My tuxedo cat is half bald. What is causing it?

Cat with a large area of hair loss that could be due to hyperthyroidism

My tuxedo cat is half bald. It started 3-4 months ago when it was a small bald patch. I have brought her 3 times to the vet, the first one said it might be caused by fleas or parasites so I got her treated for fleas, but the balding became worse and the bald spots grew larger.

The 2nd trip to the vet, I was told that it might be allergy to food, so I changed her diet to Royal Canin Skin Care.The first few weeks her fur looked less white, but then she’s started to go bald again, and even worse than before.

I have her treated with fleas every month, and she is still eating Royal Canin. She has also been showing signs of discomfort (running all around the house and excessive meowing). What might be the cause of this problem? If it is stress, what can I do to relieve it?


Hi Mysa, thanks for visiting and asking. The vet is the best person to diagnose. As you have tried and failed thus far I’ll make a suggestion but I am not a vet. This response is a discussion point. What you could do is try a different vet. Some are better than others. That sounds obvious but it can make a big difference.

I don’t think this is due to fleas because a flea bite allergy causes itching causing overgrooming,  causing localized hair loss. Also, you’ll probably see red patches (blisters) on the skin which is a symptom of an allergy.

Your cat has a large area of even hair loss and it is not due to overgrowing.

Another sign you have mentioned is:

She has also been showing signs of discomfort (running all around the house and excessive meowing)

This second sign indicates to me hyperthyroidism (excess production of the thyroid hormone). The symptoms of hyperthyroidism include:

  • hair that pulls out and hair loss
  • greater activity from the cat (you say she is running around the house)
  • increased appetite
  • weight loss

She may not have all these symptoms but she appears to have one of them: increased activity. The meowing may be due to discomfort and anxiety or just part of the increased activity.

Treatments are available – please see your vet again or a new one asap. Hyperthyroidism can cause other health problems such as high blood pressure which in turn causes other problems such as heart, kidney, and eye problems.

Hyperthyroidism is almost always associated with cancer. But as stated, it is treatable.

Ask your vet about this. He should palpate (gently feel) the area under the chin with the head lifted. He may feel a small lump. He’ll do blood work etc..

If it is due to something else such as stress Feliway may help. This is my best shot answering your query.

Good luck to both of you.

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Michael Broad

Hi, I'm a 71-year-old retired solicitor (attorney in the US). Before qualifying I worked in many jobs including professional photography. I have a girlfriend, Michelle. I love nature, cats and all animals. I am concerned about their welfare.

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  • You need to be hyper-vigilent on this issue. Look at food ingredients, chemicals used in the home, perfumes, air fresheners, fleas/flea treatments, stress from any number of things. Is the cats scratching? This indicates itching, which indicates a reaction to something. It could be an allergy to a food ingredient. Look at the ingredients on the label for Royal Canin Hair & Skin care food: Notice any potential offenders?
    Chicken meal, corn gluten meal, chicken fat, rice, corn, natural chicken flavor, chicken, dried brewers yeast, rice hulls, pea fiber, dried beet pulp (sugar removed), soya oil, anchovy oil (source of EPA/DHA), calcium sulfate, potassium chloride, DL-methionine, dried egg product, taurine, Vitamins [DL-alpha tocopherol acetate (source of vitamin E), inositol, niacin supplement, L-ascorbyl-2-polyphosphate (source of vitamin C), D-calcium pantothenate, biotin, pyridoxine hydrochloride (vitamin B6), riboflavin supplement (vitamin B2), thiamine mononitrate (vitamin B1), vitamin A acetate, folic acid, vitamin B12 supplement, vitamin D3 supplement], choline chloride, L-cystine, sodium tripolyphosphate, Trace Minerals [zinc proteinate, zinc oxide, ferrous sulfate, manganese proteinate, copper proteinate, copper sulfate, manganous oxide, calcium iodate, sodium selenite], marigold extract (Tagetes erecta L.), rosemary extract, preserved with natural mixed tocopherols (source of vitamin E) and citric acid.

    Allergies can be tough to figure out. Start keeping a journal with brief daily notes about what food is eaten. Check the labels. Be informed about what the ingredients mean.

    Is the cat indoors or out or both? They can be allergic to grass or the chemicals used in it.

    Any new stresses in the household? New items? New people? New problems?

    I doubt if a vet would be very helpful in this case. I'd try on my own first, but that's because I have a very investigative nature. Must have been a detective in my past life!

    I hope you find the answer.

    • Hair loss has many causes. Dr Fogle a well-known vet/author says that almost every time the cause is over grooming due to an itchy skin which in turn is due to a wide range of possible causes such as allergies, parasites etc.. There are too many chemicals in the home, some of them built into the furnishings (e.g. carpets). These chemicals can cause allergic reactions. Then there is food allergies - the list goes on. Flea allergies are the biggest cause.

  • I have been thinking of bringing her to another vet too. Hyperthyroidism does sound serious if not treated and she has 3 of the 4 symptoms you mentioned. Thank you so much for your help!

    • Hi Mysa. It could be hyperthyroidism. I would recommend a different vet. It always pays to find one that you feel is good. Experience counts too, you know. A vet should be 35 years of age at least if he qualified at say 25. Ten years is about right to get experience and to keep fresh. That is just my opinion.

      Experience counts and a young vet has not got it. I have no idea how old your vet is.

      Good luck and if what I wrote helps even a tiny bit it will please me a lot.

  • I wonder how old this cat is. Hyperthyroidism sounds not so good. Isn't that a kidney thing. Does it come from a dry food only diet?

      • Being young indicates that it is not hyperthyroidism. Most cats with this disease are older or old. However, about 6% are under aged 10 so younger cats can suffer from it.

        I have never seen stress cause such a loss of hair. If it is stress do you see signs of stress? Hiding, looking anxious etc. How much time do you spend at home? Separation can cause stress.

    • It's a thyroid malfunction. It is fairly commonplace and that in itself is one reason why it should be looked at. On the information this cat fits but it may be far more complicated.

    • The one thing which IS a constant is the monthly flea treatment. Maybe thats what is causing the problem.

      Try a different flea treatment?

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