Despite the widespread availability of safe and effective treatments, internal and external parasites remain common in dogs, particularly in those who do not receive routine veterinary care.65,66 Year-round, broad-spectrum control products with efficacy against heartworm, intestinal parasites, fleas, and ticks prevent disease in dogs by preventing the most common internal and external parasites.67 Regular treatment for parasites also decreases environmental contamination with infective stages, thereby reducing transmission and possible zoonotic exposure (Canine Life Stage Checklists). Treating for hookworms and ascarids is particularly important in puppies, with deworming beginning as soon as 2 wk of age and repeated every 2 wk until routine monthly treatment is initiated using products with efficacy against intestinal parasites.66,68 Dogs remain susceptible to intestinal helminths throughout their life. These infections can be controlled by continuing monthly deworming year-round for the life of the dog. In addition, starting heartworm preventive in puppies as early as label allows, generally no later than 8 wk of age and 2–3 lb of body weight, and continuing year-round for the life of the dog, protects dogs from this potentially fatal disease.69
Fecal examination for parasites is useful to evaluate compliance with preventive use, monitor product efficacy, and screen for infection with a broad range of internal parasites. Puppies are more likely to harbor parasites and thus benefit from several fecal examinations in the first year of life.66,70 Screening fecal samples for intestinal parasites at least annually is also important in young adult and older dogs, although more frequent testing may be warranted depending on use of preventive and overall risk assessment based on lifestyle.67,70 Annual heartworm testing is also an important part of canine health care. Some studies report that the prevalence of canine heartworm infection in the southeastern United States has increased ~20% in recent years.71,72 Heartworm testing beginning at 7–12 mo of age allows early detection and treatment. Heartworm testing is particularly important for young adult dogs for which prevention was delayed and for recently acquired adult dogs with an unknown history of preventive use.67,72
Consistent administration of ectoparasite control products is important for dogs throughout the different life stages. Although the risk of fleas and ticks is not uniform across all geographic areas and lifestyles, preventives should be in place to protect canine health and limit home infestations and subsequent zoonotic risk.67 In the past two decades, ticks and the diseases they transmit have increased in number and intensity in North America, and several tick species have expanded geographically.73–75 Practices should become knowledgeable of the specific risks in their area. Canine infection with some tick-borne disease agents, as evidenced by national antibody prevalence surveys, has increased 41–167%.29 Disease, at times severe, has been associated with infection or coinfection with tick-borne pathogens.76,77 Tick control products have been shown to limit transmission of several disease agents in both experimental and natural settings.76–81 For these reasons, the Companion Animal Parasite Council recommends that all dogs be maintained year-round on broad-spectrum flea and tick control products, and that dogs be tested annually for infection with tick-borne pathogens.67 The AAHA-AVMA Preventive Healthcare Guidelines acknowledge the appropriate use of tick control protocols based on individual patient risk assessment.82
The 2019 AAHA Canine Life Stage Guidelines are supported by generous educational grants from Boehringer Ingelheim Animal Health USA Inc., CareCredit, Elanco Animal Health, Hill’s ® Pet Nutrition, Inc., IDEXX Laboratories, Inc., Merck Animal Health and Zoetis Petcare.