Broad-Spectrum Parasite Protection: Do Your Clients Know the Common Parasitic Risks?

Posted by Elizabeth Racine, DVM

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As veterinarians, we’ve all received the emergency call from the panicked pet owner who found worms in their pet’s stool. Yet despite the grossness factor that horrifies pet owners, recent studies have shown that many of our clients are even less compliant with their pet’s parasite protection than we may have previously realized.

With the increasing prevalence of parasites and vector-borne illnesses, it is more important than ever to encourage year-round compliance with parasite control recommendations.

As a veterinarian, you are a critical resource for public health and play an important role in effectively communicating the risks of inadequate parasite protection to clients. By explaining the value of year-round broad-spectrum parasite protection and helping owners choose appropriate products for their pets, you can protect pets from harmful parasites, some of which can be zoonotic..

What is broad-spectrum parasite protection?

The Companion Animal Parasite Council (CAPC), the American Animal Hospital Association (AAHA), and the American Veterinary Medical Association (AVMA) recommend that all pets be maintained on broad-spectrum parasite control. This means that every pet should be protected against heartworm, intestinal parasites, ticks, and fleas year-round, regardless of geographic location or lifestyle. This unanimous endorsement underscores the importance of treating and controlling parasites in the pet population.

However, despite veterinary recommendations for year-round coverage, many pet owners still do not understand what broad-spectrum parasite protection really means. Clients are often confused about the type of coverage provided by the products they are using. For example, they might be giving their dog an oral tick and flea control product and think that it also protects against internal parasites—inadvertently leaving gaps in their pet’s coverage. Highlighting these gaps and discussing the prevalence of the parasites not covered by the client’s current protocol—including the number of recent positive cases in your own clinic, if such data is available—can be the key to motivating better compliance.

Changes in parasite prevalence put pets at risk

While previous recommendations have varied by region, it is important to note that many parasites are now a global concern. Heartworm disease, for example, is no longer limited to southern European countries and the southern United States.

A recent U.S. study in Colorado—a state where heartworm disease was previously considered uncommon—indicated that heartworm prevalence in that state has risen a whopping 67.5 percent in just four years, from 2013 to 2017 (1). Meanwhile, heartworm infections in dogs also increased by 21.7 percent in the United States as a whole from 2013 to 2016, a survey revealed (2). It is clear from these results that year-round prevention is essential, even in areas where heartworm prevalence has historically been perceived to be low.

Although the Colorado study implicated the movement of animals from shelter and rescue environments for this change, veterinarians must keep in mind that traveling with owned pets is also becoming increasingly common. A 2019 paper discusses how the global movement of dogs—both rescue animals and pets—has impacted the spread of parasitic illnesses such as Echinococcus, heartworm disease, and tick-borne illnesses to new geographic regions worldwide (3).

Now more than ever, our veterinary patients are exposed to new environments and diseases outside their home regions. When choosing parasite control protocols for our patients, we can no longer rely solely on local prevalence data to guide our decisions.  Ensuring all patients are maintained on year-round broad-spectrum protection can help reduce the spread of disease both to and from your local area.

Parasites and Zoonosis

Many pet owners are unaware of the risks of zoonotic parasites, and households with young children or elderly adults are of particular concern. The CDC estimates that 5 percent of the U.S. population has been infected with Toxocara (4), and has listed this condition as one of its five neglected parasitic infections in the country.

A study published in 2016 demonstrated that cats were two to three times more likely to shed Toxocara eggs in their feces compared to dogs, and may serve as an important reservoir for transmission to humans (5). The authors note that cats not only have a higher risk of infection through predation, but also have been historically less likely to receive routine fecal examinations, worming treatments, and preventive care in general.  These findings emphasize the importance of educating clients about preventive care for all pets in the household—not just those presenting to the veterinary clinic.

Despite the zoonotic risk associated with poor parasite protection, veterinary professionals as a whole may be falling short when discussing parasite control medications with pet owners. A retrospective study conducted at the University of Pennsylvania veterinary teaching hospital in the U.S. found that only 13 percent to 23 percent of pet owners were questioned about the use of parasite protection as part of the medical history (6). Owners of higher risk patients, such as those with a prior history of parasites, were no more likely to be questioned about their use of parasite control medications than pet owners with healthy animals.

Veterinarians are in a prime position to make a real impact by better communicating the need for year-round parasite protection. By ensuring the entire veterinary team is comfortable discussing parasite control with pet owners and taking advantage of opportunities to review the client’s preventive care program, veterinary hospitals can drastically improve compliance.

Communicating with Clients

Most veterinarians are already aware of the risks of poor compliance in parasite protection. The challenge then becomes to discuss these recommendations in a way that motivates the complacent client to take action, too.

Interestingly, a 2017 study published in Parasites & Vectors found that although the majority of veterinarians studied recommended year-round parasite control, only 62 percent of clients recalled that recommendation when surveyed after the visit (7). The study authors advised that making a clear and distinct recommendation for parasite control, explaining the significance of the recommendation, and providing a written summary of recommendations made during the visit may all help to improve pet owner recall and subsequent compliance.

In many regions, clients are also under the impression that parasite protection is only essential in the summer months. While this may have been true in the past, the body of evidence and data now showing an increase in parasitic risks means year-round protection is rightly being advocated.

This provides an excellent opportunity to discuss the seasonality of parasites with clients, as a recent study demonstrated that the prevalence of whipworm and roundworm is actually highest in the winter (8). Whipworm eggs are especially resilient and can persist in the environment for a long period before potentially infecting a dog. Whipworm is particularly prevalent in adult dogs, and adults are at higher risk for recurrent infections (9). Similarly, ticks can be active any time the temperature is above freezing. As the prevalence of these parasites continues to change, pets left unprotected during the winter months are at an even greater risk.

Clients should also be made aware that due to weather fluctuations, milder winters often see a resurgence of previously seasonal parasites such as ticks and mosquitoes, leaving pets at risk for vector-borne illnesses such as Lyme disease and heartworm disease. Using a monthly external parasite medication like Credelio® (lotilaner) through the winter will ensure that pets are protected from ticks and fleas even when temperatures rise unexpectedly.

In addition to helping clients understand the importance of broad-spectrum parasite protocols from a health standpoint, veterinarians may also be able to improve compliance by showing clients how easy it is to keep their pets protected. Chewable products like Interceptor® Plus (milbemycin oxime/praziquantel) are easy for clients to administer at home, and offer coverage for heartworm disease and the most common intestinal worms, including tapeworm.

Finally, veterinary practices can also build revenue and improve compliance by offering regular reminders for clients to keep pets up-to-date on parasite control medications and routine health screenings.


Year-round broad-spectrum parasite control protocols are an essential aspect of good preventive veterinary care for all pets regardless of their age, location, or lifestyle.  Clients should be counseled on the risks of skipping monthly parasite protection, including how this may affect their pets and their families. 

The way pets and people interact has changed in recent years, with dogs accompanying their owners everywhere from parks and stores to restaurants and hotels. As more people travel with their pets, it facilitates the transmission of parasites, some of which are zoonotic. Some areas are seeing increases in parasite prevalence as dogs are being moved across the U.S.—and the world. As parasitic risks continue to shift, we as veterinarians need to re-evaluate and re-emphasize the need for consistent broad-spectrum protection.

Disclaimer: The author received compensation from Elanco US Inc., the maker of Interceptor Plus and Credelio, for her services in writing this article.

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Interceptor® Plus Indications

Interceptor Plus is indicated for the prevention of heartworm disease caused by Dirofilaria immitis and for the treatment and control of adult roundworm (Toxocara canisToxascaris leonina), adult hookworm (Ancylostoma caninum), adult whipworm (Trichuris vulpis), and adult tapeworm (Taenia pisiformisEchinococcus multilocularisEchinococcus granulosus and Dipylidium caninum) infections in dogs and puppies six weeks of age and older and two pounds of body weight or greater.

Interceptor® Plus Important Safety Information

Treatment with fewer than 6 monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention. Prior to administration of Interceptor Plus, dogs should be tested for existing heartworm infections.  The safety of Interceptor Plus has not been evaluated in dogs used for breeding or in lactating females. The following adverse reactions have been reported in dogs after administration of milbemycin oxime or praziquantel:  vomiting, diarrhea, depression/lethargy, ataxia, anorexia, convulsions, weakness, and salivation. For full prescribing information see Interceptor Plus package insert.

Credelio® Indications

Credelio kills adult fleas and is indicated for the treatment and prevention of flea infestations (Ctenocephalides felis) and the treatment and control of tick infestations [Amblyomma americanum (lone star tick), Dermacentor variabilis (American dog tick), Ixodes scapularis (black-legged tick) and Rhipicephalus sanguineus (brown dog tick)] for one month in dogs and puppies 8 weeks of age and older, and weighing 4.4 pounds or greater. 

Credelio® Important Safety Information

Lotilaner, is a member of the isoxazoline class. This class has been associated with neurologic adverse reactions including tremors, ataxia, and seizures. Seizures have been reported in dogs receiving this class of drugs, even in dogs without a history of seizures. Use with caution in dogs with a history of seizures or neurologic disorders. The safe use of Credelio in breeding, pregnant or lactating dogs has not been evaluated. The most frequently reported adverse reactions are weight loss, elevated blood urea nitrogen, increased urination, and diarrhea. For full prescribing information see Credelio package insert.