Multi-Duo Plus Main Uses
Comprehensive Internal and External Parasite Control: Multi-Duo is a prescription bundle for dogs only that combines Advantage Multi and K9 Advantix II into a single purchase, covering both internal and external parasites with a monthly alternating topical schedule.
Advantage Multi Component — applied once monthly:
Prevention of heartworm disease (Dirofilaria immitis)
Treatment of flea infestations (Ctenocephalides felis)
Treatment and control of the adult stage of fox lungworm (Crenosoma vulpis), the treatment and control of parasitic infestations caused by the adult stage of the common flea (Ctenocephalides felis), ear mites (Otodectes cynotis), sarcoptic mange mites (Sarcoptes scabiei var. canis), and as an aid in the treatment and control of generalized demodectic mange (Demodex canis).
K9 Advantix II Component — applied once monthly:
Treatment and prevention of fleas (all life stages including eggs and larvae)
Control of ticks (Ixodes scapularis, Dermacentor variabilis, Amblyomma americanum, Rhipicephalus sanguineus), chewing lice, and mosquitoes
Repels biting flies and stable flies
 
Multi-Duo Plus Active Ingredients
Imidacloprid (Advantage Multi; K9 Advantix II): A neonicotinoid insecticide that targets nicotinic acetylcholine receptors in the insect nervous system, causing paralysis and death of adult fleas and lice on contact, with no bite required.
Moxidectin (Advantage Multi): A macrocyclic lactone endectocide absorbed systemically through the skin. Disrupts chloride channel neurotransmission in internal parasites, eliminating heartworm larvae, roundworms, hookworms, and whipworms.
Permethrin (K9 Advantix II) and Pyriproxyfen (K9 Advantix II): Permethrin is a pyrethroid insecticide with both contact-kill and repellent activity against ticks, mosquitoes, and flies. Pyriproxyfen is a juvenile hormone analogue that disrupts flea egg and larval development, breaking the flea life cycle. Permethrin is highly toxic to cats.
Action Mechanism: The two products alternate monthly. Advantage Multi delivers systemic internal parasite and flea coverage; K9 Advantix II delivers surface-active external pest protection and repellency.
 
Multi-Duo Plus Dosage & Administration
Bundle contents (by dog weight):
Green: up to 4.5 kg — Advantage Multi 10 (6 × 0.4 mL tubes) + K9 Advantix II Small (2 box of 4 tubes each)
Aqua: 4.6 to 9 kg — Advantage Multi 20 (6 × 1.0 mL tubes) + K9 Advantix II Medium (2 box of 4 tubes each)
Red: 9.1 to 25 kg — Advantage Multi 55 (6 × 2.5 mL tubes) + K9 Advantix II Large (2 box of 4 tubes each)
Blue: 25.1 to 45 kg — Advantage Multi 100 (6 × 4.0 mL tubes) + K9 Advantix II Extra Large (2 box of 4 tubes each)
Application frequency: One product applied once monthly, alternating between Advantage Multi and K9 Advantix II each month as directed by your veterinarian.
Application method:
Part the coat until skin is visible at the back of the neck
Apply the entire tube contents directly to exposed skin
Do not apply to fur. Dog should be standing during application.
Bathing and water exposure:
Advantage Multi: water exposure (swimming, rain) beginning 60 minutes after treatment, or shampooing/bathing 90 minutes after treatment, does not reduce heartworm prevention efficacy
K9 Advantix II: do not bathe or allow water exposure for 3 days after application. Duration of protection may be shortened by shampooing, water immersion, or exposure to rain
 
Multi-Duo Plus Safety & Side Effects
Common side effects (Advantage Multi): Transient skin reactions at the application site (redness, oiliness, hair clumping). Rarely, lethargy or vomiting if accidentally ingested.
Common side effects (K9 Advantix II): Mild, temporary skin irritation at the application site. Rarely, localised hair loss or scratching.
Critical warning — cats: Permethrin in K9 Advantix II is highly toxic to cats and can be fatal. Do not apply to cats. Cats in the same household must be separated from treated dogs for at least 48 hours after K9 Advantix II application.
MDR1/ABCB1 gene mutation: Use Advantage Multi with caution in dogs with MDR1 mutation. These dogs are more sensitive to avermectins and may develop severe toxicity if they ingest this product, including depression, salivation, dilated pupils, incoordination, generalized muscle tremors, coma, or death. The most common breeds with this mutation include Collies and Collie crosses.
Concurrent products: Do not apply other pesticide products containing imidacloprid, permethrin, or pyriproxyfen alongside K9 Advantix II.
Breeding, pregnant, or nursing animals: Consult a veterinarian before use.
For dog use only. Keep out of reach of children. Wash hands after application.
 
Multi-Duo Plus Manufacturer Information
Manufacturer: Elanco Canada Limited
Official Website: https://www.elanco.com/en-ca
Brand Introduction: Elanco Canada Limited is a global leader in animal health with a strong Canadian presence. Multi-Duo is an Elanco-bundled prescription product combining Advantage Multi and K9 Advantix II for Canadian dog owners seeking comprehensive year-round parasite protection under veterinary supervision.