Not in the way you've probably been told. The yeast most commonly linked to itchy, smelly skin and recurring ear infections in dogs is Malassezia pachydermatis. It lives naturally on your dog's skin and in their ears, it feeds on fats (lipids) produced by the skin, and it does not live in the gut. Cutting carbohydrates from your dog's food doesn't starve it.
The idea that carbs feed yeast largely comes from confusing different types of yeast and how they behave. This article explains the difference, the one situation where carbohydrates in your dog's food do matter for their skin, and what actually helps a dog with a yeast problem.
Where does the "cut the carbs" advice come from?
If you have searched for help with a yeasty dog, you have probably met it quickly: cut the carbs, because sugar feeds yeast. It sounds logical. But it doesn't match how the yeast on your dog's skin works, and following it can mean the real cause of the problem goes unaddressed.
The advice comes from humans, and from a different organism. Candida is a yeast that can live in the human gut, and it does use sugars. Low-sugar diets are often suggested for people with Candida problems, although even in humans the evidence for that is limited. The advice was then carried over to dogs, where the yeast, where it lives and what it feeds on are all different.
| Malassezia (dogs) | Candida (humans) | |
|---|---|---|
| Where it lives | Skin, ears and mucosal surfaces | Gut, among other sites |
| What it feeds on | Lipids (fats); it cannot make its own | Sugars, among other things |
| Does cutting carbs help? | No direct mechanism | Sometimes suggested; limited evidence |
What is Malassezia, and what does it feed on?
Malassezia is the yeast behind the greasy coat, musty smell and ears that never quite clear up that many owners of sensitive dogs will recognise. In dogs it is almost always Malassezia pachydermatis.
Two facts about it matter here.
It lives on the skin, not in the gut. Malassezia species are found almost exclusively on the skin and mucosal surfaces of warm-blooded animals (Guillot & Bond, Frontiers in Cellular and Infection Microbiology, 2020). It is a normal resident of healthy dog skin. The problem is not that it is there, but that it overgrows.
It feeds on fats. Malassezia species lack the gene for fatty acid synthase, so they cannot make their own fats and must take them from the skin (Guillot & Bond, 2020). When researchers tested M. pachydermatis directly, none of the strains could grow using glucose as their only source of carbon, which confirmed that the yeast needs lipids (Puig et al., PLOS ONE, 2017).
A yeast that can't make its own fats, and can't grow on sugar alone, isn't being fed by the carbohydrate in your dog's dinner.
Does low-carb or grain-free food help a yeasty dog?
Not because of the carbohydrate itself. There is no direct route from the starch in your dog's food to the yeast on their skin, so lowering carbohydrate across the board, or switching to grain-free, isn't a treatment for yeast.
There is one indirect possibility worth being honest about. Dietary sugar could, in theory, disrupt the gut microbiome and raise inflammation in the body, which might give an opportunistic organism like Malassezia a foothold it wouldn't otherwise have. That is biologically plausible, but it is not supported by strong evidence, and we are not going to present it as if it were. Anyone telling you confidently that carbohydrates cause yeast infections in dogs is going further than the science does.
When do carbohydrates in dog food matter for skin?
When your dog is allergic to that specific ingredient.
A dog that reacts to potato, peas or a particular grain may show skin signs when they eat it. That is a food allergy showing up on the skin, and any yeast overgrowth that follows is a result of the inflammation, not of the sugar. The answer is to identify and remove the ingredient your dog reacts to, which is what an elimination diet is for, rather than to cut carbohydrate generally.
The difference matters. "Cut all carbs" and "find the ingredient your dog reacts to" lead to very different diets and very different results.
Is the brewer's yeast in dog food a problem for a yeasty dog?
No. Owners often spot brewer's yeast on a label and reasonably wonder whether they are feeding the problem. Brewer's yeast (Saccharomyces cerevisiae) is used in dog food as a nutritional ingredient, a source of B vitamins. It does not live on the skin, and it has nothing in common with Malassezia beyond the word "yeast".
As with any ingredient, a small number of dogs can be sensitive to brewer's yeast itself. That is an ingredient sensitivity, not a yeast infection.
For transparency: brewer's yeast is in Good Gut Grub (4%), all three of our wet recipes and Top Dog All-In-One. All-Day Buffet does not contain it.
What actually helps a dog with a yeast problem?
Yeast overgrowth is nearly always a sign of something else rather than a diagnosis on its own. Something has disrupted the skin's defences, and Malassezia has taken the opportunity. Common underlying causes include:
- Allergy, to food or to something in the environment. This is the most common, and it is why recurring yeast problems and recurring ear infections so often go together.
- Moisture and skin shape, such as skin folds, heavy ears and dogs that swim.
- Hormonal conditions such as hypothyroidism or Cushing's disease.
- Anything else that weakens the skin's normal defences.
Treating the yeast clears the current flare-up. Finding out what let it overgrow is what helps reduce the chance of the next one. If your vet suspects a food allergy, an elimination diet based on a protein your dog has never eaten is the way to find out. It needs to be run carefully and for long enough to give a clear answer, with your vet's guidance; our guide to hypoallergenic dog food explains how elimination diets work.
When should I see my vet?
An active yeast overgrowth needs veterinary treatment in its own right, such as medicated washes, ear cleaning or antifungal medication (Bond et al., Veterinary Dermatology, 2020). Diet may address an underlying cause; it does not treat an existing infection. If your dog's skin is broken, smelly, painful or infected, book an appointment. If ear infections keep coming back despite treatment, ask your vet about investigating an underlying allergy.
Where Grub Club fits
If your vet suspects a food allergy, a complete food based on a single protein your dog hasn't eaten before can form the basis of an elimination diet. Our complete foods use one novel animal protein, black soldier fly larvae, and contain no chicken, beef, lamb, fish, dairy, wheat or soya.
If your dog may react to potato or peas, the choice of food matters: All-Day Buffet contains pea protein and potato, while Good Gut Grub contains neither, using tapioca and fava bean instead.
Our foods are not prescription diets and have not been clinically tested as a treatment for yeast infections, food allergy or any skin condition. You can book a free consultation with our vet if you would like to talk it through.
References
- Guillot, J. and Bond, R. (2020). Malassezia yeasts in veterinary dermatology: an updated overview. Frontiers in Cellular and Infection Microbiology, 10, 79. doi:10.3389/fcimb.2020.00079
- Puig, L., Bragulat, M.R., Castellá, G. and Cabañes, F.J. (2017). Characterization of the species Malassezia pachydermatis and re-evaluation of its lipid dependence using a synthetic agar medium. PLOS ONE, 12(6), e0179148. doi:10.1371/journal.pone.0179148
- Bond, R. et al. (2020). Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology. Veterinary Dermatology, 31(1). doi:10.1111/vde.12809
