An animal’s body has a very complicated immune system for fighting infections and for helping to remove foreign invaders. Unfortunately, this system can sometimes go wrong by over-reacting to normally harmless substances. Such reactions form the basis of allergies. Substances capable of evoking allergic reactions are known as allergens. These can give rise to a number of conditions, particularly skin problems, but may also cause respiratory problems such as asthma and bowel upsets, including diarrhoea and colitis.

Allergy related problems are now becoming common. Most sensitive animals react to more than one allergen. Common allergens include grasses, pollens, moulds, house dust mites, forage mites, flea saliva, wheat gluten and foods additives.


Flea Allergy Dermatitis

Some animals are so sensitive to fleas that just a single bite can trigger an allergic skin reaction, causing intense itching and scratching.

Flea allergy reactions tend to affect the area around the pelvis, above the tail base and around the back legs. You may notice small sores and scabs, together with loss of hair and raw areas. Scratching and rubbing are common.

Atopic Dermatitis

This is commonly caused either by inhaled allergens such as pollens, or ingested allergens including wheat or beef proteins, or allergies to parasites, especially fleas.

As a general guide, pollen allergies tend to be strongly seasonal, whilst allergies to foods are not normally seasonally biased and occur all year round. Flea allergy reactions occur predominantly from the spring to autumn, peaking in April and August, but may be present to some degree all year. Allergies to house dust and forage mites tend to be all year round, often intensifying in the winter months when animals spend more time inside the house.

Symptoms include:

  • General itching
  • Scratching & biting
  • Areas of inflamed red skin
  • Sores that become infected
  • Red ears and ear infections
  • Itchy feet

Long standing cases may also develop other symptoms:

  • Thickened, elephant-like skin
  • Seborrhoeic, greasy, smelly skin
  • Flaky, scaly areas
  • Change in skin pigmentation from pink to black
  • Loss of hair
  • General debility

Contact Allergies

This type of allergy is triggered by something that comes into direct contact with the skin and often affects the tummy area, inside the front and back legs and the feet. You might see inflamed sores or blotches, which the animal may lick repeatedly. Common allergens include washing powders, man-made fabrics and grasses.

Food Allergies

Reactions to food can give rise to skin problems, behavioural disturbances, chronic diarrhoea and colitis.

Any food ingredient can be responsible for an allergy, however the most common foods implicated in allergies include:

  • Milk
  • Beef
  • Pork
  • Wheat gluten
  • Soya
  • Food additives

One way of identifying the problem is to put the animal onto a diet of limited ingredients unlikely to trigger an allergy. For dogs this list might include lamb, chicken, rabbit, tofu and fish as protein sources and rice or potato as carbohydrate sources. Vegetables can be added if necessary. For cats suitable foods include lamb, chicken, rabbit, venison and dogfish, together with rice. Always use filtered water, if possible, and avoid all treats.

If the feeding regime is successful, other foods can be introduced, one at a time, to see if a reaction is triggered. Eventually, you will know what foods your animal can tolerate. If you plan to undertake a feeding trial, then stick to your chosen diet for at least 6 weeks to gauge its effectiveness.

Where this is impractical, it is now possible for your vet to perform a blood screen to check for the most common food allergens. The tests can be extended to include environmental allergens as well.


Denes produces a variety of pet foods, supplements, aromatherapy products and licensed herbal medicines, which can help solve some chronic allergy related problems.


You can use some of our recipes in feeding trials to determine which ingredients your cat or dog may be sensitive to.

All of Denes recipes are free from:

  • Artificial additives, including colours, flavourings and preservatives
  • Soya protein
  • Dairy products

The following Denes recipes are free from:


Dog recipes – canned

Dog recipes – dry


Dog recipes – canned

Dog recipes – dry


Dog recipes – canned


Herbal remedies can often help with allergic problems and have the advantage that they are free from side effects and can be used long term.

  • Denes Greenleaf Capsules. These have a natural anti-inflammatory effect and also help cleanse the skin of toxins. They can help stop itching and scratching.
  • Denes Garlic Oil Capsules. These help fight the secondary skin infections that commonly complicate chronic allergic skin problems. Garlic will also help deter fleas.
  • Denes Tranquil+ Powder. Sedative herbs like valerian, vervain and skullcap, constituents of Denes Tranquil Plus Tablets, can help where skin irritation is causing some distress by helping to calm your pet.
  • Denes Digestion+ Powder. Where dietary allergies result in diarrhoea, it is worth considering using Denes Digestion+ Powder. These are based on Marshmallow root, Agrimony, Peppermint leaf, Liquorice root, Ginger root, Slippery Elm and Kaolin and will help soothe the bowel and encourage more solid motions.
  • Denes Probiotic+ Powder. This is a useful supplement to use where a dietary allergy is suspected and will help by supporting the growth of friendly bacteria in the bowel. This will help balance the digestive system.
  • Denes Probiotic+ Fibre Powder. Also contains Ground Whole Psyllium Seed which will help with the lining of the bowel.
  • Denes All-in-One+ Powder. Allergic skin problems can sometimes lead to loss of hair and poor coat quality. The seaweed content in Denes All-in-One+ Powder can help improve both coat growth and condition.
  • Denes Organic Omega 3 Oil. A balanced blend of organic omega 3 oils containing high levels of ALA, promoting the condition health of the coat and skin. skin and helping control the symptoms associated with skin allergies.
  • Aloe vera. Useful in controlling the symptoms associated with skin allergies by supporting the immune system. Especially good where the overall skin condition is poor. Can also be applied externally to soothe and heal sore skin.

For external use we recommend:

  • Skin Balm. This is based on tea tree oil, which has antiseptic and anti-fungal properties. Encourages the bodies natural healing processes.
  • Hot Itch Lotion. This will help soothe red, raw, hot areas.
  • Liquid Garlic. This will help to deter fleas and can be used to soothe sore or infected areas.
  • Essential Oil Shampoo. This contains seaweed and birch extracts as well as essential oils of lavender and cedarwood and will help to deter fleas and improve the appearance and feel of the coat.


Homeopathy provides another alternative way of dealing with allergic based skin problems. Useful remedies from our range include:

Other Denes fact sheets to read