INTOXICATION OF DOMESTIC AND WILD ANIMALS BY ANTICOAGULANT RODENTICIDES — A SYNTHESIS OF DATA FROM THE FRENCH NATIONAL VETERINARY ANTIPOISON CENTER

During the period from 1980 to 1985 the laboratory of toxicological analysis associated with the National Veterinary Antipoison Center received 1,343 samples for research of anticoagulant rodenticide (e.g., 14.1% of total samples): 79% concerned animals, 31% baits. Six compounds marketed in France were investigated (warfarin, chlorophacinone, bromadiolone, difenacoum, coumachlore, coumatetralyl). In two-thirds of the samples, none of these substances could be found. Warfarin was by far the most incriminated rodenticide (23.1%), and dogs represented the most affected species (65.7%). However, its occurrence decreases regularly. The other compounds were found with a very low frequency (1 to 3%). In 70% of the cases, baits were prepared with criminal intention of killing animals other than rodents. INTRODUCTION Rodenticides, mainly anticoagulant compounds, are one of the most common causes of animal intoxication. From the beginning of their use in rodent control, their toxicity to nontarget species, both domestic animals and wildlife, was claimed by some authors (Fabre 1953, Papnorth 1958, Zundel 1960), and some accidental intoxications were recorded (Clark 1954, Reihart 1952). Several epidemiological studies from different countries have attempted to assess their toxicological effects (Buck 1976, Freeman 1972, Lorgue 1983, Rampaud 1982, Rochette 1985, Studdert 1985, Von Kammermann 1978). The French National Veterinary antipoison center has its own laboratory, performing chemical analysis on samples of animals and baits. The aim of this study was to investigate the actual frequency of suspected or proved intoxications by anticoagulant rodenticides during a period of the last 6 years. During this period 9,527 cases or suspicions of animal intoxication, both individual or collective, were submitted to analysis. In 1,343 of them (14.1%) anticoagulant rodenticides were detected. Some preliminary observations have to be made: one case means one or several animals intoxicated. samples were analyzed for the presence of the most common compounds marketed in France (warfarin, chlorophacinone, bromadiolone, difenacoum, coumachlore, coumatetralyl). A negative result means that none of the rodenticides was detectable (above the level of detection), and a positive result that one of them was present in the analyzed sample. Intoxication is not always related to the presence of an anticoagulant compound; thus intoxication is firmly proven only if analytical data fully agree with clinical findings. analyses involved thin-layer chromatography and/or high-performance liquid chromatography with the lowest limit of detection in the range 10 to 250 ppb. baits were classified as "accidental" or "criminal" baits. An "accidental" bait is primarily intended to kill rodents as demonstrated by its components (cereals, millings) and its site of application. criminal bait is not prepared in order to kill rodents; from its composition (sugar, meat) and its site of application (in a lift, for example), one can see that its first intention is to destroy nontarget species. REQUESTS FOR ANALYSIS GENERAL SURVEY Results for animal samples and baits are presented in Table 1. The proportion of animal samples in comparison with baits did not change from 1980 to 1985. Each year, this proportion was above 80% of all samples. Dogs are most affected at a very constant rate (63.1% of total requests). Dogs represent by far the population showing the highest hazard. This can be explained by the fact that they are very close to man and thus to the rat, and that they can ingest any substance and moreover any bait. *Current address: Centre National dInformations Toxicologiques Veterinaires, Ecole Nationale Veterinaire de Lyon, B.P. 31, 69752 Charbonnieres Cedex, France. 1986, Proceedings Twelfth Vertebrate Pest Conference (T.P. Salmon, Ed.). Printed at Univ. of California, Davis, Calif. 82 Cats are more suspicious; thus they are by far less affected. Pigs are highly susceptible to anticoagulant. However, we had only few requests, probably as a consequence of, on one hand, strict application procedures and, on the other hand, industrial animal husbandry, restraining the possibility of ingesting toxic baits. The situation is the same for poultry. Very few requests concern cattle and horses. This is in relation to low susceptibility and limited availability in normal breeding conditions. Every year we receive samples of wildlife species (8 to 14% of total requests). Hare, rabbit, boar, pigeon and duck are the most affected species. We can notice the high number of criminal baits (71.2%). Table 1. Requests for analysis. a. ANALYTICAL DATA Global Results Data are shown in Table 2 and 3.