Environmental Dermatitis – Patients in this category are physically and nutritionally normal, but present with signs of pruritus, hair loss and skin irritation. By careful discourse with the owner regarding diet, activity, medical history and 
environment, and by performing a thorough physical exam, the veterinarian can rule out the other categories of dermatitis. Through the analysis of the patient’s history, the veterinarian will discover that the patient spends time swimming or excavating gopher holes or romping through fields where thistles seem prevalent. Many dogs are very sensitive to simple lawn grasses. And by matching what is visible on the patient’s skin with a probable environmental irritant – the cause of the skin problem can be determined and corrective measures taken. An example is Moist Eczema, often called a “Hot Spot”. (See the photo below-right and more in the discussion of Hot Spots.) These skin lesions often occur as a result of moisture on the skin surface from rain, pond or lake water. Minute scratches on the skin
from, for example, a clipper blade, may trigger other cases. Especially in dense coated dogs or dogs where there is an accumulation of mats or shedding hair, moisture on the skin may remain long enough to allow superficial bacteria to reproduce (sort of like an organic soup!) and create an infection. Some cases of Moist Eczema will spread very rapidly and require rather aggressive therapy to correct. Contact with plastics can create ”Environmental Dermatitis”.
Nutritional Dermatitis – Correction of these cases should be a “no brainer”, but even today, many veterinarians and pet owners really believe the “Complete and Balanced” statement on pet food labels. Unfortunately, many dogs and cats live their entire lives in less than optimum health because their caretaker feeds the least expensive food they can find… and feels secure in doing so because of that “Complete and Balanced” statement.
In my thirty-five years of practice, I have seen hundreds of dogs and cats whose lives changed dramatically, and where the pet’s caretakers were shocked and surprised at the remarkable difference in their pets, by the simple act of providing the pet with a high quality, meat-based diet. Look at Nutrition in ThePetCenter.com for some common sense information about sound feeding principles. Take a look at the photo of a dog in less than optimum health that has been eating a “Complete and Balanced” diet for years. Without proper nourishment this dog’s entire body, not just its skin and coat, will be continuously in a state of stress. High quality, (more expensive!) meat-based dog foods seldom, if ever, create the kind of skin and coat seen in the photo above. If you feed dry commercial dog food, be certain that the first ingredient listed is meat such as beef, poultry, lamb or fish. PetFoodDirect.com displays a number of high quality diets and their ingredient lists, too, so you can compare all kinds of diets for quality ingredients.
Will supplements help? Absolutely! But if the diet is a high quality, meat-based brand, the need for supplements is much less critical. It has been my experience that supplements such a Omega Fatty Acids, Vitamins and table scraps will always help a dog that is eating a generic, commercial dry dog food; and on occasion, supplements may even show positive benefits in a dog eating a high quality diet. Many types of dermatological problems are avoided if the dog or cat is consuming an optimum diet. In some cases, adding a supplement such as DermCaps, a popular Omega Fatty Acid supplement with a number of beneficial ingredients, is the key factor in avoiding repeated episodes of Hot Spots and other skin afflictions. If your dog or cat seems to lack good coat and skin health, consider upgrading the diet to a meat-based ingredient formula and adding a supplement such as DermCaps.
Allergic Dermatitis – I’ll be honest. There’s no way to cover this topic in one article. Veterinarians spend entire weekends and lots of money attending seminars on this topic alone! It is common, it can be lifelong, it is a challenge to diagnose, and once identified it can be resistant to attempts at treatment. All the other categories of dermatitis must be ruled out (especially those elusive Sarcoptic mites) before a diagnosis of Allergic Dermatitis can be made. Food ingredients, synthetic and natural fibers, medications and pharmaceutical products, plant material and even dust all can trigger an Allergic Dermatitis.
Even common bacteria on the dog’s skin can provoke an allergic reaction to themselves! These cases of sensitivity to normal resident bacteria are very challenging to correct. No matter what kind of allergic dermatitis afflicts the dog, the ultimate cellular cause of the inflammation and resulting “itch-and-scratch-bite-and-lick” activity has a common cause… the release of histamine from skin Mast cells, the deposition of antigen/antibody protein complexes within tissues, the dilation of some blood vessels and constriction of others, the release of toxic chemicals from broken intracellular structures, and chemical and physical irritation of sensory nerve endings.
To what are dogs allergic? Take a look around you right now. Odds are that your dog could be allergic to half-a-dozen different substances in the very room you sit; that doesn’t even include microscopic substances in the air you and your dog breath! Food, carpeting, blankets, dust mites, mold spores in the air, pollen, plastic food dishes, furniture stuffing and ornamental plants all have the potential to trigger an allergic reaction in your dog. Food allergies are so common that pet food manufacturers have invested millions of dollars in research, development, promotion and delivery of “antigen specific” diets to help in the therapy of dogs with food allergies.
How to allergies develop? Each individual’s biochemistry is determined by millions of genetic variables. On occasion, an individual’s various immune responses may over-react to a certain material and “learn” to recognize this substance in case of future contact with it.
The offending agent is called an antigen. Flea saliva is a good example of an antigen that triggers “flea bite” hypersensitivity. When an antigen makes contact with the dog, the dog’s immune defenses – all primed and ready for a fight since it has previously identified the antigen as an enemy – set to work to disarm the antigen. Unfortunately, during the course of the battle (called an antigen/antibody reaction) side effects of the battle can cause tissue irritation, inflammation, swelling and cell destruction. That’s when we notice the dog going into the “itch-and-scratch-bite-and-lick” mode! There’s a biochemical war going on within the dog!
Immunologists have classified a number of different types of allergic reactions. Skin and blood tests are common methods of attempting to identify what the patient is allergic to. Probably the most common type of Allergic Dermatitis seen in dogs is
Atopic Dermatitis. This situation is triggered by a number of antigens including inhaled substances such as molds, dust, pollens and other static and airborne microscopic organic substances. Dogs with Atopy lick and chew at their paws (see photo on right) and scratch their face, eyelids and ears. This disorder can be very troubling for dogs and frustrating for the owner. One minute the dog may look and feel normal, the next it will chew its paw or face raw from the intense pruritus. There is a new product available to treat Atopic Dermatitis in dogs called Atopica. For many patients, this medication has truly been a “life saver”.
Treatment of Allergic Dermatitis includes topical medicated soothing baths, ointments and sprays. The use of oral antihistamines can neutralize some of the destructive effects of internally released histamine. More effective in alleviating the discomfort of allergies is cortisone. This potent hormone, normally secreted by the adrenal glands, can be manufactured commercially. Numerous derivatives of cortisone are used in pill, injectable, spray, liquid and ointment form. Caution: If you are sent home with a prescription for cortisone, or your dog has simply been given “a cortisone shot to stop the itching”, your dog may ultimately be worse off than before if the true diagnosis happens to be an unrecognized case of Sarcoptic mites! Be patient, yes, but be persistent, too. If your dog is itching, scratching, and licking, or if the skin and coat are not healthy appearing, you and your dog need a diagnosis before treatment is started.
A key point to remember is this: There is no cure for allergies! All we can do is avoid the food, material or parasite that is triggering the immune response, desensitize the patient through immune modulation techniques, and assure that the patient is eating a high quality diet.
