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RESEARCH ARTICLE
Contents Vol 37(3)

Acetaminophen as an oral toxicant for Nile monitor lizards (Varanus niloticus) and Burmese pythons (Python molurus bivittatus)

Richard E. Mauldin A B and Peter J. Savarie A
+ Author Affiliations
- Author Affiliations

A United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, 4101 LaPorte Avenue, Fort Collins, Colorado 80521, USA.

B Corresponding author. Email: Richard.E.Mauldin@usda.gov

Wildlife Research 37(3) 215-222 https://doi.org/10.1071/WR08168
Submitted: 26 November 2008  Accepted: 27 January 2010   Published: 18 May 2010

Abstract

Context. Invasive species are a growing global problem. Biological invasions can result in numerous harmful impacts on local ecologies, and non-native herpetofauna are frequently ignored. Nile monitor lizards (Varanus niloticus) and Burmese pythons (Python molurus bivittatus, recently reassessed as Python bivittatus bivittatus), have become established in southern Florida. Both are large, semi-aquatic predators that pose serious threats to a variety of threatened and endangered species, as well as to the unique ecology of the area.

Aims. Acetaminophen (CAS#103-90-2), a lethal oral toxicant for the invasive brown treesnake (Boiga irregularis) on Guam, was investigated as a possible toxicant in juvenile Burmese pythons and Nile monitors.

Methods. Dead neonatal mouse (DNM) baits containing 0, 10, 20, or 40 mg acetaminophen were force-fed to Nile monitors, whereas DNM containing doses of 0, 20, 40, or 80 mg were freely consumed by Burmese pythons. Subjects were frequently observed post-treatment for general condition and position, with special attention paid to activity (if any), behaviour, respiration, bleeding, emesis, ataxia, and mortality.

Key results. In Nile monitors, acetaminophen doses of 10, 20, or 40 mg resulted in 0, 50 and 100% mortality, respectively. In Burmese pythons, doses of 20, 40, or 80 mg resulted in 14.3, 85.7 and 100% mortality, respectively. No mortality was observed in control individuals of either species. A negative correlation between dosage (mg kg–1) and time-to-death was observed in both species. Dosages ranging from 522 to 2438 mg kg–1 and 263 to 703 mg kg–1 were uniformly lethal to monitors and pythons, respectively. Neither species exhibited signs of pain or discomfort following acetaminophen treatment.

Conclusions. Acetaminophen is an effective toxicant in juvenile Nile monitors and Burmese pythons. Further investigation into acetaminophen toxicity in adults of these species is merited.

Implications. Although further investigation into adult lethal dosages and strategies to optimise bait deployment while minimising secondary hazards is required, acetaminophen may have a role to play in the control of these invasive species in Florida.

Additional keywords: acetaminophen, Burmese python, Florida, invasive species, Nile monitor, Python molurus bivittatus, Varanus niloticus.


Acknowledgements

We thank Doug Beard of Flora and Fauna of South Florida and Mike Cole of Ballroom Pythons South for their efforts in obtaining late-season juvenile pythons and monitors. We also deeply appreciate the efforts of the Animal Care Staff at the National Wildlife Research Center in accommodating and caring for these animals. We also thank Christi Yoder for performing the statistical analyses, Jerry Hurley for the preparation of acetaminophen tablets, and Carol Furcolow and Doreen Griffin of the Analytical Chemistry Project at NWRC for the acetaminophen tablet analysis.


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