13 - Antiparasitic Drugs

Abstract

•When considering choice of antiparasitic drugs, consultation of product labels, package inserts, regulatory documents, and current literature will provide the most up-to-date information regarding product availability and indications.•Use of an approved product for the relevant host and parasite should be considered as the first-line treatment if available.•Treatment for some parasitic infections, especially those caused by trematode and protozoan parasites, often requires the extra-label use of an approved drug or the use of a drug not approved for use in dogs and/or cats.•Appropriate drug selection is only one component of treating parasitism. Use of a multimodal approach with multiple therapeutics that have unique mechanisms of action or alterations of the environment or host behavior is often necessary to appropriately break the life cycle and prevent a reinfection or reinfestation.•Treatment failure is often due to one or many of a myriad of factors including but not limited to: inadequate dosage, improper storage, abbreviated duration, failure to control reinfection/reinfestation, lack of understanding of the life cycle, poor client compliance/adherence, or parasite resistance. Although resistance has been documented in the United States for a few parasites of dogs and/or cats, treatment failure secondary to any of the other listed reasons is still far more common.