Yeast Infection in Dogs – What Is It and What to Do About It
Is your dog itching like mad on his ears and other parts of his body? Perhaps he’s suffering from a yeast infection. Fungal infection in dogs is quite common and is typically not life-threatening. However, it may be very uncomfortable for your pet.
In this post, you’ll learn everything you need to know about yeast infection in dogs. Find out why yeast invades your dog’s skin, what its symptoms are, and what remedies are available to treat it. We’ll also take a look at possible complications and how you can prevent fungal infections in the future.
What is a Yeast Infection in Dogs?
Yeast infection is a skin condition caused by an overgrowth of yeasts. The infection causes widespread inflammation and itching of the skin and ears. Yeast infection in dogs is also called yeast dermatitis.
This skin condition typically hits dogs living in hot and humid environments, where yeasts tend to thrive. Meanwhile, it can also present as a secondary infection in dogs who are immunocompromised or those suffering from underlying conditions such as:
- Food allergies
- Contact allergies
- Flea allergies
- External skin parasites
- Hormonal disorders
- Underlying skin conditions such as atopic dermatitis
- Cancer
Dogs who are on long-term chemotherapy with antibiotics, steroids, or immunosuppressive cancer drugs are also at risk for yeast dermatitis.
In severe cases, fungal infections of the skin may spread to the blood and other internal body parts. This could create infections in the lungs, spleen, blood, liver, eyes, brain, and bones. Left unattended, these yeast infection complications may cause significant damage to internal organs and will require more aggressive treatment to save the dog from further injuries or death.
Yeast Species Behind Canine Yeast Infections
Two primary yeast species can cause fungal infections in dogs:
Malassezia
The Malassezia yeast species is the most common cause of yeast infections in dogs. Canine Malassezia dermatitis is another term for the infection caused by this particular yeast group.
Specifically, it’s Malassezia pachydermatis that often triggers a yeast dermatitis episode in dogs. But Malassezia sympodialis is another related yeast that can also cause an infection, albeit rarely.
Malassezia pachydermatis has a distinct oval, round, or peanut-like shape with a monopolar budding. Meanwhile, the rarer Malassezia sympodialis exhibits a smaller built with a rounded bulbous shape and a narrow monopolar budding.
The yeast species can colonize many dog breeds. But certain breeds are found to be more susceptible to Malassezia dermatitis infection:
- Shih Tzus
- Poodles
- Boxers
- Basset Hounds
- English Setters
- Dachshunds
- American Cocker Spaniels
- Australian Silky Terriers
- West Highland White Terriers
- German Shepherds
Malassezia yeasts are normally present in the dogs’ skin at low numbers. They’re often found on the external ears and other mucocutaneous parts of the body such as the nose, excess skin folds, paw pads, armpits, and anal areas.
Now, these otherwise quiet fungi turn into a pathogenic form when the host dog becomes sick or immunosuppressed. An overgrowth happens, leading to skin inflammation and dermatitis. The mechanism on how these seemingly normal fungal florae turn into pathogenic ones remains quite unclear.
Malassezia pachydermatis is also the culprit for ceruminous otitis externa. This is an infection of the external ear canal, including the outer ear’s pinna. Malassezia yeast causes an allergic reaction in the ears, causing itch, discomfort, and discharges to come out of the ears. Otitis externa caused by Malassezia can either be unilateral (one side of the ear only) or bilateral (both ears).
Candida albicans
Candida albicans is another organism that can create a fungal infection in dogs called Candidiasis. It is a single-celled opportunistic organism, which means they’re normal skin dwellers just like Malassezia but turn pathogenic under certain conditions. Candida albicans can usually be found in the dog’s external genitalia, gastrointestinal tract, nose, and nasopharynx.
A dog gets infected with Candidiasis when the yeast rapidly overgrows. This is due to a sudden weakness in the immune system. Candidiasis may also infect dogs:
- With disrupted mucosal membranes
- Undergoing strong antibiotics or cancer treatments
- Suffering from diabetes mellitus
If left untreated, Candida albicans often evolve into multi-celled fungal organisms with hair-like projections called rhizoids. It then clings to the intestinal walls via the rhizoids, grabbing food and nutrients from the dog’s gut. As a result, the infected dog gets leaky gut syndrome and various nutritional deficiencies. Several problems may then stem from these conditions such as allergy symptoms, weight loss, and poor circulation. Candidiasis may also manifest itself in ear infections, food sensitivities, and skin or coat problems.
Symptoms of Canine Yeast Infections
Yeast infections in general can present with several troublesome symptoms. We’ll enumerate the signs and symptoms of yeast infections as seen in Malassezia dermatitis and Candidiasis, respectively.
Malassezia dermatitis
- Skin inflammation – can either be generalized or localized around the ears, neck, armpits, nasal folds, in between the digits and paw pads, and the anal area
- Intense itchiness
- Sores
- Redness
- Oily and greasy coat
- Hair loss
- Rancid and foul-smelling skin
- Yellowish-green discharge in the ears
- Redness around the lips and the muzzle, suggestive of intense facial itchiness
Canine Candidiasis
- Rashes and fungal skin issues almost similar to Malassezia’s symptoms
- Urinary tract infections, evidenced by difficult urination and/or scanty urine
- Fatigue or complete lethargy
- Digestion problems
- Itchy and watery eyes (with or without discharge)
- Oral thrush
- Unusually foul-smelling bowel movements
- Constipation
- Halitosis (bad breath) that’s even worse than typical dog breath
- Ear discharge
How Are Skin Yeast Infections Diagnosed?
Some cases of skin yeast infections can be diagnosed by vets simply by assessing and looking at the affected skin. However, to be sure what kind of yeast a dog has been infected, vets may perform other diagnostic tests.
Cytologic examinations are commonly used by vets to determine a yeast infection. The veterinarian will take samples of your dog’s affected skin or hairs. These will be evaluated under a microscope, looking for yeast such as Malassezia or Candida albicans. There are five techniques to get skin samples from your dog:
Clear acetate tape sampling
This method uses a clear acetate tape (usually Scotch Tape) to obtain yeast organisms. The tape is gently pressed to the dog’s skin, bringing with it skin samples and microscopic organisms. The samples are then viewed under a microscope.
Skin Scraping
This sampling technique uses a blade to gently scrape some surface skin cells from your dog. The collected sample is then checked for the presence of yeast under the microscope.
Impression Smear
A microscope slide is directly pressed onto the dog’s affected skin. This allows yeast organisms to be directly impressed or transferred to the slide, ready for microscope viewing.
Cotton Swab Sampling
A sterile moistened cotton swab is rubbed on the affected skin to collect samples of yeast organisms and other infectious agents. The specimen on the swab is then transferred carefully to the microscope slide.
Skin Biopsy
This is a mildly invasive procedure wherein a small skin plug is removed from your dog. A local anesthetic will be applied to your dog before the procedure. Skin biopsy is the most invasive sampling technique, yet it gives the most detailed information about the causative agents of your dog’s yeast infection.
Often, cytologic exams are enough to effectively pinpoint a yeast infection on the skin. The sampling technique to be used will depend on the presenting signs and symptoms, as well as the severity or mildness of your dog’s condition. Your vet may also identify other infectious agents exacerbating your dog’s condition such as bacteria, viruses, or other fungi types.
Diagnosing Yeast Ear Infections
If your vet suspects an ear infection, he’ll use an otoscope to check your dog’s ears. This is to see if there’s anything inside the ear canal that may be causing the yeast infection.
Sometimes, otitis externa can truly be painful for dogs. An otoscopic examination may not be possible in such cases. Vets typically sedate the dog first so that he won’t feel the pain as his ears are examined. The vet will then palpate and assess the ear canal to check for swelling, itchiness, fibrosis, discharges, and any other physical symptoms present.
Note that Malassezia and Candida albicans can both produce ear discharges and infections in a dog. Hence, your dog’s vet may collect ear discharge samples to confirm what kind of yeast has overgrown and invaded your dog’s ears. The vet may also determine the presence of bacteria and other organisms that may be causing additional discomfort for your dog.
Treatment for Yeast Infections in Dogs
Yeast infections are primarily treated topically. However, severe cases where there is already a widespread internal infection may require a systemic treatment course as well.
Malassezia Dermatitis Treatment
Topical and systemic treatment can both be done to eradicate Malassezia pachydermatis. Spot treatments are good for mild cases where only localized small areas are affected.
Your vet may require you to bathe the dog in an antifungal shampoo. According to an evidence-based review, a shampoo comprised of 2% miconazole nitrate and 2% chlorhexidine gluconate is effective when used twice a week. As you bathe your dog, allow 10 minutes for the shampoo’s lather to stay in your dog’s skin and coat before rinsing.
Ketoconazole and itraconazole are two oral antifungal treatments that may be prescribed in conjunction with topical treatment. They may also be prescribed as the sole treatment method if topical therapy proves to be impractical or ineffective. The typical dosing for these oral medications is as follows:
- Ketoconazole – 5-10 mg/kg given once or twice a day
- Itraconazole – 5 mg/kg given once a day or two consecutive days every week
Your vet will decide on the best dosage and schedules depending on your pet’s condition. Note that recurring cases of Malassezia dermatitis may require higher doses.
While topical medications take care of the skin, the itchiness often doesn’t go away quickly. Give your dog some time and consider directly dealing with his scratching behavior by providing distractions [1] such as toys. You may also place your dog on an Elizabethan collar to help him control his urge to scratch so that it won’t interfere with the treatment placed on his skin.
Otitis Externa Caused by Malassezia Treatment
Your vet will primarily address the inflammation and pain that otitis externa is causing to your dog. Anti-inflammatory therapy with glucocorticoids is given topically to relieve pain, tone down the swelling, and provide comfort to the dog. Products containing mometasone, fluocinolone, betamethasone, and dexamethasone may be initially administered to your dog.
Once pain and swelling are relieved, the treatment course targeting the underlying causes is commenced. Your dog will be more eager to comply with treatment when he isn’t feeling extreme pain, itchiness, and swelling on his ears.
Now, your vet may gently clean your dog’s ears to get rid of all the discharges and other impurities. Ear drops such as the antifungal/antibacterial combo of enrofloxacin will be given to the affected ear. This medication is used to treat ear infections caused by bacteria, fungi, and yeasts.
Veterinary drops containing nystatin, clotrimazole, or ketoconazole may also be used to specifically target Malassezia in your dog’s ears. They come in a compound ear drop form, with other ingredients such as antibiotics and corticosteroids.
Systemic treatment is usually not required in otitis externa brought about by Malassezia overgrowth. Such treatment should start only if the dog’s ear infection is suspected to be deeper (otitis media or otitis interna) and in recurrent and chronic cases of otitis externa.
Candidiasis in Dogs Treatment
Topical antifungals such as nystatin ointment, amphotericin B, 1% iodine solution, or antifungal shampoo combinations are used to treat oral and skin symptoms of candidiasis in dogs. Your vet will determine how long these topical treatments should last, depending on the severity of candida infection in your dog.
Candida albicans overgrowth in the gastrointestinal tract is treated with oral antifungals. It can either be ketoconazole or fluconazole.
Treating Candida albicans overgrowth and infection also requires strengthening your dog’s immune system. Note that candidiasis often happens when a dog becomes weak and immunocompromised for some reason. That’s why giving his system a boost through proper nutrition, adequate rest, moderate exercise, and anxiety reduction will all help in beating Candida albicans overgrowth in his body.
If your dog has diabetes, your vet will develop a treatment plan centered on controlling Cushing’s disease and other complications that may occur during a Candida overgrowth.
Candida albicans flourishes inside a dog’s body when there are enough sugar stores for them to feast on. Your vet will advise a diet rich in nutritious foods and low in sugar so that the yeasts will gradually return to normal levels in the gut.
Yeast Infection Prevention
The best way to ensure that your dogs are protected from yeast infections is to keep them generally healthy. It’s really all about the basics of giving your dog nutrition, safety, security, and comfort [2].
So, you must:
- Give your dog ample food and water
- Provide moderate physical activity
- Practice good overall hygiene
- Spare enough time for him to rest and sleep
- Remove any environmental hazards detrimental to his safety
All these healthy dog lifestyle practices will bring your dog in a tip-top state, up his immune defenses, and keep yeast overgrowth at bay.
Also, you can help your dog prevent reinfection by strictly following the treatment options set by your veterinarian. Don’t stop treatment just because your dog already “looks healthier and recovered”. Continue the antifungal treatments for the prescribed duration so that your dog won’t be resistant to the medications in the long run.
Wrapping It All Up
Yeasts are normal dwellers in a dog’s body. However, an overgrowth and subsequent infection may be triggered by factors such as a weakened immune system and underlying medical conditions.
Yeast infection in dogs can either be caused by Malassezia pachydermatis or Candida albicans overgrowth. Malassezia often produces skin and ear-related symptoms, while Candida infections are more systemic.
Nevertheless, your dog’s veterinarian will diagnose the condition and provide the ample antifungal regimens to bring back your dog to a healthier and yeast-balanced state!
References:
- Volhard, J. & Volhard, W. (2010). Dog training for dummies (3rd ed.). Wiley Publishing, Inc.
- Sundance, K. (2017). Dog training 101: Step-by-step instructions for raising a happy, well-behaved dog. Quarto Publishing Group USA Inc.
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5603939/
- Taboada J., (2018). Candidiasis. MSD MANUAL Veterinary Manual. https://www.msdvetmanual.com/generalized-conditions/fungal-infections/candidiasis
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6294027/
- Negre A., Bensignor E., Guillot J., (2009). Evidence-based veterinary dermatology: A systematic review of interventions for Malassezia dermatitis in dogs. Veterinary dermatology. https://www.researchgate.net/publication/23800300_Evidence-based_veterinary_dermatology_A_systematic_review_of_interventions_for_Malassezia_dermatitis_in_dogs
- Wikipedia. Elizabethan collar. Wikipedia Org. https://en.wikipedia.org/wiki/Elizabethan_collar
- Woodward M., (2020). Otitis Externa in Animals. MSD MANUAL Veterinary Manual. https://www.msdvetmanual.com/ear-disorders/otitis-externa/overview-of-otitis-externa
- Paterson S., (2016). Topical ear treatment – options, indications and limitations of current therapy. Wiley Online Library. https://onlinelibrary.wiley.com/doi/full/10.1111/jsap.12583
- Food and Drugs Administration. Treating Cushing’s Disease in Dogs. FDA website. https://www.fda.gov/consumers/consumer-updates/treating-cushings-disease-dogs
- Guillot J., Bond R., (2020). Malassezia Yeasts in Veterinary Dermatology: An Updated Overview. Department of Clinical Sciences and Services, Royal Veterinary College, Hatfield, United Kingdom. https://www.frontiersin.org/articles/10.3389/fcimb.2020.00079/full
