Skin disease - more than just skin deep
Vet Roberta Baxter explains how skin disease in dogs can be complicated, with a combination of triggers and treatments. One of the most frustrating problems vets see in their consulting rooms is skin disease. Dogs seem particularly prone to developing skin problems and are frequently brought in because of itching, licking, hair loss, dandruff and sores.
Since these problems often have many factors contributing to them they can be difficult — if not impossible — to cure. Often the best owners can hope for is to manage a dog’s problem with medication, with ongoing treatment often being necessary.
Allergies and fleas
There are a number of causes of skin disease and often several combine to give a dog unhealthy skin that requires treatment. While allergies often cause humans to sneeze and have runny noses dogs tend to suffer with itchy skin. It is not really understood why allergies seem so common these days, although some people believe higher levels of pollutants in the environment affect some animals’ immune systems adversely, making allergies more frequent.
Puppies are particularly susceptible to allergens. As their immune system is developing environmental allergens such as pollen can cause a reaction in genetically predisposed individuals.
The time of year pups are born is also a factor; those born in the spring are more likely to become allergic to pollen because levels are high while their immune systems are developing. Similarly, if a young pup has a heavy burden of fleas it may make a flea saliva allergy more likely. Other allergies have less obvious triggers — dogs may suddenly develop allergies to things they have tolerated for years for no discernible reason. Other common allergens include food ingredients such as beef, pork, wheat and oats.
Bedding, carpets, carpet cleaners and even plastics used in the manufacture of toys and bowls can also cause skin reactions. Allergies can cause a dog to be itchy all over, or the area of irritation may be confined to the paws and face. Secondary skin damage, such as sores, areas of infection and hair loss, is caused by the dog scratching or biting himself.
The other most common cause of skin disease is parasites. Fleas, mites and lice are commonly found on dogs and young pups in particular. Skin parasites cause irritation merely by their presence but can also damage skin and cause minfection when they bite. You may be able to see fleas when checking through your dog’s coat or may even spot them jumping off him — they are 1 – 3mm long and brownish. You could also do a flea dirt test (see box) which can identify any flea faeces in the fur.
Lice can also be seen with the naked eye throughout the coat. They are also 1 – 3mm long but are paler cream or reddish in colour and generally attach themselves to a hair shaft so they don’t appear to move. Their eggs (whitish nits attached to a hair shaft) may also be seen with the naked eye. Mites on the other hand are too small for humans to see. Several species exist but all cause severe itchiness, which may be confined to areas such as the face and paws, or may be widespread.
Skin infections can be the main problem a dog has but more often they result from another disease, scratching and self trauma due to itchy allergies or parasites, or are associated with a dog’s physical features such as pronounced, hard to clean skin folds. Dogs with underlying hormonal, autoimmune, or liver or kidney disease are also predisposed to suffer from unhealthy skin which is more prone to infection.
Too frequent bathing (more than once every two to four weeks) or a deficiency in certain nutrients can also play a role. Hormonal disease can also have a direct effect on a dog’s skin and cause hair loss, particularly over a dog’s flanks. Such hair loss is generally not associated with obvious itchiness or skin disease but is a consequence of the effect of certain hormones on hair growth.
It’s important to identify the root cause of skin disease so appropriate treatment can be chosen. Blood tests can check liver and kidney function and the healthiness of the immune system. They can also help identify any hormonal problems. Specific tests for antibodies to mites are also available, as are ones for allergy antibodies directed against common allergens. Skin scrapes and biopsies can be used to detect mites and other parasites and to check for some immune diseases.
Vets can also take swabs of bacteria and yeasts to help them identify any infections. In some cases just one or two tests are needed to clarify a dog’s problem but because skin diseases often have a combination of causes a dog may have to have all the tests.
Effective anti-parasitic therapy is often one of the first steps. A flea collar or powder is rarely effective enough to treat affected dogs, instead spot-ons prescribed by a vet are generally needed and products to kill eggs and larvae in the house may also be advised. In addition, antibiotics and anti-inflammatories may be used to treat any inflammation and infection. There are a number of possible treatments for allergies. Reducing the allergens in a dog’s environment by being up to date with effective anti-parasitic treatments, washing bedding with non-biological detergents and feeding a good quality low-allergy food often helps.
Antihistamine medicines can also be used to reduce reactions. In addition, allergytesting lets owners know which specific allergens need to be excluded from their dog’s life and can allow for more effective treatment. For instance, a dog with an allergy to beef and wheat should respond well to a hypo-allergenic diet based on fish and corn with no added treats.
Dogs can also have specific hyposensitization treatment which involves injecting the dog with increasing (but tiny) amounts of the substance he is allergic to in order to increase his tolerance of it. This approach is particularly useful for dogs allergic to things like grass pollen which cannot be practically avoided. Any other diseases a dog has, such as liver, kidney, immune or hormonal conditions, must also be addressed appropriately.
Is there a cure?
For many dogs a cure is not possible and in addition to ongoing therapy, treatment to keep the skin as healthy as possible may be necessary. Essential fatty acid supplements help improve skin quality and healthiness and a dog may need extra vitamins and other nutrients too. Medicated shampoos can help reduce itchiness and regular anti-parasitic treatments are paramount. Ongoing therapy with anti-inflammatory medicines (often steroids are the only things that are really effective) and antihistamines may be needed, as well as antibiotics.
There is little else that can be done other than the approaches already mentioned. The frustrating nature of skin disease means that complementary and alternative therapies are often tried and anecdotal support has been given to a range of treatments from acupuncture (for which there is some evidence of benefits in some cases) to homoeopathy and herbal treatments. The key message is that each dog with skin disease is very much an individual and needs a tailored, multifaceted approach in order to best manage his skin problem.
Wet paper test for fleas
To detect the presence of fleas, wet a piece of white paper and then hold it near your dog’s rump and give him a good scratch. Flea dirt hiding in the coat may be flicked on to the paper, where it will dissolve in the moisture leaving a red streak, differentiating it from other specks of dirt in the coat (the red is your dog’s blood which the fleas have eaten and digested).