Scratch, scratch, scratch. Vet Neil Mcintosh offers some advice on itchy dogs.

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Let’s take a look at itchy dogs in general, which of course include an itchy labrador. It must be said that itching, or pruritus, is simply a clinical sign that something is not right. Setting aside those few dogs that scratch due to boredom or anxiety, there are three main causes – though I may be in danger of oversimplifying the problem.

Allergic skin disease

Also referred to as atopy, allergies in dogs are common, often inherited (so always beware the itchy mum when choosing a puppy) and can be difficult to diagnose accurately, as many dogs are allergic to multiple items. This category can be subdivided into:

  1. Food allergy – Humans with food allergies will vomit and have diarrhoea. Affected dogs itch – hence an itchy labrador. Owners often mistakenly look to incriminate newly introduced foods as the cause, but it is usually regular dietary components that are the culprits. Blood tests can help to pinpoint allergens, but often it is best to feed novel proteins and carbohydrates (salmon and potato, for example) or hydrolysed foods for a period of two months, with the exclusion of everything else. (Read more advice on allergies to food.)
  2. Inhaled/environmental allergy – This is the most common and, as you might expect, is generally worse in the summer, as pollens are usually implicated. Remember, however, that the pollen season can extend from March to October. Affected dogs are worse on high pollen count days and often suffer from secondary bacterial and yeast infections, as bugs are spread around the damaged skin during scratching. These infections also cause itching, so can be a cause of apparent failure of steroid therapy. The latter can reduce the immune system’s response and encourage infection. (Read our advice on pollen allergies and dogs.)
  3. Contact allergy – Pick an item (carpet, bedding, car seat cover, shampoo and so on) and there will have been a dog that has reacted to it. Remember also that while you might be able to apply deodorant to normal skin without a problem, the same substance may irritate skin that is already inflamed. Again, secondary infections are common. (Take a look at our list of best gundog beds.)

Hormonally induced skin disease

This category includes:

  1. Hypothyroidism (underactive thyroid) – This is characterised by lethargy, weight gain, a pot-bellied appearance and skin changes, including flaking, drying and pyoderma.
  2. Cushing’s disease – This is caused by an increase in steroid production in the adrenal glands, resulting in excessive thirst and skin thinning. In both cases, affected dogs may present as being itchy.
  3. Sarcoptic mange – In my opinion, this is the most likely cause of a dog’s non-responsive-to-steroid itching. Sarcoptes scabiei is a burrowing mite that creates intense itching in dogs, along with considerable discomfort and secondary infection. The life cycle is pretty vile, so look away now if you are squeamish. The female mites burrow into the skin and create moulting pouches. The male then tunnels in after her and they mate, resulting in her being fertile for her two-month lifespan. Typically, she will lay two to three eggs a day, with these hatching within the week. Eventually, the movement of the mites, coupled with an intense allergic reaction to their excretions and secretions, results in classic symptoms – mainly itching. (Read what diseases could my dog pick up from foxes.)
disease from foxes

This urban fox has bald patches that look sore, which are signs of sarcoptic mange

Sarcoptes is highly contagious and it leads to initial crusting and itching around the head and ears before progressing to widespread dermatitis. A mousy smell is often apparent. Scratching becomes continuous and the skin gets flaky, sore, thickened and inflamed. Misdiagnosis is common, as the clinical signs are similar to allergic skin disease. Unfortunately, inappropriate treatment with steroids or immune-mediating medication will only make the condition much, much worse. Treatment used to be very complicated, but antibiotics and appropriate parasiticides in the form of a simple, single chew are effective. Any dog, including an itchy labrador, suffering from pruritus that does not respond to steroids deserves further investigation. Additionally, the use of steroids to treat allergic skin disease has largely been superseded by newer medications that have far less side-effects, including a monoclonal antibody that turns off itching at the cellular level, and is administered by monthly injection.