So your dog has an itch and is driving you insane?
Children get asthma, dogs get eczema. Vets call this Atopy or Atopic Dermatitis and, after fleas, it is by far the most common allergy in dogs; more than 9 out of 10 allergic dogs.
It starts young and persists for the lifetime of the animal. The dog is reacting to dust and pollens in the air which are absorbed through the lungs, primarily, but also directly through the skin. These microscopic particles are called allergens.
The treatment options can be long and confusing and this short article is intended as a guide so that you can see what works, what doesn’t and how much it is likely to cost.
Obviously, if an allergic dog can breathe clean, particle-free air without dust, then it will not have an allergic reaction. That is easier said than done, especially for dogs that are reacting to pollens in the springtime (like hay fever in people). These dogs, with seasonal allergies, scratch when plant pollens are at their highest. While their people are sneezing their way through spring, their dogs are scratching! However, keeping the dog away from grassy and open areas may help, but is not easy to do.
Non-seasonal allergic dogs scratch all year round and are reacting to dust which is in the air all the time. More than three quarters of these are reacting to human dust mites and their faeces. These tiny bugs live in the mattresses of our beds, feeding off dead human skin flakes. Often dogs like these will be much better sleeping out of the bedroom where there is a lower concentration of dust mites. Also, using mattress covers, pillow covers, insecticidal mattress sprays, HEPA filters on vacuums, and air purifiers will all help reduce the itch. Basically, everything you would do for an asthmatic child.
This very old drug is still the mainstay of treatment for Atopic dogs, mainly because it is so effective. In fact, if it doesn’t immediately work then either your dog has some other condition, like an infection, or has not got Atopic Dermatitis!
The cons of using cortisone are the side effects; most common and noticeable of these is the hunger and thirst which may lead to incontinence and weight gain. Other more serious side effects, at high doses, include skin thinning, hair loss, liver enlargement, lethargy and, very rarely, diabetes. However, wisely used at lowest doses, it is still very safe and effective, especially for mild allergies or flare-ups. The cost of cortisone tablets will be a few cents per day.
Cortisone is now available in a pump-action skin spray called Cortavance which is very effective and is not absorbed into the body, therefore producing minimal side effects. It is in a water-based form so it does not cause matting of the hair. However, it costs more - around 50 cents per day, depending on how much and how often it is used. Cortavance is very good on itchy feet, for short term treatments, although prolonged use of topical cortisone will cause the skin to thin over time. Long-acting forms of injectable cortisone are available which are useful for seasonal allergies where they are only being used for part of the year.
These, again, have been around for a long time but are very poor at controlling itching in dogs as histamine, by itself, does not produce itching in dogs. A recent survey of dermatologists found that over 90% of them considered antihistamines to be effective in only 20% of dogs or less. It is highly unlikely that antihistamines will control allergy in dogs by themselves, but may reduce the need for other drugs. Older antihistamines, like Phenergan, are very cheap but newer human ones are much more expensive, in the order of a dollar per day but still not very effective. Antihistamines are best used to reduce the amount of other drugs used.
Azathioprine (Imuran ™)
Imuran has been used to reduce the amount of corticosteroids required to control the itch and this has been found to be an effective and cheap option. On the downside, it can cause bone marrow suppression and predispose to infections, although low doses seem to be safe.
Cyclopsorin (Atopica ™)
Cyclosporin has been around for approximately 10 years and has proved to be a very effective drug. 75% of dogs will respond with a reduction in itching of 75%. This means that 25% of dogs will fail to respond and more so if other factors such as infection and concurrent food allergies are taken into account.
It has minimal side effects but some dogs may vomit. It is slow to take effect and most dogs will not improve for 3 weeks, with it taking 6 weeks before full response can be measured. Initially, Cyclosporin is expensive; treatment is daily and works out to be $15 per day for a 20kg dog but, as treatment progresses, this drops to $4 per day as the dog is only treated twice a week.
Oclacitinib (Apoquel ®)
This is a newer itch-control drug and blocks the itch transmitters on a cellular level. It is very effective, almost as much as cortisone, and more than 90% of dogs will show a massive improvement within a couple of days of beginning treatment. It will also reduce the itch from other allergies such as food and flea allergy. Initially, it is used twice daily, dropping to once a day once control is established. Initially, at twice a day dosing, this is about $5 per day for a 20kg dog but this drops to half of that after a couple of weeks. Dosage will always need to be once daily and this cannot be reduced.
This treatment offers the only hope of “curing” an allergic dog. Historically, it has been expensive but is dropping markedly nowadays.
Essentially, what each dog is allergic to is identified by a blood test or intradermal testing (where small amounts of allergen are injected and the reaction they induce is measured). Once the cocktail of allergens is identified, a lab can produce vaccines in increasing concentration to try to get the dog’s immune system to stop reacting to normal pollens and dust.
The vaccine used to be given by injection and there was always the risk of anaphylactic shock but, recently, the preferred method is by drops given under the dog’s tongue and this can safely be done at home. Roughly a third of dogs will be cured by this method, another third will be helped and require less other drugs to control itching and the remaining third will have no response at all. The cost used to measure in the thousands but has now dropped to several hundred dollars for the whole thing. It is definitely worth the expense as it offers the only hope of cure for Atopic dogs.
Other Treatments which Help
None of these are an answer in themselves.
Treatments include oatmeal shampoos, skin conditioners, sorbolene, keri oil sprays and paw paw based moisturisers which all are humectants. A humectant causes the skin cells to swell and tightens the junction between the cells in the skin which helps to reduce the number of allergens which can penetrate.
Essential fatty acid supplements in fish oils are natural anti-inflammatories and can help.