Food allergies in dogs


How can I look after my pet’s skin and coat?
By regularly and carefully checking your pet’s skin and coat, you will often notice changes that were not immediately apparent. For example, you might notice dandruff, a splinter or a mass (lump) that only recently appeared…. Similarly, your pet’s behaviour can be very significant. If he keeps scratching or licking, it is important to check the affected areas closely. Do not hesitate to contact your vet if you are unsure.
The level or care your pet’s skin needs depends on several factors, such as:

  • Species: cats are often more difficult to handle than dogs.
  • Lifestyle: does he mainly live indoors or outdoors?
  • Coat type: long or short hair? Rough or silky?
  • Skin type: oily, dry or normal?

Generally speaking:

  • Check your dog after walks for splinters or grass seeds and remove any ticks or fleas you come across.
  • Dry your dog if he is wet (with a clean bath towel), without forgetting his ears.
  • Regularly groom your pet with a suitable brush or comb. This untangles any knots that may have formed and also removes dead hair.
  • Only wash your pet with shampoos specifically designed for cats and dogs. Companion animals have more acidic skin than humans, so human shampoos may irritate your pet’s skin. If the shampoo you use was prescribed by your vet as part of your pet’s skin treatment, make sure you follow recommendations regarding contact time and frequency of application for this local treatment to be fully effective.

My vet suspects a food allergy: What does this mean?
Food allergies are caused by dietary allergens encountered during feeding. Animal proteins (beef, chicken…) are most commonly involved.
Mechanisms behind allergies
During the ‘sensitisation’ period (which may last several months, sometimes years), the animal is in contact with the allergen but does not show any symptoms. During this phase, however, he develops antibodies to the dietary allergen. In cases of allergic reactions, these antibodies recognise the allergen, leading to histamine release, which is responsible for the clinical signs.
Dietary treatment aims to eliminate all contact between your cat or dog’s body and the proteins to which he is allergic.
There are two types of hypoallergenic diets. They contain:

  • Either Selected proteins. In this case, the animal should be exclusively fed one type of protein (combined with one type of carbohydrate) that he has never been in contact with. This type of diet may be home-made. In this case, it is essential for pet parents to seek veterinary advice to ensure that the diet has the right protein, vitamin and mineral balance. This approach requires the pet parent to be highly committed to preparing meals and to have sufficient storage space available.
  • Or Hydrolysed proteins. These are proteins that have been broken down into little sections, called polypeptides or hydrolysates. These peptides are so small that they are no longer recognised as allergens by immune cells, and therefore do not trigger allergic reactions. Royal Canin Hypoallergenic diet was developed using this principle. Hypoallergenic diet is available from veterinary clinics only. Signs presented by affected animals may vary from case to case: some animals present digestive symptoms (e.g. chronic diarrhea, regular vomiting, flatulence), others will simply show skin symptoms (e.g. pruritus, regular ear infections, skin inflammation) while a proportion of affected animals will display a combination of digestive and skin symptoms. This is why this condition, which is actually fairly uncommon, often takes time and diligence to be diagnosed. Your vet may suggest an ‘exclusion diet’ to be able to accurately diagnose that your pet is allergic to a dietary protein. This involves your animal being exclusively fed a diet known to be hypoallergenic, for approximately two months. If your pet is allergic, his symptoms will improve during the test, and he will have to be fed a hypoallergenic diet for life.

Advice for pet parents

  • It is essential that you only feed your pet the prescribed diet (no table scraps or treats), or its beneficial effect will be cancelled out.
  • Tell your friends and family about your pet’s allergy and about the need to comply with the exclusion diet.
  • Ensue stringent compliance with the parasite control programme (fleas and ticks) prescribed by your vet.

Why is my pet scratching?
Animals may express itchiness by simply scratching themselves with their back feet, but also by nibbling particular body areas, rubbing or rolling on the floor.
There are many different reasons why animals scratch. The leading cause is contact with fleas: when they bite, fleas secrete irritating saliva that causes itchiness.
In animals suffering from a ‘flea bite allergy’, a few bites are enough for the animal to scratch frenetically. However, fleas cannot always be seen on the animal, since their small size (a few millimeters at most) means that they hide between hair.
How do I know if my pet has fleas?
The most common indicator of fleas is finding flea droppings (small black flecks) on the animal. Droplets of water will become reddish when mixed with these droppings.
Therefore, regular flea treatment of pets and their environment (including other animals) is advisable in all animals, and essential in all allergic pets.
Other less common causes of pruritus (itching) in cats and dogs include:

  • Other parasites (lice, harvest mites, cheyletiella…). It should be pointed out that sarcoptic mange (transmissible to humans) is very uncommon.
  • Skin infections
  • Canine atopic dermatitis
  • Dietary allergies/intolerances

The large number of reasons why pets can be itchy implies that many different treatments are possible. Your vet will carry out any additional investigations required for him to reach a diagnosis, which is essential to prescribing the right treatment.