Food allergy and its relationship with environmental allergy

Allergies may not be life-threatening conditions; we agree on that. But they are among the most frustrating, annoying, and difficult chronic disorders to deal with. You probably already know by now that dogs, like people, can be allergic, and that allergies may be caused by many allergens commonly found in everyday life. Some dogs may react to food, others to environmental elements, others to parasites, or a combination of them all! Allergens are not the only cause to blame, though. Genetics plays an important role. Animals developing an allergy are unfortunate enough to have a genetic predisposition that makes their skin weaker and, therefore, susceptible to allergens entering from the outside. But how does it apply to the allergens that come from the inside, as food is? Is it maybe a different disease? Well, yes and no…This is, in fact, an intriguing question!

The truth about canine allergies

Allergies in dogs can be complex, as many dogs react to multiple allergens which can be difficult to identify. Affected dogs often have close contact with these allergens as they are frequently found around the house and in the outdoor environment, making them hard to avoid.

Common causes of allergies in dogs are fleas, pollens, dust and storage mites. All of them share the fact of contacting a weakened skin barrier, overcome the defenses, and lead to a exaggerated immune response whose first sign is…yes you guess…itch!!!

While flea allergy does not have a specific test , environmental allergens can be determined by serological tests , that determines if the animal has developed antibodies, and intradermal tests, that mimics a mini-allergen attack in a controlled way, allowing the veterinarian to identify the allergens.

It would be nice if food allergens could also be signaled and then eliminated from the diet, don’t you think? But things are not so easy.

What is my dog allergic to?

Food allergies can occur at any age and, even if your dog has been fed the same diet for a long time, they could still develop an allergy to an ingredient within the diet. When dogs encounter a food allergen, they most commonly become itchy and develop signs of skin disease, same as with environmental allergens. Those common signs include itchy skin, licking at paws and between toes, licking around the anal area, scooting, inflamed (reddened) skin or ears, dandruff in coat, hot spots – sore skin lesions , secondary hair loss and skin and ear infection, runny eyes or nose sneezing . Wow!

However, unlike other allergies, some dogs may also show digestive signs as loose stools, gas passing , or vomiting, either in isolation or combined with skin disease.

Dogs suffering from a food allergy may only show a few of these signs, which can make it difficult for owners to recognize. In addition, they may have other allergies, so may show additional signs of flea and/or environmental allergies. If your pet has developed skin disease or any digestive problems, you should get them checked by your vet.

So, in fact, an active search for food allergies is the first step in the diagnostic process, as they are very closely related. Symptoms can be exactly the same and having one allergy doesn't exclude suffering from another. Some dogs will be, poor them, multi-allergic!!

An elimination diet trial is the only way to diagnose food allergies. This involves feeding a novel protein your dog has never eaten before. To make this easier for owners, several commercially available hydrolysed diets can be used. The protein in a hydrolysed diet has been broken down into smaller components to prevent your dog’s immune system from triggering a reaction. Otherwise, a homemade diet can be chosen, though this can be very difficult to formulate and ensure there is no contamination from other allergens – making it costly and time-consuming to prepare. You should speak to your vet for help choosing the best diet for your dog.

An elimination diet trial will usually last between 6 to 10 weeks and during this time your pet will only be able to eat their new diet. This means treats, table scraps, scavenging on walks, flavoured toothpaste and flavoured tablets need to be avoided. During this time, you should see an improvement in your dog’s skin and digestive signs. Yes, it is hard, but you will not need to feed your dog their elimination diet forever, because at the end of the trial, you will need to challenge your dog by introducing various foods one at a time to determine which foods trigger their allergy. This will enable you to build up a list of foods your dog cannot tolerate, so you can find a suitable diet that does not cause any reactions. If you decide not to do the challenge, then you will never know for sure whether the dog actually has a food allergy, or if other allergies or itchy stimuli are the real problem. And the good news is that, once you have identified the offending food, keeping it away from your dog will contribute to making him better! Is not that nice?

Food allergies can cause cross-reactions

As a curiosity, cross-reactions in humans can occur in some individuals, when their immune system reacts to additional foods similar in structure. For example, people with a peanut allergy can also be allergic to other legumes, such as soybeans. However, while some individuals will develop a cross-reaction, others will not. And, interestingly enough, tick-bites may cause cross-reactions too! In the USA and Australia there has been found to be a link between the development of sudden red meat allergies and tick bites in people. This food allergy occurs following exposure to a carbohydrate named Alpha-Gal and can result in severe anaphylaxis with many affected people having knowingly suffered from a tick bite in the hours before the reaction. Treatment for affected individuals is allergen avoidance, meaning red meat needs to be removed from the diet.

While true cross-reaction between an environmental allergen or parasites and a food allergy is unusual, if a pet is allergic to several different allergens, it can make diagnosis very difficult. This is why the process of diagnosing a food allergy needs to be followed very carefully, as in many patients, the symptoms will vary from day to day whether or not we have removed the allergen from the diet. This can occur because of higher or lower pollen counts, for example, or the presence of a parasite bite. Itching is considered a “cumulative phenomenon”, in that everything that causes an itchy sensation adds up, and the total is what we see in how often the dog or cat is scratching.

More commonly, food allergies are also seen in animals with other allergic condition. This combination of different but overlapping allergies is seen in Atopic Dermatitis, where the dog or cat has a genetic predisposition to allergies developing.

Treating food allergies-as a whole

Food allergies are managed by allergy avoidance. This means that any food your dog is allergic to should be excluded from their diet to prevent any skin disease or digestive signs recurring. The foods your dog needs to avoid will vary depending on their allergies, but as individual ingredients are difficult to identify, in general, hydrolysed diets are recommended as they are quite palatable, safe, and effective for most cases.

However, if your dog has a flare-up of their skin signs, treatment will be needed. This may include oral medications to control the immune response and topical treatments with creams, shampoos, and sprays to control the itch and treat any skin infection present. Topical treatments are frequently used to treat skin disease because they can be targeted at specific areas of the skin that need treatment, and often have reduced side effects compared to oral medications.

All dogs who suffer from allergies will need long-term topical skin management to help maintain a healthy skin barrier function and reduce the risk of skin infections developing due to bacterial or yeast overgrowth. DOUXO® S3 PYO contains chlorhexidine, an antibacterial agent, so is ideal for eliminating any microbial overgrowth and keeping the skin free of infection. The shampoo formulation is perfect for long-term use, as it does not dry out the skin and can be used alongside DOUXO® S3 PYO mousse and pads.

For itchy dogs, DOUXO® S3 CALM will soothe itchy and irritated skin, reducing redness and the severity of any flare-ups. It also helps restore the skin’s microflora, improving the skin barrier function and providing protection against allergens. DOUXO® S3 CALM pads are ideal for daily use between your dog’s toes, on their lips and around their anal area to help relieve itching, while the shampoo is ideal for long-term treatment of generalised skin irritations. Between baths, DOUXO® S3 CALM mousse is ideal for keeping your dog’s skin calm, hydrated and healthy.

Food allergens can cause severe skin signs, especially if your dog also suffers from environmental or flea allergies. However, spending time investigating which food allergens affect your dog and carefully caring for their skin long-term can significantly improve their quality of life and reduce the risk of future flare-ups.

We recommend DOUXO® S3 CALM and DOUXO® S3 PYO