Friday, December 23, 2011

When Dogs Itch in Winter by Shelley R. Epstein, VMD, CVH


This has been an unusually itchy winter for dogs here at WAH, so we thought it might be a good idea to discuss this topic. Typically, November or December comes, and the number of itchy dog cases drops off precipitously. But this year, the opposite has occurred!

Believe it or not, the number one cause is fleas! Yes, fleas. In the cold weather.

Itching from fleas is typically random on the body. Some dogs will “corn cob” their legs, chewing them up and down the length. Most dogs just chew and scratch anywhere on their bodies, with some dogs focusing on the lower back/tail/anal area.

And we’re seeing these problems even on some dogs that have been faithfully wearing flea/tick preventive products! Why is this, you may be wondering?

Quick flea trivia for edification and cocktail party banter:

Fleas love 80 degrees and 80% humidity. Obviously, not the current conditions, but sure describes this past summer.

Another fact: One adult female flea will lay 2000 eggs, which drop off your dog or cat and land wherever the dog/cat goes: your yard, house, bed, sofa, etc. Fleas are particularly appreciative of you if you have carpeting. They get way down in the pile where it’s really humid. They don’t love you as much if you have hardwood or laminate floors because the surface exposes their precious eggs to the air and dries them out. But they can make due with the cracks those floors provide.

So, putting these facts together, we had a tremendously fruitful season for flea reproduction! And even though it’s getting cooler and occasionally drier, many fleas have survived and found a safe haven on your dog (or cat).

What about those expensive flea products that you’ve been using faithfully? Could you still have a flea problem?

Yes, for a few reasons.

First, the products all work in slightly different ways. The best products, of course, would kill the fleas before your dog is bitten. By the way, it is believed that the flea saliva is what stimulates an allergic reaction in the dog. So of course, you’d like the flea to diet before it bites your dog.

Advantage and Advantix (the latter also kills ticks) both kill the fleas before they bite your dog. But occasionally we’ll see dogs with fleas who are wearing this product. Take a close look at your dog. If you can easily catch a flea and it doesn’t hop off your finger, it was already poisoned by the product. The fact that your dog had fleas this late in the season means your dog’s environment has a flea infestation.

Here’s a trivial fact, actually studied by a Pew family member. We’ve known that the flea life cycle is egg-larva-pupa-adult. Well it’s those pesky pupa that can survive a nuclear holocaust, or at least the climatic ravages of winter. And (here’s what the Pew person found out) those pupa sense the vibrations of the normal host- dog or cat- walking by and instantaneously molt into adults and hop on the dog or cat. Then the Advantage/Advantix starts to poison them, before your pet is bitten.

It’s a common misconception that if your house were infested, you would have the fleas hopping on you. As you can see from the Pew studies, the fleas (thankfully) much prefer the dog or cat, and will only hop on you if your dog or cat is too filled up with fleas. We’ve heard numerous stories of people going into abandoned homes that were previously occupied by pet-owning people…and the fleas swarmed onto the poor unsuspecting person, actually coating their pants black! That’s really gross, but you get the point.

For these situations, we recommend one dose of Advantage/Advantix now and one in a month, then resume when the ideal flea climate returns. Oh-here’s another great trivia fact about fleas and Advantage: The product coats the skin cells which fall off around the house, and the poor unsuspecting larva eat them and DIE! This gives the product an environmental effect. In the past 15 years or so that the product has been out, we’ve seen a marked decline in the need for house products to kill fleas.

But in those rare cases in which the fleas are still in the house and hopping on the dog, even if you are using one of these products, you may need to call in an exterminator. Most companies use products to instantly kill any adult fleas, and they use growth regulators to kills the eggs. Most will give you a 90-day guarantee.  But remember, nothing kills the pupa, so expect the problem to resume, hopefully to a lesser extent, when the weather warms up. Hopefully the flea product on your dog will suffice next season.

But what about Frontline? Honestly, for the past few years, we’ve observed that this product is not working as well for flea problems. The company insists that independent studies on fleas collected from all over the country show no resistance to the product. They offer two explanations for why their product might “seem” to not be working:
1.     There’s a wild animal roaming your yard at night, depositing flea eggs in the yard, a source of reinfestation for your dog and
2.     Perhaps your dog is at the high end of the dose range so naturally there will be less product spread on a larger surface area.
But this doesn’t explain why Advantage seems to be working under those same conditions. We have no doubt that Frontline placed in a petri dish with fleas will kill them. So we don’t have any great explanation for the failures that we’re seeing many times a week. In any case, we’ve stopped recommending this product for flea control.

This blog is not to promote any particular flea product. We’re just letting you know which ones we use and have the most experience with, good or bad. This past season, we started using Vectra, and we have not had any complaints about its efficacy. And if you prefer natural products, we’ve found the cedar oil sprays are very effective, although they require much more frequent application, up to daily if you have a bad problem. They are more labor intensive as you must be sure to coat every square inch of your dog or the resilient fleas will find that one area that you’ve missed. We do currently carry Dr. Ben’s cedar oil flea/tick spray.

So the #1 cause of itching this winter is likely fleas.  The warm humid weather is a conspirator. And some flea products aren’t working that well.

The #2 cause of itching in the winter is inhalant allergies. Of course, dogs can have both problems (allergies exacerbated by fleas).

Typically, allergies appear as licking/chewing the toes and feet, with some dogs rubbing their eyes, muzzles, ears, and armpits/groin. In contrast to flea-induced itching, allergies tend to focus on these areas only.

Allergies can be to just about anything. In the winter, the most common allergens are house dust mites and molds. Some dogs are even allergic to cats and humans.

The treatments are numerous and largely palliative.  Here is a list of possibilities:

1.     Antihistamines
2.     Diet improvement. Visit our webpage on diet: http://wilmingtonanimalhospital.com/info_nutrition.php
3.     Dietary supplements, like fish oil, Missing Link, etc.
4.     Allergy testing and allergy vaccines at a veterinary dermatologist’s
5.     Steroids like prednisolone. We use Natural Hydrocortisone which has far less side effects than its chemical derivative prednisolone.
6.     Immunosuppressive drugs like Atopica.
7.     Shampoos to soothe the itching or treat secondary infections
8.     Antibiotics for secondary infections.

It’s important to emphasize that fleas and inhalant allergies comprise about 85-95% of the skin problems we see in dogs in the winter. However, there are many other causes of itching in the winter. It’s always best to let one of our veterinarians examine your dog to assess the condition and make individualized recommendations for treatment and prevention. Please see our website for more information about our hospital and how to schedule an appointment: WilmingtonAnimalHospital.com. If you're already a client, you can visit our website and sign on to Pet Portal to access your pet's reminders, receive email reminders (and text messages if you'd like), and many other great free services.

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