Dermatitis: Nutrition’s role in itchy pets

My pet won’t stop itching! Could it be dermatitis?

Dermatitis is a skin condition resulting in hair loss and itchy, often dry or blistered skin. This is a very common concern in dogs and cats, in fact surveys have found that it is the most common reason for visits to the vet. There are many causes of dermatitis in pets, but nutrition can play a role in both development and treatment of this condition. Dermatitis can be uncomfortable for your pet and frustrating to treat, it will require you to work closely with your vet to help your pet feel more comfortable.

First steps

If your pet is showing signs of dermatitis, the first step is a vet visit to investigate why. Useful information to collect before your appointment:

Record how itchy your pet seems each day on a scale from 1-10 to compare how your pet is feeling day to day
Be sure to report behaviours such as paw licking or chewing, these are often related to itchiness
Take pictures of your pet’s fur colour and compare them to past pictures
Note whether your pet has been shaking their head or scratching their ears more than usual, dermatitis is often correlated with ear infections
Make notes about behaviour changes, such as increased scratching or reluctance to be touched

An infographic containing the text: "Canadian Academy of Veterinary Dermatology. Dog and Cat Itch Scale. How severe is your pet's itching? Pruritus (itching) manifests itself by scratching, nibbling, licking, when a pet rubs against objects or people, or when a pet rubs its back. The scale below is designed to measure the severity of itching. Read all the descriptions starting from the bottom, then place a mark anywhere on the vertical line to indicate the point at which you think your pet's level of itchiness currently lies. The mark may be placed between two descriptions, if necessary. 10. Itching does not stop whatever is happening, even in the consulting room (needs to be physically restrained from itching) Extreme severe itching / almost continuous. 8. Itching might occur at night (if observed) and also when eating, playing. exercising or being distracted. Severe itching / prolonged episodes. 6. Itching might occur at night (if observed) and also when eating, playing, exercising or being distracted. Moderate itching / regular episodes. 4. Does not itch when sleeping, eating, playing, exercising, or being distracted. Mild itching / a bit more frequent. 2. The dog/cat is slightly itchier than it was before the skin problem started. Very mild itching / only occasional episodes. 0. Normal dog. cat - I don't think itching is a problem. — The CAVD Itch Scale

Nutritional causes of dermatitis

Dermatitis can be related to diet, for example this condition can occur due to deficiencies in certain nutrients; such as copper, zinc and certain vitamins, although food allergies are more common. Check the label on the packaging of your pet’s food to ensure that it has an AAFCO nutritional adequacy statement indicating that it is complete and balanced, and therefore is not lacking any essential nutrients. If your pet is eating a homemade diet, consult a veterinary nutritionist to ensure the diet is balanced and the appropriate supplements are given. This is particularly important while your pet is young, as growing pets are more sensitive to nutrient deficiencies.

Food allergies are another possible cause of dermatitis and most pets with food allergies are allergic to one or more protein sources. Allergies develop after a long period of exposure, meaning that pets can develop allergies to the protein they have been eating for a long time. Animal-based proteins are particularly common allergens; especially beef, dairy and wheat in dogs, and beef, dairy and fish in cats, due to their frequent use. However dogs and cats can develop an allergy to any protein they have been exposed to. If your vet suspects a food allergy, they will suggest a food elimination trial to diagnose the allergy. Tests using blood, fur or saliva are not accurate for the detection of food allergies in pets and should therefore not be used.

What is a food elimination trial?

The gold standard for diagnosing a food allergy involves strictly feeding an elimination diet
Hydrolyzed protein diet: In these diets, proteins are broken into tiny pieces, to decrease the chance of the immune system responding to them. These diets also have the lowest chance that a new allergy develops
Novel protein diet: Another option is a diet that contains a protein source that your pet has never been exposed to and that is not used often in pet food products
Past foods: Your veterinarian will need to know all the foods your pet has been exposed to in their lifetime, to ensure the selected protein is one they have not been exposed to
Remove other foods: Elimination trials must be very strict, no other food should be given; otherwise if your pet continues to have dermatitis, it will not be clear whether this is due to continued exposure to the food allergen or a different cause, making the results inaccurate
Length of diet trial: The elimination diet must be continued as only food source for at least 6 weeks to give your pet time to respond

Whether you are trying a hydrolyzed or novel protein diet, the best choice will be a veterinary therapeutic diet, although over the counter novel protein diets from retail stores do exist, the risk of cross-contamination makes them less ideal as a diagnostic test. If your pet responds to the elimination diet and is no longer showing signs of allergies, your vet may direct you to start adding new protein sources to their diet, one at a time, and watch for signs of the dermatitis returning. This will allow you to determine which protein they are allergic to, so that it can be avoided in the future.

How to make sure your elimination diet test is accurate

Avoid flavoured medications, for example monthly preventatives should be switched to topical versions
Don’t give any treats or snacks beyond the elimination diet food, including dental treats
Check with your vet before giving your pet any supplements, some supplements contain ingredients that your pet could be allergic to
Change your pet’s food bowls, puzzle feeders, even the tool you use to scoop the food
Prevent access to the garbage, dropped food, other pet food and anything they may find while out on a walk

How nutrition can help treat environmental allergies

Pets can also be allergic to environmental allergens, which are harder to avoid than food allergens. Because an elimination diet won’t help with environmental allergies, if your pet remains itchy on a hydrolyzed diet, or if their allergies fluctuate with the seasons, your vet may suspect environmental allergies. Nutrition is still an important part of the treatment of environmental allergies, certain nutrients can improve skin and coat health and reduce scratching.

Water: often overlooked, but water is the most important nutrient. Dehydrated skin isn’t healthy skin!
Omega-6 fatty acids: such as linoleic acid (LA) and Gamma linolenic acid (GLA) have anti-inflammatory properties and are essential for skin health, deficiencies in this nutrient will cause scaly skin and water loss through the skin
Omega-3 fatty acids: particularly EPA and DHA, can be included in your pet’s diet, or added as a supplement to decrease skin inflammation. These usually come from fish oils and are far less likely to trigger a reaction than fish protein, but if your vet is concerned about a fish allergy they may suggest an alternative, for example an algae based supplement
Zinc: is important for skin and coat health, although deficiencies are rare unless the diet is unbalanced. Certain animals including Nordic breed dogs can have decreased zinc absorption in their intestines, causing deficiencies in these individuals

Many pet foods already contain these nutrients, so make sure to talk to your vet before adding a supplement, you can have too much of a good thing! Some pets have both food and environmental allergies, so a combination of diet, supplements, and other medications may be needed to help these pets feel comfortable.

Next steps

In addition to nutrient deficiencies and food and environmental allergies, there are many other causes of dermatitis, including parasites. Untreated dermatitis is uncomfortable for your pet, frustrating for you and can result in chronic health problems. If you notice your pet scratching, losing fur, or developing dry or blistered skin, contact your vet to set up an appointment. Being prepared with a record of when symptoms appeared and any changes you have noticed over time will help your vet make a diagnosis, but tests will likely also be needed to find the source of the problem. In addition to nutritional recommendations, your vet may also prescribe topical medications or baths to help decrease itchiness, heal skin damaged by scratching or treat other underlying causes of dermatitis. Don’t delay on treating dermatitis, your pet will thank you!

If you suspect your pet has dermatitis, consult your veterinarian prior to making any diet changes. Your veterinary healthcare team will work with your to select a diet that works best for your pet and your feeding preferences.

Written by:

Emily Fowler, BScH, DVM 2024

Reviewed by:

Dr. Caitlin Grant, DVM, DVSc

Claude F, Linek M, Fontaine J, Beco L, Rostaher A, Fischer N, et al. Western blot analysis of sera from dogs with suspected food allergy. Vet dermatol. 2017 January 16 (cited 2022 June 7);28(2): 189-e42.

Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ. Small animal clinical nutrition 5^th ed. Topeka: Mark Morris Institute; 2010.

Hill P. Diagnosing Cutaneous Food Allergies in Dogs and Cats – Some Practical Considerations. In practice (London 1979). 1999 June 1 (cited 2022 June 7);21(6): 287–294.

Verlinden A, Hesta M, Millet S, Janssens GPJ. Food allergy in dogs and cats: a review. ProQuest. 2006 (cited 2022 June 17);46(3): 259-273.