Monday, November 5, 2018

Fleas, Ticks, and the FDA.


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.