Chocolate, like many of the things we eat regularly, is a potentially fatal poison, and so it should come as no surprise that a study by the unimaginatively-named John Johnston (at the USDA National Wildlife Research Center) shows that our favourite sweet could prove to be an effective pesticide, for use against coyotes [1].
Chocolate, or rather the theobromine and caffiene it contains, is potentially fatal to many creatures, but of course "the poison is the dose." Humans are particularly efficient metabolizers of theobromine, but the same isn't true for dogs or cats. Whereas it would take dozens of pounds of chocolate to kill a human (probably more than you could physically eat), just 20 mg per kg of theobromine is enough to cause symptoms, while more than 60mg per kg can induce seizures (see the Merck Veterinary Manual).
To put those figures into perspective, milk chocolate contains around 60mg of theobromine per ounce, so if you have a dog weighing 20kg (44lbs), about a pound and a quarter (or half a kilo) of milk chocolate could bring on seizures.
The full set of symptoms for chocolate toxicosis are described in the manual thus:
Clinical signs of chocolate toxicosis usually occur within 6-12 hr of ingestion. Initial signs may include polydipsia, vomiting, diarrhea, abdominal distention, and restlessness. Signs may progress to hyperactivity, polyuria, ataxia, tremors, and seizures. Tachycardia, premature ventricular contractions, tachypnea, cyanosis, hypertension, hyperthermia, bradycardia, hypotension, or coma may occur. Hypokalemia may occur late in the course of the toxicosis, contributing to cardiac dysfunction. Death is generally due to cardiac arrhythmias, hyperthermia, or respiratory failure. The high fat content of chocolate products may trigger pancreatitis in susceptible animals.
Cats are actually somewhat more sensitive than dogs, but they have a useful defense - cats don't find chocolate tasty. Dogs on the other hand love it, which is bad for dogs, but handy if you're a farmer with a major coyote problem that you'd like to deal with without introducing too many nasty chemicals into the environment. And that brings us to the device below - a CLOD, or as only Americans would call it, a Coyote Lure Operative Device.
Coyotes are to American agriculture what Professor Nutt is to the Daily Mail or Katie Price is to people who want to read a newspaper without being confronted by giant fake breasts every two minutes. As well as being responsible for around three-quarters of all livestock losses due to animal predators (costing some US$44m in losses), other damage caused by coyotes apparently includes:
"...collisions with aircraft, attacks on pets and children, damage to fruit and vegetable crops, predation on game species such as elk and deer, and predation on poultry. In addition to directly damaging fruit and vegetable crops, coyotes also contribute to crop losses via damage to hose irrigation systems. Coyotes have also been implicated in the transmission and spread of epizootic rabies in the United States."
In short, coyotes are responsible for pretty much everything from the global recession to 9/11. If you're living in America and you can't find a pen, the chances are that a coyote has nicked it. Clearly it's time for some mass extermination. We're talking US$40m here. That's, like, Arnie's fuel budget for a month.
Leaving skepticism about the need for this aside, chocolate - or rather the engineered chocolate-mimic used in the trial has a number of advantages as a pesticide. It's safe for humans and many other animals while fatal to coyotes, who love it. Better yet, by carefully adjusting the ratio of theobromine to caffeine in their chocolate mimic (to 5:1), the USDA researchers were able to pretty much remove pre-mortality symptons - the coyotes ate the chocolate, and then later they died. As the researchers point out:
"The results from this research clearly demonstrate that theobromine/caffeine mixtures have potential as a pest coyote toxicant that is effective, selective, and potentially more socially acceptable than fluoroacetate or sodium cyanide."
Of course, numerous coyotes were killed in the course of establishing the 5:1 ratio as the best proportion of theobromine to caffeine to use. " Coyotes dosed with the 1:1 and 1:2 mixtures exhibited undesirable symptoms of toxicosis and were euthanized. " The search for safer pesticides is always a noble one, but personally I'd like to see evidence of a larger problem than a measly US$44m of damage caused before we start breaking out the toxic Mars Bars.
[1] Johnston, J. (2005). Evaluation of Cocoa- and Coffee-Derived Methylxanthines as Toxicants for the Control of Pest Coyotes Journal of Agricultural and Food Chemistry, 53 (10), 4069-4075 DOI: 10.1021/jf050166p
http://layscience.net/trackback/807
My lovely family dog dug into the Green & Blacks that was left lying around at the end of last Christmas. At 85% cocoa solids, it couldn't have been a worse choice. She devoured nearly 0.5 kg in 5 minutes without us seeing.
The onslaught of illness follow that lasted 4 months, losing half her body weight, shutting off her pancreas and causing what would have been an excruciating death, had it not been for the quick action of the vet.
I'd read about theobromine before, but never seen such a unbelievable reaction to it. I wonder how the figures for poisoning have changed since high % cocoa chocolate increased in popularity?
I hear people also leave out antifreeze, the glycol component of which tastes sweet, thus dogs like. Cats of course have lost their functioning sweet receptors, so turn their backs on it.
The family dog, by the way, is completely well again now (£1300 in vet bills later), and chocolate is banned from the household.
All of which just goes to show that cats are smarter than dogs.
Thanks for this. The tone of the article suggests you think chocolate poisoning may be gratuitous - and I agree.
There's another way of controlling coyotes taking livestock (and you can't really blame them for eating easy food when every other shop is a KFC or Burger King). It's just more expensive.
There's a reaction called the Garcia reflex (discovered by, er, Garcia). Mammals are very good at learning, from just one exposure, what has made them sick. Ever had food poisoning and sworn off the prawns/cream cheese roulades/German sausage for ever? If you lace a sheep carcass with an emetic, any properly wired-up mammal will never touch the food source again. It's all subconscious.
Mine is mozarella chesse sticks BTW (Gak!)
Two downsides:
- An animal will choose the most novel foodsource as the noxious one (ever had twelve pints, but it was the Scotch egg that made you sick?). This means you have to do it every few years to educate the young ones before they start eating sheep.
- Indiscriminate poisoning of all canids in the vicinity is cheaper
Sad, huh?
Yes, I was trying to strike a balance between the part of me that thinks using chocolate as a pesticide is a fairly clever idea, and the part of me that feels it's at best ethically dubious. I 'm not convinced that $40-odd million of damage is enough to justify wide-scale poisoning of a large mammal... And the argument about aircraft accidents is like saying we should eradicate badgers because they keep hitting cars.
Martin is the editor of layscience.net.
Follow Me!
RSS | Twitter
Everyone has this wrong. Chocolate is actually one of the four main food groups and nutritionists need to come to grips with this. We need to raise up chocolate to "hero status" and give it its due. I, for one, actually worship chocolate. casino en ligne
I personally find slaughtering coyotes repulsive. That said, there has been an explosion of the coyote population in the last few years. Once confined to the prairie and desert regions of North America, they're now found pretty well everywhere, including the city of Vancouver, and certainly in our area a little up the BC coast, thanks largely to human destruction of the wolf population. Now wolves are making a comeback (in our area, at any rate)I expect the coyote population will be held in check. Of course, then the farmers will want to cull the wolf population again. Sigh...
4 main food groups? I say there are two: chocolate and garlic. garlic for earthly, carnal pleasure and chocolate for spiritual satisfaction. And-- bonus!! both go with red wine!
Mary - you would love my Coq-au-Vin... I make it with garlic, red wine and dark chocolate...
Martin is the editor of layscience.net.
Follow Me!
RSS | Twitter
An additional problem--coyotes breed at a rate to keep constant populations in an area. Killing most of them off just means they ones left will breed faster.
Cindy, do you have a reference for your assertion that "Coyotes breed at a rate to keep constant populations in an area."
http://texnat.tamu.edu/symposia/coyote/p5.htm
I was under the impression that the actual dynamics of coyote population changes were much more subtle than the simple model you propose.
Where I live (ruruburbia Northern California) coyotes are the apex predators. It is possible that they are becoming more aggressive
http://news.nationalgeographic.com/news/2005/06/0607_050607_coyotes.html
On the whole, I'm in favor of humane coyote-population management strategies, especially in the human-woodland interface.
Anecdote /= data, but I have observed one several-hundred acre parcel that had aggressive coyote population management until 2000. It was rare to see a coyote around the human-used part of this parcel, and when you did, it was a specimen who appeared to be in ill health (skinny, poor coat condition, etc.)
In the last two years, there are at least five identifiable individual coyotes (different coat colors, male vs. female, also ear shapes) who frequent the human-used part of this parcel. Each are brazen about appearing in daylight.
The parcel supports a large number of deer. There's also been an observed change in the way the coyotes hunt the deer. Prior to 2000, deer predation seemed to be opportunistic (finding & consuming fawns or weak/stressed deer). In the last two years, packs of +3 coyotes have been observed on +2 occasions, chasing adult male deer into a fence corner too high for the deer to jump. The coyote gang have been seen to bite at both the heads and hindquarters of the cornered deer.