SKIN ALLERGIES

Although any dog could potentially be affected by most skin disorders, certain breeds and age groups are statistically more prone to some problems than to others. Some of the reasons are genetic predispositions to specific problems, non-specific factors related to body conformation and hair coat, and environmental factors related to the function for which that breed may be chosen. This discussion will focus on several common breeds and several of their common skin disorders, followed by some disorders more typical of puppies and adolescents.

West Highland White Terriers
West Highland white terriers, or "Westies," as a breed, seem to have a higher incidence of airborne allergies than many other breeds, although there are certainly many breeds in which this disorder is quite common. As explained in a previous article, airborne allergies are typically manifested as pruritus (itchiness) of paws, underarms, groin area, ears, and/or the front (flexion surface) of the elbows or rear legs. This type of allergy usually begins with just pruritus and no visible signs of redness or irritation. It is only later, when self-trauma (licking, rubbing, scratching, etc.) and other secondary problems occur that the skin is likely to appear abnormal. Because the tendency to airborne allergies is thought to be hereditary and because dogs have often produced or fathered their first litter before the full scope of these allergies in an individual is manifested, they can easily be passed on to their offspring generation after generation. Many breeders themselves do not realize that these allergies are hereditary, nor are they usually informed of allergy problems by the purchasers of their puppies, who don't realize it themselves. Thus the trait is perpetuated.

Because Westies have white fur, a good clue that they have been licking excessively is the appearance of a pinkish- or reddish-brown stain on the fur. Saliva has substances in it that eventually cause this kind of staining. Many Westies also have a higher production of surface skin oils than other dogs, which leaves them prone to developing secondary bacterial and yeast infections by providing a local skin environment that favours growth of these organisms. 

Some tip-offs that these secondary problems are occurring are:
1. small scabs or subtle bumps that can be felt under the fur but are often not visibly apparent;
2. pruritus (itchiness) that started for no obvious cause but later became red and irritated;
3. a pronounced "doggy" odour that returns soon after bathing; and
4. a recurrent skin "condition" that was initially well-controlled with medication earlier in its course, but now is getting worse in spite of medication.

** All of these are signs that a return trip to your veterinarian is in order, since it is likely that one or more secondary problems are developing.

Boxers and other breeds with very short, stiff hairs (such as Dobermans, Great Danes, and Dalmatians) are prone, especially during adolescence, to developing infections on their chin and lips that closely resemble "teenage acne" in people. In fact, "acne" is what this disorder is usually called. The cause, however, is not adolescent hormone fluctuations, but repeated "bumping" of those stiff chin and lip hairs on objects such as chew toys, food dishes, and the ground itself, an action which not only inflames the hair follicles by driving those stiff hairs into them repeatedly, but may actually break off the individual hairs below the skin surface and rupture the hair follicles, releasing hair protein and other irritating follicle contents into the tissues under the skin. The hair follicle begins to "ooze," trying to expel the foreign material, and it becomes chronically infected secondarily, repeatedly discharging small amounts of bloody fluid from small nodules, each of which is at the base of a hair or where a hair used to be.

There is a dual approach to therapy for these acne cases:
   . treatment of the deep-seated infection and
   . prevention of further hair follicle trauma.

This usually requires long-term oral antibiotics, topical therapy for cleansing the follicles and soothing the skin, and a change in play and eating habits. The goal here is to minimize activities that cause the chin and lips to bump into hard objects by using shallow dishes for drinking and eating and by NOT using hard chew-toys, especially during rough play.

Cocker Spaniels
Cocker Spaniels and ear problems are so common that some veterinarians are actually surprised to meet an older Cocker who has never had to deal with them. There are several reasons why Cockers are predisposed to ear infections:
The physical conformation of the ear is pendulous, with a long, narrow ear canal and excessive hair around the opening. These characteristics result in excess wax being trapped in the canal and in decreased air circulation which would help prevent secondary yeast and bacterial overgrowth.
Cockers tend to be fairly heavy ear wax producers. If this wax becomes trapped in the ear canal, it is the perfect growth medium for both bacteria and yeast.
There is a rather high incidence of both airborne and food allergies in Cocker spaniels, both of which frequently cause ear prorates and inflammation. The head shaking, ear flapping, and ear scratching that goes along with them are very conducive to developing secondary infections.
With long-standing or recurrent ear infections, Cockers are very likely to develop unusually thickened ear canals, which may even progress to the point where the excess scar tissue calcifies, becoming like bone. This reaction decreases the ear's natural defences even further by allowing wax to build up, by decreasing air circulation, and by making treatment itself physically difficult by reducing access to the ear canal.
As discussed in the previous topic on ear infections, the approach to chronic, recurrent ear problems is often one of life-long management rather than cure. Sometimes the secondary problems become so severe that surgery becomes necessary in order to open up access to the deeper ear structures.

German Shepherds
This breed, for some reason, seems particularly prone to developing a type of folliculitis (hair follicle infection) in which the hair follicle ruptures inside the skin, releasing protein (keratin) from the hair and debris from the infection. This sets up a particularly nasty, chronic infection, where there is not only an infection in the deeper layers of the skin, but also a reaction to the protein keratin (from the fragments of hair) similar to the reaction to a foreign substance, like an embedded splinter. The thick hair coat in this breed also make the local skin environment favourable for bacterial growth. The deep infections, officially called "Furunculosis," require aggressive, long-term antibiotics (3 - 4 months, in many cases) and labor-intensive topical therapy. Inadequate treatment, either with an ineffective antibiotic or for an insufficient length of time, sets the stage for recurrent problems that are extremely difficult to handle later. Because the infections are deep, in areas where moisture and lack of air circulation are problems, and where scar tissue build-up may reduce adequate penetration by antibiotics, different drugs than the "standard" skin drugs may be required, sometimes at higher than "standard" dosages. There are some individuals who are never able to be completely without medications. These dogs may require continual treatment or may require the type of "pulse therapy" that was described in the previous topic. It is essential, therefore, that skin infections in German Shepherds be addressed and treated promptly, before they develop into a nasty furunculosis problem that may take months, or even a life-time, to correct.

Young Dogs
Fortunately, there are many skin disorders that would be extremely uncommon in dogs under 6 months of age. Airborne allergies, for example, are quite rare in dogs under one year. The common hormone disorders are also rare in puppies. Puppies and young adolescents do, however, have certain things that are typical of that age group, partly because their skin is more "delicate" and has less well developed natural defences, and partly because they have not had time to become sensitised to many of the substances in the environment. There are also hormone fluctuations and stresses that are unique to canine "puberty."

Contagious external parasitism's such as fleas, Sarcoptic mange, ear mites, lice, and other "critters" are easily transmitted from mother to pups or among pups housed in multiple-dog situations. Young puppies that come from shelters or "puppy mills" and have skin problems when they arrive are very frequently harbouring one or more types of skin parasites.

Young adolescents (5 - 12 months) commonly develop a non-contagious type of mange called Demodectic mange, which is caused by small, cigar-shaped mites living in hair follicles. This type of mange is called "non-contagious" because it is transmitted only during the first few days of life, from mother to pups, and it is presumed that virtually all dogs harbour Demodex mites in at least some of their hair follicles. The factors that cause the mites to reproduce are not understood fully, but it is postulated that hormonal influences play a role. The "Localized" form of Demodex is common in adolescents and is self-limiting and self-"curing," causing one or perhaps several focal, circumscribed areas of hair loss with only a little, if any, sign of dermatitis. In a small percentage of dogs the areas of hair loss may become numerous and may begin to coalesce, creating a situation which is termed "Generalized Demodex." The generalized form of Demodectic mange is thought to be caused by a specific, hereditary deficiency in one part of the immune system. It is difficult to treat and affected dogs should not be bred. A more complete discussion of Demodectic mange is also found in one of the previous topics on Dermatology.

Impetigo is a term for "pimples" caused by a non-contagious Staph. infection in puppies. It is actually a misnomer because it implies a similarity with Impetigo in humans, which is highly contagious. NO Staph. infection of the skin in dogs (puppy or adult) is contagious between animals or from animals to people. Impetigo in puppies is a superficial infection of the hair follicles, often on areas of the body that are exposed frequently to moisture or irritants, such as the groin or face. Often just mild topical antibacterial therapy is all that is needed for treatment, or occasionally a short course of oral antibiotics.

Juvenile Cellulitis (often misleadingly termed "Puppy Strangles") is an uncommon, but alarming disorder that can be seen in puppies from 3 weeks to 4 months of age. It appears initially as acute swelling of the face, primarily of the lips, eyelids, chin, and muzzle. It may easily be confused, early on, with a sudden allergic reaction typical of a bee sting or a vaccine reaction. However, it progresses rapidly into bumps and pustules which drain and scab. The lymph nodes under the neck may enlarge dramatically, which is what precipitated the term "puppy strangles." Half of the cases are lethargic. Up to one quarter of the cases may show fever, appetite loss, and joint pain. The cause of Juvenile Cellulitis is unknown, although an immune basis is postulated, because of the rapid response to immune-suppressive doses of steroids. Early, aggressive steroid treatment is needed to avoid excessive scar formation. If evidence of concurrent bacterial infection is present, then antibiotics are indicated. The good news is that a relapse is extremely unlikely.

Conclusion
The purpose of this entire series on Dermatology has been to provide dog owners with some basic knowledge about the more common skin and ear disorders. This knowledge is invaluable in providing the dog's veterinarian, who should always be involved in these problems, with enough background to make an accurate assessment. It is important to develop a relationship with a veterinarian who is experienced in some of the more subtle presentations of skin problems, especially those of a chronic or recurrent nature. It is also important for the owner, who is with the dog daily under a variety of seasonal and environmental conditions, to be able to provide the veterinarian with clues to help to sort out some of the variables that could be common to several disorders. Be sure that you can tell your vet exactly when the problem started and exactly what it looked like at the very beginning, before secondary problems complicated the situation. Identify which treatments and remedies worked or didn't work. If the problem returned, what was the time period involved? Try to identify any seasonal or environmental factors and, if possible, see if you can find out if any relatives of your dog are affected. Also note whether any other pets or even humans have any skin problems. If your dog has been seen by another veterinarian, try to get any pertinent medical records, including laboratory tests and medications, with dosage, frequency, and duration of treatment.

Skin disorders can be frustrating, life-long problems. Although many are not serious, others can easily become serious through ignorance of proper skin care and treatment. Everything you learn gives you wisdom in providing your dog with the best health care possible.


Internet advice...
dog.com and Dr. Pinkston do not offer advice on specific medical problems since any answer given without examining a dog thoroughly, in person, would be incomplete, at best. It is too easy to jump to erroneous conclusions and give unintentionally misleading advice.

If your dog has a problem that has not resolved with treatment, Dr. Pinkston highly recommends that you consult your own vet about performing additional diagnostic tests, if warranted. If your vet has already done as much as possible at that clinic, you might ask to be referred to a specialist. If that is not possible in your area, then consider getting a second opinion. Keep in mind, though, that your own vet may not realize the full extent of the problem or your concerns about it. It is always a good idea to start by explaining to your vet that a particular problem has not been resolved and that you are really worried about it.

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