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Cat Health and Wellness

8 Surprisingly Common Allergic Reactions in Cats

We know that humans can be allergic to cats, but we often forget that cats have allergies, too. If your cat is wheezing, sneezing, or scratching incessantly, this could be due to an allergic reaction.

What are cats allergic to? Allergens can be split into three main categories: food, household, and environmental. Food allergies cause bloating, vomiting, and diarrhea, whereas household and environmental allergies cause itchiness, wheezing, and lethargy. The commonest allergens are beef, fragrances, and flea bites.

Allergies cannot be ‘treated’ in the traditional sense, but they can be managed and controlled. One of the main challenges is figuring out what your cat is allergic to. We’ll identify the most common allergens in cats and show you how to keep them under control.

Do Cats Have Allergies?

A small proportion of domestic cats in the U.S. (slightly less than 5%) get allergies. This equates to around 4.5 million cats across the country.

We don’t know exactly what causes allergies in cats. They may be caused by genetic factors, nutritional status, or being over-exposed (or under-exposed) to certain substances at a young age.

The substance that causes an allergic reaction is called an allergen. Most allergens fall into one of the following three categories:

  • Food
  • Household
  • Environmental (seasonal or year-round)

Just about anything can cause an allergic response, but we will focus on the most common food, household, and environmental allergens.

Symptoms of Allergies in Cats

An allergic reaction occurs when the cat’s immune system feels threatened by a particular substance (i.e., an allergen). The cat’s immune system produces antibodies to fight off the presumed threat, and it is this overreaction which causes unpleasant symptoms such as:

  • Itchiness and scratching – perhaps leading to skin lesions
  • Sneezing, coughing, and wheezing
  • Runny eyes and nose
  • Facial swelling
  • Lethargy and loss of appetite
  • Bloating, gas, vomiting, and diarrhea
  • Anaphylaxis in rare cases (difficulty breathing, rapid heart rate, and collapse)

You can predict what type of allergy your cat has by looking closely at her symptoms. For example, itching, sneezing, and wheezing tend to occur in response to household/environmental allergies, whereas bloating and diarrhea often indicate a food allergy. However, there can be some crossover between the two, and some cats may have multiple allergies.

Foods Allergy vs. Food Intolerance

Food allergies should be distinguished from food intolerances. Food allergies trigger an immune response whereas food intolerances do not. Also, a true food allergy has the potential to cause anaphylaxis, whereas a food intolerance does not.

Many cats are intolerant to foods such as sucrose (simple sugar) and lactose (milk). This is because they don’t have enough of the enzymes needed to process these foods (sucrase and lactase). The main symptoms of food intolerance include bloating, gas, diarrhea, and itchy skin.

what are the symptoms of a cat allergy?

Most cats also digest complex carbohydrates (starches) at a slower rate than other animals, but this, too, is not classed as an allergy.

A true allergy is characterized by an immune response to a food substance. True food allergies are less common than intolerances, but they still affect around 5% of cats.

1) Beef

Contrary to popular belief, meat proteins are more likely to cause allergies than cereals or grains.

According to tandfonline, beef is the most commonly diagnosed allergy in cats. It is four times more common than a poultry allergy, and five times more common than a barley/wheat allergy.

Low-priced cat foods tend to contain beef byproducts because they are cheap and easy to source.

2) Dairy

Although many cats are lactose intolerant, a small number of cats are allergic to the casein (protein) in milk.  You can usually tell if your cat is lactose intolerant or allergic to milk by the severity of their symptoms.

For example, cats who are lactose intolerant will experience bloating, mild itchiness, and diarrhea. Cats who are allergic to casein will often experience swelling, severe diarrhea, intense scratching, vomiting, and difficulty breathing.

3) Fish

Fish allergies are more than twice as common as wheat/barley allergies in cats. It is thought that salmon and tuna are most likely to cause an allergic reaction. Most owners should limit or avoid tuna entirely because it contains high levels of mercury.

Household Allergens that Affect Cats

What are cats allergic to inside the home? You’ll find that many household products are harmful to cats. For example, small amounts of ammonia (found in oven cleaners) bleach, and chlorine (found in many detergents) can be toxic for cats – not because they are allergens, but because they are irritants. These products have the potential to cause skin damage, liver disease, and cancer.

Though potentially toxic, ammonia, chlorine, and bleach are not usually considered allergens. Unlike allergens, these chemicals will cause harm to all cats – not just a few. So, are there any “allergens” in the household that affect only a small percentage of cats? Here are two of the most common household allergens:

4) Fragrances

Fragrances are found in perfumes, air fresheners, liquid cleaners, fabric conditioners, candles, cat litters, and oil burners/diffusers. There are 26 fragrance compounds that are known to cause allergic reactions in a small percentage of people and animals. The most common culprits include:

  • Benzyl alcohol
  • Benzyl salicylate
  • Cinnamyl alcohol
  • Cinnamal
  • Citral
  • Coumarin
  • Eugenol
  • Hydroxycitronella

Fragrances can be inhaled or may come in direct contact with the cat’s skin. For example, if you wash your floor with a fragranced floor cleaner and your cat goes to lay on the floor, she will come into contact with the substance.

can cats be allergic to other cats?

Inhaling the fragrance may cause a runny nose, wheezing, and lethargy. If the fragrance comes into contact with the cat’s skin, this may cause scratching/itching, redness, bumpy skin, and swelling.

Going “natural” with your products is not enough because natural, organic, chemical-free products still may contain potent essential oils or fragrance compounds that are allergenic. The best option is to look for “scent free” cleaning products and cat litters – and skip the scented candles altogether.

5) Wool (Lanolin)

A small number of cats are allergic to the lanolin in wool products. Lanolin is the greasy substance animals secrete onto their wool to keep it clean and waterproof.

Cats who have a lanolin allergy will probably experience:

  • A rash or bumps on the skin
  • Scratching
  • Lethargy
  • Sore eyes / weepy nose
  • Breathing problems (in severe cases)

Lanolin can be found in woolen blankets, rugs, and jumpers, but it is also extracted and used in some household and beauty products. According to the Department for Health and Human Services, lanolin can be found in the following products:

  • Leather cleaner
  • Hand cleaners
  • Haircare products (including pet haircare)
  • Cosmetics
  • “Paw Balm” for pets

If you suspect a lanolin allergy, you may need to switch some of the cleaning products or cosmetics in your household. Even if your cat doesn’t come in direct contact with the products, they may be inhaled or transferred by your own hands.

The resource from the Department for Health and Human Services is handy for determining which brands and products contain lanolin.

6) House Dust (Dust Mites)

Dust mites are a common allergy in cats as well as humans. Dust mites are the tiny insects that live in house dust; they are not visible to the naked eye.

Keeping your house super clean can help to protect against this allergy. This involves dusting and vacuuming daily. Also, you should purchase a “dust-free” cat litter and wash your cat’s bedding regularly.

Environmental Allergens that Affect Cats

What are cats allergic to outside the home? Cats can be allergic to many different environmental factors – some seasonal and some year-round. If you have an outdoorsy, adventurous cat, it may be hard to keep her away from the final two allergens:

7) Grass Pollen

3-5% of cats are thought to be allergic to at least one type of grass pollen. This allergy can cause symptoms such as wheezing, a dripping nose, and excessive scratching.

In the northern areas of the U.S., grass mostly pollinates in spring and early summer, but in the southern regions, grass tends to pollinate throughout the year.

If your cat enjoys the outdoors, but they have a grass allergy, it would be a shame to keep them inside permanently.  There are other things you can do to minimize the effects of a grass allergy:

  • Check local pollen counts on a daily basis and keep your cat inside if the count is very high. If the count is moderate, limit their time outdoors to 30 minutes.
  • Keep the lawn very short at all times. Close all windows and doors when mowing the law.
  • Wash your cat’s bed/blanket often.
  • If you’ve spent all day outdoors, wash your hands and change clothes before petting your cat.
  • A cat with a pollen allergy may benefit from being washed once a week with a specialist cat shampoo to remove pollen from their fur.

In addition to grass, tree, mildew, and weeds can cause allergic reactions in cats.

8) Flea Bites

Flea bites are probably the most common allergy of all. Cats who go outside and come into contact with other animals are more likely to encounter fleas, but indoor cats can be affected, too.

Symptoms of a flea allergy include:

  • Intense scratching
  • Hair loss, bleeding, and scabs (usually on the head)
  • Restlessness
  • Coughing and wheezing (if more severe)

Treating fleas as soon as they arise is very important. However, it’s important to mention that some cats are also allergic to flea treatment products.

If you suspect your cat has a flea allergy, it’s best to take them to the vet for treatment as your vet can choose a hypoallergenic treatment that’s less likely to cause further irritation.

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Can Cats Develop Allergies at Any Age?

It’s more common for allergies to develop in kittens and younger cats (less than one-year-old). However, it is entirely possible for an older cat to develop an allergy. Older-onset food allergies are more common than any other type of allergy.

How to Manage a Food Allergy

Food allergies can be quite tricky to manage. The most challenging part is establishing what food your cat is allergic to.

As mentioned, protein is more likely to cause an allergy than any other type of food. So, changing the source of your cat’s protein is a great first move. You have several options:

Rabbit or Chicken Cat Food

Feed your cat rabbit or chicken-based cat foods. Research suggests that these proteins are less likely to cause an allergic reaction. Rabbit/chicken-based cat foods are affordable and easy to buy.

Novel Protein

Try a completely novel form of protein that your cat has not eaten before such as duck, kangaroo, goat, or venison. These diets tend to be more expensive, so they might be difficult to maintain in the long term.

Hydrolyzed Protein

Look for a cat food made from hydrolyzed protein. Essentially, this means the protein has been partially broken down into its amino acids, so it is less likely to cause an allergic reaction. These diets are slightly more expensive than regular pet foods.

Hypoallergenic Cat Food

Some cat foods labeled ‘hypoallergenic’ contain hydrolyzed forms of protein. Others are considered hypoallergenic because they contain a few ingredients (one protein, one carb, and added nutrients).

These minimalist cat foods are less likely to cause a reaction. Hypoallergic cat foods can be bought in the supermarket or the vet’s office.

Home-Prepared Elimination Diet

If you prepare your cat’s food yourself, or feed her mostly leftovers, you could start eliminating one food type from her diet for two weeks at a time, to determine what is causing the reaction.

If you discover the source of the allergy, you can then eliminate this from her diet. Preparing your cat’s meals is risky because you may accidentally cause a nutrient deficiency.

Do Food Allergies Cause Irritable Bowel Disease?

Irritable bowel disease (IBD) is on the rise amongst domestic cats, but what causes this disease? Many different factors are thought to cause irritable bowel disease – one of which is food allergies.

Other causes include stress, the use of corticosteroids, genetics, and bacteria in the gut. The bottom line is, diagnosing food allergies and eliminating these foods from your cat’s diet may help to cure IBD, but this is not always the case.

Are you Sure That Your Cat Has an Allergy?

Other conditions can occasionally mimic the symptoms of an allergy. These conditions include:

  • Hyperesthesia – This condition causes the cat’s skin to ripple uncontrollably. It can lead to obsessive-compulsive scratching and strange behaviors. It is often linked to stress but may be caused by other factors. Stress is also a cause of IBD so reducing stress in the household can improve a variety of conditions in cats.
  • Asthma – There are some links between allergies and asthma, but the links are not clear. The most significant risk factors for asthma include being overweight and living around smoke. The symptoms of asthma include wheezing, lethargy and difficulty breathing.
  • Another Chronic Disease – Kidney disease, diabetes, and other long-term conditions can mimic some of the allergy symptoms such as lethargy, swelling, and difficulty breathing.

Whether you think it’s an allergy, or something else, take your cat to the vet for a full examination.

How to Manage Allergies in Cats

As you’d probably expect, the best way to manage allergies is to eliminate the allergen from your cat’s diet/environment. However, the first challenge is to establish what your cat is allergic to.

So, take note of your pet’s diet, the time of year, and any environmental influences that might be playing a role. Then, take your cat to the vet for a full examination. Through discussion with your vet, you may be able to determine a cause. Your vet may also run blood tests or other diagnostic tests.

If your cat has a food allergy, you should place them on a specialist diet such as a hydrolyzed protein diet or hypoallergenic diet. If symptoms do not improve after six weeks, see your vet again.

If the allergen is in your environment, try your best to eliminate it. This may involve cleaning more regularly and closing doors and windows to stop pollen from entering the house. Think carefully about the products you use, and check ingredients lists to see if there are any allergens on there.

Finally, fleas are the most common allergy in cats so you should provide preventative flea treatment for your cat, even if she lives indoors. Whether your cat has a flea allergy or not, keeping her flea-free will help to stay comfortable and happy.