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Why is My Pet Itchy?

Why is My Pet Itchy?
May 23, 2022

Thump, thump, thump, thump, thump!… if you have an itchy pet that sound can be all too familiar. It’s the sound of their back foot hitting the floor as they try to relieve that pesky itch. Maybe your pet is losing fur or has recurrent ear infections. You have treated for fleas, and still, nothing seems to help.

Fleas are normally the first thing we think of when we see a pet scratching, and while it’s true that the number of fleas increases as the weather warms up, and allergies to fleas are common, pets can suffer from environmental and food-borne allergies just like we do! Allergies can occur due to sensitivities to cleaning products we use around the home—even to wool carpeting or bedding materials.

There are several things you can do at home, such as bathing with medicated shampoos, but severe cases may require prescription medication or skin allergy testing to discover your pet’s specific allergy. Here is a breakdown of the most common sources of your pet’s itch:

Flea Allergies

Flea allergy dermatitis (FAD) is a leading cause of allergic reactions in dogs, and while normal cats experience only minor skin irritation in response to fleabites, cats with flea allergies have severe reactions to even a single fleabite. When a flea bites your pet, some of its saliva which contains a variety of histamine-like compounds, enzymes, polypeptides, and amino acids is injected into the skin when the flea draws blood out. Some pets then have an allergic response to the antigens in the flea’s saliva.

An allergic reaction occurs when the body’s immune system overreacts or is hypersensitive to a normally harmless antigen. Pets experiencing allergic reactions are likely to be restless and unable to get comfortable, and much time is spent scratching, licking, and chewing at the skin and paws. Hair loss and open lesions, sores, and hot spots can result from this, leading to a secondary bacterial skin infection.

FAD is most likely to occur in the summer, although here in hot, humid Florida, flea infestations can occur throughout the year. Surprisingly, fleas don’t usually “live” on your pet. They hop on for a few minutes, or even a few hours to feed, and then they are off again, hiding in the pet’s environment. Fleas typically do not like to feed on people (we are too cold for their tastes), so humans rarely suffer flea bites. Therefore, it is common for pet owners to not realize there’s a flea problem unless it becomes severe. Pets with FAD only have to have one flea to be itchy for days. Pets who excessively self-groom can even appear to be completely flea free!

Dogs with other types of allergies, such as environmental allergens like dust mites, molds, and grass or tree pollens, tend to be more susceptible to FAD than dogs that don’t have any other allergies.

How are flea allergies treated?

Since it is the injection of flea saliva that causes the allergic response, the important first step is to prevent fleas from biting your pet. Even if you haven’t seen fleas on your pet in a while, it is important to continue vigilant flea treatment. Monthly oral and topical flea preventives make it easy and affordable to keep your pet parasite free.

The second step is to eliminate the existing infestation in the pet’s home environment. This includes washing pet blankets, beds, and carriers, along with throw rugs. Areas where the pet frequently rests such as sofas, chairs, and beds should be thoroughly vacuumed to help remove flea eggs and larvae, with special attention given to crevices between cushions and under furniture.

The yard is another area that may need flea control. Wildlife, feral, or outdoor cats, and even the neighbor’s dog may be a source of yard infestation. Just brief outings in the yard can result in fleas hopping onto your pet. People can unwittingly carry these hitchhikers inside with them, exposing pets to re-infestation. Outdoor flea treatments should concentrate on shady areas of flea development, such as under porches and beneath shrubs.

Sometimes, the elimination of fleas can be accomplished without the need for premise treatment because, through regular monthly use of topical or oral preventives, most fleas are killed before reproducing. However, even if the topical or monthly flea prevention used is 100% effective, getting control of an infestation can take 3-6 months due to the existing flea life stages in the environment.

Eliminating fleas from your pet and their environment may not occur rapidly enough to relieve symptoms of FAD. Short-acting steroids or antihistamines can be administered until flea control is successful. Secondary skin infections that can result from FAD can be treated with antibiotics or anti-inflammatory medication.

Food Allergies

We hear a lot about food allergies and food intolerances these days—most of us have at least one friend who has one or the other. But what is the difference between the two terms? Simply put, a food allergy causes the immune system to react in some way and can cause a wide range of symptoms, it can even be life-threatening; whereas intolerance is usually less serious and the symptoms are often limited to digestive problems. The same is true for food allergies in pets, but they can be a little more difficult to determine.

So, is it a food allergy or intolerance?

A pet can have an adverse reaction to food and it can often mimic a food allergy because there are only so many ways that the body can demonstrate a problem with food. In a pet with an allergy, the immune system overreacts and produces antibodies to substances that it would normally see as harmless and tolerable. An allergic reaction to food generally requires several exposures before the immune system begins to exhibit signs, while food intolerances usually occur the first time a pet is exposed to a certain food.

There may also be other reasons your pet is reacting to food. These include food poisoning (caused by your dog eating spoiled food or contaminated food), problematic foods like chocolate or onions, ingesting too much vitamin A or D, or ingesting plants that cause digestive upset. Plants are particularly problematic for cats. Overindulgence in fat or grease can also cause problems.

It is important to distinguish between a pet’s adverse reaction to something they should not have eaten versus a food allergy or sensitivity involving the immune system. Sensitivities or allergies typically result in skin and gastrointestinal signs. Most pets come to the vet with itchy skin or vomiting and/or diarrhea. There are less obvious signs; as well as such symptoms as hyperactivity, lethargy (lack of energy), weight loss, and scooting. Knowing the types of food your pet eats—including treats and any “human food”—and also the timing and severity of any signs and symptoms your pet develops will help your veterinarian distinguish between an adverse food reaction and a true food allergy.

Are some ingredients more likely to cause allergies than others?

Proteins seem to cause the most allergic response in dogs, especially dairy products, beef, lamb, chicken, chicken eggs, or soy, but any food ingredient can produce an allergic response.

How do I find out if my pet has a food allergy? Can we find out what the allergy is to?

Diagnosing allergies in pets is a lot like diagnosing them in humans. An elimination diet can be strictly adhered to for 8-12 weeks. During this time you’ll feed your pet a hypoallergenic pet food or a hydrolyzed protein diet formulated specifically for pets with allergies. This diet consists of limited ingredients known for being well-tolerated by most dogs or cats. It’s essential not to feed your pet any treats or table scraps during this period. Even an accidentally eaten tidbit of the offending protein can result in the invalidation of the test.

There are also blood tests that claim to identify specific foods your pet is allergic to. Unfortunately, in dogs and cats, these tests have been proven to be unreliable and are not typically a useful tool for diagnosing a food allergy.

How are food allergies treated?

The only truly successful treatment for food allergies is avoidance. Medication may be required during severe episodes, but the majority of allergies can be treated with a hypoallergenic diet. Once a diet is found that does not cause a reaction, your pet will need to stick to that particular diet. In rare instances, commercial diets are not available that your pet can tolerate, and a diet prepared at home may be necessary.

Environmental Allergies

Just as in humans, dogs can develop atopic dermatitis due to allergic reactions to environmental allergens. Many of these allergies occur seasonally, such as ragweed, grass, and tree pollens. However, others are with us year-round, such as molds, mildew, and dust mites.

The resulting allergy symptoms in humans are easy to spot: sneezing, runny nose, and watery eyes. Although dogs do sometimes display respiratory symptoms to allergies like humans, in most cases, inhalant allergy results in itchy, inflamed skin. The dog may rub their face, lick or chew its feet, and scratch under its arms. This inflamed skin can also pave the way for secondary bacterial or yeast infections on the skin or in the ears.

Inhalant allergy is less understood in cats than in dogs. As mentioned, when humans inhale these allergens, we develop respiratory symptoms. The cat’s primary reaction is severe, generalized itching that can last for just a few weeks at a time once or twice a year, or the cat may itch constantly, depending on how many types of allergens your cat is sensitive to.

How are Environmental Allergies Treated?

Skin testing or blood tests may be able to identify the allergens, then the dog can be protected from exposure to them as much as possible. Keep in mind that because most of these allergens are everywhere in the environment, this can be very difficult, and recurrent bouts are likely to occur. While a permanent cure is not usually possible, symptoms can be controlled.

In humans, allergies may be treated by “allergy shots“. These shots are designed to retrain your immune system by exposing it to very small amounts of whatever it is reacting to, such as pollen or ragweed. So the next time it is exposed to these things outside, it is less likely to overreact. This treatment is also available for dogs and cats. It can take 6 to 12 months for these shots to have a significant impact (other medications may be needed in the meantime to control symptoms) but can significantly reduce future outbreaks once the therapy is working.

Your veterinarian may be able to treat the symptoms and help your dog or cat live comfortably with the help of anti-inflammatory therapy. Corticosteroids, or antihistamines, can quickly block the allergic reaction. Newer alternatives are available to block specific chemical signals associated with an itch in pets. These drugs include daily oral medications and long-acting injections.

Immunosuppressive drug therapy can also be utilized, targeting the immune cells involved to reduce the reaction that your pet is experiencing. It can take up to 30 days to see maximum benefits, therefore it is not used for sudden allergic flare-ups.

Your vet may also recommend using a spray or bathing your pet with a hypoallergenic or medicated shampoo that can soothe itchy inflamed skin.

Contact Allergies

Contact allergies are the least common type of allergy in pets. They result in a local reaction on the skin from direct contact with an allergen. Examples of contact allergies include reactions to shampoos, flea collars, lawn pesticides, or certain types of bedding or carpet, such as wool. If the pet is allergic to a substance, there will be itching and skin irritation at the points of contact, most commonly the feet and belly. Treatment can be as easy as removing the source of the allergy, once it is identified.

A word of caution: The symptoms of allergies can be confused with other disorders or occur concurrently with them. For instance, environmental-allergy-affected dogs will often react to several allergens and often experience flea or food allergies as well. The road to allergy diagnosis and treatment can take longer than just one or two visits, but by working with your veterinarian, long-term relief is possible.

Northeast Animal Hospital