Hi Lourdes,

Thanks for your question.

This is a very common problem and there could be a few reasons for it. Here they are:

1. The treatment dosage or duration was not sufficient.
2. The diagnosis is wrong and it is not solely a bacterial infection (it could be a bacterial infection on top of an underlying condition, or it could not be a bacterial infection at all).
3. The bacteria is resistant to that particular antibiotic.
4. There is a contributing environmental or medical issue causing the failure of the treatment.

The first thing I would consider is to perform a bacterial skin culture and sensitivity. This is where a swab is taken of the surface bacteria and it is grown in the lab to identify it and indicate which antibiotics will be successful in eliminating it. There are many times that resistant infections do not respond to first-line antibiotics.

I also recommend that you perform further diagnostic tests to determine if this is actually a different condition or if there is an underlying condition contributing to it. For example, I would recommend a skin scraping to see if there is a yeast infection as well or instead of, a bacterial infection. I would also recommend routine blood work and urine testing to determine if there is an underlying health issue, such as Cushing’s disease or diabetes mellitus, which could be interfering with the body’s ability to fight the suspected infection.

Lastly, I would have your veterinarian review the dosage and treatment regime you have performed. They may want to review the dosage, possibly extend the treatment, add another medication to assist it or other such possibilities. You could consider visiting a veterinary dermatologist if treatment continues to fail.

I hope this helps.

Dr. Clayton Greenway