Heart Shield Plus® for Dogs (Ivermectin/Pyrantel)

Heart Shield Plus® flavored chewables for dogs is a high quality, cost-effective solution to the year-round threat of heartworms, roundworms and hookworms.

Just one highly effective Heart Shield Plus® flavored chewable given monthly is guaranteed to protect your dog against heartworm disease and treat and control common zoonotic roundworms and hookworms. And it contains the veterinarian preferred medicine for heartworm prevention — ivermectin/pyrantel.

  • For heartworm prevention in dogs
  • For treatment and control of roundworms and hookworms
  • Easy to give – dogs love the flavored chewable
  • Safe to treat dogs, even puppies as young as six weeks and pregnant or nursing dogs



It is called heartworm because the parasites cripple the heart until it cannot function. Death can result without warning as symptoms do not show up until the later stages of the disease. It takes about seven months, once a dog is bitten by an infected mosquito, for the larvae to mature into adult heartworms. They then lodge in the heart, lungs and surrounding blood vessels, begin reproducing and move to other parts of the body. Over time, these organs will stop working, causing intense pain for your dog and, if not treated, will lead to death.

Heartworm disease is transmitted by the bite of a mosquito that is carrying the infective stage of the parasite. In the United States, heartworm prevalence is highest along the southeastern Atlantic and Gulf Coasts, but it has been found in all 50 states. Adult worms can grow up to 12 inches in length, can live 5-7 years, and a dog can have as many as 250 worms in its system. If you live in an area with mosquitoes, it is important that you consider heartworm prevention medication for your dog along with regular checkups by your veterinarian.

Heartworm disease can be challenging and expensive to treat, but is easily prevented. Heartworm treatment is usually long and tedious with no assurance that the dog will completely recover from the disease if it has digressed too far. Your best chance of detecting this disease early is regular checkups by your veterinarian. You can easily prevent the disease by giving your dog the correct monthly dosage of Heart Shield®  Plus flavored chewables year-round.


Heart Shield Plus® flavored chewables are an effective and easy to administer product. Just one flavored chewable tablet administered on the same day each month is all your dog needs to remain protected from heartworm, roundworm and hookworm infections.



Ivermectin is a broad-spectrum antiparasitic which kills microfilariae (larval heartworms), but not adult worms. It requires a prescription from your veterinarian who first must determine that your dog does not already have the disease before administering the preventive. If worms have already infected your dog, another form of treatment should be prescribed.


Pyrantel Pamoate is used as a deworming agent in the treatment of hookworms and roundworms. It acts as a depolarizing neuromuscular blocking agent which causes the worm to “lose its grip” on the intestinal wall and be eliminated through your pet’s feces.


Prevention is always easier, safer and less expensive than treating a disease once it’s become established in your pet. Use Heart Shield Plus® flavored chewables monthly to prevent heartworm, hookworm and roundworm in your dog.



Understanding the worm’s life cycle will help you understand why it is wiser to prevent a heartworm infection than wait and treat the disease once the worms have matured and settled in the heart and lungs.

The heartworm goes through a total of four molts to mature into an adult worm. The first two occur inside the mosquito and the next two occur inside the final host. Heartworm disease begins with an infected animal that has circulating microfilariae in its blood. As the mosquito stops by for a meal it also sucks up a number of circulating microfilariae in the blood. Once inside the mosquito’s body, the microfilariae go through two molts over 14 days or longer depending on the environment’s temperature. They go through their first two molts and change from an L1 to an L2 and then an L2 to an L3 (third stage of development of the larva). At the L3 stage, they are able to migrate into the mosquito’s salivary glands, which enables them to enter into your pet though a mosquito’s small bite wound. Once inside your pet, the heartworm takes at least 6 to 7 months to go through the last two molts and to become sexually mature before the infection can be detected by a heartworm test.

The L3 larva goes through its first molt to the L4 within the first 15 days and as early as 2-5 days after infection. The second molt from the L4 to the L5 occurs within the next 2 months. The L5 larva is considered a juvenile adult and works its way through the host’s tissues all the way to the heart as early as 70 days after first entering the host. The majority of L5 heartworm larvae arrive in the heart by 90 days, where they stay and grow rapidly in length and size. It will continue to live in the heart until it dies, typically between 5-7 years.

Monthly heartworm preventatives work by interfering with the maturation of the immature (larval) heartworm into an adult. The ivermectin in Heart Shield Plus flavored chewables, given every 30 days, has a retroactive effect and kills larvae at the L3 and L4 stages that have invaded the dog in the preceding month.


Roundworms and hookworms are common intestinal parasite diseases that can be transmitted between animals and humans. Humans can ingest infected worm eggs that have been passed through the pet’s feces and into the environment. The eggs hatch in the human intestinal tract, and the immature worms travel to various tissues in the body, including the eyes and brain, causing serious reactions.

Walking barefoot on the beach or other areas where pets deposit feces gives hookworms an opportunity to penetrate the skin.


Heartworm symptoms do not show up until the disease has progressed significantly, so it is important to have your dog checked regularly. The most notable symptom of heartworm in dogs is coughing. Dogs with heartworm have a soft, dry cough due to the parasites finding their way toward the lungs. The lungs get irritated as heartworms multiply in and around the area. Dogs suffering from heartworm tend to be tire easily and avoid exercise. As the disease progresses, dogs lose weight, breathe more rapidly and may cough after exercise to the point of fainting. The ribs become prominent and the chest starts to bulge. Your veterinarian can tell if your dog is infected by heartworm through a simple blood test. The earlier a diagnosis is made and treatment is begun, the better the chances your pet will recover.

Signs of roundworm infection are: weight loss, dull hair, and a potbellied appearance. A cough may mean the roundworms have moved into the lungs. Adult roundworms may be seen in your dog’s feces or vomit. Roundworms are white or light brown in color and may be several inches long.

Hookworms suck blood, causing internal blood loss. This is a serious threat to dogs, especially young puppies that may not survive the blood loss without transfusions. In older animals the blood loss may be more chronic, and the pet may have diarrhea and show weight loss.


Most veterinarians and the American Heartworm Society recommend treating your dog each month year-round. By not following this advice, you could put your pet at risk for developing heartworm, roundworm, and hookworm infections. Left untreated, heartworms infect the right side of the heart and the major vessels that distribute blood to and from the lungs, causing inflammation and interfering with blood flow. This leads to clots in the lung (pulmonary thromboembolisms) and congestive heart failure. Liver or kidney failure can also result. Death can be caused by one or a combination of these problems.

To best protect yourself and your family, your pets should be given the correct dosage of Heart Shield Plus® flavored chewables monthly all year-round. See why Heart Shield Plus® is the best choice for your dog.

Why Choose Heart Shield Plus®?

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