Sentinel Spectrum (milbemycin oxime + lufenuron + praziquantel) Heartworm and Flea Prevention Chewables for Dogs is used to prevent heartworm disease and flea populations, and to treat tapeworm, hookworm, roundworm, and whipworm infections in dogs and puppies. Sentinel Spectrum contains milbemycin oxime, lufenuron, and praziquantel in a palatable formula given once per month. Approved for dogs and puppies at least 2 lbs. and 6 weeks of age. Milbemycin oxime, lufenuron, and praziquantel.