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Pollen allergies in dogs are a common cause of itchy skin
This week on Ireland AM, I brought Oscar with me: he’s a terrier who has classic signs of pollen allergy, and he also suffers from dust mite allergy. This means that he is itchy all year round, but it always gets worse at this time of year because of the increase in pollens.
- A blood test was done which showed that Oscar is allergic to five different grass pollens, as well as to 4 different dust mites
- Some dogs are only allergic to pollens, in which case they have a strictly seasonal allergic skin itchiness, starting around now.
- Dogs don’t tend to suffer from hay fever (snuffling, runny eyes, sneezing) – they just get itchy skin
Atopy is the most common type of pollen allergy in dogs
Atopy (atopic dermatitis) is an inherited allergic skin disease of dogs: it’s more common in some breeds ( such as West Highland White Terriers) and it’s almost never seen in other breeds (such as Greyhounds). The allergy can be to pollens, but also to moulds and house dust mites.
The cause of the allergy is an inherited defect in the normal skin barrier, allowing tiny particles to penetrate the outer layers of the skin, provoking an allergic reaction of the lower sensitive areas and causing inflammation here (redness, itchiness, etc).
Once the inflammation starts, there’s a vicious circle, with dogs licking and scratching themselves, further damaging the skin and making it even more inflamed. Bacteria and yeasts that normally live harmlessly on the skin can then move into the inflamed and damaged areas, leading to secondary infections, with toxin and irritant production causing more itching.
Classic signs of atopy
The classic signs of atopy are itchiness affecting the following areas
The first signs of atopy are usually seen between 9 months and 3 years of age, but it can also develop in younger and older dogs.
The main signs are licking or chewing of:
- the paws
- area under the tail.
- There’s also scratching, especially of the ears..
Hair loss, redness of the skin and secondary infections with yeast or bacteria are often seen, making the situation even worse as time passes..
- There is no definitive test to confirm a diagnosis of atopy: it’s a matter of ruling out other causes of itchy skin, and making a diagnosis based on the history of the animal, and the areas that are itchy.
- Other possible causes of itchiness that need to be ruled out include parasites and food allergy.
- Laboratory tests including blood tests, skin scrapings, skin swabs and skin biopsies may be required.
- A special diet is needed for 6 – 8 weeks to make sure that the dog is not allergic to anything in his food
- Once this has all been done, the only diagnosis that is left is atopy, or pollen/dust allergy
The aim of treatment is to
- reduce inflammation and itchiness
- treat secondary infections of yeasts and bacteria
- Reducing pollen burden by avoiding grass, staying in on pollen-rich days, washing dog down after walks outside
- Specific immunotherapy to “vaccinate” against pollens (see below)
- Anti-inflammatories (see below)
- Medicated shampoos
- Continual flea protection programme as fleas will aggravate an already itchy dog
- Essential fatty acids help to reinforce the skin barrier function and improve the itchiness of around 25% of allergic dogs.
- Antihistamines are rarely sufficient on their own but can help to reduce the dose of other medications
Once the specific pollens have been identified via a skin test or a blood test, a solution can be manufactured that includes these pollens. This is given by injection regularly, eventually once a month, and continued for life. This gets the body used to the presence of the pollens and so the allergic reaction is reduced. It works well in 50 – 70% of cases.
- Corticosteroids (usually prednisolone – small white tablets) are usually the first drug of choice, but they do have side effects which may outweigh the benefits. The side effects are kept to a minimum by giving the medication only on every second day.
- Cyclosporine (e.g. Atopica) is one of the most effective treatments for atopy. In more than half of patients the disease is effectively controlled after a few months and medication can be reduced to every other day or twice weekly treatment. There are some adverse side effects, of which the most common are vomiting and diarrhoea which often resolve without stopping treatment. The drug is expensive but it’s often effective enough that owners are prepared to pay the extra cost.
- Oclacitinib (Apoquel) is a new drug to the control of itching associated with allergic and atopic dermatitis in dogs over 12 months of age. Its mode of action specifically targets and inhibits the cytokines involved in skin inflammation/. The drug takes effect within 24 hours, and again, it does not have the side effects so often seen with prednisolone. It is more costly than prednisolone, but not as pricey as cyclosporine.
What about Oscar? Why is he not itching any more?
Oscar is on regular immunotherapy, and he also takes Apoquel every day. He has responded very well to this combination of treatment.
To find out more, watch the video below..