Nothing Will Cure My Cat's Crusty Skin and Bacterial Infection

CatChannel and CAT FANCY cat veterinary expert Arnold Plotnick, DVM, describes the right steps to take to treat a cat's skin infection.

By Arnold Plotnick, DVM | Posted: October, 14, 2011, 3 a.m. EDT

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Q: We have a female cat (about a year old) who has developed a serious bacterial infection on her ears, face, nose, toes and back. The cat started with itchy lesions in her ears, and she was treated for ear mites, then she developed a hard thick crust on the rest of her "areas" that glowed under a black light. My vet treated for ringworm.

Our cat’s veterinarian has been treating her with prednisone, griseofulvin, Clavamox, miconazole nitrate and medicated baths. She is negative for FIV and other known viruses, however, she is anemic, so we have been giving her Pet-tinic. Results of a culture showed only bacteria. We also have been putting tea tree oil on her back and ears and she has shown improvement on her back but not the ears (there is crusty black substance that comes out when cleaned). She improved tremendously after her first vet treatment, but about 3 weeks later she got worse. We are not sure if it is hereditary since she was a stray. We are contemplating euthanasia at this point. However, we thought we would ask if you had any suggestions before we make this decision.

A: It is very difficult to comment on cat skin problems without seeing the skin lesions myself, but I will try.  

You have a young cat that started out with itchy ears. Certainly, ear mites would have to be high on the list of possible causes. You said that she was treated for that. I’m assuming that the treatment was definitive and that she was re-evaluated afterward and that no mites were detected. You then said that she developed hard thick crusts on the rest of her body – her face, nose, toes and back, and that these glowed under a black light. Veterinarians use a black light (called a Wood’s lamp) to identify the best hairs to sample for performing a fungal culture for ringworm.  You don’t mention if your veterinarian did an actual fungal culture and whether or not it was positive.  Crusts and flakes on the skin can sometimes appear to be glowing under a black light, when in fact they are not glowing with the characteristic “apple green” color that suggests ringworm. Glowing hairs should not be assumed to be ringworm. Glowing hairs should be plucked and cultured for ringworm.

Your cat’s vet must think this is ringworm, because he’s treating with griseofulvin, miconazole nitrate, and medicated baths. Griseofulvin is effective against ringworm, but it’s “old school”; better, more effective options exist. I’m not sure what “miconazole nitrate” is. Is this a topical cream? Also, “medicated baths” is a vague term. I’m assuming this means you are shampooing with an anti-fungal shampoo. If this is ringworm, your cat should respond to treatment in a few weeks.

Clavamox is an antibiotic that is usually very effective against bacterial skin infections and would also be appropriate if a secondary bacterial skin infection is present. Prednisone is often prescribed for some skin problems, but it is not an appropriate drug to use if ringworm or a bacterial skin infection is suspected. In fact, prednisone could actually make things worse. From what you’ve written, it seems as if your vet is throwing the entire pharmacy at the cat. You said that she improved tremendously after her “first vet treatment,” but I’m not sure what treatment you’re referring to. She was given so many things that it is impossible to say which component of the therapy was the effective one.

A challenging case like this probably needs to be evaluated by a board-certified veterinary dermatologist.  I’m not a dermatologist, but if I were evaluating your cat, I’d have you stop all treatments, and I’d start with the basics: a skin scraping to look for mites, and a fungal culture to check for ringworm.  Then I’d prescribe a course of antibiotics to see if it’s a bacterial skin infection.

Itching and lesions around the head and face in a young cat could very well be food allergy, and I would test for that by having you feed a hypoallergenic diet – a diet containing a protein source that your cat has not encountered.  All (good) veterinarians stock these prescription diets in their hospitals. I would also perform a skin biopsy.  Immune-mediated disorders, in which the immune system “attacks” various components of the skin, can affect the ears and toes and can cause thick crusts, which you’ve described.  Most cats with these disorders tend to be older than yours, but I’ve seen it in young cats occasionally.  Diagnosis is made via skin biopsy.  This is easy to do.
Ask your veterinarian  for a referral to a board-certified veterinary dermatologist.  I’m sure you’re frustrated at not seeing any improvement in your cat, but there is an explanation for your cat’s skin condition, and I’m certain a veterinary dermatologist can provide the answer.
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Reader Comments

cheryl    tomahawk, WI

9/26/2014 7:24:23 PM

Sorry, that is supposed to say Vet rx

cheryl    tomahawk, WI

9/26/2014 7:22:51 PM

Try very rx for any infection, it's natural and is good for a lot of animals. Used it on my bunny and my dog for ear infection, helped clear it up, just make sure to follow directions for each animal

Anon    City, CA

5/6/2012 12:42:24 PM


Tony Larkman    Brisbane, AL

10/18/2011 4:11:15 PM

Tea tree oil should NEVER be used on cats.

An extract from our website (


Tea tree oil is poisonous to cats and use in felines is strongly contraindicated. There are other essential oils that are just as dangerous to cats such as peppermint and pennyroyal. The main problem is that because of their small size and body weight, combined with a liver that does not easily process essential oils like tea tree oil, cats can have a severe toxic reaction to amounts that many other animals wouldn’t even notice. Cats groom themselves frequently by licking their coat which means they will ingest any oil that is left on the coat which may quickly exceed their tolerance. If your cat is going to have a reaction to tea tree oil, you will usually see it within 2 to 8 hours following application.

Symptoms include:

loss of muscular coordination
shaking and tremors
a change in behavior

If you notice any of these consult a qualified veterinarian as soon as possible.

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