Managing itchy skin


ITCHY SKIN PROBLEMS IN THE DOG

RULE 1 Find a vet you trust and stick with them – every time you go to a new vet they have to start again from scratch (so to speak).

RULE 2 keeps working until you get a diagnosis (different to a cure).

RULE 3 Accept that in many of these cases there is NO CURE only management.

Possible causes of itching in the dog include

Mange
Skin infections – bacterial and fungal
Underlying hormonal problem which predisposes to skin infections and so to scratching
Flea allergy
Contact allergy
Food allergy
ATOPY
(allergy to airborne allergens such as pollens and dust mites)

So in the initial work up of a problem like this the vet has to first eliminate the condition that is simply treatable i.e. Mange (skin scrapings – response to insecticidal washes, Advocate or Ivermectin).

If bacterial or fungal infections are identified these can be treated but unfortunately these are usually secondary problems and the primary cause will be an underlying problem such as Cushing’s syndrome (an over production of cortisol and suppression of the immune system) or Atopy so in these cases you usually see the problem coming back

Flea allergy is the number one cause of itching in all dogs and you don’t need to be able to see the fleas. If your dog is scratching over the base of the tail then it is almost invariably flea allergy. In any itching dog, flea control must be 100% effective – 99% will allow your dog to be bitten occasionally and start off a whole cycle of scratching again. Dogs with atopy, contact allergy or food allergy often also have flea allergy so flea control is absolutely vital in any itching dog. Do not rely on the fact that you can’t see any fleas.

For inside dogs use an Insect Growth Regulator (IGR) fogger for the house, give the dog an oral IGR with monthly products such as Advocate or use Frontline plus monthly or a “synthetic pyrethroid” weekly.

TREAT ALL AMIMALS IN THE FAMILY

Contact allergies usually appear over the belly – things like Kikuyu or chemicals in your carpet can cause this – the dog gets itchy so it drags itself on the offending surface to scratch and makes things much worse. It seems that contact allergy usually has some other component to it (eg food or flea allergy or atopy) which makes the dog itchy in the first place.

Food Allergy can be hard to diagnose because it requires up to 12 weeks on a very restricted diet and many owners find this hard to manage. Animals become allergic to proteins in the diet and the key to an effective elimination diet is to feed only one protein source for up to 12 weeks with only one source of carbohydrate added.

The protein has to be one which the dog has never eaten before – eg fish, rabbit, kangaroo, buffalo venison, turkey or horse! There is no point at all in just changing the dog food. You need to recognise that everything is a potential source of contamination – no meaty flavoured heartworm tablets or vitamin pills, no treats…. And this has to go on for 12 weeks!

Many “hypoallergenic” diets are available commercially but they are extremely expensive and studies suggest that they are less effective than a home made elimination diet. If you go down this path then a diet I have found to be cheap and effective and also easy to prepare is salmon and sardines and potatoes.

If your dog stops scratching after 8 -12 weeks on this diet you need to then introduce protein sources one at a time to see if the dog starts to scratch. Each new food needs to be fed for at least a week before it can be give the ‘all clear’. If no new foods trigger off scratching  while you are still feeding a diet based predominantly on fish then you can conclude that the Omega3 rich fish based diet itself is reducing the reactivity of the skin. Omega3 fatty acid supplements have been shown to be effective in reducing itchiness in 80% of dogs after a period of 8 weeks.

Atopy is basically the diagnosis you are left with when all else has been eliminated. Everyone knows people who are atopic – they are the ones who get hay fever or asthma in the spring, who get eczema when they come near your dog or cat.

Dogs manifest atopy as skin problems. The most common manifestations are ear infections, foot chewing, itchy faces or hot spots. The problems usually occur early i.e. from 1-3 years of age and often also include conjunctivitis or bacterial or fungal skin infections which can lead to itching all over. Diagnosis can be supported with blood tests. Atopy has a hereditary component but is also strongly affected by environmental factors and so occurs more commonly in some areas than others.

Management of atopy requires a range of approaches and different drugs and treatments work differently in different dogs.

Management of Atopy includes:

FLEA CONTROL – absolutely essential in any skin management program

Antibiotics may be required to control any secondary complications such as bacterial or fungal infections

 Ear lotions such as Leo ear cleaner or Epiotic may be needed on a weekly basis to wash ears and prevent outbreaks of irritation

Anti itch shampoos and lotions – oatmeal and coal tar based shampoos and a number of specific vet products some of which contain cortisone as a wash. The vet products may be expensive but they are the ones most likely to work.

Topical cortisone. Ointments and sprays containing corticosteriods can provide symptomatic relief with minimal risks of side effects and reduced need for tablets.

Antihistamines – never likely to be effective alone they do help in about 20 – 30% of cases. Different drugs have different effects and each one needs to be assessed for several weeks

Essential fatty acid supplementation is effective in up to 80% of cases and is often complementary to the use of antihistamines. The omega 3 fatty acids which are found in cold water fish oils have a vital role in skin membrane metabolism. Specific omega 3 supplements can be bought in health food shops chemists and vet surgeries but simply introducing sardines and canned salmon into your dogs diet regularly may reduce the scratching you see.

Identification of the allergens and desensetisation is expensive and requires regular treatment for up to 12 months and has been shown to “produce good to excellent results in 50-75% of cases” (that means that in a quarter to half of all cases the results are neither “good or excellent”)

Weight Control. Overweight dogs are more likely to have skin problems – possibly because subcutaneous fat keeps the skin warmer and so more reactive or perhaps because their diet is inappropriate.

A “natural” diet based on raw lean bones, eggs, liver, fish and green vegetables will reduce blood glucose and help your dog to lose weight.

Nicotinamide, pantothenic acid, histidine, inositol and choline have been demonstrated to limit skin cell water loss, improving skin hydration and reducing the colonisation of the skin with bacteria and fungi which probably initiate the allergic response. Muscle meat, fat and liver are rich sources of these compounds.

High blood glucose has been shown to stimulate the production of some pro-inflammatory cytokines and to be involved in chronic inflammatory disease processes. I could not find any specific research in dogs to support this, but given that they are carnivorous it seems reasonable to assume that avoiding grain based diets is at least worth trying in order to reduce skin irritation. Most commercial dog foods have at least 40% of their calories supplied by grain. Barley is used as the grain source in some “hypoallergenic” commercial diets and some owners have found that a whole food diet based on barley as a carbohydrate source have been beneficial in reducing skin irritation

Cortisone tablets or injections may in the end be the only way you can control your dogs itching especially in the spring. Tablets are a much safer and more reliable way of treating your dog and you should aim for alternate day treatment with the lowest possible dose which will still keep the scratching under control. Repeated injections are easier but prolonged cortisone treatment will cause immune system supression, obesity, thinning skin and joint deterioration.

Atopica is a drug that has been recently released for the treatment of atopy. It is highly effective and avoids many of the problems of cortisone treatment however it is expensive and would be best prescribed by a veterinary dermatologist.

In Summary

It helps, when thinking about allergic skin conditions, to think of the condition as having a threshold.

If the environment is right then the condition may be there but never expressed because the skin is not being irritated and so stays below the threshold.

Management involves managing the dogs environment – keeping the skin soothed, avoiding all offending agents where possible and trying to keep the skin below the threshold of irritation above which itching, sore ears etc are seen.