As we discussed, itching in dogs and cats can be due to a number of reasons such as for example: Ectoparacites (fleas, mites and lice), skin infections, immune disorders and allergy.

I think there is a possibility that your pet is suffering from an allergy based on the history, age, breed and described clinical signs.

A true allergy is an over-reaction by the body's immune system to a stimulus that the body usually can  tolerate and this can be divided into two main types:

- Food allergy (allergy to a protein source)

- Atopy (allergy to something in the environment such as pollen, house dust mites, etc).

In dogs, allergies often present in the form of itching. The dog will respond to the itching by licking, biting and scratching. This behavior can have different degrees of intensity and result in different degrees of 'self trauma'.

In order to make a correct diagnosis, it is essential that the examinations are carried out systematically and it is important to realise, and accept, that this takes time and that several visits to the veterinary clinic are often necessary.

A typical investigation might proceed like this:

- The first step usually involves an investigation to rule out that the itch is caused by ectoparasites such as fleas, mites and lice. Samples are often taken from the skin and fur (skin scrapes and hair plucks). Ectoparasites can be difficult to diagnose in some cases and therefore treatment for ectoparacites are often used to minimise the risk of these ectoparacites being the cause of the signs.   

- It is then ruled out that the itching is caused by a bacterial or fungal infection. This is done by a visual inspection and in some samples of fur and skin are examined in the laboratory. 

If both parasites and infection are ruled out as the cause, the vet may chose to start the dog on an elimination diet:

- The dog receives a special food, which consists of proteins that the dog has not previously eaten or proteins, within the food, that have been processed in a way that means that the immune system does not react to them.

The dog is usually on this diet for 8 weeks. It is very important that the dog does not get anything else to eat, such as leftovers, treats or chew bones during this 'trial period'. This is because exposure to even very small amounts of 'bad' protein can cause the dog to continue itching.

If the dog's itch improves or resolves as a result of this diet change, then it is likely that it is allergic to certain proteins in the food:

- To confirm this, you can provoke the dog's immune system by giving it food you suspect the dog is allergic to. If the dog then starts to itch, the diagnosis is clear - the dog has a food allergy.

If it only gets a little better or doesn't get any better from this diet, you move on to investigate whether the dog may be atopic (allergic to something in the environment):

- There are several ways to investigate this and one popular way is by taking a blood test which is then analysed for certain types of antibodies. 

- If the blood test shows high levels of antibodies against certain substances, a vaccine can be made especially for this dog.

- The aim of the vaccine is to make the immune system more tolerant and less reactive. The vaccines are administered via injection under the skin once a month or as a drop under the dog's tongue daily.

Some patients manage well by this treatment alone, others have to be bathed regularly in special medicated shampoo in addition, and some also have to receive steriods or other medication that help control the itch. 

Unfortunately, in some patients there is no effect from the vaccine treatment at all but luckily there are several other ways to manage allergies. Together with the vet, your pet is prescribed a treatment which is tailored to and optimal for the individual dog.

I hope this has given you a little insight into some but not all possible ways of investigating itchiness in dogs.