How can you protect your pet from fleas, ticks and other parasites?

Parasites, including ticks, fleas, worms, and more, can wreak havoc on your pet’s health, causing headaches and many problems.

A huge number of parasites can cause illness in pets. Ectoparasites (such as ticks, fleas, mosquitoes, mites, and lice) cause disease from outside the body. Endoparasites, including heartworms, roundworms, hookworms, tapeworms, and coccidia, cause internal diseases.

The specific parasites your pet is most likely to contract depends on the region of the world where you live, your pet’s age, and your lifestyle. For example, heartworm infestations are more common in the southern United States, and intestinal worms are more common in puppies and kittens than in adults. If your dog runs on trails, he is more likely to be exposed to ticks.

It is important to protect your pet because parasites can make them sick, as well as you or your family.

Ectoparasites cause skin irritation, and some (such as ticks, fleas, and lice) feed on your pet’s blood, which can cause anemia and lethargy. Ectoparasites also carry pathogens that can cause life-threatening diseases, such as ehrlichiosis in dogs and cytauxzoonosis in cats. Additionally, they can transmit endoparasites, such as mosquito-borne heartworms and flea-borne tapeworms.

Some ectoparasites, such as scabies mites, also bite humans and cause itchy rashes. Additionally, ticks and fleas that pets bring home can transmit infectious diseases to humans.

This includes cat scratch disease, caused by Bartonella bacteria, which is transmitted by fleas. Cats (especially young ones) can have large amounts of this bacteria in their blood without showing symptoms. Fleas that feed on Bartonella -the infected cats—shed the bacteria in their feces. The disease is called cat scratch disease because cats can introduce contaminated feces into the skin by scratching.

When Bartonella spreads to the body, most infected people develop swollen lymph nodes near the site of the scratch, but in immunocompromised people, Bartonella can cause life-threatening diseases of the heart, eyes, spleen, and liver.

Among endoparasites, perhaps the most dangerous are hookworms (which attach to the pet’s intestinal lining and feed on its blood) and heartworms (which cause heart and pulmonary artery disease). In addition to being unpleasant, roundworms and tapeworms are common causes of diarrhea and stunt growth in puppies and kittens.

Worms in your pet’s feces can also cause illness in humans. Hookworms can migrate through the skin, causing a skin rash called cutaneous larva migrans (known for the unsightly rashes on the buttocks of people who sit on beaches contaminated with dog feces in the Caribbean). Children who play in sandboxes contaminated with feces can accidentally ingest intestinal worms, which can migrate to the eye and cause blindness (ocular larva migrans). Although rare, inadvertent ingestion of Echinococcus tapeworm eggs can cause life-threatening cystic liver disease.

Fortunately, all of these diseases can be avoided by using the right pet parasite preventive products.

How to prevent parasites?

Globally, pet parasite prevention products (known as parasiticides) represent a multi-billion dollar market. Competition among veterinary pharmaceutical companies has driven the development of highly effective, safe and practical products.

Choosing the right one for your pet can be complicated, so it’s best to talk to your veterinarian about it. This is because:

The products are available in different formulations. These include topical treatments (also known as spot treatments), chewables, injectables, and collars.

Some products are long-acting (can be administered monthly or every three months) and even ultra-long-acting (can be administered annually).

Products vary in their ability to protect against parasites and diseases. There are preventatives that work against fleas but not ticks, as well as combination products designed to prevent fleas, ticks, heartworms, and intestinal worms.

Some products are labeled for prevention of the American dog tick but not against the lone star tick (Amblyomma), or they must be given more frequently to prevent the Amblyomma tick. Some products must be ingested by ticks and fleas to be effective, while others repel ticks and prevent their bites altogether. Many products now contain compounds known as isoxazolines (fluralaner, lotilaner, sarolaner, afoxolaner), which are very effective against fleas, ticks and mites, acting within eight hours.

Products that repel ectoparasites are needed in regions where parasites can transmit pathogens within eight hours.

However, resistance to parasiticides has been detected in fleas, brown dog ticks, heartworms, hookworms and tapeworms, so a one-size-fits-all approach may not be the most appropriate.

The emergence of resistant parasites is a major concern that has led to the development of risk-based guidelines for the use of parasiticides in pets by groups such as the European Scientific Council on Pet Parasites and the Canadian Expert Panel on Parasitology.

Are preventive products safe?

Most products are very safe if used according to label directions. However, many products containing pyrethroids (including flea and tick products sold in pet stores) are toxic to cats; so much so that using them even on a dog that lives with a cat can make it sick.

There are also concerns about the environmental safety of pet parasiticides. Products containing imidacloprid and fipronil are of particular concern as they persist in the environment for long periods.

In addition to being present in pet products, both have been widely used in agriculture to prevent crop damage. Due to the negative effects of imidacloprid on bees, its use in extensive crops has been banned by the European Union. When pets treated with topical parasiticides or antiparasitic collars bathe, or when they swim in lakes and rivers, the parasiticides can contaminate the environment and cause toxicity in aquatic insects and fish. Researchers have also expressed concern about the reproductive effects of birds incorporating contaminated pet hair into their nests.

The relative contribution of pet parasiticide use to environmental pollution versus their use in agriculture remains a topic of heated debate, but if your pet swims, it is probably best to avoid using topical products that are known to be toxic to aquatic animals.

General advice for the safe and responsible use of parasiticides:

• Use products only for the animal for which they are intended. Never use a dog product on a cat. Unless directed by your veterinarian, avoid using products containing pyrethroids on dogs if you have cats at home.
• Read and follow the instructions on the product label carefully.
• Consult with your veterinarian about treatment options to minimize environmental risks, including the best product if your pet swims or bathes frequently.
• Return unused parasiticides to your veterinarian for proper disposal.
• Combine dewormers with measures to reduce parasites in the environment. Remove weeds and tall grass (ticks), reduce standing water (mosquitoes), and pick up your pet’s feces, preventing your dog from ingesting it (worms).