Atopic dermatitis

So what are these other diseases? Flea infestation and the allergy are the most important causes of itchiness in dogs in the UK. Practically all dogs will have fleas at some time during their lives. The rump and hind end are most often affected. Nibbling and itching gives a rough feel to the coat and, if severe, pyotraumatic dermatitis or alopecia will result.

Very importantly, dogs with atopic dermatitis are often allergic to fleas as well, so it is pointless making a diagnosis of atopy without taking rigorous flea-control measures. Similarly, other parasitic infestations such as lice or sarcoptic mange may mimic atopy and these should be carefully ruled out.

Food sensitivity is an uncommon cause of allergic skin disease, which accounts for a small percentage of the cases seen by dermatologists. Although a rare condition, all allergic dogs should undergo food trials before being committed to long-term drug therapy.

Food sensitivity may coexist with atopy or flea allergy and so partial responses may be seen to food changes. Bacterial infections are a common cause of pruritus in the dog and these can be as a result of atopic dermatitis or any other skin condition that damages the integrity of the skin.

Non-allergic causes of bacterial infection include hormonal problems such as hypothyroidism and parasitic problems such as demodex infestation. These are normally non-itchy conditions, but as soon as there is bacterial involvement this changes and it can be difficult to make the correct diagnosis.