Toxicant. A toxicant is any substance (natural or synthetic) capable of causing ill health.Examples: pesticides, benzene, cyanide.
UHPLC (ultra‐high‐performance liquid chromatography). As implied by the term “ultra”, UHPLC offers higher speed of analysis, and better sensitivity, reproducibility, and specificity over HPLC.
Seeking a Laboratory
Define your testing objective first and foremost. Different laboratories offer different types of tests. A test is a tool. Always use the right tool for the job.
Toxicology laboratories can be subdivided into different functionalities:Environmental, occupational, experimental, and pharmaceutical toxicology laboratories engage in very specific subsections of toxicology.Veterinary diagnostic laboratories and equine drug testing or doping control laboratories offer many of the tests that can be useful to the practitioner looking to determine a cause of illness or death. If there are legal implications (lawsuits, penalties, etc.), the laboratory should be experienced in forensic sample handling and chain of custody procedures. Contacting the laboratory as soon as possible should allow them to provide information to ensure that proper procedures are performed from collection to shipping as well as for testing. The designated laboratory should be accredited for the testing technology requested and utilized.
Veterinary diagnostic laboratories (VDLs). The focus of a VDL is on the diagnosis and prevention of disease in animals. Individual specialized test offerings may vary from laboratory to laboratory. The VDL should be the first stop when the causative agent is unknown, and a consultation with the chief toxicologist should be conducted prior to collecting/submitting samples, whenever possible.
Equine drug testing/doping control laboratory. These laboratories are specialized in testing methods designed for the detection of prohibited compounds in performance animals. Due to the large number of drug compounds these laboratories routinely test for, and the availability of advanced analytical instrumentation, many laboratories can offer a very broad scope of drug coverage with superior sensitivity. However, the scope of coverage is not always uniform among different laboratories beyond a base panel of commonly regulated medications, and most do not offer testing for pesticides, rodenticides, industrial chemicals, etc. Test results obtained from previous testing at a VDL and clinical history should be shared, when possible, to ensure the best possible test selection and avoid analyte overlap.
Private analytical laboratories. These laboratories perform a variety of testing on food, water, dietary supplements, industrial chemicals, pharmaceuticals, etc. Larger facilities can offer state‐of‐the‐art equipment and scientific staff and may be able to test for exotic analytes.
Samples
High‐quality samples are essential for optimizing the laboratory testing to be performed. The best sample should be chosen based on the suspected compound/analyte. Communication with the laboratory about specific samples to obtain and submit often improves the outcome.Blood (whole blood – not clotted) (serum/plasma). Avoid hemolysis. Some compounds may require specific collection tubes (check with laboratory).Saliva.Ocular fluid.Urine.Hair.Bile/stomach contents.Liver/kidney/spleen.Injection site/muscle.Materials found in the animal’s environment (syringes, unlabeled pharmaceuticals, tongue ties, feed remnants, dietary supplements/botanicals, etc.).
The minimum volume for collection will depend on the number of tests to be performed on the sample(s). Check with the laboratory before collection, whenever possible.
Store samples under appropriate conditions for the analyte.
Potential Analytical Targets
Rodenticides, insecticides, herbicides, fertilizers, feed additives, drugs (human/veterinary, OTC/prescription/compounded products), research chemicals, paint components, household products, poisonous plants, microbial toxins, animal venoms, heavy metals, ionophores, fumonisin, taxine, cardiac glycosides, and others.
Abbreviations
See Appendix 1 for a complete list.
Suggested Reading
1 Ghaedi M, El‐Khoury JM. Pre‐analytical variation: the leading cause of error in laboratory medicine. Clinical Laboratory News 2016. Available at: https://www.aacc.org/cln/articles/2016/july/preanalytical‐variation‐the‐leading‐cause‐of‐error‐in‐laboratory‐medicine (accessed April 3, 2021).
2 https://www.vet.cornell.edu/animal‐health‐diagnostic‐center/laboratories/toxicology
3 http://www.vdl.uky.edu/LaboratoryServices/Sections/Toxicology.aspx
4 https://cahfs.vetmed.ucdavis.edu/tests‐and‐fees/diagnostic‐services/toxicology
5 https://vet.purdue.edu/addl/Toxicology‐Analytical‐Chemistry.php
Author: Petra Hartmann‐Fischbach, MS, FAORC Director, DTS
Consulting Editors: Dionne Benson, DVM, JD; Lynn R. Hovda, RPh, DVM, MS, DACVIM
Chapter 4 Treating an Intoxicated Animal: Antidotes and Therapeutic Medications
The incidence, prevalence, case fatality rate, and mortality rate vary with each specific toxicant, dose, animal factors such as age, nutritional status, or concurrent disease, or exposure to other toxicants.
If information is available, determine how and when the animal was exposed to the toxicant.
Clinical signs vary with the different toxicants. Not all potential signs are seen in each affected animal. Signs can vary with disease progression. The current clinical observation is just a snapshot of the toxicosis.
There is limited availability of FDA‐approved drugs to treat animals. The majority are used in an extra‐label or unapproved manner.
Currently, only seven FDA‐approved “antidotes” are used to treat animal toxicoses. Of these, only two are used in horses (pralidoxime hydrochloride and tolazoline hydrochloride).
Some antivenoms and antitoxins are approved by the USDA for equine use.
Mechanism of Action
Mechanisms of action vary with different toxicants and are discussed in the specific chapters dealing with those toxicants.
Briefly, toxicants can