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What's Behind Your Dog's Allergies?

What's causing your dog to itch? It's probably dog allergies. But is it food, dust mites ... or you? There are hundreds of possibilities.

Here's how to rule out some of them, and get down to the likeliest ones. Once you know what's causing the itch, you can take action to provide your dog with some much-needed relief.

Let's get down to business. Does your dog itch all year-round, or just in certain seasons? If it's seasonal, skip to that section.

There are only a few causes of year-round canine allergies:


This is the first thing many people think of as causing canine allergies. But it's actually one of the least likely. True food allergies are uncommon in dogs, with only about 15% of allergic dogs being allergic to food.

A dog may be sensitive to a protein source in his food, or to the protein part of grains such as wheat, soy or corn. Wheat gluten is another one which frequently causes some dog itching and scratching problems. If you have an itchy dog, avoid foods with soy.

Try switching to a food with a different protein source, or with a different grain content than you've been feeding. Test this food for 6 weeks and see if there's any difference. If food does seem to be the problem, rotate different foods through your dog's diet. Canine allergies develop after exposure to an ingredient, and the more exposure, the more likely an allergy will develop.

If your dog is itching, another food-related cause may be mold. Molds grow on wheat, corn, and peanut hulls used in petfood. These produce toxic by-products called mycotoxins, which can suppress the immune system, leading to dog itching problems.

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If you live somewhere humid, or if your kitchen and bathroom are unventilated, mold spores may be causing your canine to itch.

Mold grows wherever and whenever there is moisture. Depending on where you live and what your drainage conditions are like, this can be seasonal or year-round. The itching follows the mold growth.

If your house has ever flooded, or if the basement gets wet, you could be in for some nasty black mold called Stachybotros. In quantity, that one can sicken and kill dogs, children and adults, too.

Other, less toxic molds, such as Penicillium, are more common. Molds vary by region, but all can cause allergic reactions in people and animals.

What to do? Keep the humidity low in your house by running the air conditioner regularly. Fix any leaks. Use the exhaust fan in the bathroom after showering, and, when cooking, use the one over the stove (make sure it vents outside).

Check your air conditioning unit to make sure there's no rust buildup in the condenser pan (where the air blows over the coils and moisture condenses and drains out). Make sure the drain is unclogged, and pour a few tablespoons of bleach down the drain pipe every few months to keep it clean. To further reduce mold, install an electrostatic furnace filter and use it. (See details below.)

There's usually no need to clean the ducts, unless you've had a severe mold problem, or if the moisture situation hasn't been resolved.

Clean out mold, mildew and dust wherever you find it: bathrooms, mini-blinds, bookshelves, ceiling fan paddles, electronics.

Other animals.

Yes, your dog may be allergic to your cat! Male and long-haired cats put out more allergen than female and shorthaired cats. The allergen is known as FelD1 (pronounced feldy-one by those in the know). This protein is found in cat saliva, and to a lesser degree, in their anal sacs. When the cat licks himself, the saliva dries and flakes off, then floats away.

Cat allergen is very lightweight, and very sticky. It sticks to walls, furniture, carpet and drapes. It's also a very potent allergen, and it's persistent: it'll stay active in a home environment for at least 10 years.

Best bet: bathe the cats regularly (monthly, if they'll tolerate it). I take my cats into the shower stall with me, and use a handheld shower. Allerpet® C, and DanderSeal® are products which are supposed to seal the allergen to the body, but nothing beats a bath.

Another great product is Allersearch X-Mite powder (order from Aller-caire, 800-547-8095). Sprinkle the powder on the carpet and furniture, let it sit a few hours, then vacuum it up. The powder contains tannic acid (from tea) to denature the cat allergen down at dog level. (It may stain white carpet and fabric, so be careful.) There's also an Allersearch spray for surfaces (not cats). A cat-allergic friend sprays the area around his chair when he visits cat families. That keeps him safe for several hours.

HEPA air filters have also been shown to trap a large amount of the cat allergen which floats through the air. (In our tests, the best is the Cloud 9® Sterile Aire®. Aller-caire has the best prices.)


That's right. Your dog may be allergic to you or other family members. People put out allergen, just like cats. It's in our skin, which flakes off throughout the day and night. (Extreme case: dandruff.) The owner of an allergy testing lab for animals told me that, at one time, 40% of dogs' blood tested by his lab indicated a probable allergy to human allergen.

The solution in this case: allergy shots. (These were discontinued for some years, due to government concern about injecting human cells into other humans in the form of allergy shots. AIDS was the worry. I understand they're available again.)

Other dogs.

As with cats and people, other dogs, birds, and furry critters are possible allergy-inducers. Again, keeping everybody clean makes a difference. One other tidbit: Dogs who spend a lot of time outside can bring pollen in on their fur. One good shake and it spreads throughout the house. Keep them clean!

Seasonal dog allergies.

This is the most common cause of dog itching and scratching. They usually develop after a couple of years of exposure, if they're going to develop at all. No one really understands why one individual will develop allergies, while the next one won't. Genetics are thought to play a part, since allergies often run in families. Repeated exposure is important, too. Other scientists theorize that it may have something to do with immunizations given at an early age, or with lack of exposure to certain diseases at an early age. We're learning a lot about the immune system, but there's a whole lot more to explore.

Pinpointing the cause of seasonal allergies is best done with a "scratch test" at the vet's office. Pollen extracts are injected just under a shaved area of skin, and reactions are noted a few minutes later. This usually runs a few hundred dollars.

You can zero in on some of the culprits yourself, for much less. One question to ask is, "What am I allergic to?" For some reason, people and pets are often allergic to the same things.

If that's not the case, do a little bit of sleuthing. First, turn on your local TV news and watch the weather segment. There's a good chance they'll give an allergy report, which will tell you which pollens (or mold) are a problem that day. By tracking the daily pollen count to see what's highest when your dog is scratching, you'll have a good idea of what's causing the allergy.

In general, though, the earliest spring pollens are the tree pollens, followed by grass pollen (which lasts into the summer). Interestingly, flower pollen is usually not a problem -- and neither is very large-sized pollen, such as from pine trees.


When allergists talk about seasonal allergies, they're usually referring to seasonal pollens. But insects are also a seasonal issue.

Summertime is bug season, and, when the temperature hits 80 degrees F., and the humidity hits 80%, mosquitos and fleas start to "pop." These pests bite, and their saliva gets injected under the skin. The body reacts to these alien proteins, and the skin becomes inflamed and itchy.

Spraying a permethrin fogger in the yard (I like Raid® Yard Guard) will kill these guys nicely. (Use sparingly around cats -- high doses of permethrin can kill them.) Be sure to spray shady areas and tall grass, where mosquitos and fleas hide.

I also recommend using one of the new wave of veterinary-sold flea products on your pets. Advantage®, Frontline Topspot®, and the new Revolution® are all very effective and safe for dogs with allergies. (Only occasionally will there be an allergic reaction where these products are applied.) Frontline also works on ticks. Revolution is even better, killing ticks, ear mites, and the mites responsible for that itchy skin problem, demodectic mange. Revolution also replaces heartworm preventive.

What else can you do to give your dog some relief?

Veterinary dermatologist Alice Jeromin says antihistamines work for less than 20% of allergic dogs. Side effects include sleepiness and sometimes, constipation, and occasionally, hyperexcitability (especially with chlor-pheneriamine). Use antihistamines cautiously with epileptic dogs, and those with glaucoma and heart problems. Don't use with pregnant animals.


Or a generic equivalent -- from the drugstore is inexpensive and effective. (She suggests using 1 mg per pound of dog weight two or three times a day.) Tavist® or its equivalent is also safe for use with dogs (1.34 mg twice a day for dogs under 30 lbs., and 2.68 mg twice a day for dogs over 40 lbs. are the recommended dosages.) Your vet may prescribe Atarax® or another antihistamine as a dog allergy remedy.

Shampoos and topical sprays

(with steroids or tea tree oil) can offer a few minutes relief, although I've found that shampoos tend to irritate more than soothe.

Vets favor steroids such as Prednisone

in the form of pills or shots. They're cheap, and usually effective. But they have very bad long-term side effects, including damage to various internal organs, and incontinence. I suggest using these only as an emergency "interrupt button" to shut down the immune response, temporarily. Use steroids only occasionally, then wean the dog off them by skipping days. This helps restart the dog's systems.

For pollen allergies, allergy shots

Can be effective for many, but not all, canines. They'll set you back a few hundred dollars a year, in addition to the few hundred you'll spend on the tests. They usually take at least six months to work, and during those six months, you'll be visiting the vet several times a month.

Air filtration

Keep your doors and windows closed, and install a really good furnace/air conditioning filter. The best are "permanent" electrostatic filters. You can buy them at Home Depot or similar stores.

Electrostatic filters

are made of several layers of plastic. Each layer takes on either a negative or positive charge as air flows past. Dirt and pollen particles with opposite charges stick to the plastic.

These work well. In our tests, there was a major reduction in dirt and pollen (measured with a laser particle counter) when the furnace or air conditioning was run for 15 minutes at a time. If its in between seasons, just switch the fan from Auto to On and let it run for 15 minutes to an hour. Don't forget to shut it off, though. The fan motor isn't designed to run constantly, and can burn out prematurely.

Electrostatic filters only cost $45 or so. Two hints: first, get one that fits well. Air flows around an ill-fitting filter, not through it -- air takes the path of least resistance. If you need a filter custom-made for your system, call Tepco at 512-834-9561.

Second, be sure to clean your filter monthly by spraying it, from the back, with a hose or a hand-held shower. I also use a little bit of antibacterial liquid soap to get all the dog and cat hair off.

A good alternative to the electrostatic filter is the 3M Filtrete® furnace air filter. These are sold at hardware stores, too. They're extremely effective. You don't have to clean them, just replace them every few months.

There's also a 3M Filtrete vacuum cleaner bag for most vacuums. In our tests, these dramatically reduced the amount of dust, allergen and pollens pumped back into the air by the vacuum cleaner. Get these at a vacuum cleaner store.

If you want to get the air extremely clean in one room, put a Cloud 9 HEPA filter where your dog sleeps (or where you sleep, if you have allergies).

For a fast, natural, dog allergy treatment, try Skin-eze™ chewable tablets for dogs. These herbal tablets work wonderfully (see for details).

In this article, we've touched on many of the major causes of itching and scratching in dogs (and itching is the main symptom of dog allergies). There are plenty of other causes, such as a whole host of skin diseases. These may be caused by viruses, fungi or parasites. Sebaceous gland cysts and small tumors can also be itchy, and are common in older dogs (see a veterinary dermatologist for an analysis of unusual lumps, bumps, and patchy skin).

The technology doesn't exist to cure dog allergies. But if you can sniff out the instigators and reduce the allergen load, your dog will be happier -- without the scratching, chewing, and rolling around in the dirt!

From Good Dog! Magazine

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