Ingredients for Allergy Relief in Dogs

As a human, you’ve likely had a brush with allergies. Be they food allergies or seasonal allergies, people all across the globe fall victim to a variety of triggers unique to their geography, diet, habits and more.

Dogs, too, can suffer from many different allergic diseases based on their circumstances or genetics: flea allergy dermatitis, atopic dermatitis (atopy), food intolerance/allergy, contact dermatitis, and insect bite hypersensitivity are among the most common.¹ And in dogs, most allergic responses manifest as skin or gastrointestinal issues.² 

Skip ahead or keep reading:

• Fatty Acids
• Vitamin E
• B-vitamins
• Vitamin A
• Vitamin C
• Zinc
• Probiotics
• Prebiotics
• Yeast Fermentate

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How do I know what allergic disease my dog is suffering from?

True food allergies in dogs (that is to say, allergies that trigger a real immune response) aren’t actually all that common.^1,2 

Food intolerances on the other hand, which are not immune mediated, are far more prevalent.^1,2 Take canine atopic dermatitis, a chronic environmental allergic skin disease commonly characterized by pruritus (aka itchy skin).^1,3 While food intolerances/allergies more often cause gastrointestinal issues (i.e. vomiting and diarrhea) than canine atopic dermatitis, they’re similarly associated with causing pruritus.² 

This overlap of symptoms can make it difficult to identify the source of your dog’s skin allergies.¹

And just to make things more complicated…

Many dogs with allergies aren’t just allergic to one thing. Most dogs with one food sensitivity, are likely to have another, or even cross-react between similar foods.² Additionally, about 20-30% of dogs with food allergies have been found to also have another form of allergic disease, such as atopic dermatitis.^2,4 It isn’t even unheard of for a dog to suffer from adverse food reactions, atopic dermatitis, and flea allergy all simultaneously!^2,5 

Confusing, we know. So let’s clear some things up.

So your dog is itchy and you’re not sure why

For starters keeping a clean home — and a clean dog — are important in making sure you’re eliminating contact and environmental irritants.² To further eliminate concurrent allergic diseases, make sure they’re up-to-date on their flea prevention medication, as flea allergy dermatitis is the most common canine allergic disease.¹⁰ 

Food trials, skin tests, and blood tests can all help to determine the source of your dog’s irritation, but many of these tests can be unreliable, and in the case of food trials, difficult to adhere to entirely.^1,2 Many medications and treatment options also exist to help alleviate allergies, though no truly curative therapy exists to date,¹¹ and there can be undesired side effects such as hair loss, gastrointestinal upset, and weight gain to name a few.^3,12  

What types of ingredients could be useful in treating dog allergies?

The skin microbiome of allergic dogs has been shown to vary from that of healthy dogs, notably in its species abundance. Although, it is not yet clear if these alterations in the skin microbiome are a result of the allergic disease or part of the cause.⁷ 

Allergic dogs have been found to have reduced concentrations of key skin antioxidants and nutrients.¹⁴

Appropriately, oxidative stress (imbalance between damaging free radicals and protective antioxidants) and other environmental factors have also been associated with the fostering of allergic symptoms in dogs.^14,15 Skin barrier defects are also thought to further allow allergens to infiltrate the skin, aggravating symptoms.³ Newer research is also showing that the gut microbiome may be associated with allergic symptoms in dogs, and thus ingredients that can help shape the microbiome could benefit canine allergies.^8,16

Fatty acids

Dogs with allergic diseases have been found to carry reduced fatty acid levels in their skin, as well as impaired fatty acid metabolism.¹⁷ Accordingly, interventions providing fatty acids have seen a lot of success in the management of canine allergies.³ 

When it comes to fatty acids, you’ve probably heard about fish oil and all the potential benefits it has for both you and your dog. While the evidence behind fish oil is booming, in terms of allergies it isn’t the only fatty acid containing oil that deserves some praise. Polyunsaturated fatty acids, notably omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and omega-6 fatty acid: gamma-Linolenic acid (GLA) have demonstrated their ability to help alleviate canine allergic symptoms.^3,18 

The right balance of these essential fatty acids can be anti-inflammatory and support the canine immune system which can help relieve allergy symptoms and additionally protect the skin barrier.^3,18 So for dog allergies, beyond fish oil (which is a great source of omega-3 fatty acids) consider other healthful oils (high in omega-6 fatty acids) such as flaxseed oil, soybean oil, evening primrose oil, and borage seed oil.^13,19,20 

… and here’s the evidence to prove it.

In a recent study, a blend of marine fish oil and evening primrose oil, providing EPA, DHA, and GLA, given to allergic dogs daily with an omega-6: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 respond as well to the treatment.¹⁸ In another study, allergic dogs that received fish and borage seed oils (source of EPA, DHA, GLA, cis-linoleic acid (LA)) showed improved clinical symptoms and lowered usage of immune-suppressive medications.²¹ Additionally, fish and borage seed oils, given together at different doses, improved canine skin condition and allergic symptoms, with a larger effect seen with the higher dose.²⁰ The literature supporting fatty acids and canine allergies continues, and it’s clear both omega-3 and omega-6 fatty acids have a role to play. 

Vitamin E

Normally, vitamin E can be found in high concentrations within the skin of dogs (and humans!).^14,25 It’s an essential fat-soluble vitamin, and a potent antioxidant, with a critical role in protecting the canine skin barrier.^14,25 Correspondingly, it has been found that dogs with atopic dermatitis have remarkably lower levels of vitamin E compared to their healthy counterparts.²⁶

One study showed that dogs with atopic dermatitis supplemented once daily with vitamin E (8.1 IU/kg body weight) for 8 weeks showed significant improvements in the severity of their symptoms.¹⁴ Additionally, dogs provided vitamin E had notably higher plasma levels by the end of the study compared to dogs on a placebo. Additional research has used vitamin E as an ingredient in provided diets or supplements. A dermatologic diet given to dogs with atopic dermatitis containing 210 mg vitamin E per 1000 kcal diet (for reference dogs need at least 8.4 mg vitamin E per 1000 kcal everyday),²⁸ helped to reduce itching, scratching, and redness.¹³ 

Taken together, there’s a clear supporting role for vitamin E when it comes to allergies in dogs. Although, continued research will help us gain a better insight of its applications, including the optimal dose. 

B-vitamins

Deficiencies in B-vitamins in dogs, while uncommon, are associated with poor skin conditions.³⁰ B-complex vitamins including pantothenate (B₅), nicotinamide (B₃), pyridoxine (B₆) as well as B-vitamin-like nutrients inositol (B₈) and choline (B₄) have been shown to benefit the canine skin barrier and early signs of allergic diseases.^15,31 

Of nutrients screened in vitro for their ability to benefit canine skin barrier function, several B-vitamins came out on top (pantothenate, choline, nicotinamide, proline, pyridoxine and inositol).³¹ In a follow up 12-week feeding study pantothenate, choline, nicotinamide, and inositol, were some of the best performing nutrients for maintaining the canine skin barrier.³¹ In response to this study, an early intervention trial tested if these skin-benefiting nutrients could subsequently prevent the occurrence of atopic dermatitis in Labradors (a more susceptible breed).¹⁵ A B-vitamin fortified diet fed to pregnant Labrador retrievers and then to their respective puppies, reduced the frequency of allergic symptoms associated with atopic dermatitis.¹⁵ While this early intervention trial further advocates for B-vitamins in the treatment of canine allergic diseases, more clinical trials in adult dogs are warranted. 

Nutrients with emerging evidence

There are a lot of nutrients with the potential to benefit canine allergies through different modes of action ー dermatological, immune, gastrointestinal and microbiome support. We think the following nutrients hold the potential to be helpful to dog allergies, however, the research is a little more limited. 

Vitamin A & Carotenoids

Vitamin A is a fat-soluble vitamin, that can more broadly be classified as retinol and its derivatives.³⁰ Vitamin A has a lot of important functions in dogs, one of them being maintaining the integrity of the skin. Both deficiency and excess vitamin A in dogs has been associated with poor skin and coat conditions.³⁰ 

Carotenoids, are also fat-soluble compounds, and they are responsible for the bright colors we see in fruits and vegetables.³² Lutein and β-carotene are two of the more common carotenoids in the diet, although there are hundreds!³² β-carotene is classified as a pro-vitamin A carotenoid, meaning dogs can convert it into vitamin A in their body, and use it as their vitamin A source.^30,33 

Lutein, on the other hand cannot be converted to vitamin A.³³ However, carotenoids, lutein and β-carotene alike, are powerful antioxidants, and they’ve both been shown to reduced oxidative damage and impact immune response in dogs,^34–36 properties that could certainly benefit allergies.

Lutein and β-carotene have both illustrated the ability to dose-dependently enhance immune response in dogs in independent studies.^35,36 Additionally, β-carotene was again shown to promote a heightened immune response when given to young dogs (18 - 19 months),³⁷ but this effect was even more pronounced in senior dogs.³⁸ Lutein provided to dogs also illustrated a favorable immunomodulatory effect.³⁹ While the impact of these immunological shifts on allergies remains unknown, indications point to vitamin A and carotenoids as benefiting canine allergies. 

Vitamin C

Vitamin C, also known as ascorbic acid, is another potent antioxidant, important for maintaining skin health in dogs,⁴⁰ with the potential to benefit allergic diseases.²⁷  Interestingly enough, dogs don’t have a dietary requirement for vitamin C as they can actually make it themselves. However, supplementation has shown to raise blood levels in dogs,⁴¹ and may be therapeutic to conditions like allergies.

Supplementation with vitamin C in healthy dogs showed some ability to impact the immune system, but the response was limited.⁴¹ An in vitro study (a study done in “test tubes” not in actual dogs) demonstrated that vitamin C in combination with other anti-inflammatory and antibacterial ingredients was able to support canine skin health, and theorized that this would be therapeutic to canine skin diseases including allergic conditions.⁴² 

Zinc

Zinc plays many roles in the canine body that could possibly be related to the development of allergic skin diseases. 

Critical for maintenance of regular skin health, zinc contributes to both the inflammatory and immune systems, and is crucial for fatty acid metabolism.³⁰ While the research on zinc in allergic diseases is limited, its inclusions in a functional diet (65 mg/1000 kcal) fed to allergic dogs, helped to improve symptoms of atopic dermatitis, including itching and scratching.¹³ 

Likewise, zinc (100 mg/1000 kcal) alongside essential fatty acid linoleic acid (LA) given to healthy dogs on a nutritionally balanced diet led to improved coat condition.⁴³ So the potential for zinc supplementation to benefit canine allergies is there, but more research is required to confirm this. 

Microbiome-altering ingredients

Evidence is mounting that a healthy microbiome, or microorganisms that live in the gut, may be associated with preventing allergic diseases in dogs.¹⁶ Dysbiosis (an imbalanced microbiome) has been further thought to induce allergy symptoms in dogs.⁴⁴ Therefore, ingredients that can help shape the microbiome, increase healthy bacteria and promote diversity, may hence have a therapeutic role in canine allergies.  

Probiotics

Probiotics have proved to be an effective way of altering the microbiome of humans and dogs alike, and have been shown to provide a host of benefits.¹⁶ With regards to allergies specifically, Lactobacillus rhamnosus GG and Lactobacillus sakei probio-65 are two bacterial strains that have successfully displayed the ability to benefit allergy symptoms.^45,46 

While not significant, Lactobacillus rhamnosus GG given to pregnant mothers with atopic dermatitis and resulting puppies altered immunologic indicators of allergy, suggesting a possible role for probiotics in the prevention of canine allergic diseases with early intervention.⁴⁵ While Lactobacillus sakei probio-65 given to allergic dogs was able to show significant improvements in symptoms of atopic dermatitis.⁴⁶

Prebiotics

Classically, prebiotics are considered a type of fermentable fiber that promotes the development and maintenance of healthy gut bacteria.¹⁶ 

Nowadays, the definition is sometimes broadened to any non-digestible but fermentable nutrient that serves to benefit the gut microbiome.¹⁶ Compared to probiotics, the evidence for the benefit of prebiotics on allergic symptoms is even more limited,⁴⁸ however, given their proven ability to benefit and diversity the canine microbiome, and the evidence in support of a healthy microbiome for allergy treatment,¹⁶ it seems like we can connect the dots. 

In mice, prebiotics: fructooligosaccharides (FOS), galactooligosaccharides (GOS), and inulin have all shown protective effects against allergies.⁴⁸ In dogs, FOS, mannanoligosaccharides (MOS),^49,50 inulin (from chicory),⁵¹ and fermentable fiber blends have shown the ability to impact the immune system,⁵² and therefore might subsequently be beneficial to canine allergies, but more examination is needed. 

Yeast Fermentate 

Baker’s yeast fermented to contain a blend of powerful ingredients ー antioxidants, phytonutrients, proteins ー has also displayed the ability to support the immune system and allergy symptoms in humans and early animal studies.^53,54 

While the literature in humans expands to digestive health, microbiome impact, cold and flu,⁵⁵ the research in dogs is introductory. What we do know is that even high doses of yeast fermentate have proven to be safe for dogs, yeast has been associated with improving certain antibody levels that are notoriously low in dogs with atopic dermatitis,⁵⁶ and it may improve immune response, inflammation and microbiome health.⁵⁷ 

To date, no studies have shown it possesses the same allergy symptom sparing and immune defense properties in dogs, but the possibility definitely raises some exciting prospects.

Hydrolyzed diets

The first step to determining environmental allergens as the culprit behind allergy symptoms is often ruling out food allergens. This can be done with a strict elimination diet containing a novel protein source or with a hydrolyzed protein diet. 

Oftentimes, when dogs do have a true food allergy, it’s usually caused by protein. Hydrolyzing proteins break down the protein structure, but retain the essential amino acids. This means that they can be consumed as a protein source while reducing allergic reactions by preventing identification by the immune system.⁵⁸ 

In theory, dogs who would normally react to the intact protein source, for example chicken, will not react to the hydrolyzed form.⁵⁸ 

Bottom Line

There are a lot of nutrients and ingredients out there that might benefit canine allergy symptoms that could be worth trying if your dog suffers from allergies and has yet to find relief. 

Of course, discuss these changes with your veterinarian, so they can help ensure the safety of your pet and recommend an appropriate and tolerable dose. 

A lot of the evidence behind some of these nutrients is currently limited and only with more research will we be able to confirm these speculated advantages.

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References:

1. Hensel, P., Santoro, D., Favrot, C., Hill, P. & Griffin, C. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification. BMC Vet. Res. 11, 196 (2015).
2. Verlinden, A., Hesta, M., Millet, S. & Janssens, G. P. J. Food allergy in dogs and cats: a review. Crit. Rev. Food Sci. Nutr. 46, 259–273 (2006).
3. Schumann, J., Basiouni, S., Gück, T. & Fuhrmann, H. Treating canine atopic dermatitis with unsaturated fatty acids: the role of mast cells and potential mechanisms of action. J. Anim. Physiol. Anim. Nutr. 98, 1013–1020 (2014).
4. Roudebush, P. & Schick, R. O. Evalution of a Commerical Canned Lamb and Rice Diet for the Management of Adverse Reactions to Food in Dogs. Vet. Dermatol. 5, 63–67 (1994).
5. Carlotti, D. N., Remy, I. & Prost, C. Food Allergy In Dogs And Cats. A Review and Report of 43 Cases. Vet. Dermatol. 1, 55–62 (1990).
6. Nagle, T. M., Torres, S. M., Horne, K. L., Grover, R. & Stevens, M. T. A randomized, double-blind, placebo-controlled trial to investigate the efficacy and safety of a Chinese herbal product (P07P) for the treatment of canine atopic dermatitis. Vet. Dermatol. 12, 265–274 (2001).
7. Rodrigues Hoffmann, A. et al. The skin microbiome in healthy and allergic dogs. PLoS One 9, e83197 (2014).
8. Craig, J. M. Atopic dermatitis and the intestinal microbiota in humans and dogs. Vet Med Sci 2, 95–105 (2016).
9. Halliwell, R. E. W. Allergic skin diseases in dogs and cats: an introduction. European Journal of Companion Animal Practice 19, 209–211 (2009).
10. Lam, A. & Yu, A. Overview of flea allergy dermatitis. Compend. Contin. Educ. Vet. 31, E1–10 (2009).
11. Noli, C. et al. Conjugated linoleic acid and black currant seed oil in the treatment of canine atopic dermatitis: A preliminary report. The Veterinary Journal 173, 413–421 (2007).
12. Müller, M. R. et al. Evaluation of cyclosporine-sparing effects of polyunsaturated fatty acids in the treatment of canine atopic dermatitis. Vet. J. 210, 77–81 (2016).
13. Witzel-Rollins, A. et al. Non-controlled, open-label clinical trial to assess the effectiveness of a dietetic food on pruritus and dermatologic scoring in atopic dogs. BMC Vet. Res. 15, 220 (2019).
14. Plevnik Kapun, A. et al. Vitamin E supplementation in canine atopic dermatitis: improvement of clinical signs and effects on oxidative stress markers. Vet. Rec. 175, 560 (2014).
15. van Beeck, F. L., Watson, A., Bos, M., Biourge, V. & Willemse, T. The effect of long-term feeding of skin barrier-fortified diets on the owner-assessed incidence of atopic dermatitis symptoms in Labrador retrievers. J. Nutr. Sci. 4, e5 (2015).
16. Wernimont, S. M. et al. The Effects of Nutrition on the Gastrointestinal Microbiome of Cats and Dogs: Impact on Health and Disease. Front. Microbiol. 11, 1266 (2020).
17. Olivry, T., Marsella, R. & Hillier, A. The ACVD task force on canine atopic dermatitis (XXIII): are essential fatty acids effective? Vet. Immunol. Immunopathol. 81, 347–362 (2001).
18. Abba, C., Mussa, P. P., Vercelli, A. & Raviri, G. Essential fatty acids supplementation in different-stage atopic dogs fed on a controlled diet. J. Anim. Physiol. Anim. Nutr. 89, 203–207 (2005).
19. Scarff, D. H. & Lloyd, D. H. Double blind, placebo-controlled, crossover study of evening primrose oil in the treatment of canine atopy. Vet. Rec. 131, 97–99 (1992).
20. Harvey, R. G. A blinded, placebo-controlled study of the efficacy of borage seed oil and fish oil in the management of canine atopy. Vet. Rec. 144, 405–407 (1999).
21. Saevik, B. K. et al. A randomized, controlled study to evaluate the steroid sparing effect of essential fatty acid supplementation in the treatment of canine atopic dermatitis. Vet. Dermatol. 15, 137–145 (2004).
22. Bensignor, E., Morgan, D. M. & Nuttall, T. Efficacy of an essential fatty acid-enriched diet in managing canine atopic dermatitis: a randomized, single-blinded, cross-over study. Vet. Dermatol. 19, 156–162 (2008).
23. Scott, D. W., Miller, W. H., Jr, Reinhart, G. A., Mohammed, H. O. & Bagladi, M. S. Effect of an omega-3/omega-6 fatty acid-containing commercial lamb and rice diet on pruritus in atopic dogs: results of a single-blinded study. Can. J. Vet. Res. 61, 145–153 (1997).
24. Nesbitt, G. H., Freeman, L. M. & Hannah, S. S. Effect of n-3 fatty acid ratio and dose on clinical manifestations, plasma fatty acids and inflammatory mediators in dogs with pruritus. Vet. Dermatol. 14, 67–74 (2003).
25. Jewell, D. E., Yu, S. & Joshi, D. K. Effects of serum vitamin E levels on skin vitamin E levels in dogs and cats. Vet. Ther. 3, 235–243 (2002).
26. Plevnik Kapun, A. et al. Plasma and skin vitamin E concentrations in canine atopic dermatitis. Vet. Q. 33, 2–6 (2013).
27. Kapun, A. P., Salobir, J., Levart, A., Kotnik, T. & Svete, A. N. Oxidative stress markers in canine atopic dermatitis. Res. Vet. Sci. 92, 469–470 (2012).
28. Association of American Feed Control Officials. 2019 AAFCO Official Publication. (Association of American Feed Control Officials, 04/2019).
29. Popa, I. et al. Analysis of epidermal lipids in normal and atopic dogs, before and after administration of an oral omega-6/omega-3 fatty acid feed supplement. A pilot study. Vet. Res. Commun. 35, 501–509 (2011).
30. Watson, T. D. Diet and skin disease in dogs and cats. J. Nutr. 128, 2783S–2789S (1998).
31. Watson, A. L. et al. Dietary constituents are able to play a beneficial role in canine epidermal barrier function. Exp. Dermatol. 15, 74–81 (2006).
32. Olson, J. A. & Krinsky, N. I. Introduction: the colorful, fascinating world of the carotenoids: important physiologic modulators. FASEB J. 9, 1547–1550 (1995).
33. Green, A. S. & Fascetti, A. J. Meeting the Vitamin A Requirement: The Efficacy and Importance of β-Carotene in Animal Species. ScientificWorldJournal 2016, 7393620 (2016).
34. Baskin, C. R. et al. Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs. Am. J. Vet. Res. 61, 886–891 (2000).
35. Kim, H. W. et al. Dietary lutein stimulates immune response in the canine. Vet. Immunol. Immunopathol. 74, 315–327 (2000).
36. Chew, B. P. et al. Dietary β-Carotene Stimulates Cell-Mediated and Humoral Immune Response in Dogs. J. Nutr. 130, 1910–1913 (2000).
37. Chew, B. P. et al. Dietary beta-carotene is taken up by blood plasma and leukocytes in dogs. J. Nutr. 130, 1788–1791 (2000).
38. Massimino, S. et al. Effects of Age and Dietary β-Carotene on Immunological Variables in Dogs. J. Vet. Intern. Med. 17, 835–842 (2003).
39. Alarça, L. G. et al. Dietary lutein supplementation on diet digestibility and blood parameters of dogs. Cienc. Rural 46, 2195–2201 (2016).
40. Beigh, S. A., Soodan, J. S., Singh, R., Khan, A. M. & Dar, M. A. Evaluation of trace elements, oxidant/antioxidant status, vitamin C and β-carotene in dogs with dermatophytosis. Mycoses 57, 358–365 (2014).
41. Hesta, M. et al. The effect of vitamin C supplementation in healthy dogs on antioxidative capacity and immune parameters. J. Anim. Physiol. Anim. Nutr. 93, 26–34 (2009).
42. Fray, T. R. et al. A Combination of Aloe Vera, Curcumin, Vitamin C, and Taurine Increases Canine Fibroblast Migration and Decreases Tritiated Water Diffusion across Canine Keratinocytes In Vitro. J. Nutr. 134, 2117S–2119S (2004).
43. Marsh, K. A., Ruedisueli, F. L., Coe, S. L. & Watson, T. G. D. Effects of zinc and linoleic acid supplementation on the skin and coat quality of dogs receiving a complete and balanced diet. Vet. Dermatol. 11, 277–284 (2000).
44. Tizard, I. R. & Jones, S. W. The Microbiota Regulates Immunity and Immunologic Diseases in Dogs and Cats. Vet. Clin. North Am. Small Anim. Pract. 48, 307–322 (2018).
45. Marsella, R. Evaluation of Lactobacillus rhamnosus strain GG for the prevention of atopic dermatitis in dogs. Am. J. Vet. Res. 70, 735–740 (2009).
46. Kim, H. et al. A Double-Blind, Placebo Controlled-Trial of a Probiotic Strain Lactobacillus sakei Probio-65 for the Prevention of Canine Atopic Dermatitis. J. Microbiol. Biotechnol. 25, 1966–1969 (2015).
47. Kumar, S. et al. Probiotic Potential of a Lactobacillus Bacterium of Canine Faecal-Origin and Its Impact on Select Gut Health Indices and Immune Response of Dogs. Probiotics Antimicrob. Proteins 9, 262–277 (2017).
48. Gourbeyre, P., Denery, S. & Bodinier, M. Probiotics, prebiotics, and synbiotics: impact on the gut immune system and allergic reactions. J. Leukoc. Biol. 89, 685–695 (2011).
49. Swanson, K. S. et al. Effects of supplemental fructooligosaccharides plus mannanoligosaccharides on immune function and ileal and fecal microbial populations in adult dogs. Arch. Tierernahr. 56, 309–318 (2002).
50. Swanson, K. S. et al. Supplemental Fructooligosaccharides and Mannanoligosaccharides Influence Immune Function, Ileal and Total Tract Nutrient Digestibilities, Microbial Populations and Concentrations of Protein Catabolites in the Large Bowel of Dogs. J. Nutr. 132, 980–989 (2002).
51. Grieshop, C. M. et al. Gastrointestinal and immunological responses of senior dogs to chicory and mannan-oligosaccharides. Arch. Anim. Nutr. 58, 483–493 (2004).
52. Field, C. J., McBurney, M. I., Massimino, S., Hayek, M. G. & Sunvold, G. D. The fermentable fiber content of the diet alters the function and composition of canine gut associated lymphoid tissue. Vet. Immunol. Immunopathol. 72, 325–341 (1999).
53. Evans, M., Reeves, S. & Robinson, L. E. A dried yeast fermentate prevents and reduces inflammation in two separate experimental immune models. Evid. Based. Complement. Alternat. Med. 2012, 973041 (2012).
54. Moyad, M. A. et al. Immunogenic yeast-based fermentation product reduces allergic rhinitis-induced nasal congestion: a randomized, double-blind, placebo-controlled trial. Adv. Ther. 26, 795–804 (2009).
55. Research | Embria Health Sciences. https://www.embriahealth.com/products/epicor/research/.
56. Rowe, E. W., Roth, J. A., J., N. & Madson, E. Effect of EpiCor fermentate on immune response, safety, and welfare of dogs.
57. Lin, C.-Y. et al. Effects of a Saccharomyces cerevisiae fermentation product on fecal characteristics, nutrient digestibility, fecal fermentative end-products, fecal microbial populations, immune function, and diet palatability in adult dogs1. J. Anim. Sci. 97, 1586–1599 (2019).
58. Cave, N. J. Hydrolyzed protein diets for dogs and cats. Vet. Clin. North Am. Small Anim. Pract. 36, 1251–68, vi (2006).