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Itchy dog problems

4th June 2017

One of the common things we see all kinds of pets for here at Orchard Vets – cats, dogs and small furry pets – is skin problems. Putting up with a pet scratching at all hours of the day or night can be enough to drive owners crazy, and just think of the poor pets! Itchy skin can happen for many reasons, and it is important to have a consultation with your vet to discuss the best diagnostic tests and treatments that may be appropriate for your pet.

Skin parasites

The most common cause of itchy skin, by far, is good old fashioned fleas!  There’s a number of different flea control products available – from ‘spot-on’ topical products such as Stronghold or Advocate, oral tablets such as Bravecto, and even an injectable product for cats (Program).  Treatment is necessary year-round, not just in the summer.  In our cosy, centrally-heated houses flea larvae can hatch out all year round.

“In the house?” I hear you say… yes!  95% of the flea life cycle happens in the environment, not on the pet!  A female adult flea lays eggs, which drop off the pet, and into dark crevices.  There the eggs hatch out, and develop into larvae.  These larvae feed on ‘flea dirt’ – the black flecks you might see in the coat of a pet with fleas – which is actually flea faeces.  Yuck!  The larvae then develop into pupae before hatching into an adult flea.  Pupae are really tough, and if conditions are not right for hatching, can survive in suspended animation for years.  For this reason, if there has been a breakdown in flea control we strongly recommend treating the house with a product such as Indorex to resolve things more quickly.

As well as fleas, there are other parasitic infections that can cause a pet to be itchy.  ‘Fox mange’ is the common name given to one of these.  This is due to tiny, microscopic mites living under the skin.  If your vet suspects that your pet is suffering from mange they will advise a skin scrape to look for the mites.

Allergic dermatitis

If parasitic infections have been ruled out, and a pet is still itchy, it’s possible they may have allergic skin disease.  The most common form of this is known as atopy or atopic dermatitis.

It can be very difficult to diagnose with certainty that a pet has allergic skin disease;  it requires ruling out a lot of other causes of itchy skin, and ideally a biopsy of the skin. This is examined under the microscope for changes characteristic of a hypersensitivity response. In allergic skin disease, substances called allergens settling on the skin cause the animal to become very itchy.  The scientific name for an itch is ‘pruritis’.  Skin becomes red and inflamed, and quickly damaged by the pet scratching, which leads to further infection from bacteria.

When I am talking to owners whose pets have been diagnosed with an allergy, or where we are very strongly suspicious of an allergic process, I like to talk about managing the process by breaking it into three main areas:

Avoiding the allergens

One way of keeping allergic pets comfortable is to avoid exposing them to the allergens which provoke a reaction. However, this can be easier said than done in some cases! For a start, knowing exactly which allergens provoke a response relies on testing them. A tiny amount of the purified substances is injected into their skin, and the response measured. This is carried out by a specialist dermatologist, and isn’t always practical for all pet owners. We can sometimes work out from looking carefully at the times the pet is most itchy which allergens are most likely to cause problems, but sometimes it is more useful to talk about the most common allergens and what to do about them.

One of the most common substances to which pets are allergic is flea saliva. Strictly speaking, this is flea allergic dermatitis or FAD and not atopy, but I always talk about flea control as it isn’t uncommon for pets to have multiple allergies.

Pets with flea allergy are itchy for different reasons than pets that are itchy because they have a lot of fleas. In a non-allergic pet with fleas, each flea bite itches a little, so if they have a lot of bites, they itch a lot. However, in a pet with flea allergy, one flea bite triggers the hypersensitivity reaction described above, so they itch a lot from just one bite.

Strict flea control is vital if you have an allergic pet. This must mean the correct dose of an effective product is given as often as the manufacturer recommends; it must be given to all pets in the household, not just the allergic pet. The product should kill all the life stages of a flea, not just the adult, and must be the type of product that kills fleas when they jump on the pet, rather than relying on them biting and taking a blood meal.

Other common allergens for pets include household dust mites, and grass or tree pollens. This often leads to a seasonal pattern in pruritis (rather like hayfever in people). These can be much harder to avoid. Household flea sprays such as Indorex also have a claim to kill household dust mites, which could be useful. After walks in pollen season, rinsing your pets coat, especially their feet, can reduce the reaction to allergens.

Increasing overall skin health

Often the easiest way to think of the skin is like a brick wall – the skin cells make up the bricks, and the natural oils that lie on the surface of the skin are like the mortar between the bricks. This ‘mortar’ fills in the cracks between the skin, preventing allergens coming into contact with the immune system. Keeping the skin moisturised and nourished can help keep this oily substance (known as sebum) at a healthy level.  This reduces the overall tendency of the skin to flare up and react to allergens.

One way of doing this is by using a shampoo advised by your vet to help keep your pet’s skin healthy. These may contain oatmeal, a natural moisturiser with an anti-inflammatory effect, or agents to reduce the level of bacteria and yeast on the skin, or degreasing agents if your pets coat has too much oil in it (no-one ever said dermatology was simple, unfortunately!)

Additionally, a diet rich in the correct balance of omega oils can also help maintain the general health of the skin. Many commercial diets will provide a good omega oil balance.  Some, such as Royal Canin’s Skin Care range are specially formulated to help maintain healthy skin.  They have high omega oil levels and increased levels of Vitamin E to help support the skin. Alternatively, there are omega oil supplements, such as Yumega, which you can add to your dog’s diet to help maintain the oil barrier layer of their skin and coat.

Altering the immune response to allergens

In some dogs with milder allergic problems, the methods above are sufficient to prevent flare ups of skin problems. However, in cases where the disease is more severe, medication may be required to modify the immune system.  This prevents excessive reaction to allergens. If this is required for your pet, your veterinarian will discuss with you which medications are available and might be suited to your pet.  You can then make an informed decision about keeping them comfortable and happy, and hopefully itch-free! Even if your dog does require medication, using the methods and products suggested above can help make the medication more effective.

What about food allergies?

You might have noticed we didn’t mention food allergies in the paragraphs above.  Itchy skin due to a reaction to food is actually quite uncommon, though it can occur.  The most common culprits in this case are the large, complex protein molecules.  Previously, chicken and rice based diets were often recommended in suspected cases; chicken was an uncommon ingredient in pet foods.  Nowadays, there is such a variety of diets that finding one containing a type of meat the pet has never had before can be very difficult.  To diagnose a food allergy, a strict diet trial is necessary.  Preferably, this should be with a diet where the protein molecules have been hydrolysed – broken down in to smaller pieces that don’t trigger an immune reaction.  If you suspect a food allergy in your dog, book an appointment with the vet for an assessment and advice.

 

Lucy Fleming, MRCVS