Ketoconazole is an antifungal medicine used predominantly for treating fungal infections, though it has additional properties which can help in the treatment of truncal alopecia. In the past it was used for Cushing’s disease but this is no longer common as the medicine can place extra stress on the liver, even leading to liver failure in rare cases. It is derived from the organic compound imidazole and works by inhibiting the process vital for the growth of fungus. In large doses it can puncture holes in the cell membrane of fungal structures destroying them by causing essential components to leak out.

If you notice your dog becoming patchy and shedding large amounts of hair you should speak to the vet for diagnosis as they could have mange or lupus.

Fungistatic Vs Fungicide: Know The Difference

Derivatives of imidazole including ketoconazole are usually fungistatic. This means that instead of directly killing fungi, they limit its growth and rely on natural processes to eliminate the infection from the body. When used in higher doses, they can become fungicidal and attack cell membranes. Fungistatic drugs are more often used as they tend to be safer, but they may not be a good option for treating life threatening infections or when the dog’s immune system function is reduced. If you’re interested in further comparing the differences you can check out the page on

Safe Dosage

Note: Do not give ketoconazole to your dog unless you have permission from your vet.

The chosen dosage and form of ketoconazole is highly dependent upon the condition being treated and the actions required. In most cases of external fungal infection it can be applied topically. Just enough should be applied to adequately cover the infected site. For internal infection it is given in pill form and often begins at a dosage of 2.2 mg/lb twice daily (this is a common dosage for treating systemic coccidioidomycos). This dosage has been mapped out on the chart below:

Chart of the canine ketoconazole dosage

For some conditions the pill-form dosage may be as high as 10 mg/lb or more. For safety reasons you shouldn’t begin administering this medicine unless your vet has advised you to do so. You should wear gloves when using the topical form and wash your hands thoroughly after application.

Example: If a dog weighs 50 lbs you would give them 109 mg, which is about half of a regular 200 mg pill.

Is It Safe?

Ketoconazole is commonly prescribed by vets, even though it has not yet been approved by the FDA for veterinary purposes. Some ‘azole’ antifungal medicines have been approved for veterinary use by the FDA, however, including thiabendazole. When treating certain conditions like aspergillosis, thiabendazole is thought to be just as effective. You can read the study here.

Even though ketoconazole isn’t FDA-approved, many veterinary professionals consider it to be safe for use. Safety regarding the external use of ketoconazole creams and shampoos has not yet been established, however there are typically less side effects reported following topical use aside from skin irritation in rare cases.

Contraindications & Drug Interactions

There aren’t many contraindications associated with this medicine, though it could be unsuitable for dogs with liver problems, especially when given at higher doses. Drug interactions are relatively extensive.

Safety Guidelines

To ensure safety through treatment you should always visit the vet for a recommended dosage and plan of treatment before you begin administering the medicine. It has no effect on kidney function which means it’s safe for those with kidney disease and may even aid the condition.

During long term or high dose use you should have your vet monitor your dog’s liver function.

Minimizing The Risk Of Hypocorticolism

Because the drug inhibits cortisol production, some dogs will require prednisone to be given in conjunction to avoid developing symptoms of Addison’s disease.

How Can It Be Used?

As an antifungal medicine it is usually introduced for the treatment of fungal infections, internal or external. Aside from this it can be used to treat the following conditions:

  • Cushing’s syndrome (rarely)
  • Truncal alopecia
  • Histoplasmosis
  • Blastomycosis
  • Meningitis

There is not yet much evidence supporting its effectiveness for treating alopecia (another term for hair loss). However, it is commonly used for androgenetic alopecia in humans (Nizoral shampoo), which is similar to truncal alopecia when it occurs as a result of hyperandrogenism. If your dog suffers from this condition you can find out more on the topic of hyperandrogenism in dogs here.

What’s the difference between Cushing’s syndrome/disease?

Cushing’s disease and Cushing’s syndrome are two different things. Cushing’s syndrome occurs when a dog is exposed to high levels of cortisol for long period of time while Cushing’s disease is when the adrenal or pituitary gland are causing the body to produce too much cortisol. Cushing’s syndrome can occur as a result of Cushing’s disease but can also be caused by treatment with corticosteroids such as prednisone. It’s important to note that ketoconazole was not licensed for thise purpose, which means treatment of this condition with the drug is considered off-label. We do not recommended it due to the potential for liver damage when given to dogs with Cushing’s.

Side Effects In Dogs

Serious complications during treatment are uncommon. Liver damage predominantly occurs when very high doses are used or when the dog has existing liver problems. Here are some of the adverse effects your pet may experience:

Most Common

  • Loss of appetite
  • Nausea
  • Diarrhea
  • Vomiting


  • Liver damage
  • Changes in the coat color
  • Infertility (in males)
  • Hypocortisolism
  • Skin irritation

Watch out for signs of drowsiness combined with a yellow tint to the gums and whites of the eyes. These signs often indicate liver damage and require immediate attention from a vet.

Note: If your dog suffers with nausea or vomiting, most often when the pill-form is used, you may want to ask your vet about itraconazole. Itraconazole can treat many similar conditions with a reduced incidence of nausea.


Call the vet immediately if you suspect your dog has received an overdose. While the effects of an overdose are not yet known, we can reasonably assume that excessive stress is placed upon the liver.