Let's talk Preventatives

While our pets do not live or walk in plastic bubbles, using preventatives is the easiest way to keep their health in check and pesky critters that can carry diseases off their fur! 

What do we mean when we say preventatives?

You may hear the same questions every time you come to the vet, “What preventatives is your pet on?” While easy for us in the animal field to answer, this jargon is sometimes confusing and misleading. 

When discussing preventatives, veterinarians generally mean flea, tick, and heartworm preventatives. They come in different forms (topical, collar, oral, injectable), time-frames of administration (monthly up to yearly), and brands. You can get individual preventatives for flea/tick and heartworm, or go for combination medications that are all-in one.

All forms commonly have the same function to get a set amount of medication into the pets blood stream. This allows for the pet to have a degree of protection when encountering external parasites and helps reduce the chances of disease transmission.

What is flea/tick prevention?

Flea and tick preventatives are recommended for all dogs. Fleas tend to thrive in warm and humid environments, but they can pose a year-round or seasonal problem depending on your climate, location, and animal density. Ticks can be found in wooded areas, forests, and locations where animals may roam. While ticks were previously noted in select areas of the country, they can now be easily found in nearly every region of the United States.

Flea and tick preventatives come in two forms: adulticidal and repellant. Adulticidal medication is meant to kill the external parasites once they take a bite, also known as a “blood meal”, from their intended host, i.e. your dog. Repellants are intended to act as a mini shield on your pet and not allow those parasites to get onto the host or take a bite.

Both forms of flea/tick preventatives are beneficial to pets. In certain cases, like very active pets, frequently outdoors, flea allergic, or living in areas heavily trafficked by animals, both forms can used with alternating schedules to provided added coverage to pets. Talk to your veterinarian to see if this is right for your pet and their lifestyle.

What is heartworm prevention?

Heartworm prevention is also recommended for all dogs. These medications help prevent the development of heartworm disease, a disease that can have a life threating impact on your pet and other pets in the area. Heartworms are a parasite that can infect a variety of animals, but tend to be seen primarily in dogs, cats, and ferrets. This parasite is transmitted by mosquitos from animal to animal.

Heartworm positive dogs can have circulating amounts of young worms, called microfilaria, in their blood. A mosquito can take a bite from an infected dog, have the microfilaria enter their system, and in 2 weeks be ready to transfer infected larvae into a new animal. Once in their new host, it will take around 6 months for the young worms to turn into adult heartworms.

Heartworm prevention is intended to stop the “baby worms” from developing into adult heartworms. Because of how easily it can be transmitted and the impact it can have on your dog and those in the community, preventatives are recommended year round for all dogs and cats.

Infections use to be most common in regions where mosquitos were prevalent, specifically in southern states. However, infection rates in other locations have increased with confirmed heartworm cases identified in the contiguous United States and Hawaii.

To understand if your dog is heartworm positive, reach out to veterinarian to learn about simple blood testing, your dog’s status and which heartworm preventative is right for them!

What about intestinal parasites?

Most heartworm preventatives also act as intestinal parasite dewormers. Depending on the preventative selected, some cover two and even up to four parasites that can be commonly found in dogs.

Other cases can have individual deworming medications added on depending on the type and volume of parasites found. Routine fecal testing is recommended for all dogs, regardless of region or climate.

When should preventatives be given?

In most areas of the United States, flea, tick and mosquito seasons can be year-round. Because of this, preventatives are recommended for dog throughout the entire year.

A common misconception is to avoid administration of preventatives in the winter months. Unfortunately, not all external parasites die in colder weather. Fleas can still hatch in temperatures below 40F and find warm places to lay eggs. Certain tick species can also survive colder climates by becoming dormant or hitching a ride to a host, i.e. your dog. If these parasites have already made it into your home, the warmer temperatures indoors are a perfect breeding ground for future infections.

The exact timeframe of administration depends on the preventative and manufacture recommendations. The newest options allow for monthly, every 3-month, or 6 month administration/applications. 

Because I am forgetful, I tend to stick to the monthly options and set a year-round reminder on my phone.

New flea/tick preventatives on the block?

The newest generation of products, known as the isoxazoline class, are the best thing since sliced bread for vets! This new class of drug includes 4 products that are currently on the market; Nexgard, Bravecto, Simparica, Credellio.

This new class of medication answered 2 important requirements for vets, that were just not available with the older products on the market: Can we use these in puppies? And How quickly do they work?

Two of the four products are labeled for use in puppies 8 weeks or older, allowing veterinarians to start covering the youngest and most vulnerable population of pets as early as possible. These products also focus on killing ticks once on the host within hours of attaching, reducing the chances of disease transmission. 

What about concerns with adverse reactions?

Like with all good things, controversy and concern tends to follow. The biggest downside to the newest flea and tick preventatives is the FDA label warning of neurologic adverse reactions like ataxia, seizures, and tremors.

This label warning came after 3 dogs with known history of neurologic issues were included in the efficacy studies for Nexgard. Two of the dogs during the 90 day trial had neurologic episodes, causing the FDA to place the warning on the label for the entire class of medications.

In spite of the warning, the FDA considers “products in the isoxazoline class to be safe and effective for dogs.” After careful review of medical histories and owner discussions, I safely and routinely recommend these new preventatives. I also give these products to my dogs on a monthly basis.

Are generic and brand-specific preventatives the same thing?

While the price may be appealing, try your best not to skimp and purchase brand name products. The effectiveness of generic or “knock-off” brands is not well known. You may be purchasing an applying product to your dog and still see positive disease transmission and external parasites on your pet.

Saving money the first go around may cost you more in the end. Talk to your veterinarian regarding preventative options for your pet. Investing in them now, will save you time, money, and headaches later.


The more you know, the better they’ll feel!

Dr. Nicky

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