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WHAT IS A MAST CELL TUMOR?
A normal mast cell is part of our immunologic defense systems against invading organisms. Mast cells are meant to participate in the war against parasites, as opposed to the war against bacterial or viral invaders. Mast cells are bound within tissues that interface with the external world such as the skin, respiratory or intestinal tract. They do not circulate through the body. The mast cell possesses granules of especially inflammatory biochemicals meant for use against invading parasites. (Think of these as small bombs that can be released.) Their foot is planted in the mast cell while their arms lift up hoping to capture the antigen for which they were individually designed. When the antigen comes by and is grasped, this should indicate that a parasite is near and the mast cell, like a land mine, degranulates releasing its toxic biochemical weapons. These chemicals are harmful to the parasite plus serve as signals to other immune cells that a battle is in progress and for them to come and join in. The problem is that we live in a clean world without a lot of parasites. What unfortunately tends to happen is that the mast cell system is stimulated with other antigens that are of similar shape or size as parasitic antigens. These "next best" antigens are usually pollen proteins and the result is an allergy. Instead of killing an invading parasite, the mast cell biochemicals produce local redness, itch, swelling, and other symptoms we associate with allergic reactions. As if the mast cell isn't enough of a troublemaker in this regard, the mast cell can form a tumor made of many mast cells. When this happens, the cells of the tumor are unstable. This means they release their toxic granules with simple contact or even at random creating allergic symptoms that do not correlate with exposure to any particular antigen. Mast cell tumors are notoriously invasive and difficult to treat. Mast cell tumors are especially common in dogs accounting for approximately one skin tumor in every five. The Boxer is at an especially high risk, as are related breeds: English Bulldog, Boston Terrier. Also at higher than average risk are the Shar Pei, Labrador Retriever, Golden Retriever, Schnauzer, and Cocker Spaniel. Most mast cell tumors arise in the skin but technically they can arise anywhere that mast cells are found. The mast cell tumor does not have a characteristic appearance though because of the tumor's ability to cause swelling through the release of granules, it is not unusual for the owner to notice a sudden change in the size of the growth or, for that matter, that the growth is itchy or bothersome to the patient. Diagnosis can often be made with a needle aspirate, which collects some cells of the tumor with a needle, and the cells are examined under the microscope. The granules have distinct staining characteristics and can be recognized easily. An actual tissue biopsy, however, is needed to grade the tumor; grading is crucial to determining prognosis. Therapy for mast cell tumors consists of surgery, radiation therapy, and chemotherapy (as is the case for almost all types of cancer). What combination of the above is chosen depends on the extent of spread and malignant characteristics of the tumor. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ As always, we recommend that you check with your veterinarian for your pet’s immediate health needs and concerns. If you have questions about your pet’s health, care, and well-being, email your question to: NtTAskOurVet@aol.com |
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MYTH: “Food allergy ought to produce intestinal signs as it is the intestinal tract that is exposed to the allergen.” FACT: In pets, it is usually the skin that suffers with a food allergy. Food allergy is one of the itchiest conditions in veterinary dermatology. Making matters worse is the fact that food allergies tend to be resistant to cortisone therapies which makes itch control especially difficult.
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MYTH: “Food allergy is a less likely cause of my pet’s skin disease as we have been feeding the same food for years and the skin problem is a recent development.” FACT: It takes time to develop a food allergy, typically months to years. The immune system must be exposed and must develop enough antibodies to trigger an allergic reaction and this requires multiple exposures to the food in question. A reaction to a food that occurs on the first exposure to that food is not an allergic reaction. Such reactions are called “food intolerances” and involve toxins within the food but not an allergic reaction.
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MYTH: “Soy and corn are common food allergens and it is best to seek pet foods without these ingredients to avoid problems.” FACT: The most common food allergens for dogs are: beef, dairy, and wheat. These three ingredients account for 68% of canine food allergies. The most common food allergens in cats are: beef, dairy, and fish. These three ingredients account for 80% of feline food allergies.
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MYTH: “If it looks like my pet might have a food allergy, I should be able to manage the problem by switching to another diet.” FACT: Unfortunately for food allergic pets, most pet food diets contain some sort of mixture of beef, dairy, wheat, lamb, fish, and chicken. This means that simply changing foods is bound to lead to exposure to the same allergens. There are two ways to address food allergy: feeding a diet based on a truly novel protein source (this usually means an exotic diet like venison, duck, kangaroo, rabbit or even alligator) OR feeding a diet where the protein has been pre-digested into units too small to interest the immune system.
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MYTH: “My pet got only partly better after the food trial so that means it didn’t work.” FACT: Animals commonly have several allergies concurrently. A food allergy responding to a test diet at the same time an inhalant allergy is active will look like a partial response. On the other side of the coin, an inhalant allergy can become inactive should the weather change substantially during the diet trial. This would make a diet appear to be successful by coincidence. In order to determine if a response to a diet trial is real, at the end of the trial the patient is challenged with the original diet. If itching re-starts within feeding 2 weeks of the challenge, food allergy can be diagnosed.
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Q: Our 7 month old kitten was given Bansect flea medicine for dogs. The cat started having seizures about 3 hours later and they are now almost constant. Now we think that we should not have used a dog flea treatment on our cat? - email from Brooke A: Ten years ago, fleas were controlled old fashioned way: fogging and spraying the house, powdering, spraying and shampooing the pets. The pets hated it. It smelled funny. It was hard work and it hardly worked. Today we can give a Capstar pill to rid a pet of fleas within an hour or so. We can apply oils behind a pet's neck and achieve 30 days of flea protection. The spread of these new generation long-acting topical flea products has brought flea control to a new level of both convenience and effectiveness. And there are many of these topicals to choose from; in fact, sometimes it seems like every year there is a new one. Many people do not realize that these are not simply different brands of the same product. In reality, the prescription flea topicals are totally different from the over-the-counter ones and completely different from each other. It is the over-the-counter products that are largely the same and it is important to know when it might be a good idea to buy them and when it would be a waste of money. Going back to the days before the new generation products, there was one product that could dissolve in a dog's skin oils and thus spread in the oil film all over a dog's skin surface. A single application lasted for about a month. Its ability to spread in skin oil by itself was termed "translocation" and was due to the chemical properties of its active ingredient: "permethrin". For hundreds of years insects have been controlled by using extracts from pyrethrum flowers. These natural insecticides, called "pyrethrins", were highly effective and are still widely used today. Still, one of the problems with them was that they were very short-acting and could not deliver sustained insect killing power. Scientists began modifying pyrethrins and developed many pyrethrin versions that could last for long time periods. The pyrethrin derivatives are called pyrethroids. They are easily identified on a product label by their "ethrin" suffix. Common examples include: resmethrin, allethrin, and, of course, permethrin. The permethrin based topical products offered many advantages:
** Relative low cost compared to prescription products But there were some problems as well:
** The high concentrations of permethrin needed for the translocation
effect are extremely toxic to cats. This created not only a marketing
problem but a health issue for families with both dogs and cats. Should You Use a Permethrin Product on Your Dog? The bottom line for this decision involves weighing the pros and cons already listed.
If you are planning to use a permethrin product for flea control,
weigh the low price against the resistance level of the fleas in your
home. After some 20 years of permethrin use, these products are not
reliable for flea control. If they work for you, terrific. If not, a
better product is probably worth the extra money. You may want to use a prescription product for fleas and combine it with a permethrin product for ticks. Permethrin products are compatible with all the prescription topicals and orals. If you are not sure what to use or what is compatible with what, always ask your veterinarian. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ As always, we recommend that you check with your veterinarian for your pet’s immediate health needs and concerns. If you have questions about your pet’s health, care, and well-being, email your question to: NtTAskOurVet@aol.com |
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The Itching Pet
Excessive licking, chewing, and scratching can make a pet’s life miserable for month after month, even year after year. For rapid relief of itch and inflammation, nothing matches the corticosteroids. There are some animals that seem unable to live with any degree of comfort without these medications. Unfortunately, corticosteroids have widespread and potentially dangerous actions throughout the body when they are used for inappropriately long periods and it is generally desirable to minimize their use if possible. Ideally, corticosteroids are used for a few really tough itch weeks and other forms of itch management are used for general itch maintenance. The following list includes assorted non-steroidal methods for relieving itch and reducing the amount of corticosteroid hormones needed. Antihistamine Trials - Diphenhydramine (Benadryl), Clemastine fumarate (Tavist), Hydroxyzine (Atarax), Chlorpheniramine (Chlor-Trimeton) Histamine, a biological chemical, is the chief mediator of inflammation in humans. Histamine is not the major mediator of inflammation in the dog, thus these medications are not as reliable for dogs as they are for us. Antihistamines are not free of side effects; they are notorious for drowsiness in some individuals. Still, this is vastly preferable to the systemic disruption caused by the corticosteroid group. In cats, antihistamines are substantially more reliable than in dogs so that the chances of a given antihistamine working are usually pretty good. For both cats and dogs, using antihistamines together with a corticosteroid hormone will decrease the amount of corticosteroid hormone needed to control the itching (i.e., less hormone is needed to get the job done if it is given with an antihistamine). Fatty Acid Supplementation - Fish oil provides essential fatty acids, particularly omega-3 fatty acids, which have natural anti-inflammatory benefits. While this finding has primarily been utilized in the treatment of itchy skin, many arthritic dogs and cats have also benefited from supplementation. While there are no toxic issues to be concerned with, these products require at least one month to build up to adequate amounts. Effects are not usually dramatic but can be helpful. Flaxseed oil is the best nonanimal substitute for fish oil. Cyclosporine (Atopica) - Cyclosporine is an immune system modulating drug originally developed for use in organ transplant patients, but which is also useful in other immune-mediated diseases. Since allergy is an immune-mediated condition, cyclosporine was investigated as an alternative to corticosteroids and found effective for most patients. Topicals - Colloidal Oatmeal Shampoos/Crème Rinses, Sprays, Lotions, Lime Sulfur Dip, Humilac Spray, Witch Hazel, 100% Aloe Vera Gel. When using any dip on inflamed skin one should be aware that the use of cool water is considered much more soothing than warm water. Ten minutes or more of skin contact is the minimum requirement for any medicated shampoo, premature rinsing will not allow for the therapeutic benefit to be realized. Herbal Formulations - Treatment with herbal formulations is aimed at cooling the heat that rises to the surface, clearing the wind that causes the itching and strengthening the Yin to balance the original condition. Because of the intensity and duration of the situation, it may be a slow process to rebalance all the organs involved. Severe itching amounts to a reduction in life quality. It is important not to develop the mindset that corticosteroids should be avoided at all costs. This would not be fair to the itching pet. Steroids are valuable tools in the relief of pain and suffering and have an important place in the therapy of the itchy pet. The goal is not to avoid steroid use if possible but to avoid long term dependence on steroids if possible. Despite all of the above management tricks, some pets will still require long term steroid use to achieve any reasonable comfort. There are monitoring protocols in place for such cases. It should also not be forgotten that underlying allergies and recurring skin infections can be addressed specifically and that as these conditions are managed, the itch is also managed. Steroid hormones have many side effects and, as helpful as they are for allergic skin diseases, it is best to reserve them for only the itchiest episodes. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ As always, we recommend that you check with your veterinarian for your pet’s immediate health needs and concerns. If you have questions about your pet’s health, care, and well-being, email your question to: NtTAskOurVet@aol.com |
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Polysulfated Glycosaminoglycan
A joint consists of articulating bones, a fibrous capsule enclosing the joint, and slippery lubricating joint fluid to facilitate the gliding of the two bones across each other when the joint is flexed. The bones are capped by cushions of cartilage to facilitate frictionless gliding. Cartilage consists of what is called matrix (which makes up 95% of cartilage, the other 5% being chondrocytes, the cells that secrete the matrix). Cartilage matrix consists of collagen (tough structural fibers) and proteoglycans (water absorbent molecules). The function of a proteoglycan is to soak up water thus creating a cushion, sort of like a water bed, to absorb the pressure exerted on the joint as it works. Over years, either through injury or poor conformation, cartilage wears down or is damaged and arthritis results. The body must then make more matrix and will require the raw materials to do so. Polysulfated GAGs may be injected into the body where they will be distributed to any joints currently effecting cartilage repair. It turns out, however, that polysulfated GAGs represent more than just building materials. They have anti-inflammatory properties of their own that help slow down the actual damage to the cartilage. They also promote enzyme systems that facilitate other aspects of joint repair beyond simply making more matrix. They help the joint create more lubricating fluid as well. The active ingredient in Adequan® is polysulfated GAG, which is mostly chondroitin sulfate, extracted from cow tissue (the trachea, to be exact). In treating arthritis, injections are given twic |