What are Xanthines and Why Should I Make Sure My Dog Avoids Them?
During this holiday season, think before you walk out of the room. You may have left something deadly on your counter. For your dog that is.
So far, one might say, we are failing as doggie parents. Another might say, our experience is typical, I wouldn’t know because I have never owned a dog before. But in the 7 months we have had a dog in our home it has broken my nose and we have lost it three times. Well, we haven’t lost it so much as it has taken off like a stallion leaving us with no other response than, crap.
When we picked up our precious little pup from the breeder we were not warned of putting one’s face too close to the dog while it slept. There were no precautions about what an idiot you were going to look like dashing through the neighborhood chasing a white flash that finally settles at a distant neighbor’s dog bowl – turned out to be lovely people.
No, there was but one warning. The breeder looked directly at my two little boys and said, do not let the dog have chocolate. My husband and I backed up the warning with a classic parental expression; we raised our eyebrows and nodded our heads, as if we were well aware of what the breeder was talking about. We do the same thing when the doctor tells the children they need to eat more vegetables- eyebrows up, head to and fro.
What right did we have to our smirky confidence? The poor dog didn’t even make it a year before we tested the theory on the warning – twice.
To our credit, the first time it happened my husband and I were not at home. We were away for the weekend and arrived home to the distinctive (di-stink-tive, ha!) smell of vomit.
In our absence the puppy had taken a few liberties and started exploring counters. What he found was a bag of semi-sweet chocolate chips which he consumed entirely while his sitter was out.
According the Merck Veterinary Manual, “Chocolate toxicosis may result in potentially life-threatening cardiac arrhythmias and CNS dysfunction.” I have no idea what the later is, but something tells me I don’t want to find out. The manual goes on to note, “Contributing factors include indiscriminate eating habits,” yes, that describes my dog, any dog, really, “and readily available sources of chocolate.”-oops!
A five-membered (aromatic) carbon ring with nitrogen in positions 1 and 3 is called imidazole. A six-membered aromatic ring with nitrogen in positions 1 and 3 is called pyrimidine. When the two rings are bound together, sharing carbons 4 and 5, the resulting compound is purine. If you then take purine and add oxygen to carbons 2 and 6 (you really should be writing this down) of the pyrimidine side you get a compound that you might recognize, if you pay attention to chemical structures printed on t-shirts and coffee mugs.
Xanthines are a class of compound found in coffee, tea and chocolate. Caffeine is its most popular member. Theobromine, which contains no bromine, is also well known. Neither xanthine, is good for dogs.
The chemical structures of theobromine and caffeine are important because they mimic a compound prevalent in our central nervous system (oh, CNS!). The compound is adenosine and it has many functions in the body. It is the mellow ying to caffeine’s hyper yang. Adenosine is involved in energy transfer, promotes sleep, and slows heart rate. When xanthines are introduced into the body they block adenosine receptors and kick start a biochemical party. Considering the effects of xanthines in humans, you can imagine how they can be lethal in an animal 75% smaller than us.
Back to the Merck Veterinary Manual:
“The toxic principles in chocolate are the methylxanthines theobromine (3,7-dimethylxanthine) and caffeine (1,3,7-trimethylxanthine). Although the concentration of theobromine in chocolate is 3-10 times that of caffeine, both constituents contribute to the clinical syndrome seen in chocolate toxicosis. The exact amount of methylxanthines in chocolate varies due to natural variation of cocoa beans and variation within brands of chocolate products.”
Our dog has lived to tell about his chocolate tango, twice, because there are varying amounts of cocoa in a given chocolate source. For example, you particularly want to avoid having your dog consume dry cocoa. A few decades ago two enviable scientists analyzed “seventy-nine cocoa or chocolate products and eighteen carob products.” They averaged the theobromine and caffeine content across brands and tabulated the results for every imaginable chocolate product. If you ever wanted to calculate your caffeine intake from chocolate, this is your source! Dry cocoa contains the most theobromine and caffeine of all types of chocolate.
Most recently our dog ate a chocolate pudding pie at Thanksgiving. Chocolate pudding is way down the list just below chocolate cereals. Chocolate pudding contains essentially no chocolate; it is mostly just gelatin and milk.
The semi-sweet chocolate chips that the dog consumed are extremely dangerous, however, only baker’s chocolate separates them from dry cocoa. Semi-sweet morsels contain an average of 5.65 mg/g of theobromine. Let’s say my dog ate three-quarters of the bag that is about 270 g, which equates to 1525.5 mg of theobromine consumed. The Merck Veterinary Manual warns that 100-200 mg/kg is a fatal dose. My dog weighs roughly 29.5 kg, that means a fatal dose for him is between 2950 and 4425 mg. A cardiotoxic dose for my dog is about 1180 mg and 590 mg is enough to make the dog really, really sick.
Just like people, every dog’s body will process xanthines differently. It probably helped that my dog is young and athletic. He processed the chemicals quickly. Caffeine leaves a dog’s system within a few hours, but dogs metabolize theobromine more slowly, so unfortunately he had to suffer through its effects for the better part of a day. We are grateful there was no damage to his heart.
This time of year be cautious with all those holiday treats. If you are a dog owner it is probably best to store the chocolate behind a closed door. Then you can ensure everyone’s holidays will be happy.
