The main sign is scratching, which often results in skin irritation and fur loss. If your dog shows regular signs of itchiness and chew at their back, towards the tail it could be a sign of a flea allergy.
Some dogs chew the tops of their tails as they can’t reach the back, but it’s the area over the pelvis that typically irritates them the most. Some dogs suffering from a skin allergy might chew their front feet or rub their faces on the carpet as their ears or lips are itchy.
If you see these regular signs it’s best to get in touch with your vet who can investigate the irritant. Normally preventative treatment is recommended to try and eliminate the cause by determining the allergen. For example if the allergy is caused by flea or mites, your dog will need to be treated with an effective flea and mite treatment which your vet can prescribe.
Many allergies are seasonal such as certain pollens and your vet may choose to suppress the allergy via medication during the short period of time that the dog is subjected to the allergen.
Your vet may suggest allergy testing via a blood test or trying to eliminate things individually from your dog’s environment until the cause is identified. This method is typically used when food allergies are suspected.
Less common options include Immunotherapy whereby once the specific allergens have been identified, a specially prepared injection containing altered allergens are injected under the dog’s skin with the aim of de-sensitising your dog’s response to the offending allergens over a period of time. This is typically used in cases for dogs whereby avoidance of the allergen is impossible or symptoms happen for long periods of time.