.
Antibiotics may be given orally or applied topically to treat bacterial infections.
Similar antifungal products are available for yeast infections in the skin.
Allergies can be treated with steroids (injectable, oral, and topical forms are all available), as well as hyposensitization therapy and food trials.
In those less-common cases where an autoimmune disease is the cause of a cat’s itch, immunosuppression is the treatment, sometimes with steroids, but usually with drugs like cyclosporine, at least for long-term control.
Apoquel, a drug commonly used to control itch in dogs, is being experimentally used by veterinary dermatologists to treat itchy cats. Research demonstrates its safety in this species, but efficacy is still being researched.
At present, most veterinarians in general practice do not have enough experience with Apoquel in cats to make recommendations about its use in that species.
How to Prevent Itchy Skin in Cats
Keeping your cat on a flea and tick preventative life-long is the most important strategy for minimizing the risk of itchy skin disease, even if he never goes outdoors and shows no obvious of skin disease.
Beyond that, prevention strategies are mostly aimed at reducing itch or decreasing the frequency and severity of flare-ups in animals already known to have skin disease.
Primrose and Fish Oils
Primrose oil and fish oil supplements provide minimal relief for itchy cats by themselves but can work synergistically with other therapies already being given to those cats. Because these supplements are so cheap, safe, and widely available, many cat owners will administer these supplements anyway in an attempt to reduce the chance that their cat will develop skin disease.
The efficacy of this method is currently unknown.
Similarly, daily oral administration of antihistamines is a strategy used to reduce the frequency and severity of flare-ups in chronically itchy cats, but administration in cats that are currently not itchy is unlikely to prevent skin disease.
There is some emerging evidence that daily administration of probiotics is useful in avoiding some types of itchy skin in pets, but this is by no means a cure-all for an itchy cat.
Featured image: iStock.com/Nils Jacobi
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