NexGard is a prescription medication used for the treatment and prevention of flea and tick infestations in dogs. It contains the active ingredient afoxolaner, which belongs to a class of drugs called isoxazolines. Afoxolaner works by interfering with the nervous system of fleas and ticks, causing paralysis and ultimately death.
 
NexGard is available in chewable tablet form and is administered orally to dogs. It is important to follow the dosing instructions provided by a veterinarian and to use caution when administering NexGard to dogs with a history of seizures or other neurological disorders. Possible side effects of NexGard include vomiting, diarrhea, lethargy, and loss of appetite.