Specialized dog foods may curb cutaneous adverse food reaction

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The human-animal bond is the treasured connection between a pet and its pet owner. One of the most important aspects of this integral link is the quality and type of nutrition in the pet’s diet. Dietary nutrition plays a crucial role in the development of young dogs and the maintenance of health throughout life.¹ There are several disease processes associated with poor nutrition. For example, specific nutrients, feeding methods, and electrolyte balances have been shown to influence hip dysplasia in dogs.² Dogs with diseases may have different nutritional requirements and should be fed specific diets.

Pet owners may become overwhelmed with the vast selection of dietary options available for their pets. There are approximately 400 dog breeds recognized worldwide, with large variations in body size and weight. Dogs can consume and utilize energy from both animal-based products and plant-based foods.³ Diet is an important contributor to dogs’ social interactions and mental well-being. Studies have shown that diets rich in vitamins and minerals may decrease antisocial behavior. When fed a poorly balanced diet, dogs may develop cognitive deficits and neuropathology similar to those seen in humans with dementia.⁴ Studies have shown that dog food enriched with antioxidants decreased the rate of cognitive decline in elderly beagles.⁵

Proper nutrition also plays a pivotal role in canine hypersensitivity disorders. These conditions, especially atopic dermatitis (AD), can be frustrating to manage for both the pet owner and the veterinary clinician. AD affects approximately 10% of the canine population. AD in the canine patient is often due to environmental allergens, but it also can be a manifestation of cutaneous adverse food reaction (CAFR). A patient presenting with AD due to a dietary allergy can appear clinically identical to one with AD due to aeroallergens.⁶ It is up to the veterinary clinician to differentiate between them by means of history and exclusion.

CAFR can manifest at any age. Recently published data indicate that the average age at onset was approximately 3 years.⁷ Dogs diagnosed with food-induced AD tended to be younger (< 1 year) or older (> 6 years) than those with aeroallergen-induced AD. It should be noted that the age of onset ranged from less than 1 to 13 years of age. Approximately 40% of affected patients present before the age of 1 year. There is no known strong sex predilection for dogs with CAFR. Although any breed may be affected, the condition appears to be more common in German shepherds, Labrador retrievers, and West Highland white terriers.⁸

The most common clinical sign seen with canine CAFR is a nonseasonal pruritus—more than 90% of affected dogs experience it. In some intense cases, the pruritus may not respond to anti-inflammatory doses of glucocorticoids. The veterinary clinician should keep in mind that pruritus can manifest in several ways, including excessive grooming, licking, rubbing, and head shaking. Many patients will experience a generalized pruritus, but specific areas, such as the paws, ventrum, or ears, may be focal points of discomfort.

In addition to generalized pruritus, 10% to 20% of canine patients affected with CAFR develop systemic signs, with diarrhea being the most common. Other clinical signs include vomiting, increased flatulence, tenesmus, and increased bowel movements. Additionally, secondary infections with both bacteria and yeast are common in these patients due to the self-trauma and overcolonization of these microorganisms.

When CAFR is suspected, a detailed discussion with the pet owner should include information about the diagnostics needed to confirm the condition. The gold standard in diagnosing CAFR is a limited ingredient or hydrolyzed diet trial followed by a positive provocation challenge.⁹ This may be difficult for some pet owners as these diets can be more expensive than the regular diet. The majority of dogs should be fed this strict dietary regimen for up to 8 weeks to assess the full benefit; no unauthorized treats or human food should be given. Although home-cooked diet trials are a possibility as long as the owner is counseled on nutritional balance, it is highly recommended that only commercially available veterinary therapeutic diets be used. There have been data indicating that over-the-counter diets may contain unintentionally added proteins that are not listed in the ingredient list, such as chicken. Some commercially available veterinary therapeutic diet options for dermatological conditions include: BLUE Natural Veterinary Diet HF, BLUE Natural Veterinary Diet NP, Royal Canin Ultamino, Royal Canin Selected Protein PR, Hill’s z/d, Hill’s d/d Potato & Salmon, Purina Pro Plan HA Hydrolyzed (chicken flavor), and Rayne Clinical Nutrition Kangaroo-MAINT with Chickpea (Table 1).

There is still much that is unknown about CAFR, and it remains the center of a considerable amount of research. It is imperative that the veterinary clinician remember to develop a treatment plan for the patient that centers on the prevention of flares. No plan is perfect, and CAFR flares should be anticipated. The pet owner should be counseled on the expected flares and how to control them without panic. The goal in managing CAFR is to improve the quality of life for the canine patient and improve the human-animal bond.

References

1. Tanprasertsuk J, Tate DE, Shmalberg J. Roles of plant-based ingredients and phytonutrients in canine nutrition and health. J Anim Physiol Anim Nutr (Berl). Published online September 8, 2021. doi:10.1111/jpn.13626
2. Olivry T, DeBoer DJ, Favrot C, et al. Treatment of canine atopic dermatitis: 2010 clinical practice guidelines from the International Task Force on Canine Atopic Dermatitis. Vet Dermatol. 2010;21(3):233-248. doi:10.1111/j.1365-3164.2010.00889.x
3. Olivry T, DeBoer DJ, Favrot C, et al. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Vet Res. 2015;11:210. doi:10.1186/s12917-015-0514-6
4. Massey KA, Blakeslee C, Pitkow HS. A review of physiological and metabolic effects of essential amino acids. Amino Acids. 1998;14(4):271-300. doi:10.1007/BF01318848
5. Miller W, Griffin C, Campbell K. Muller & Kirk’s Small Animal Dermatology 7th Edition. Elsevier; 2013.
6. Studzinski CM, Araujo JA, Milgram NW. The canine model of human cognitive aging and dementia: pharmacological validity of the model for assessment of human cognitive-enhancing drugs, Prog Neuropsychopharmacol Biol Psychiatry. 2005;29(3):489-498. doi:10.1016/j.pnpbp.2004.12.014
7. Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (3): prevalence of cutaneous adverse food reactions in dogs and cats. BMC Vet Res. 2017;13(1):51. doi:10.1186/s12917-017-0973-z
8. Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (7): signalment and cutaneous manifestations of dogs and cats with adverse food reactions. BMC Vet Res. 2019;15(1):140. doi:10.1186/s12917-019-1880-2
9. Richardson DC. The role of nutrition in canine hip dysplasia. Vet Clin North Am Small Anim. 1992;22(3):529-540. doi:10.1016/s0195-5616(92)50053-5