Heartgard Plus Chewables for Dogs 51-100 lbs (23-45 kg)

Description

Heartgard Plus Chewables for Dogs 51-100 lbs (23-45 kg) contain ivermectin at 272 mcg and pyrantel at 227 mg per brown-coded chewable, formulated for monthly oral administration in large-breed dogs. Approved by FDA under NADA #140-971 and manufactured by Boehringer Ingelheim Animal Health USA Inc., this variant addresses heartworm larval prevention alongside treatment and control of five intestinal nematode species in a single monthly dose. Dogs weighing between 51 and 100 lbs receive one brown-coded chewable every 30 days; dogs exceeding 100 lbs require a combination of tablets from lower weight-band variants to achieve the correct per-kilogram dose.

Recommended for

Dogs weighing 51 to 100 lbs (23 to 45 kg), from 6 weeks of age.

Indication/Coverage

For dogs suffering from, or at risk from, mixed parasitic infections, Heartgard Plus Chewables (51-100 lbs) address the following labeled indications:

• Heartworm prevention (Dirofilaria immitis, L3/L4 larvae): Ivermectin at 6 mcg/kg eliminates tissue-stage larvae within the 30-day window following mosquito-transmitted infection, blocking progression to the adult worm stage.
• Roundworm treatment and control (Toxocara canis, Toxascaris leonina, adults): Pyrantel pamoate induces neuromuscular paralysis in both roundworm species through acetylcholine-mediated depolarising blockade, causing expulsion from the gastrointestinal tract.
• Hookworm treatment and control (Ancylostoma caninum, Uncinaria stenocephala, Ancylostoma braziliense, adults): Pyrantel pamoate eliminates all three hookworm species through the same depolarising neuromuscular blockade, covering the primary hookworm ( caninum), the northern hookworm (U. stenocephala), and the subtropical species (A. braziliense).

Key Benefits

The following attributes are specific to the 51-100 lbs variant and reflect labeled data from Boehringer Ingelheim’s clinical and safety studies:

• Large-breed suitability. A single brown-coded chewable delivers the full labeled dose for dogs from 51 lbs up to and including 100 lbs, eliminating the calculation complexity of multi-tablet combinations required above this weight band.
• Labeled from 6 weeks. The safety profile supports use in large-breed puppies from 6 weeks of age, including breeds such as Labrador Retrievers and German Shepherds that reach 51 lbs well before reaching skeletal maturity.
• Dual pharmacological mechanism. Ivermectin potentiates glutamate-gated chloride channels to paralyse and clear immitis larvae, while pyrantel pamoate acts as a depolarising neuromuscular blocking agent against adult intestinal nematodes through a separate receptor pathway.
• 30-day retroactive larval clearance. Each dose eliminates heartworm larvae acquired up to 30 days prior, providing a backward-acting coverage window that accommodates minor delays in administration without leaving a gap in protection.
• Six-parasite coverage per dose. One chewable addresses heartworm, two roundworm species, and three hookworm species, removing the need for a separate intestinal worming product in dogs maintained on this monthly regimen.
• Oral format for handling-resistant large dogs. Large dogs that resist physical restraint for spot-on application accept the beef-flavored chewable at first offering in the majority of cases; the oral route removes the coat-parting and skin-contact requirements of topical administration.
• Established safety in breeding animals. Boehringer Ingelheim’s clinical trials confirmed no adverse effects in pregnant bitches, stud dogs used for breeding, and puppies aged 6 weeks and older at the labeled 6 mcg/kg ivermectin dose, including large breeds.
• 10x safety margin in sensitive breeds. Heartgard Plus demonstrated no signs of toxicity at 60 mcg/kg in Collie-breed dogs, establishing a safety margin more than ten times the recommended dose for even the most ivermectin-sensitive individuals within this weight band.

Caution

Hazards to Humans

Keep Heartgard Plus Chewables out of reach of children at all times and away from food storage or preparation areas. Accidental ingestion by a person requires immediate contact with a physician; a Poison Control Center can advise the treating physician on management. Wash hands after handling the chewable.

Hazards to Domestic Animals

Heartgard Plus Chewables (51-100 lbs) are for oral administration in dogs aged 6 weeks and older, weighing between 51 and 100 lbs (23 to 45 kg). Dogs with a confirmed or suspected existing heartworm infection must undergo adulticide treatment to eliminate adult D. immitis and microfilariae before starting this preventive, as the labeled ivermectin dose does not act against adult worms. Consult a veterinarian prior to use in debilitated, aged, pregnant, or nursing dogs. Dogs with a confirmed or suspected MDR1 (ABCB1) gene mutation, including Collies and related herding breeds, should not receive this product without prior veterinary assessment.

Possible Side Effects

Monitor your dog for at least several minutes immediately after administration and remain observant during the 24 hours following each monthly dose, particularly after the first treatment.

Based on FDA/CVM post-approval adverse drug experience reporting, the following reactions have been documented in decreasing order of reporting frequency:

• Vomiting: The most frequently reported post-approval adverse event; clinical field trials recorded vomiting within 24 hours in 1.1% of administered doses, with higher frequency captured in real-world post-approval data.
• Diarrhea: Reported alongside vomiting as a primary gastrointestinal sign; a transient hypersensitivity-type diarrhea has been observed specifically in dogs carrying circulating microfilariae, attributed to immune response to dying larvae rather than direct drug toxicity.
• Lethargy and anorexia: Reduced activity and appetite suppression have been recorded in post-approval submissions; signs that persist beyond 48 hours or worsen over time require veterinary evaluation.
• Neurological signs: Seizures, ataxia, and muscle tremors appear in post-approval reports at lower frequency. Large herding breeds with MDR1 mutations carry elevated susceptibility; any dog with a prior seizure history should not receive this product without veterinary clearance.
• Hypersalivation and pruritus: Excessive salivation and skin itching have been noted at lower reporting frequency and are generally self-limiting.
• Choking and intestinal obstruction: Obstruction cases have been reported following whole-tablet ingestion without adequate chewing. Large dogs that swallow treats rapidly should receive the chewable broken into pieces before administration.

Contact a veterinarian if any of these signs develop or recur.