Efficacy of anthelmintics on South American camelid (llama and alpaca) farms in Georgia

The number of South American camelid (SAC; llama and alpaca) farms is growing in the southeastern United States, and infection with gastrointestinal nematodes (GIN) is a major health concern in this region. There is widespread resistance to anthelmintic remedies in small ruminants (sheep and goats), but a paucity of information on llamas and alpacas. Anthelmintic resistance was evaluated on three SAC farms (two llama; one alpaca) in Georgia in the southern United States using fecal egg count reduction (FECR) tests. For each farm, animals were randomly assigned to 1 of 5 treatment groups based on initial fecal egg count (FEC) and number of animals available (2–5 groups, n = 9–11 per treatment). Ivermectin (IVM, subcutaneous injection; 0.3 mg/kg body weight (BW)) and a control group were tested on an alpaca farm, and fenbendazole (FBZ, oral; 10 mg/kg BW; two farms), moxidectin (MOX oral; 0.2 mg/kg BW; two farms), and levamisole (LEV, oral; 8 mg/kg BW; one farm) were added for the llama farms. Anthelmintic efficacy was determined by comparing FEC of treatment and control animals 14 days post-treatment, with resistance evaluated using the World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines. Based upon these guidelines, there was GIN resistance to IVM in both llamas and alpacas in Georgia and to FBZ on both llama farms where this drug was tested. There was MOX resistance on one llama farm using the FECR test, while there was no resistance to LEV detected in this study. These data demonstrate a serious emerging problem in the United States of llama and alpaca GIN resistant to drugs from two of the three major anthelmintic classes.