A bumper crop of naturally-occurring yeast can affect her outer, middle or inner ears and once it gets hold it will cause her to scratch incessantly. Outer ear infections are easy to both spot and treat but infections of the inner ear will need medical intervention.
If she is scratching, shaking her head and generally smells like sweet cheese your dog may have an ear infection.
What is a yeast infection?
Yeast is a fungus. It is a collection of microbes that thrives on our skin and the skin of dogs. By a force of nature yeast numbers are kept within manageable proportions but in some circumstances the yeast will begin to bud rapidly.
Of a dog, yeast prefers to live on the skin, paws and ears. If the conditions of the yeast’s habitat change (more on this later) they will proliferate and cause an infection. Without medical intervention diseases also can spread.
In addition, the animal may suffer an allergic reaction to the proteins in the yeast.
What causes a yeast infection?
Trying to find a cause of a yeast infection is rather like trying to find a cause for grass growing. If the yeast’s environment is just right it will grow, and if 'un-mown' by the body’s defences it will grow in abundance.
A dog with a lower immune system than normal (through sickness or surgery) is more susceptible to the illness because the immune system regulates the spread of yeast.
Yeast abundance can be found anywhere on a dog’s body but the anatomy of a dog’s ear is the perfect budding ground. The ear canal drops almost vertically down from the pinna (ear flap) and then makes a sharp turn towards the brain. This tight, moist and warm tube is favoured by the yeast.
An influx of water (after swimming), or contamination by debris (such as dirt) or airborne particles (such as mould and pollen) can enhance the yeast’s living quarters and stimulate its growth.
Breeds prone to yeast infection of the ear
Any dog is prone to an overgrowth of yeast but some are more prone than others. Because of their inherited genetic code or physical characteristics the following breeds warrant special vigilance to prevent yeast infections:
- Shih Tzu
- Basset Hound
- Cocker Spaniel
- German shepherd
- West Highland Terrier
- Shar Pei
What are the physical signs of a yeast infection?
You should be able to diagnose a yeast infection quite easily. What may not be so easy is for you to determine whether an infection of the pinna has spread to the inner ear. In all cases, you should contact your local vet for advice.
Smell: Yeast and bacteria release similar pungent smells as they set to work on your dog’s skin. However, a cheesy and vaguely sweet smell is in itself not a credible marker of the yeast infection.
Discharge: Brown or yellow discharge may be observed leaking from the ear.
Changes in colour and texture: The skin of the pinna may appear red and sore; in the later stages of a yeast infection it can even turn black.
Swelling: Areas overloaded with yeast may feel swollen and hot; one of the causes of this is the dog’s tendency to scratch the infected area.
Scaly, flaky or oily skin
Hair loss: Hair loss (around the ear in the case of infection of the ear) is observed in dogs with extreme yeast infections. This is caused not only by the action of the yeast but also by the dog’s scratching.
What are the behavioural signs of a yeast infection (specific to the ear)?
An abundance of yeast in the middle or inner ears will cause your dog to shake her head in an attempt to soothe the itchy feeling.
Walking in circles
Inner ear infections can affect the balancing mechanisms of the ear. A yeast infection can also cause her to feel dizzy.
Loss of hearing
Naturally, any infection or obstruction in the canals of the ear will lessen her ability to hear.
Licking and scratching
Her instinctive reaction to the itchiness of the yeast infection is to scratch incessantly. She may also be allergic to the yeast proteins, which will compound the itch.
What are the treatments of a yeast infection?
In order to prescribe the right course of treatment your vet must first establish (1) whether or not the yeast infection is an isolated occurrence, (2) what underlying symptoms may have encouraged the yeast to grow and (3) whether or not there are any bacterial infections at play. There are several tests your vet may do:
Physical inspection: Often a vet is able to determine a yeast infection at first glance.
Blood screening and urology: To ascertain underlying causes of the yeast infection.
Impression smear: Collection of yeast buds by pressing a slide against the infected skin.
Skin scrape: Collection of yeast buds using a special ‘scraper’.
Biopsy: Removing a minute piece of skin in order to study the infection.
Otoscopy: To visually inspect the infection and check for any damage to the inner ear.
Identifying and treating the cause of the yeast infection should prevent its return.
Should your vet diagnose a yeast infection of the inner ear or a widespread infection they will prescribe your dog oral medications such as fluconazole and terbinafine. Infections of the pinna and less widespread infections can be treated with topical medicines (for the skin). Your vet may also recommend your dipping the dog in a disinfectant solution.
Regular checks of your dog’s immune system and a diet of nutritious, immuno-boosting food can prevent further outbreaks of infection. A dog that has a good number of immunoglobulins in her blood is well-placed to fight infections both fungal and bacterial.