We’ve gotten several calls about the FDA press release last
month with respect to oral flea and tick control products and adverse
effects. Considering that here we are,
well into November and the temperature is still cracking 60 degrees, well above
the active temperature minimum zone for parasite activity, I thought that I would address the
issue.
Flea and Tick Diseases
First off, I think it is important to realize that ticks and fleas should be a concern beyond the icky factor that bugs crawling on our pets elicit. These parasites carry diseases. We know that ticks carry Lyme disease which can infect dogs, cats and us. But they also carry Ehrlichia, Anaplasma, Rocky Mountain Spotted Fever as well as a host of other diseases. One tick causes an allergy in people (and possibly pets) to red meat. That’s right, one bite and say good bye to slow cooked barbecue next summer. Fleas can carry a host of diseases as well including Bartonella (cat scratch disease) as well as typhus, plague, and tularemia. So the question is not should you use flea and tick control, but rather which product is the safest and most effective.What We Used to do About Fleas and Ticks
Historically, (going way back to ancient history), we used
really toxic products, many banned due to their horrific side effects for pets
and people. These sprays, dips and
powders killed fleas and mammals. I
think back with a shudder to the summers that I worked in kennels as a student
applying organophosphate dips to dogs.
No fleas on them, and no mosquitoes on me. Hopefully, I’ll have no long term
ill effects.
A revolution in flea and tick control came about with the
release of Frontline. The active ingredient
is Fipronil to kill adult fleas and ticks paired with a growth inhibitor to
prevent the immature fleas from developing into adults. The product was safe for mammals and when
applied once a month prevented fleas and ticks from pestering our pets. It is actually used in agriculture as well to
treat food crops. It was rapidly followed to
market by Advantage and Advantix (dogs only) for topical use to prevent flea
and tick infestations in our pets. A host of over the counter products made
their way to market, some less effective, many more dangerous. A few years ago, we started to notice that
there was resistance developing in the fleas and ticks and these products were
starting to lose their effectiveness.
What We Do Now About Fleas and Ticks
Bayer had the next innovation in external parasite
control. The Seresto collar kills fleas
and ticks for up to 8 months. We have
found them to be very safe and effective, for both dogs and cats. The efficacy is diminished by frequent
bathing so we recommend changing the collars every 6 months. This is the product that I use on Bella.
Many people don’t like the idea of a collar and their cats
do not go outdoors. That does not put
them at zero risk for fleas or heartworm, although the chances of picking up a
tick is quite low. For these pets we recommend Advantage Multi or Revolution
once a month. This product will safely
prevent fleas, heartworm and intestinal parasites. Combine with the collar for full
protection. We did have a case of feline
heartworm this month in a cat that hasn’t been outdoors for over 10 years. Go figure, mosquitoes can get in the house.
The next round of products to market was for dogs. Isoxazolines are an oral product that will
kill fleas and ticks, some for up to 3 months (although not all ticks and not
as well as the monthly products). These
are the products that the FDA released the new warnings about, so let’s talk
about that for a bit.
The FDA
When a new drug is approved, it must go through thorough
testing for both safety and efficacy. Drugs
must be shown to be effective, that’s why we picked the two drugs that we
prescribe, Simperica and Credelio, both are very effective over the dosage
interval of once a month. As far as
safety, new drugs must be given to a group of animals at the label dose, as well as
3x and 5x the label dose, alone and in combination with other commonly
administered medications. All side
effects must be reported. A single dog,
under 6 months of age, had transient neurological side effects at 5x the label
dose of Simperica. Therefore, the FDA granted a
label for Simperica for dogs over 6 months of age. Credelio did not report this side effect so
was given a label for dogs over 8 weeks of age. We are currently following the label
recommendations. Puppies under 6 months old get Credelio, over 6 months we are satisfied with the safety and efficacy of
Simperica. We have had no side effects
from either medication in our patients.
Furthermore, when I questioned my colleagues, none have reported any
side effects in their patients. However,
there must have been some side effects reported to the FDA, because they are
working on adding more information to the labels for all drugs in this
class. Keep in mind, that the current
package insert already carries this information where applicable. Furthermore, if you read the entire press
release, beyond the sensational headlines that are springing up all over the
internet, you will find that the FDA says that “these products continue to be
safe and effective for the majority of animals”, adding that it <the FDA>
carefully reviewed studies and other data on Bravecto, Credelio, Nexgard, and
Simparica prior to approval. The agency is asking the manufacturers to change
product labeling in order to provide veterinarians and pet owners with the
information they need to make treatment decisions for each pet on an individual
basis.”
We recognize our clients’ concerns for their pets’ safety
and continue to monitor studies as they become available. Not using flea and tick control is not safe
either as insect borne diseases are seriously dangerous to our pets and
ourselves. We are striving to provide a
balance so that we can keep our pets and families safe.