Poisonings at The Animal Ark

The Animal Ark is a non-profit wildlife sanctuary and animal education center based in Reno, Nevada. They currently house and care for:

Bears including two North American Black Bears

Canids including an Arctic Fox, two Coyotes, a Kit Fox, two Red Foxes, and two Gray Wolves

Felines including an Asian Tiger, two Bobcats, three Canadian Lynx, two Cheetahs, a Jaguar, and two Mountain Lions.

Raptors including an American Kestrel, a Barn Owl, a Great Horned Owl, and a Red Tailed Hawk

Reptiles including two Desert Tortoises

And other animals including an American Badger and a Raccoon.

It was first reported in the media in February 2015, Shere Khan, a 21-year old Bengal Tiger, unexpectedly and rapidly became ill, began exhibiting symptoms of a stroke, and then eventually was euthanized due to his condition.

Shere Khan, the Bengal Tiger

Digital image courtesy of the Animal Ark official website - http://animalark.org/animals/shere-khan/

The next day Animal Ark employees found that two other animals, Maddie the Gray Wolf and Jamar the Cheetah, had become ill with similar symptoms. Maddie was found dead and Jamar was found unresponsive in a coma.

Jamar, the Cheetah

Digital image courtesy of the Animal Ark official website - http://animalark.org/animals/moyo-jamar/

Maddie and Monty, the Gray Wolves

Digital image courtesy of the Animal Ark official website -http://animalark.org/animals/maddie-and-monty/

What happened?

Let’s enter the wonderful world of animal and wildlife forensic toxicology.

Biological specimens were acquired from Maddie and Jamar and toxicological analyses were undertaken. No specimens were acquired from Shere Khan as he had already been buried. While I work in a postmortem toxicology laboratory, the instrumentation used in animal and wildlife forensic toxicology is the same – high performance liquid chromatography (HPLC), gas chromatography with mass spectrometry (GC/MS), headspace gas chromatography with flame ionization detection (GC-FID), liquid chromatography with tandem (triple quadrupole) mass spectrometry (LC/MS/MS), liquid chromatography with time of flight mass spectrometry (LC/ToF or LC/qTOF), etc.

According to media reports, Pentobarbital and Phenytoin were detected in the gastric contents of Maddie. The same substances were found in the urine of Jamar. It was hypothesized that the substances had found their way into the food supply. Through investigation and a little bit of analytical chemistry it was determined that a specific brand of meat given to the animals was contaminated with Pentobarbital and Phenytoin. This news then led to a product recall. As the identified meat company is simply a distributor, this recall led to food product being returned from 10 different zoos and wildlife sanctuaries across the USA.

On a good note, after intensive medical treatment, Jamar the Cheetah survived the ordeal.

So, we exactly are Pentobarbital and Phenytoin?

Pentobarbital is a barbiturate derivative that was first synthesized in 1930 and is considered a Schedule II controlled substance by the United States Drug Enforcement Administration (DEA). It has been used clinically in humans as a short-acting and potent sedative-hypnotic agent for insomnia, pre-anesthesia, and as an anticonvulsant. It has other uses in treating Reye’s syndrome and traumatic brain injury as well in veterinary anesthesia. Pentobarbital is also one of the drugs that has been used in human and animal euthanasia. In November 2013, a Missouri death row inmate died from a dose of the drug during the lethal injection/capital punishment process. Its pharmacological mechanism of action is via GABA receptor potentiation, AMPA and kainate receptor inhibition. The drug also increases the duration or time that chloride ion channels are open. The molecular formula is C11H18N2O3 and molecular weight is 226.2 g/mol. Different forms of the drug exist on the market such as capsules, tablets, suppositories, and solutions for intramuscular and intravenous injection. The most common trade name is Nembutal. It is biotransformed and excreted into the urine as unchanged drug and various hydroxylated and carboxylated metabolites. Symptoms of overdose include impaired psychomotor function, incoordination, slowed or slurred speech, hypotension, severe respiratory depression, and coma. Over the last several decades, the substance has been implicated in many deaths – many of which have been accidental overdoses.

Phenytoin is a hydantoin derivative substance that is used as anticonvulsant drug and was first synthesized in 1908. It is one of the main substances used clinically in treating epilepsy. Phenytoin is also classified as a class 1b antiarrhythmic substance and is sometimes used after cardiac glycoside (i.e. Digitalis, Nerium oleander) poisoning. Its pharmacological mechanism of action is via binding to sodium channels and blocking  the repetitive firing of action potentials. It is not considered to be a Federally controlled substance in the United States and it is available by prescription only. One common trade name is Dilantin. Molecular formula is C15H12N2O2 and molecular weight is 252.2 g/mol. The drug is available in normal release and extended release capsules, liquid suspension, and a solution for intramuscular or intravenous injection. Phenytoin is excreted in the urine primarily as unchanged drug and hydroxylated metabolites. Pentobarbital is formed as a metabolite of the barbiturate derivative, Thiopental, also known as Sodium Pentothal, by desulphuration. Symptoms of overdose include dizziness, drowsiness, slowed and slurred speech, ataxia, hyperglycemia, and blurred vision. Central nervous system and respiratory depression is generally not caused by Phenytoin in normal dosages. When compared to other drugs, Phenytoin has accounted for relatively few deaths, though acute intoxication with the substance is not unheard of.

Now, the next logical question is how did the substances come to be in the food supply? It turns out that the food product was procured from a horse that was euthanized with Pentobarbital and Phenytoin. One common product used in euthanasia of cattle, horses, pigs, dogs, and cats is called Euthasol from LeVet Pharma. It is a solution of 400 mg/mL Pentobarbital and is available in 100 mL or 250 mL volumes. Another version of Euthasol from Virbac USA that is for use in dogs contains 390 mg/mL Pentobarbital sodium and 20 mg/mL Phenytoin sodium.

Truly a sad story. One in which there seems to be no malice or intent, but an oversight into the quality of the product that made it into the food supply.

If you haven't already done so, please visit the Animal Ark's website. They care for some truly beautiful creatures and do some amazing work.

References

Baselt, R.C. (2014) Pentobarbital Disposition of Toxic Drugs and Chemicals in Man. Tenth Edition. Pages 1575-1577. Biomedical Publications, Seal Beach, CA 90740.

Baselt, R.C. (2014) Phenytoin. Disposition of Toxic Drugs and Chemicals in Man. Tenth Edition. Pages 1625-1628. Biomedical Publications, Seal Beach, CA 90740.

 

Pentobarbital. Compound Summary. CID 4737. Pubchem. NCBI. http://pubchem.ncbi.nlm.nih.gov/compound/4737?from=summary

Accessed: 3/23/2014

Dilantin (Phenytoin Sodium injection), FDA approved label, 10/2011. http://www.accessdata.fda.gov/drugsatfda_docs/label/2011/010151s036lbl.pdf

Accessed: 3/23/2014

Digital images of Shere Khan, Jamar, and Maddie and Monty can be found at the Animal Ark official website - http://animalark.org/the-animals/

 

The Case of Jagger the Irish Setter

At the beginning of March, it was reported that a European show dog, a 3-year old Irish Setter named Jagger, had died with possible suspicious circumstances while competing in the Crufts show in the United Kingdom. Toxicological analyses were completed on specimens drawn during autopsy of the animal. According to the latest reports, the dog’s blood was positive for aldicarb and carbofuran - two substances that should not be found. At all.

What are aldicarb and carbofuran?

 

They are pesticides.

 

Highly potent pesticides.

 

Highly potent and restricted pesticides.
 

 

Aldicarb is a carbamate pesticide primarily used historically as a nematicide in potato production, but also used for the control of pests such as aphids and spider mites. Its IUPAC name is 2-methyl-2-(methylthio)propanal O-(N-methylcarbamoyl)oxime. Molecular formula is C₇H₁₄N2O₂S and molecular weight is 190.2 g/mol. Aldicarb is excreted in the urine primarily as metabolites over approximately 1-10 days. Common urinary metabolites include aldicarb sulfoxide, aldicarb sulfone, aldicarb oxime, and aldicarb nitrile. The trade name for aldicarb is Temik. Its use was banned in 2003 in the European Union.

Carbofuran is a carbamate pesticide that is used on various field crops such as potatoes and corn. It is also effective against soybean aphids. Its IUPAC name is 2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl-methylcarbamate. Molecular formula is C₁₂H₁₅NO₃ and molecular weight is 221.2 g/mol. Carbofuran is excreted in the urine primarily as 3-hydroxycarbofuran, carbofuranphenol, and 3-ketocarofuranphenol. Trade names for carbofuran include Furadan and Curater. It has been banned for use on all crops grown for human consumption in the European Union since 2008 and in the United States since 2009. Carbofuran is highly toxic to vertebrate organisms. It has an LD₅₀ of 19 mg/kg in dogs and 8-14 mg/kg in rats.

How do these substances act in the body?

From a pharmacological perspective, these substances act via the parasympathetic nervous system (PSNS) as reversible inhibitors of the enzyme acetylcholinesterase (AChE). Typically, acetylcholine (ACh) is released into the neural synaptic cleft and binds to ACh receptors post-synapse, which then relays a signal from the nerve. AChE halts the signal transmission via hydrolysis of ACh into acetate and choline. AChE functions rapidly and has a very high catalytic activity – it has been demonstrated that AChE can degrade about 25,000 molecules of ACh per second. Choline is then taken up by the presynaptic nerve and ACh is constructed from choline and Acetyl Coenzyme A (acetyl-CoA) via another enzyme, choline acetyltransferase.  As AChE inhbitors, aldicarb and carbofuran inhibit or slow down the normal function of this enzymatic pathway of ACh which results in an accumulation of ACh in the neural synaptic cleft. This accumulation can result in devastating consequences for the organism.

The mnemonic SLUDGEM has been used to describe the symptoms and effects of substances such as these:

Salivation stimulation, usually excessively

Lacrimal stimulation, leading to tearing or watery eyes

Urination via urethral internal sphincter muscle relaxation and contraction of the detrusor muscle

Defecation via internal anal sphincter relaxation

Gastrointestinal upset via changes in smooth muscle tone possibly leading to diarrhea

Emesis or vomiting

Miosis or pinpoint pupils

Other adverse effects include blurred vision, bronchial secretions, bronchoconstriction, constriction of the pharynx, bradycardia, diaphoresis, hypotension, hypothermia, vasodilation, tremors, and convulsions.

Many poisonings of humans and animals have occurred using these two substances – some of these have been accidental through occupational exposure or eating contaminated crops, while others have been intentional through attempted suicide or homicide. Many deaths have occurred.

Other substances that act similarly in the body via acetylcholine include nerve agents such as VX and Sarin, organophosphate pesticides such as diazinon and parathinon, the Alzheimer’s disease medications donepezil (Aricept) and galantamine (Nivalin).

In this case - who administered the substances? By all reports, it is unknown at this time, but I'm sure one day, we'll find out who poisoned Jagger the Irish Setter.

 

References

Baselt, R.C. (2014) Aldicarb. Disposition of Toxic Drugs and Chemicals in Man. Tenth Edition. Pages 58-59. Biomedical Publications, Seal Beach, CA 90740.

Baselt, R.C. (2014) Carbofuran. Disposition of Toxic Drugs and Chemicals in Man. Tenth Edition. Pages 351-352. Biomedical Publications, Seal Beach, CA 90740.

Bayer CropScience. Temik material safety and data sheets (MSDS)
https://www.bayercropscience.us/products/insecticides/temik/label-msds
Retrieved 2015-03-17

NIOSH Pocket Guide to Chemical Hazards. Carbofuran. National Institute for Occupational Safety and Health (NIOSH). http://www.cdc.gov/niosh/npg/npgd0101.html

Retrieved 2015-03-17