Shun NagaiJust like humans, dogs can suffer from allergies, which often show up as itching or digestive issues. However, incorporating the right nutrients into dog food may help ease these symptoms and improve dogs’ overall quality of life. In this article, we take a closer look at nutrients that may help support dogs with allergies and share practical insights for developing dog food products that promote canine health.
Fatty Acids
Dogs with allergic conditions have been shown to have lower levels of fatty acids in the skin, as well as impaired fatty acid metabolism. For this reason, providing the right fatty acids is recognized as an important part of managing allergies in dogs.
You have probably heard about the many benefits of fish oil fatty acids for dogs. However, fish oil is not the only oil that contains fatty acids beneficial for allergies.
Polyunsaturated fatty acids—especially the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as the omega-6 fatty acid gamma-linolenic acid (GLA)—have been shown to help relieve allergy symptoms in dogs.
A proper balance of these essential fatty acids has anti-inflammatory effects, supports the immune system, helps reduce allergy symptoms, and also helps protect the skin barrier.
Therefore, when considering nutritional support for dogs with allergies, it is worth looking not only at fish oil, which is rich in omega-3 fatty acids, but also at ingredients rich in omega-6 fatty acids, such as flaxseed oil, soybean oil, chicken fat, and canola oil.
What the Research Shows
Recent research has found that giving allergic dogs a daily blend of fish oil and evening primrose oil—providing EPA, DHA, and GLA—with an omega-6 to omega-3 ratio of 5.5:1 improved the severity of symptoms including itching and hair loss. However, dogs with more chronic and severe symptoms did not experience major benefits.
Another study showed that allergic dogs given fish oil and borage oil—a source of EPA, DHA, GLA, and linoleic acid (LA)—demonstrated clinical improvement and required lower doses of immunosuppressive medication.
In addition, when fish oil and borage oil were given together at different dosage levels, dogs showed improvements in skin condition and allergy symptoms, with higher doses producing greater effects.
Research on fatty acids and canine allergies is ongoing, but it is already clear that both omega-3 and omega-6 fatty acids play important roles.
Vitamin E
Vitamin E (tocopherol) is normally present in canine skin. It is an essential fat-soluble vitamin and a powerful antioxidant that plays an important role in protecting the skin barrier. In line with this, dogs with atopic dermatitis have been found to have significantly lower vitamin E levels than healthy dogs.
In one study, dogs with atopic dermatitis were given vitamin E (0.01 mg/kg) once daily for eight weeks, resulting in a significant improvement in symptom severity. The study also reported that dogs receiving vitamin E had significantly higher plasma levels at the end of the trial compared with dogs given a placebo.
Another study evaluated food or supplements containing vitamin E. The skin-support diet given to dogs with atopic dermatitis contained 210 mg of vitamin E per 1,000 kcal. For reference, dogs require at least 8.4 mg of vitamin E per 1,000 kcal per day. This diet was found to help reduce itching, scratching, and redness.
Taken together, these findings make it clear that vitamin E may play a role in improving allergy symptoms in dogs. However, more research is needed to better understand optimal dosage and use.
B Vitamins
Although deficiencies in B vitamins are rare in dogs, they are closely associated with poor skin condition. The B vitamins include pantothenic acid (B5), niacinamide (B3), pyridoxine (B6), and the vitamin-like compounds inositol (B8) and choline (B4), all of which have been shown to benefit the skin barrier and early signs of allergic disease in dogs.
Among the nutrients screened for their ability to improve skin barrier function in dogs, several B vitamins—pantothenic acid, choline, niacinamide, pyridoxine, and inositol—as well as proline, showed some of the best results.
In a 12-week feeding trial, pantothenic acid, choline, niacinamide, and inositol were found to be among the most effective nutrients for maintaining the canine skin barrier.
Following this research, a study was conducted in Labrador Retrievers, a breed considered more prone to sensitivity, to determine whether these nutrients could help prevent the onset of atopic dermatitis. When pregnant Labrador Retrievers and their puppies were fed a diet fortified with B vitamins, the frequency of allergy symptoms associated with atopic dermatitis decreased.
Vitamin A and Carotenoids
Vitamin A is a fat-soluble vitamin broadly classified as retinol and its derivatives. It serves many important functions in dogs, including supporting skin health. Both vitamin A deficiency and excessive intake have been associated with deterioration in skin and coat condition in dogs.
Carotenoids are yellow or red fat-soluble pigments found in fruits and vegetables. Lutein and beta-carotene are two of the most common carotenoids in the diet, although there are actually hundreds of different types. Beta-carotene is classified as a provitamin A carotenoid, meaning dogs can convert it into vitamin A and use it in the body.
Lutein, on the other hand, cannot be converted into vitamin A. However, both lutein and beta-carotene are powerful antioxidants and have been shown to help reduce oxidative damage and support immune function in dogs.
One study found that when adult dogs aged 18 to 19 months were given beta-carotene, their immune function improved, with the effect being even more pronounced in senior dogs. Supplementation with lutein also showed immune benefits in dogs.
Although the impact of these immune effects on allergies remains unclear, the findings suggest that vitamin A and carotenoids may be beneficial for dogs with allergies.
Vitamin C
Vitamin C (ascorbic acid) is one of the key antioxidants involved in maintaining skin health in dogs and may be beneficial in allergic conditions.
Interestingly, dogs can produce vitamin C in their own bodies, so it is not an essential dietary nutrient for them. However, vitamin C supplementation has been reported to lower blood histamine levels and help reduce allergy symptoms.
When vitamin C was supplemented in healthy dogs, some effects on the immune system were observed, although the response was limited.
In another study, vitamin C combined with other anti-inflammatory and antimicrobial ingredients helped support skin health in dogs, and this was theorized to have therapeutic potential for canine skin disorders, including allergic conditions.
Hydrolysates
To determine whether allergy symptoms are caused by environmental allergens, the first step is to rule out food allergens. This can be done using novel-protein dog food or hydrolyzed-protein dog food.
In many cases, when dogs have food allergies, the trigger is usually a protein source. Hydrolyzed proteins are proteins that have been broken down structurally while still retaining essential amino acids.
As a result, even when consumed as a protein source, the dog’s body does not recognize them in the same way, meaning they are less likely to trigger an allergic reaction or cause itching. In other words, even if a dog reacts to a protein source such as chicken, it may not react to hydrolyzed chicken.
One important point is that for protein hydrolysates to remain hypoallergenic, they need to contain as many low-molecular-weight peptides as possible—ideally below 3,000 Da.
Zinc
Zinc plays many roles in the canine body, including some that may be linked to the development of allergic skin disease.
It is essential for maintaining normal skin health, contributes to both inflammation control and immune function, and is also a key element in fatty acid metabolism. Although research on zinc in allergic conditions is limited, adding zinc (65 mg/1,000 kcal) to the diet of dogs with allergies was found to improve symptoms of atopic dermatitis, including itching and scratching.
Similarly, when healthy dogs fed a balanced diet were supplemented with zinc (100 mg/1,000 kcal) together with the essential fatty acid linoleic acid (LA), improvements in coat condition were observed. These findings suggest that zinc may be helpful for dogs with allergies, although more research is needed to confirm its effects.
Probiotics
Probiotics have been shown to offer many benefits. In relation to allergies, two strains in particular—Lactobacillus rhamnosus GG and Lactobacillus sakei Probio-65—have been shown in studies to be beneficial for allergy symptoms.
When Lactobacillus rhamnosus GG was given to pregnant dogs with atopic dermatitis and their puppies, changes were observed in immune markers associated with allergies, suggesting that probiotics may help prevent allergic disease in dogs.
In addition, when Lactobacillus sakei Probio-65 was given to allergic dogs, symptoms of atopic dermatitis improved significantly.
Prebiotics
Prebiotics are indigestible food components such as oligosaccharides and dietary fiber that pass through the stomach and small intestine without being broken down or absorbed, reaching the large intestine where they serve as nutrients for beneficial gut microorganisms. They help promote the development and maintenance of a healthy intestinal microbiota.
Evidence for the effects of prebiotics on allergy symptoms is even more limited than for probiotics, but several studies suggest a possible relationship with allergy improvement.
In mouse studies, the prebiotics fructooligosaccharides (FOS), galactooligosaccharides (GOS), and inulin showed immune-related effects against allergies.
In dogs, ingredients such as fructooligosaccharides (FOS), mannan oligosaccharides (MOS), and inulin derived from chicory have been shown to influence the immune system. This suggests they may be beneficial for canine allergies, although further validation is needed.
Yeast
In human research, yeast has been studied for benefits ranging from digestive health to cold and influenza support, but research in dogs is still in the early stages.
What is currently known is that high yeast intake appears to be safe for dogs, and yeast may help improve antibody levels that are reduced in dogs with atopic dermatitis, while also supporting immune function and anti-inflammatory activity.
So far, however, there are no studies in dogs showing that yeast directly reduces allergy symptoms or definitively alters immune function in ways that improve allergies. Even so, it remains an area of growing interest.