Malassezia (yeast) dermatitis in Dogs


Malassezia (yeast) dermatitis and Ketoconazole (Nizoral Rx)

Question: Hi there.. I have an older rescue (8 yo) with a severe yeast overgrowth. He is on antibiotic therapy (cephlaxin, ketoconazole, and hydroxizine) with topical Dermapet spray, and when we remove the antibiotic his skin begins to "weep" again. This was an extremely severe case, and I am concerned about long term side effects of the ketoconazole and cannot seem to find drug information. He is starting to cough...and I am concerned about effects on the lungs. He is HW-. there any diet that possibly could help retard the growth of this horrid yeast? His worst spots have been neck/stomach/nose folds and naturally ears.

If you can point me in the right direction..I am an avid amateur researcher...

Thank you!!!!! Pam

Answer: Pam-

Ketoconazole (Nizoral Rx) is considered to be a fairly safe medication. It has a couple of known serious side effects but they affect only a small number of patients. It can definitely cause birth defects if given to a pregnant female, which obviously is not going to be a problem in this case. It will decrease the fertility of male dogs while on the medication by lowering testosterone levels but this is a reversible effect. A small number of patients will develop liver problems. This appears to be an idiosyncratic reaction, rather than a toxicity due to the dose or duration of treatment. These reactions are the serious ones that are seen with ketaconazole that affect small groups of patients (since the testosterone effect is really only important in dogs used for breeding). I can not find any mention of ketoconazole causing coughing.

More commonly, some dogs and cats will have gastrointestinal irritation leading to lack of appetite, vomiting or diarrhea. Ketoconazole lowers the serum cortisol levels in most patients during administration, which may make it necessary to give corticosteroids if highly stressful situations occur while the medication is being administered. This can be a serious side effect if the client or veterinarian are unaware of it and surgery is necessary or a severely stressful event does occur.

For Malassezia (yeast) dermatitis in dogs, ketaconazole usually has to be given for at least 30 days. If it doesn't work, itraconazole (Sporonax Rx) may be helpful, given for the same length of time. It is also important to use topical therapy. Using a shampoo that can help remove the greasiness, such as a tar and sulfur shampoo or other anti-seborrheic shampoo can be helpful. Using white vinegar mixed 1:1 with water as the rinse to get the last of the shampoo off can be very helpful, as well. Dogs should be bathed at least twice a week during the time they are being treated for Malassezia. Many dogs have both yeast infections and bacterial infections, so it is often necessary to treat for the Malassezia and bacterial infection at the same time.

Unless there is an underlying food allergy, I do not know of a diet that is helpful in the treatment of yeast skin infections.

Mike Richards, DVM 11/29/2000


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...