Allergies in dogs would seem to be on the increase, with some sources estimating that up to one in seven dogs will suffer from one of the common dog allergies.

The mechanism that causes allergies in dogs is no different to that which causes allergies in humans, with one important difference – dog allergy symptoms are usually quite different to those shown by humans suffering from an allergic reaction!

In the dog, various skin problems (particularly intense itching and resultant skin damage from scratching) are the main symptom of an allergic reaction, while humans suffering an allergic reaction tend to show upper respiratory symptoms.

Allergies in Dogs – why?

The first point to appreciate about allergies in dogs is that while some breeds may be more prone to certain types of allergies, any dog can develop one or more allergies at any time in their life.

Allergies in dogs occur when the dog’s immune system overreacts to what is called an allergen – that “thing” that induces the body’s immune system to get activated. Although their are many common allergens that are recognized, the body can actually develop an allergy to just about anything, which can make treating allergies in dogs extremely difficult.

The overreaction by the immune system after it is exposed to an allergen is commonly known as an allergic or hypersensitivity reaction.

Allergies in Dogs Explained

There are 2 basic types of canine allergic reaction. The first is an immediate reaction which occurs within about 30 minutes of the dog being exposed to the allergen. Commonly it produces raised, itchy areas of the skin with the hair sticking out in little patches which is quite noticeable. This is sometimes referred to as “hives”.

This is a common reaction to some insect bites, and so will often reoccur seasonally when that specific insect is active.

The second type of allergic reaction is called delayed hypersensitivity because the symptoms occur hours or even days after exposure to the allergen and the main symptom in this case is usually intense itching.

Apart from the two different types of allergic reaction, allergies in dogs can also be divided into 4 broad categories according to the source of the allergen. These are:

1) Allergies caused by biting insects and parasites, including fleas.
2) Allergies caused by inhaled allergens such as grasses, molds, pollens etc
3) Allergies caused by foods and drugs
4) Contact Allergies – where the dog reacts to something it lies on or stands on e.g. grass, cement etc

Allergies in Dogs – What Now

From the above we can see why the treatment of allergies in dogs is not necessarily straightforward – Benadryl and other antihistamines will not have any effect on many of the common allergies in dogs simply because, while the symptoms may be similar, there are a variety of causes of canine allergies.

Now that we are aware of the multiple possible causes of allergies in dogs, it is easier to understand that to successfully treat allergies in dogs, you have to spend the time to try and identify the actual cause of the allergy.

Another factor to consider when looking at allergies in dogs is that once a dog starts showing an allergic reaction to one allergen, the situation can frequently escalate with the dog becoming allergic to an ever increasing number of allergens

When this happens, the chances of successfully identifying all the allergens and then treating the dog successfully becomes very slim indeed.

In these cases the best (and possibly only) option is to try to keep the allergies under control and ensure that the dog has a reasonable quality of life. This approach will often involve the prolonged use of drugs which, in themselves, might not be good for the dog’s health.

It then becomes a balancing act between keeping the dog comfortable and minimizing the side effects of the drugs being used to keep the dog comfortable.

It is in everyone’s interests that once a dog starts showing signs of an allergy, that a big effort is made straight away to identify the cause of the allergy and then to set out a plan to deal with it. The sooner the situation is addressed, the less complicated it is likely to be to resolve.

Dog Allergies and Owners

As an owner of a dog which you suspect might have an allergy, you should:

1) Take careful note of the symptoms (usually scratching), when they first started and which part of the dogs body was affected first/the most.

2) Try to remember if there were any changes that took place in the dog’s life that might have initiated the allergic reaction e.g. a change in bedding, a change in diet, the onset of summer etc

3) Do not, under any circumstances, try to treat this allergy with an antihistamine such as benadryl or a cortisone derivative before a definitive diagnosis has been made. At best this might mask the symptoms and thus complicate the diagnostic process, at worst you could do your dog a lot of harm.

4) Take your dog to a veterinarian, along with all the information mentioned above, as soon as you can.

Allergies in dogs – What Your Vet Should Do?

The first thing your vet should do is ask you for all the information you have on how, where and when. In other words, your vet will want a thorough history of the dog and the problem it has.

The vet should then conduct a thorough clinical examination of the dog.

Sometimes, if you are lucky, this is enough to establish the cause of the allergy.

For example, a straight forward flea allergy will have a typical distribution of scratching and hair loss around the tail base, evidence of the presence of fleas (flea dirt, flea eggs and maybe even some fleas), and unless you are in the tropics, will have started in spring or summer (seasonal occurrence).

In many cases however, the diagnosis is sadly not that straight forward and you will need to embark on a series of tests and/or elimination diets to try to pinpoint the offending allergen!

Be warned though that this can become a long, costly and not infrequently fruitless exercise, especially when your dog is allergic to more than one allergen!

To conclude – allergies in dogs are a complicated business and should be dealt with as soon as they become evident.