What makes dogs itch?

Dogs are taken to veterinarians for itching more than for any other medical problem. But what makes dogs itch?  While there are many possible causes, most dogs that are itchy suffer from one of these six conditions:

  • Flea allergy dermatitis
FAD distribution
Flea allergy dermatitis distribution
  • Atopic dermatitis
  • Food allergy dermatitis
  • Contact dermatitis
  • Sarcoptic mange
  • Demodectic mange

To take a quick look at the body locations commonly affected, the symptoms, and the types of lesions associated with each of these conditions, check out www.itchology.com. Itchology is the app for dedicated pet parents to mange their itchy dogs.

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How itchy is your dog, really?

By Jon Plant, DVM, DACVD

Scratching, biting, chewing, rubbing, and excessive licking can all be signs of itch in dogs. A number of methods have been developed to try to quantify itching, but these are most useful in research settings.  One method is to take videos of kenneled dogs then track all itching behavior seen over a period of time.  Another idea that I have published research itchy-dogon is the use of sophisticated motion sensors attached to dogs’ collars. The most widely used method is to ask the dog’s guardian to rate the level of itch severity on a linear scale.

Why might measuring itch be important, you ask? I think of it like this: would you start a weight loss program without knowing how much you weigh? Excessive itching has a negative impact on dogs’ quality of life.  Surprisingly, most veterinary medical record standards do not require us to record itch severity. A meaningful measure of itch severity that you could share with your veterinarian would be a great step forward in helping pet owners help their itchy dogs.

Best flea control products

My two favorite flea products are Comfortis® and Trifexis®. Both products are once monthly, chewable tablets.  They contain an active ingredient against fleas, spinosad, and ComfortisTrifexis also contains milbemycin which prevents heartworms and controls some important intestinal parasites (roundworms, hookworms, and whipworms).  Fleas take a blood meal within minutes of jumping on a dog. In this way they are quickly killed by spinosad, a chemical that is much, much safer for mammals than for insects by virtue of differences in the nervous system.

We used to hear that “even one bite” could cause flea allergy.  But, the number of mites DOES matter and Comfortis and Trifexis kill fleas more quickly than other products, minimizing the number of bites.  They are not affected by getting wet or bathing in the same way that all topical products are, making them the best option for my patients that often require frequent bathing.  Comfortis and Trifexis are prescription drugs that must be prescribed by your veterinarian.  The choice between the products will depend on your pet’s specific needs and other parasite control prescriptions.

My favorite flea products for dogs

Protecting your dog from fleas is much easier than it was 20 years ago. Back then, the best we could do was knock the flea numbers down, but it was challenging with the products that were available.  Lately, the problem is knowing which of the many products out there is right for your dog. I’ll give you my 3 favorites, starting this week with number 3:

Vectra 3D is at the top of my list for topical products (spoiler alert: the top two are given orally). It combats fleas (plus ticks and mosquitoes) on three fronts:

1.  One ingredient (dinotefuran) over-stimulates the fleas’ nervous system. It acts on an insect nervous system receptor, leaving a wide margin of safety for mammals.

2. The second ingredient is permethrin, which helps repel mosquitoes, kill ticks, and fleas.

3. The third ingredient is an “insect growth regulator” called pyriproxyfen.  This ensures that even if eggs are laid by a few surviving fleas, they will not result in an infestation.

Vectra 3D is quite safe for most dogs if applied according to the label, but always consult with your veterinarian for recommendations concerning your individual dog.

Common flea myth #5

The final installment of common myths I hear about fleas

Flea Myth #5: “Product X was ineffective because the environment was so infested.” The observed effect of a product, measured in terms of the number of fleas that can be found on a pet, may indicate that this is true in the case of a heavy flea burden. However, it is all a matter of percentages.  If the product is even 90% effective, the manufacturer can claim efficacy.  But, even leaving 5% of hundreds or thousands of fleas will be too many for a lot of dogs or cats to tolerate.  The product may appear to perform adequately with a low flea burden in the environment, but not so well with a heavy burden, even though it kills the same percentage of fleas in both cases.

Common flea myth #3

The third installment of common myths I hear about fleas

flea pyramid
flea pyramid

Flea Myth #3: “We only saw a few fleas, so the house isn’t infested.” Not really.  Because fleas are reproductive machines, there can easily be hundreds of fleas in the environment for every adult you see.  Adult fleas are just the tip of the pyramid, and all the other life stages (eggs, larvae, pupae, pre-emerged adults) collect in the pet’s environment. And carefully flea combing for five minutes only turns up a fraction of the fleas on the average dog.  So remember, if you find even one flea, there are hundreds more maturing shortly!

Myth #4 next week!

Common flea myth #2

The second installment of common myths I hear about fleas

Flea Myth #2: “He couldn’t have fleas because he hasn’t been around other dogs.” In fact, once a flea acquires a host (i.e. your dog), she has found her happy place. The old saying that “the grass is greener on the other side of the fence” doesn’t apply so well to fleas. They are content to stay on the same dog for their entire adult life span, typically 2-3 months. During this time, the female flea will be biting hundreds of times every day, and laying thousands of eggs that drop off into the environment. The environment is where the fleas wait to infest your pet (see Myth #1 for more details). So, it is not normally direct contact with another flea infested animal, rather just walking through the same premises as an infested animal, whether indoors or outdoors, that is the source of new flea infestations.

Myth #3 next week!