Beyond the Diet Bowl: Hidden Micronutrient Deficiencies in Canine Atopic Dermatitis

Canine atopic dermatitis (CAD) is traditionally managed as a skin disease, with treatment centred on controlling itch and inflammation. However, emerging evidence suggests that chronic allergic skin disease may also have important systemic effects, including alterations in micronutrient metabolism that are not always apparent during routine clinical evaluation². 

Understanding these hidden nutritional changes may help veterinarians adopt a more holistic approach to long-term disease management. 

Adequate Nutrition Doesn't Always Mean Adequate Nutrient Availability 

Most commercial canine diets are formulated to meet nutritional requirements, yet dogs with CAD may still develop deficiencies in nutrients such as iron, zinc, and certain vitamins². 

The reason lies in chronic inflammation. 

Persistent immune activation alters how the body absorbs, transports, and utilises micronutrients. Consequently, nutrients may be present in the diet but unavailable to tissues where they are needed most. 

Understanding the Mucosal Block 

During inflammation, the body activates a protective response known as the mucosal block, reducing intestinal absorption of micronutrients while increasing their sequestration within storage sites². 

This mechanism evolved to limit nutrient availability to invading microorganisms. In chronic inflammatory diseases such as CAD, however, where infection is often absent, the same response can inadvertently contribute to functional nutrient deficiencies. 

As inflammation persists, this may create a cycle in which nutritional deficiencies further sustain immune activation and delay tissue repair. 

Iron: More Than an Oxygen Carrier 

Iron is essential not only for red blood cell production but also for normal immune regulation. 

Reduced iron availability can activate immune cells and promote inflammatory pathways, potentially contributing to ongoing disease activity². Importantly, these changes may occur before anemia develops, meaning routine hematology alone may not detect early iron deficiency. 

Veterinarians should therefore recognise that normal hemoglobin concentrations do not necessarily exclude clinically relevant alterations in iron metabolism. 

The Importance of Bioavailable Nutrients 

An emerging area of research focuses on improving the bioavailability of nutrients rather than simply increasing their dietary concentration. 

Delivering micronutrients in forms that remain absorbable despite chronic inflammation may help restore iron balance, improve hematological parameters, and support healthier immune function². 

Although further research is needed, this concept highlights an important shift from simply meeting dietary requirements to ensuring nutrients can be effectively utilised by the patient. 

A Broader View of CAD Management 

Successful management of CAD should extend beyond symptom control. 

Assessing nutritional status, supporting skin barrier health, and recognising the systemic effects of chronic inflammation may become increasingly important, particularly in dogs with recurrent flare-ups or incomplete responses to conventional therapy. 

As evidence continues to evolve, integrating nutritional assessment into routine dermatology practice may help identify hidden contributors to persistent disease. 

The Clinical Take-Home 

Canine atopic dermatitis affects more than the skin. Chronic inflammation can interfere with the absorption and utilisation of essential micronutrients, creating functional deficiencies that may perpetuate disease. Recognising these metabolic changes encourages a more comprehensive approach to CAD management—one that combines effective medical therapy with targeted nutritional support to optimise long-term patient outcomes². 

References (Vancouver) 

1. de Santiago MS, Arribas JL, Llamas YM, Becvarova I, Meyer H. Randomized, double-blind, placebo-controlled clinical trial measuring the effect of a dietetic food on dermatologic scoring and pruritus in dogs with atopic dermatitis. BMC veterinary research. 2021 Nov 19;17(1):354. https://doi.org/10.1186/s12917-021-03063-w 

2. Frizzo-Ramos J, et al. Lymph-targeted nutritional supplementation improves clinical outcomes and reduces medication requirements in dogs with canine atopic dermatitis: a randomized, double-blind, placebo-controlled pilot study. Front Vet Sci. 2025. Available from: https://doi.org/10.3389/fvets.2025.1657869