Stronghold For Dogs 85.1-130 lbs (40.1-60 kg)

Description

Stronghold for Dogs 85.1–130 lbs (40.1–60.0 kg) delivers 360 mg selamectin per 3.0 ml tube, manufactured by Zoetis as a topical spot-on solution for large and giant-breed dogs in this upper weight category. Selamectin is an avermectin-class macrocyclic lactone that disrupts chloride channel conductance in invertebrate nerve and muscle cells, producing paralysis and death across a spectrum of external and internal parasites through systemic distribution following transdermal absorption. This variant is approved for dogs from 6 weeks of age weighing between 40.1 and 60.0 kg, with monthly application for flea and heartworm larval prevention alongside single-dose or two-dose treatment protocols for ear mites, roundworms, biting lice, and sarcoptic mange.

Recommended for

Dogs weighing 85.1–130 lbs (40.1–60.0 kg) from 6 weeks of age.

Indication/Coverage

For dogs suffering from, or at risk from, mixed parasitic infections, Stronghold 360 mg addresses the following conditions:

• Flea treatment and prevention (Ctenocephalides spp.): Selamectin kills adult fleas on the dog, stops viable egg production, and destroys environmental larvae; ovicidal activity persists for 3 weeks post-application, severing the flea reproductive cycle at every stage present on the animal and in surrounding accessible areas.
• Heartworm prevention (Dirofilaria immitis, L3/L4 larvae): Each monthly dose eliminates susceptible larval stages acquired during the preceding interval; the product carries no activity against adult heartworms already established in the pulmonary vasculature.
• Ear mite treatment (Otodectes cynotis, adults): A single dose constitutes the full labeled treatment course; loose debris from the external ear canal should be gently cleared at the time of treatment, and a veterinary follow-up at 30 days is recommended as some dogs require a second application.
• Roundworm treatment (Toxocara canis, adults): A single dose clears adult intestinal roundworm burden from the gastrointestinal tract.
• Sarcoptic mange treatment (Sarcoptes scabiei): Complete mite elimination requires one dose on each of two consecutive months; a single dose is insufficient for this indication.
• Biting lice treatment (Trichodectes canis): A single topical application eliminates biting lice infestations in dogs within this weight range.

Key Benefits

The following properties are confirmed by the Stronghold label for the 360 mg dose covering dogs in the 40.1–60.0 kg range.

• Giant-breed dose precision: The 360 mg selamectin dose in a 3.0 ml tube maintains a minimum of 6 mg/kg across the full 40.1–60.0 kg range, sustaining the per-kilogram concentration within the labeled therapeutic window at both weight boundaries.
• Six-indication single tube: Fleas, heartworm larvae, ear mites, roundworms, sarcoptic mange, and biting lice are all addressed through one monthly tube, eliminating the need for combination pipettes within this weight band.
• Environmental flea reach: Debris shed from a selamectin-treated dog kills flea eggs and larvae in surrounding areas not directly exposed to the compound, extending flea population suppression beyond the animal itself into the spaces it regularly occupies.
• Transdermal internal delivery: Selamectin is absorbed through the skin following neck application and reaches maximum plasma concentration within approximately 3 days in dogs, providing heartworm larval and roundworm coverage through a topical route without requiring oral administration.
• Sustained 30-day plasma levels: The terminal elimination half-life of selamectin in dogs is approximately 11 days, maintaining detectable plasma concentrations across the full monthly dosing interval for consistent flea and heartworm larval protection.
• Water exposure tolerance: The Stronghold label confirms that bathing or immersion 2 or more hours after application does not reduce product efficacy, a practical consideration for large and giant-breed dogs that swim or undergo regular professional grooming.
• Pregnancy and lactation clearance: Zoetis administered Stronghold at 3 times the recommended dose to pregnant and lactating females without adverse effects, supporting its use in breeding females within this weight category.
• Established breed safety data: Zoetis safety data confirm no adverse effects at 10 times the recommended dose; field testing covered over 100 pure and mixed dog breeds, with ivermectin-sensitive collies tested separately at 5 times the recommended dose with no adverse effects observed.

Caution

Hazards to Humans

This product is highly flammable; keep it away from heat, open flame, and sparks at all times during handling. Do not smoke, eat, or drink while applying. Wash hands thoroughly with soap and water immediately after use. Flush skin or eye contact with water at once and seek medical attention for any eye exposure. Keep children away from treated dogs for at least 30 minutes or until the coat is fully dry.

Hazards to Domestic Animals

Stronghold 360 mg is for external use in dogs only; do not administer orally or by injection. This variant is not for use in dogs under 6 weeks of age, and the labeled dose covers animals between 40.1 and 60.0 kg only. Do not apply when the coat is wet. Dogs that are debilitated or in poor condition relative to their age and size should not receive this product without prior veterinary assessment. Reversible neurological signs including seizures have been reported on rare occasions with macrocyclic lactone-class products; veterinary clearance is warranted before use in any dog with a known history of neurological sensitivity. No interactions with routinely used veterinary medications or surgical procedures were identified in extensive field trials.

Possible Side Effects:

Monitor your dog after each application, with particular attention to behavior and the application site following the first dose.

Dermal reactions at the treated area are uncommon. Temporary hair clumping or a trace amount of white powder may appear at the application site within the first 24 hours; this is a documented characteristic of the drying solution, resolves without intervention, and does not indicate any compromise to safety or efficacy.

Systemic reactions are exceptional. As a macrocyclic lactone, selamectin carries a documented but very low risk of reversible neurological signs including seizures; this has been recorded only rarely across extensive breed and safety testing. Ivermectin-sensitive collie breeds were included in safety studies at 5 times the recommended dose without adverse neurological findings, though individual sensitivity in any given animal cannot be entirely ruled out.

If persistent dermal changes, altered behavior, or unexpected systemic signs emerge after dosing, discontinue use and consult a veterinarian without delay.