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  • Author or Editor: Philippe J. Berny x
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Abstract

Objective—To assess the rate and extent of ruminal degradation of warfarin, chlorophacinone, and bromadiolone in vitro and determine the oral availability and clinical and hemostatic effects of each anticoagulant rodenticide in adult sheep.

Animals—3 Texel sheep.

Procedure—Samples of ruminal fluid were incubated with each of the anticoagulants to assess the kinetics of ruminal degradation over 24 hours. To determine the plasma kinetics of the anticoagulants, each sheep received each of the anticoagulants IV or via a rumenimplanted cannula at 2-month intervals (3 rodenticide exposures/sheep). At intervals during a 240- to 360- hour period after treatment, prothrombin time (PT) was measured, plasma anticoagulant concentration was assessed, and clinical signs of rodenticide poisoning were monitored. In plasma and rumen extracts, anticoagulant concentrations were determined via high-performance liquid chromatography.

Results—In the rumen extracts, anticoagulants were slightly degraded (< 15%) over 24 hours. In vivo, oral availability of warfarin, chlorophacinone, and bromadiolone was estimated at 79%, 92%, and 88%, respectively. Although maximum PT was 80 seconds after chlorophacinone and bromadiolone treatments, no clinical signs of toxicosis were detected; PT returned to baseline values within 2 weeks.

Conclusions and Clinical Relevance—In sheep, warfarin, chlorophacinone, and bromadiolone were not degraded in the rumen but their bioavailabilities were high after oral administration; the kinetics of these compounds in sheep and other mammals are quite similar. These data suggest that the lack of susceptibility of ruminants to these anticoagulant rodenticides cannot be explained by either ruminal degradation or the specific toxicokinetics of these anticoagulants.

Received April 8, 2005. Accepted June 22, 2005.

Full access
in American Journal of Veterinary Research

Summary

A former secondary lead smelter was in operation in Granite City, Ill, until the early 1980s. As a result, the surrounding area is heavily contaminated with lead. Soil concentrations as high as 5,000 ppm have been measured in prior studies. Because of growing concerns about health defects associated with low levels of lead exposure in human beings, a major study has been conducted on people living in the area. The study reported here was a corollary to the human exposure study. Lead concentration was determined in 84 dogs and 26 cats in the town and ranged between < 5 and 28 μg/dl. None of the dogs had clinical signs of lead poisoning. The cbc and serum biochemical values did not indicate many significant differences between dogs with a high (> 10 μg/dl) or low blood lead concentration (blc). Hemoglobin concentrations were lower, and wbc counts were higher in dogs and cats with higher blc, but they were still within reference ranges. Free erythrocyte protoporphyrin concentration was determined. Normal values appeared to be similar for dogs and cats. Only animals with blc ≥ 20 μg/dl were found to have somewhat increased concentration of free erythrocyte protoporphyrin. ∂-Aminolevulinic acid dehydratase activity was measured and found to be negatively correlated with blc. The relation was strong, even at low blc (5 to 10 μg/dl) in both species. Age or sex difference was not observed. Therefore, biological changes associated with low blc were limited to blc in the 10- to 30-μg/dl range.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate the toxic effects of amitraz in dogs and their reversal by various doses of atipamezole.

Animals

6 male 1-year-old Beagles.

Procedure

Dogs were given 100 mg of amitraz/kg of body weight, PO. Atipamezole was administered at 3 dose rates. Clinical examination and blood sample collection were performed regularly for 48 hours to examine biological parameters and determine the toxicokinetics of amitraz as well as the efficacy of the antidote. A specific high-performance thin layer chromatographic method was developed to determine plasma amitraz concentrations.

Results

Clinical signs of toxicosis included sedation, bradycardia, polyuria, hypothermia, and hyperglycemia, all of which could be related to the α2-agonist activity of amitraz, and were reversed by low doses of atipamezole (50 μg/kg, IM), a potent α2-antagonist, within 10 minutes after injection. Peak plasma concentrations were observed after 5 hours, and the elimination half-life was long (about 24 hours).

Conclusions

All clinical and biological effects observed during the course of amitraz poisoning could be attributed to the parent compound itself and were reversed by low doses of atipamezole. The half-life of amitraz was substantially longer than that in other studies because of the high dose administered.

Clinical Relevance

Atipamezole can be administered IM to dogs with severe amitraz poisoning to reverse all the effects observed. (Am J Vet Res 1996;57:1506-1510)

Free access
in American Journal of Veterinary Research