Pets can get external parasites like fleas and ticks, and internal ones like heartworms and tapeworms. Watch for signs like itching or weight loss, and see your vet promptly - most parasites are treatable. Monthly preventatives and de-wormers provide relief and combat parasites.

As a veterinarian, I emphasize the importance of preventative veterinary care, which includes parasite prevention. Our furry friends are susceptible to a variety of uninvited guests: parasites.

These internal and external organisms live off their hosts, causing a range of problems, from itchy skin to serious digestive issues.

I also warn pet parents that some parasites can jump species, which means they can be transmitted from pets to humans. This makes preventative care essential to safeguard both your pet's health and your own.

Let’s explore the parasites that most often impact dogs and cats and the preventative treatments available to prevent them.

Flea Prevention

Fleas are external parasites that are small and wingless and feed on cats, dogs, and other mammals and birds, often blending into their fur due to their dark color. 

Prevention and treatment options for fleas include:

  • Topical liquid preventatives applied monthly, containing ingredients like imidacloprid and fipronil, which are effective against fleas and ticks.

  • Oral medications taken monthly to every three months, containing ingredients such as lufenuron, spinosad, afoxolaner, or fluralaner for flea prevention

  • Flea collars

  • Flea shampoos and dips, although these only provide temporary relief

Infographic showing the difference between fleas and ticks.

Tick Prevention

Like fleas, ticks are external parasites, and enlarge when feeding on the blood of our pets

Preventatives for ticks include:

  • Topical liquid preventatives containing ingredients like fipronil and imidacloprid

  • Oral medications such as fluralaner, afoxolaner, and sarolaner

  • Tick collars like Seresto, which contains imidacloprid and flumethrin

An infographic about where to check your pet for ticks, the common body parts a tick can be found.

Hookworm Prevention

Hookworms are internal parasites, typically measuring 0.5 to 1.5 centimeters in length. Dog hookworms, known as Ancylostoma caninum, and cat hookworms, Ancylostoma tubaeforme, are the most common species. 

Treatment for hookworms include:

  • Regular dewormings and/or fecal testing

  • Monthly preventatives

  • Active ingredients found in dewormers such as Milbemycin oxime, Moxidectin, Emodepside, Pyrantal Pamoate, Fenbendazole, Ivermectin, and Selamectin

Whipworm Prevention

Named for their whip-like appearance, whipworms are an internal parasite that reside in the cecum and colon of dogs and cats. Dogs are typically affected by Trichuris vulpis, while cats may be affected by Trichuris felis (T. Campanula).

Medication and treatment options for whipworms include: 

  • Regular deworming and fecal testing

  • Monthly preventatives

  • Minimizing exposure to contaminated environments

  • Medications with active ingredients such as Fenbendazole, praziquantel/pyrantal pamoate, Milbemycin, and moxidectin.

Tapeworm Prevention

Several species of tapeworms affect dogs and cats, including Dipylidium caninum (most common), Taenia, and Echinococcus. They primarily reside in the intestinal tract and have a life cycle that often involves an intermediate host, such as fleas, lice, or rodents, as well as the definitive host.

 Prevention and treatment methods for tapeworms include: 

  • Medications such as praziquantel, epsiprantel, and fenbendazole

  • Flea prevention strategies

Roundworm Prevention

Roundworms, also known as Ascarids, are the most common intestinal parasites found in pets. Dog roundworms are classified as Toxocara canis, while cat roundworms are Toxocara cati.

Prevention and treatment methods for roundworms include: 

  • Regular deworming and fecal testing

  • Monthly preventatives

  • Medications containing active ingredients such as pyrantel pamoate, fenbendazole, Milbemycin oxime, Moxidectin, Selamectin, Emodepside, and Eprinomectin.

Heartworm Prevention

Heartworms in pets are internal parasites transmitted through mosquito bites, making them prevalent worldwide in regions with suitable mosquito habitats and temperatures that permit the development of larvae within mosquitoes.

🐱 Heartworm Prevention for Cats

🐶 Heartworm Prevention for Dogs

Medication and treatment strategies for heartworms include:

  • Monthly preventatives administered orally, topically, or as injectables. These preventatives typically contain macrocyclic lactones such as ivermectin, milbemycin oxime, selamectin, doramectin, and moxidectin. 

  • These are often combined with other medications to protect against fleas, ticks, intestinal internal parasites

Test Your Knowledge of Heartworm

Test Your Knowledge of Heartworm
1. Dogs can get heartworms from other animals
2. Once dogs are treated for heartworm, they become immune to future infections
3. Heartworm disease is only a problem in some states
4. Heartworms can only live inside a pet for 6 months
5. Heartworm disease can be deadly
6. My cat cannot get heartworm disease
7. My pet only needs heartworm preventative in the spring and summer months
8. I don’t need a prescription for my dog’s heartworm prevention
9. My pet does not need an annual heartworm test if they receive heartworm prevention
10. Heartworm treatment costs about the same as prevention

Your Score is

1. Dogs can get heartworms from other animals | FALSE

Heartworms can only be transmitted to your pet by infected mosquitoes. Mosquitoes carry heartworm larvae that they have picked up from infected animals. The larvae develop in the mosquito, which can then be passed on to dogs and cats when bitten by the infected mosquito. 

When a pet is bitten, the heartworm larvae are transferred onto their cat or dog’s skin, entering the bloodstream and migrating to the heart and lungs. It takes approximately six months for larval worms to migrate, mature, and reproduce.
2. Once dogs are treated for heartworm, they become immune to future infections | FALSE
Unfortunately, dogs can be infected with heartworm multiple times.
3. Heartworm disease is only a problem in some states | FALSE
Heartworm disease has been detected in all 50 states.
4. Heartworms can only live inside a pet for 6 months | FALSE
Heartworms can live in dogs for up to seven years and cats for up to three years.
5. Heartworm disease can be deadly | TRUE
Once heartworm larvae enter a pet’s bloodstream, they reproduce rapidly, with multiple generations affecting the lungs and heart. Heartworm causes severe inflammation, which a pet’s immune system will try to fight off.  Heartworms also prevent normal blood flow, which leads to congestive heart failure. Without treatment, heartworm disease will worsen and become deadly.
6. My cat cannot get heartworm disease | FALSE
While heartworms are most common in dogs, cats can also be infected. If an infected mosquito bites a cat, heartworms can survive in their system, but not reproduce. Unfortunately, even a few worms can cause significant inflammation in a cat and there is no approved medication to kill adult heartworms in cats. Heartworm-related health problems for cats include respiratory disease (HARD) with asthma-like symptoms that can become life-threatening.
7. My pet only needs heartworm preventative in the spring and summer months | FALSE
The American Heartworm Society recommends year-round treatment for heartworm for dogs and cats. Options that your veterinarian may recommend include monthly chewables, injections or topicals.
8. I don’t need a prescription for my dog’s heartworm prevention | FALSE
The U.S. Food and Drug Administration (FDA) states that any heartworm medication is to be prescribed on the order of a licensed veterinarian. Your veterinarian will prescribe a heartworm preventative that is recommended for your pet’s species, weight, and lifestyle.
9. My pet does not need an annual heartworm test if they receive heartworm prevention | FALSE
Annual testing is necessary for pets, even when they are on a year-round heartworm prevention protocol, to make sure that the medication is working. Heartworm medications are very effective, but pets can still become infected. If you miss just one dose of a monthly medication—or give it late—it is leaving a window open to infection.
10. Heartworm treatment costs about the same as prevention | FALSE
A year’s worth of prevention is small in comparison to the cost of treatment. Heartworm treatment is available for dogs but is lengthy, expensive, and painful. A medication to kill adult worms must be injected into a dog’s muscles. Several treatments spaced 30 days apart may be needed, as well as with other medications to reduce inflammation and kill bacteria. Treatment usually lasts several months and dogs need to be kept inactive to minimize the risk of dying worms lodging in their lungs which can lead to sudden death.

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Ear Mite Prevention

Ear mites, scientifically known as Otodectes cynotis, are tiny external parasites that commonly infest the ears of dogs and cats. Infestations can also lead to ear discharge, otitis externa, and secondary infections with bacteria and yeast.

 Prevention and treatment options for ear mites:

  • Routine ear cleaning & grooming

  • Avoid contact with infected animals 

  • Treat all animals in the household

  • Solutions containing active ingredients like Milbemycin, Ivermectin, and Fipronil help to eradicate ear mites and alleviate symptoms

Natural Parasite Prevention Remedies

Exploring natural remedies for parasite prevention can be a helpful addition to your pet care routine as they may offer some relief. However, it's important to use them with caution and under the guidance of a veterinarian.

 Here are some natural remedies to consider:

  • Diatomaceous Earth

  • Herbal flea collars or sprays

  • Garlic or brewers yeast 

  • Regular grooming and hygiene practices


Make your pet's health a priority by scheduling regular wellness visits with your veterinarian. These visits aren't just about checkups; they're your pet's best defense against parasites like fleas, ticks, and intestinal worms.

During these appointments, your vet will discuss deworming, screen for parasites, and help you choose the perfect monthly preventatives tailored to your furry friend's needs.

Get Your Pet’s Health Checked Out at Home

Say goodbye to stressful vet visits and hello to a comfortable wellness exam in your pet's favorite spot.

Frequently Asked Questions

What is the safest parasite prevention for dogs and cats?

Several parasite prevention methods are generally considered safe and effective. The safest parasite prevention depends on factors such as lifestyle, age, health status, and risk of exposure to parasites. Consult with your veterinarian to determine the best parasite prevention for your pet

Should I give my dog parasite prevention?

Depending on the potential for exposure to parasites determines the need for prevention. Most dogs will have exposure to parasites within their lifetime from fleas to intestinal parasites.

How do you prevent parasites in dogs?

Regular preventatives (monthly to every 3 months) are the most effective way of preventing parasites in dogs.  Good hygiene and regular grooming are also essential.

What is the monthly worm prevention for dogs?

Several products are available for monthly worm prevention, from milbemycin oxime to moxidectin.  

What do veterinarians recommend for flea and tick control?

Flea preventatives often come in topical or oral treatments given on a monthly to every 3-month basis.  Your veterinarian can help you determine which preventative is the best fit for your pet.

What is the most effective flea and tick prevention?

Topical or oral flea and tick preventatives have proven effective and safe. 

What is the best non-prescription flea and tick treatment?

Non-prescription flea and tick treatments like diatomaceous earth may provide some relief from parasites, but it is important to consult with your veterinarian prior to use.


  1. Boy, M., Six, R. H., Thomas, C., Novotny, M. J., Smothers, C., Rowan, T., & Jernigan, A. (2000). Efficacy and safety of selamectin against fleas and heartworms in dogs and cats presented as veterinary patients in North America. Veterinary Parasitology, 91(3–4), 233–250.

  2. Rohdich, N., Zschiesche, E., Wolf, O. et al. Field effectiveness and safety of fluralaner plus moxidectin (Bravecto® Plus) against ticks and fleas: a European randomized, blinded, multicenter field study in naturally-infested client-owned cats. Parasites Vectors 11, 598 (2018).

  3. Stanneck, D., Kruedewagen, E.M., Fourie, J.J. et al. Efficacy of an imidacloprid/flumethrin collar against fleas, ticks, mites and lice on dogs. Parasites Vectors 5, 102 (2012).