Yeast Infection due to Allergies in Dogs

Yeasts such as candida and Malassezia are a natural part of a healthy dog’s microflora, but when the immune system is compromised they can begin to grow out of control, invading and colonizing any damaged tissues. Allergies are linked to yeast infections in that allergies can exacerbate infections, cause them, or be caused by them. Changes in diet, such as the elimination of foods that encourage yeast growth, like simple sugars and carbohydrates, as well as the addition of probiotics and supplements such as Omega-3s may be beneficial in preventing or diminishing the overgrowth of these fungi.

Many yeasts are a natural and healthy part of the canine microflora, but when the immune system is compromised they can grow out of control and invade damaged tissues.

Although most allergy-related yeast infections are on the skin or in the ears, systemic infections by the Candida yeast are also possible. 

• Bladder infections
• Chronic ear infections
• Crusted or flaky skin
• Darkened skin
• Discharge from ears
• Excessive drooling
• Fever
• Gastrointestinal upset
• Greasy coat
• Head shaking or tilting
• Itching 
• Lethargy
• Loss of balance
• Loss of hair
• Loss of hearing
• Musty or foul odor
• Oily skin
• Redness
• Skin lesions or sores
• Thickened skin 
• Walking in circles

Types

Candida albicans - Candida albicans is a yeast that generally lives in the digestive tract. The overgrowth of this kind of yeast can cause a disease known as candidiasis in dogs and humans. Infections by this yeast can become systemic, which untreated may lead to infections of the urinary tract, swelling of the membranes protecting the internal organs, and may even compromise the immune system. 

Malassezia pachydermatis - This yeast is often found on the skin of healthy animals, but it can flourish to excess and release destructive enzymes on host cell membranes, which can result in uncomfortable, malodorous rashes and ear infections. Although there are many types of Malassezia yeast that attack humans, M. pachydermatis is the most likely variety to act as an opportunistic pathogen on canines.

Allergies have an adverse effect on the immune system and may leave some dogs more susceptible to yeast infections. One of the symptoms of allergies, particularly in canines, is itchy and inflamed skin. Dogs often itch this skin, leaving lesions or minuscule scratches which can become ideal breeding grounds for the yeast to grow in. Certain breeds of dog may be slightly more vulnerable to yeast overgrowth. Breeds that show a predisposition to developing yeast infections can include:

• Australian Terrier
• Basset Hound
• Chihuahua
• Cocker Spaniel
• Dachshund
• Lhasa Apso
• Maltese
• Poodle
• Shetland Sheepdog
• Silky Terrier
• West Highland White Terrier

Veterinarians can often make an initial diagnosis of a dermal yeast infection just by examining the state of the skin, however, a sample of the affected area will be required for a definitive diagnosis. The skin sample will be examined microscopically to check for the yeast as well as checking for any other parasites, bacteria, or fungi that might be present. The technician examining the sample will most likely be able to identify which type of yeast is affecting your pet. Yeast infections of the ear are also common in canines, and your veterinarian will want to check and see how deeply the overgrowth has penetrated if it has infected this area as well.

Systemic yeast infections are generally diagnosed through testing of the animal’s stool. The levels of yeast in the stool will be far greater than average in dogs who have an overgrowth of yeast in their systems, even in animals with none of the skin related symptoms. If the underlying cause of the yeast infection is an allergy, that may be more challenging to diagnose. Environmental allergies, insect bite allergies, and even food allergies can initiate an explosion in the yeast population on or in your canine.

Treating the allergy is the primary concern when dealing with yeast infections activated by allergies. Certain allergies may take several weeks before the allergen is determined and eliminated, however, and the overgrowth of yeast should be addressed in the interim. With yeast infections on the skin, topical solutions are usually offered first. Anti-fungal and yeast fighting medications can be applied using shampoos, salves, sprays, and even powders, and are usually applied several times a week.

With systemic or resistant yeast infections, oral medications may be required to return the microflora to the correct balance. It is important to note that many of the medications that are prescribed to rid your pet of the excess overgrowth are actually medicines that were originally designed for humans, but are often successfully prescribed off-label for canines. These medications are often administered for several weeks, generally for at least a week or two after all signs of the infection have cleared. Bacterial infections are common with both allergies and with yeast infections, so antibiotics are often required as well.

Changes in diet can help with clearing up a yeast infection, even when the yeast infection is not due to a food allergy. Yeast feeds on sugars and carbohydrates, so limiting these components in your dog’s diet may help alleviate the overabundance of yeast being produced. The dietary addition of probiotic bacteria is usually beneficial in eliminating the overgrowth. This can be added to your dog’s diet either by using a probiotic supplement or by serving your dog yogurt with probiotics with their food. If you choose to add yogurt, plain yogurt is best as it does not have any added sugars which may nourish the yeasts you are trying to eradicate.