For those of you with pets who fall victim to skin issues this article is for you. Brace yourself! This one is packed with lots of information! One of the most frustrating ailments that we see come through our door is a dog (or cat) with itchy, sensitive skin. These can be the hardest cases to treat, mostly because there are so many different reasons as to why this pet is driving you crazy with their constant scratching, biting, and licking. Most important thing to remember, it is not a losing battle. There IS a diagnosis to be made! Once that happens then you and your veterinarian will be better able to select the proper treatment plan. There are really six main reasons why your dog or cat will itch and scratch. Keep in mind that there are entire textbooks written about these categories of dermatitis that veterinarians have to consider whenever a cat or dog has a skin problem-- or “skin case”. Most skin and coat abnormalities can be defined by or placed in one of theses categories: Environmental Nutritional Parasitic Allergic Neurogenic Infectious Lets take a brief look at each one starting with the simplest (Environmental Dermatitis) and ending with the most challenging (Neurogenic Dermatitis). 1.Environmental Dermatitis Patients with Environmental Dermatitis are physically and nutritionally normal, but show signs of itching and scratching, with hair loss and skin irritation. By discussing patient history 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 has done something to spur these symptoms such as swimming in a pond, digging in dirt or other ground cover, even running through a field with certain grass or plants. 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 cat or dogs skin problem can be determined and corrective measures taken. An example is Moist Eczema, often called a Hot Spot. 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, or thistle plants 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. 2.Nutritional Dermatitis When food is the issue, correction of these cases of dog and cat itching and scratching 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. We have seen 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. 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 as Omega Fatty Acids, and Vitamins 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 cat or dog skin problems are avoided if the animal consumes an optimum diet. In some cases, adding a supplement, such as an omega fatty acid supplement, is the key factor in avoiding repeated episodes of hot spots and other skin problems. 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. 3. Parasitic Dermatitis The most common response a pet caretaker makes when they see their dog scratching and biting at itself is “I think he’s got fleas”. And sometimes this guess is correct. Dark, copper colored and wingless, and about the size of the head of a pin, fleas are big enough that they can be seen scurrying along the skin surface trying to hide within the sheltering forest of fur. Repeated exposure to fleas can trigger a hypersensitivity (an abnormal, excessive reaction) to the bite of even a single flea. Every veterinarian has been fooled into making a diagnosis of “allergy”, not even suspecting fleas, simply because no fleas were discovered at the time of the physical exam. This is a classic example of a Parasitic Dermatitis (flea bites) triggering a complicated Allergic Dermatitis (due to the flea saliva). Interestingly, the all-too-common parasite called the tick rarely triggers itching and scratching or allergic reactions, but on occasion will leave an ulcerative lesion that is notoriously slow to heal. Chiggers, deer flies, and gnats (sometimes called No-See-Ums) can be considered nuisances and generally do not create remarkable systemic skin problems. Local treatment with first aid ointments generally is successful. Cheyletiella mites look like tiny spiders under a magnifying glass and are often called Walking Dandruff because upon close inspection it seems like little flakes of dry skin are actually moving about. Partly because they live on the surface of the skin, these tiny critters can be eliminated easily by using any common flea shampoo. And here’s a creepy thought … Cheyletiella mites can be transmitted to humans where they create, just like on the dog, alopecia (hair loss) with a dry, flaky, slightly pruritic skin surface. Sarcoptic mites are nasty critters! Also called scabies or red mange, they create very intense itching and scratching, alopecia, and inflamed skin with multiple small scabs often present. Sarcoptic mite infestation, more than any other entity, is frequently misdiagnosed as Allergic Dermatitis by even very competent and experienced veterinarians. Sarcoptic mites happen to have preferences … certain types reproduce and thrive on dogs, but they do not thrive on other species such as humans. Nevertheless, Sarcoptic mites from dogs can infest humans so if your dog has signs of scabies and you are itching and have little scabs, make sure you see your dermatologist (MD, not DVM)! Then there are Demodex mites -- also called mange. These little rascals do live and reproduce just under the skin surface in the tiny hair follicles and oil glands of the skin. Unlike Sarcoptic mites, Demodex mites can be seen on a skin scraping viewed under the microscope. They look like tiny cigars with stubby legs stuck to the front half of their body. If the dog is otherwise healthy, there are effective treatment protocols for Demodex. On the “itch scale”, Demodex causes very little itching and scratching. However, spotty hair loss is a symptom. 4.Infectious Dermatitis Bacterial, fungal and yeast organisms are notoriously obnoxious pathogens causing coat and skin problems in dogs (and cats). Fungal organisms are called dermatophytes. One type, called Microsporum canis, causes non-pruritic, circular patches of hair loss, often called ringworm. Transmissible to other dogs (and occasionally some strains of fungi can be transmitted to humans) your veterinarian can diagnose and treat skin fungal infections in the office. Yeasts, most notably a common contaminant of inflamed and environmentally stressed skin and can irritate an already diseased skin surface. Especially notorious for creating long term, low-grade external otitis, yeast infections do cause itching, scratching and inflammation. Yeast infections typically create greasy, odorous and pruritic signs in affected dogs. The skin is stressed by the waste products of the organisms and responds by releasing histamine -- which triggers further inflammation, itching and scratching and cell damage. Bacterial dermatitis rarely occurs spontaneously. Normal healthy skin has tremendous numbers of a variety of bacteria present all the time. If something upsets that balance, such as antibiotics eliminating one or two types, the remaining types have a free-for-all! Anything that damages the normal, healthy, intact skin will hamper the skin’s defense mechanisms. Any Environmental Dermatitis, such as contact with grass, plastic, an abrasion or moisture, can adversely affect the skin’s defensive barriers and opportunistic bacteria then have their way. Parasitic damage to the skin will allow invasion by bacteria and trigger the body’s healing defense mechanisms. A common skin problem in dogs, Infectious Dermatitis often is so irritating that dogs will lick continuously at the lesion and undo any healing that has taken place. A moist, sticky, inflamed skin lesion along with hair loss is characteristic of bacterial dermatitis. These can spread rapidly and even be transposed to other areas of the skin through biting, licking, and scratching of previously uninfected areas. The treatment for Infectious Dermatitis often includes clipping the hair from the area to allow the air to assist drying. The application of gentle topical medication is helpful as is the administration of oral antibiotics to fight the organisms that are deeply invading the skin. 5.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 doesnt 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 do 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 skin problems in dogs and when they go 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 and scratch their face, eyelids and ears. This skin problem 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 itching and scratching. 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. 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 to diagnose what type of skin problem it is 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. There are a number of products that address allergies in dogs and allergies in cats that may help: Hypo-Allergenic Food, Hypo-Allergenic Shampoo, Hypo-Allergenic Dog Treats, Hypo-Allergenic Cat Treats, etc. 6.Neurogenic Dermatitis This group presents a major challenge to diagnose and treat. There’s nothing left but to blame the poor dog for all that incessant licking and chewing at itself! The most commonly seen form of Neurogenic Dermatitis is called Acral Lick Dermatitis, Lick Granuloma or canine neurodermatitis. Although rarely seen in cats, in the dog something creates an impulse to lick at a specific area of skin. Characterized by persistent, obsessive licking and chewing at the target area, lick granulomas may have an unknown origin. Commonly, though, most cases have a suspected cause such as boredom, separation anxiety, frustration, confinement, or even a minor physical origin such as a tiny abrasion that captivates the dog’s interest. The dog persists in traumatizing the area, which is usually confined to an easily accessible forelimb, carpus (wrist) or ankle area, and never allows the skin to heal. Repeated episodes of self-mutilation, partial healing, then repeated trauma and healing, result in severe and disfiguring scarring. Deep bacterial infections are common and permanent skin damage results. A specialist in dermatology and a behaviorist may be the dog’s best friends in these cases of Neurogenic Dermatitis. In summary, keep in mind that any dog with skin problems or whose skin and coat are not in optimal health needs attention because that dog surely does not feel well. Be patient with your veterinarian because each category of Dermatitis must be evaluated, categories need to be ruled out, and a final diagnosis needs to be established BEFORE proper, effective treatment begins. Expect laboratory work, skin scrapings and blood tests to be required to reach that diagnosis. If your dog is suffering from Chronic Dermatitis, all is not hopeless. Be persistent in trying to identify the cause and then pursuing a treatment. And do not be bashful about requesting referral to a specialist in veterinary dermatology. These experts work with severely affected patients on a daily basis and can be an excellent resource for assistance to those poor dogs that seem incessantly to itch-and-scratch-bite-and-lick. Resolving these cases invariably puts a smile on the veterinarian’s face, the pet owners face, AND the dog’s or cats!
Posted on: Tue, 09 Sep 2014 22:46:06 +0000
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