Can dogs have allergies

An allergic reaction is a reaction that the body displays when it is faced with an “allergen” - which is the substance causing the reaction. Common allergens are:

  • Flea bites, fleas and their faeces
  • Food - not necessarily a new food. Dogs can become allergic to food they have been eating for a while.
  • Environmental factors such as grass pollen outside or house dust mites indoors. These allergens cause “Atopy” or “Atopic dermatitis”. They can also cause “hives”. These are little bumps all over the body which are quick to erupt but also quick to go – more like a nettle rash in humans.

The problem is that the symptoms can be exactly the same as for any other skin disease and frustratingly there is no specific test for allergies in dogs. Instead your vet will need to rule out other causes of skin disease. This can be a time-consuming and expensive business.

Flea allergies

Dogs are very sensitive to the presence of fleas on their skin. It is not just the irritation of the flea itself, but an allergy to the saliva of the flea which gets into the skin when the flea bites. A dog with flea/ flea bite allergy will typically be very itchy with sore skin around their back end, tail-base and hind legs. The fur will often have a thread-bare appearance. Sometimes you will see evidence of fleas or their faeces in the coat.

If you see little black “soot-like” specks; it might be flea dirt. To check; put them on a piece of wet cotton wool and see if they turn red when spread. This is evidence of fleas rather than ordinary dirt!

If your dog doesn't get regular prescription flea treatment, then your vet will want to rule this out as a first-line treatment. It is very important to treat all pets in the house, and to treat the house itself. Remember - only 5% of the flea life-cycle is on your pet! Find out more about flea prevention here >

Food allergies

True food allergy is not uncommon, but it can develop in dogs of any age and typically occurs with a food they’ve been fed for some time.

Symptoms of a food allergy

These vary but usually result in one or more of the following

  • Itching all over the body
  • Itching a specific area – e.g. face
  • Inflamed, itchy ears and feet
  • Sore bottom
  • Sickness and/ or diarrhoea
  • Passing blood or mucous in faeces.

How can you treat food allergies?

If your vet suspects that your dog may have a food allergy, they will suggest you do a diet trial. This consists of feeding a special diet (this can only be purchased at your veterinary practice) for a fixed period – usually at least 4 weeks. This is an essential step as simply feeding a different diet may be all you need to do to control the condition for life.

Special (hydrolysed or novel protein) diets need to be used.

Your vet will be happy to discuss this with you.

Atopic dermatitis

This is the name given to the skin condition resulting from a sensitivity of the dog to something in its environment. It is often an inherited disease affecting some breeds, such as terriers, more than others. For this reason, any dog that develops this disease should not be bred from as it could pass the problem onto the next generation. Signs often start when the dog is still young – typically 6 months to 3 years of age.

If you suspect Atopic dermatitis, the dog may become generally itchy, with specific areas affected. These are typically:

  • Paws
  • Ears
  • Face
  • Tummy
  • Armpits
  • Groin
  • Inner thighs
  • They may also have hay fever signs involving runny eyes and nose.

Other causes of irritation will need to be ruled out before a diagnosis can be made. This will involve ruling out parasites with anti-parasitic treatment and possibly some skin tests; a diet trial, along with possibly antibacterial and anti-fungal medications.

Once other conditions have been ruled out, ideally a blood test or skin test is performed to assess for atopy. These can give us inaccurate results if we perform these prior to ruling out other causes- hence why it is important to do this last.  A course of de-sensitisation injections can also help in some cases. This decision on how to proceed with further diagnosis and treatment will depend on the individual case involved.