Plastic Allergy in Cats

An allergy occurs when your cat’s immune system overreacts to an element that it considers to be an intruder. While allergies to plastics are rare in pets, they can occur. It can be a challenge to diagnose an allergy to plastic as there are numerous allergens that can be causing a reaction in your cat. Plastic is present in many household items (like shoes and carpeting) and pet products so an allergy to plastics can be hard on your cat.

When a cat is experiencing an allergy to plastics, it is the result of their immune system overreacting to the irritant upon having contact with it.

Skin reactions can occur in your cat should he have an allergy to plastic. The symptoms may be in the area of contact and/or seen under the front legs and between the toes, as well as around his face and groin. Should your cat experience an allergy to plastics, the following symptoms may be seen:

• Scratching, biting and/or licking his skin
• Hair loss
• Skin rashes
• Blisters/lesions or skin ulcerations
• Coughing/breathing difficulties
• Facial and limb swelling
• Appearing lethargic
• Chronic ear infections
• Inflammation in his paws
• Shaking of his head often
• Hives

Types 

There are different types of plastic that can be present in many different products; your cat can have an allergy to one or more than one of these types. Some common types of plastic include:

• Polyethylene terephthalate (PET or PETE): This type of plastic is often used to make medicine bottles, jars and rope. It may also be contained in recycled carpet
• High-density polyethylene (HDPE): This is often contained in milk jugs, small toys and bottles that hold shampoo and conditioner
• Polyvinyl chloride (PVC): Most common in plumbing pipes and industrial grade products
• Low-density polyethylene (LDPE): A flexible plastic that is found in sandwich bags, plastic wrap and grocery bags 
• Polypropylene (PP): This type of plastic can handle high temperatures and is often present in Tupperware and bottles of syrup
• Polycarbonate: Found in baby bottles, cd’s, and eyeglasses, this type of plastic performs well in high impact situations

A contact allergy occurs when the mast cells of your cat’s immune system mount an aggressive response to an element or elements of the plastic. The role of the mast cells is to protect your cat’s body from pathogens. Should your cat’s immune system be triggered by a substance, the mast cells will release a histamine (a compound that occurs naturally and causes inflammation in the tissues it comes into contact with) in order to combat what is seen as an intruder. The histamine leads to itchiness and inflammation in your cat’s skin.

Should you notice concerning symptoms in your cat, you will want to take him to the veterinarian for an examination. Your veterinarian will conduct a full physical exam and ask you for details in regards to the symptoms you have noticed, when you first saw them and any changes you have observed. Upon viewing the skin symptoms in your cat, your veterinarian will likely take a sample of his skin cells through skin scraping. This will allow him to view the cells under a microscope to see if there are any parasites, yeast or bacteria that may be causing his symptoms. Upon ruling those out, your veterinarian will consider possible causes of an allergic reaction. 

In allergies to plastics, skin reactions are often present around your cat’s face and groin, under his front legs and between his toes; though they can be in other locations of his body. Should your veterinarian think your cat is experiencing an environmental or contact allergy, he might recommend a patch test (also called an intradermal skin test) in order to confirm what is causing his symptoms. This testing involves injecting a very small amount of the allergen that your veterinarian suspects is causing the problem under your cat’s skin. This will cause a local reaction. Since plastic is not a common allergen for cats, unless it is suspected it may not be a part of the patch test. Often, an allergy to plastic will not be confirmed until all other possible allergens are ruled out, leading to plastic being a consideration.

Upon confirming that your cat has an allergy to plastic, your veterinarian will consider how to treat his allergy. Antihistamines are often the first option to try, though they are found to not be effective in all cats and over time your pet may develop an immunity to them. Shampoos and topical ointments that contain hydrocortisone are useful to minimize itching and discomfort, though you will want to do your best to ensure that your cat does not lick these products off as the chemicals can be toxic. 

Corticosteroids (either injected or administered orally) are an option, however while they are effective, they can have serious side effects upon long-term use. Because of these potential side effects, your doctor will want to monitor your cat’s blood chemistry levels while he is being treated with corticosteroids so as to make treatment changes as necessary. 

Immunotherapy is another option, though this can be time consuming and expensive and is therefore not readily available.

Often, cats with an allergy will develop a secondary bacterial infection as a result of excessive licking and scratching of the affected areas. Should that occur, an antibiotic will be prescribed.

It is important to work with your veterinarian on how to best treat your cat as you seek to reduce or eliminate his exposure to the plastic he is reacting to. In some cases, medication will need to be continued even once symptoms have resolved themselves. Follow-up appointments may be necessary so that your veterinarian can check on the results of recommended treatment and make any necessary changes.