Antifungal Therapy in Dogs

Fungal infections can result from an overgrowth of your dog’s natural body flora, or due to infection from parasitic fungi. Your dog's body surface and gut contain naturally occurring Candida or yeasts that can overgrow and create a yeast infection when your dog's natural chemical balance is affected. This usually manifests on the skin as itchiness, redness, inflammation, and sores, but can also affect internal organs. Also, parasitic fungal infections such as ringworm are common in dogs. Dogs frequently have their ears affected by fungal infections, especially dogs with floppy ears and excessive hair in the ears. When overgrowth or infection by fungal organisms occurs in your dog, your veterinarian can prescribe antifungal medication, both topically and orally, to relieve symptoms and stop yeast organisms. In addition, changes to diet may help limit fungal infections from proliferating in the future by ensuring natural flora stays balanced and does not grow out of control. 

Antifungal therapies may be given orally or topically. Often a combination of both is prescribed. Topical treatments can consist of baths or rinses and/or antifungal creams applied to the affected areas. You veterinarian may take a skin scraping of the affected area and send for laboratory analysis to determine what type of yeast organism is present, which will help determine the most effective course of treatment.

During treatment, your dog should be monitored for harmful side effects and if treatment is required, long-term blood analysis and urinalysis may be recommended to ensure your dog's liver is not being adversely affected.

Oral, systemic medications that provide antifungal therapy include:

• Ketoconazole
• Terbinafine
• Itraconazole
• Fluconazole
• Voriconazole 
• Posaconazole

Various oral medications are more or less effective for different types of infections and vary in costs and side effects. Your veterinarian can advise you on the most appropriate oral antifungal therapy for your dog.

Antifungal creams are used topically on your dog's skin where fungal infections are present. Gloves should be worn to prevent spread, if contagious fungal infections are suspected. Antifungal creams soothe irritation and kill fungal infection. Common antifungal creams contain the following active substances: 

• Chlotrimazole
• Econazole
• Itraconazole
• Ketoconazole
• Miconazole

Baths with medicated shampoos to counteract oily skin may contain sulfide, or benzoyl peroxide, and may be part of the strategy to combat yeast dermatitis in your dog. This can be followed up with an anti-fungal shampoo containing chlorhexidine, miconazole or ketoconazole. These antifungal shampoos must remain on the skin for at least 10 minutes in order to be effective and will require repeating every few days for several weeks.

If a bacterial skin infection is also present with the yeast infection, antibiotics may also be prescribed by your veterinarian.

Fungal infections are not uncommon in dogs and are usually successfully treated. If infections are left until severe skin problems and secondary infections occur, antifungal therapy can prove more challenging, and additional intervention may be required, such as antibiotics. If immune system compromise or allergies is a contributing factor, and is not addressed, recurrence of fungal infections may occur.

Your dog may experience side effects from antifungal medications including nausea, diarrhea, and loss of appetite during treatment. Supporting your dog by ensuring they stay hydrated and have appropriate food that will not further aggravate gastrointestinal symptoms is required. You will need to administer medication for several days or weeks to address yeast infection. Oral medication should be given as directed and may be given with food if appropriate to address gastric symptoms. Antifungal creams should be applied as directed to skin and gloves should be worn to prevent contamination if ringworm or other contagious fungal infection is present. If contagious conditions are present, take steps to protect other pets in the home. Care may need to be taken to ensure your dog does not lick antifungal cream off after application and an E-collar or bandage may be required.

Ear infections from yeasts require intensive cleaning and aggressive treatment with antifungal creams, and the more care provided by pet owners to remove debris and hair and to ensure medication is received, the more effective antifungal therapy will be in resolving the condition. Cleaning to remove dead candida and fungus organisms after treatment is important to prevent reinfection.

The cost of antifungal therapy depends on the type of therapy required and consultation fees from your veterinarian. Systemic oral medications range from $0.40 to $11.00 per day and may be required for several days or weeks and on an ongoing basis where chronic recurrence of infection is present. Topical preparations and baths range from $5 to $50 depending on the product and may require multiple treatments to address candida infection.

Besides gastrointestinal symptoms, toxicity and liver compromise can occur with antifungal medication, especially if administered long term. Many medications are not appropriate for pregnant or lactating dogs and your veterinarian should be informed if this is a factor.

Natural antifungal medications and diet can be administered to your dog on an ongoing basis to prevent fungal infections from taking hold in your dog. Diets that support the immune system may prevent imbalance and disorder that allow naturally occurring flora to proliferate. In addition, making sure that your dog is not exposed to damp, dirty conditions by changing bedding and bathing them when required will reduce the incidence of yeast infections. If your dog has floppy ears or hair in their ears, regular cleaning, removal of hair, and natural antifungal preparations can be used to help prevent infections in the ears. Ringworm can be avoided by limiting your dog's exposure to other pets who exhibit infection or when parasitic status is unknown.