A survey of anthelmintic use and internal parasite control in farmed deer in New Zealand

AIM: To survey parasite control programmes and anthelmintic usage over a 12-month period on deer farms in New Zealand. METHODS: A questionnaire of general farm data, policy and procedures for anthelmintic use, anthelmintic programmes for weaner and older deer, general information and understanding of parasite management practices was posted to 500 deer farmers in November 2004. RESULTS: Two hundred and twenty-seven (45.4%) replies were received, and 198 (39.6%) were suitable for analysis. Ninety four percent of respondents used anthelmintics at least once in the 12-month period; 53% treated all classes of deer and 22% treated only weaners. Seventy-four percent based anthelmintic dose on weight of the heaviest animal, and 36% used a weigh scale. Weaner deer (n=175 farms) were treated 1-13 (mean 3.2) times in their first 12 months, at the earliest commencing in January and at the latest in November. The mean interval between treatments ranged from 41 to 46 days. Yearling and adult hinds and stags were treated at least once (range 1-7 times) on 55-64% of farms, depending on class of animal. Moxidectin was the anthelmintic most commonly used (46-58%, depending on class of animal), followed by abamectin, eprinomectin, oxfendazole, ivermectin, albendazole, levamisole and doramectin. Perceived efficacy was the most common reason for choosing a type of anthelmintic. Weight gain and body condition were the most common measures used for monitoring parasitism in weaners and older deer, respectively, and few respondents used faecal egg and/or larval counts. Coughing and/or scouring were associated with parasitism in weaners on 13-14% of farms, and deaths associated with lungworm and gastrointestinal parasites were recorded on 5% and 3% of farms, respectively. Veterinary input to diagnosis was involved in 23% of events. Production losses and/or death of yearling and/or adult deer due to parasitism were reported by 27% of respondents. When planning anthelmintic treatment programmes, 63% of respondents followed advice from veterinarians. Thirty four percent always placed deer on clean or spelled pastures after treatment, while 32% did that often. Fifteen percent had incorporated forages and/or herbs with assumed anthelmintic properties into their parasite control programme. Forty-four percent were very confident of a return on investment when using anthelmintics for their deer. Respondents stated that their knowledge of the life cycle of the major parasites of deer was very good (8%), reasonably good (61%), poor (28%), or nil (3%). CONCLUSION: Anthelmintics are used on almost all deer farms, and practices and programmes vary considerably. Opportunities exist for veterinarians to assist deer farmer clients to improve their parasite control programmes.