Cutaneous adverse food reactions in the dog and cat – what's new?

This review focuses on some of the new information that has been published around cutaneous adverse food reactions in dogs and cats over the last few years, and considers parallels within the human field that may help guide further work in the prevention, diagnosis and therapy of the disease in dogs and cats.

The true prevalence of cutaneous adverse food reactions in dogs and cats is unknown. A critically appraised review of more than 30 articles describing these reactions in dogs and cats found that, among animals presenting with any disease to their veterinary surgeon, the prevalence of adverse food reactions was 1–2% and for those presenting specifically with skin disease, it ranged from 0–24%. Figures increased to 9–40% in dogs with pruritus (Figure 1) and to 8–62% in those with allergic skin disease. In cats with pruritus the range was 12-21%, and 5–13% for those with allergy (Olivry and Mueller, 2016). The authors concluded that cutaneous adverse food reactions should be considered in any companion animal presenting with non-seasonal pruritus or signs of allergic dermatitis. With a relatively high prevalence of disease, an attractive proposition may be to consider how these reactions could be prevented in companion animals. In humans, a range of different interventions have been evaluated as means of preventing ‘food allergy’. These include breastfeeding and the early introduction of allergenic foods to infants at risk for developing food allergy. Current recommendations suggest an emphasis on dietary diversity to include fruit, vegetables and fish during pregnancy, lactation and in early life for infants (Baker and Nowak-Wegrzyn, 2020). Two studies in animals suggested that keeping a dog at home before and during pregnancy decreased the risk of food allergy in 1-year-old children, but the same was not found for other pets such as cats, hamsters, guinea pigs or rabbits (Lyons et al, 2020; Smejda et al, 2020). Whether this is directly related to the presence of the dog or a result of other environmental, dietary or lifestyle choices associated with dog ownership is yet to be established. Similar studies have not yet been undertaken in the veterinary field, although a recent study from Finland suggested a link between feeding pattern and environmental factors in the development of canine atopic dermatitis. A retrospective analysis of 406 dogs with atopic dermatitis suggested that the feeding of a non-processed meat-based diet during the prenatal and early postnatal periods had a significant effect on reducing the incidence of canine atopic dermatitis in adult dogs, compared to the feeding of an ultra-processed carbohydrate-based diet, which increased the risk (Hemida et al, 2020). Other factors that were found to decrease the risk included maternal deworming programmes and sunlight exposure during the early postnatal period (Hemida et al, 2020). On the basis of this retrospective study, it is worth speculating whether the feeding of specific diets during the perinatal period could reduce the incidence of cutaneous adverse food reactions in dogs and cats.