I wouldn’t blame you for thinking something along the lines of “just like everyone else,” but I’m here to tell you otherwise.
Being a veterinarian is a lot like being a human doctor. Besides the fact that both professions practice medicine, albeit on different subjects, they both require top grades and many years of school. They usually necessitate one to go into debt, to work long hours, to have extreme empathy and to be on call for days at a time.
Given their similarities, we’d expect them to have similar mortality rates and causes of death, but that isn’t the case. Veterinarians are at an extremely elevated risk for suicide.
While it seems that cats, and in rare circumstances, dogs, can become infected with SARS-CoV-2, there is no need to panic. Pets tend to exhibit very mild symptoms and make full recoveries. There’s no evidence at this time that COVID-19 can be spread from animals to humans, and although the same cannot be said for humans to animals, the transmission rates seem very low.
If you ask a dog owner what dogs cannot eat, they’ll list some foods like onions, garlic, rhubarb, grapes and chocolate. (As an aside, if they say grains, don’t listen to them.) Dogs’ inability to safely consume chocolate is common knowledge, but thanks to their proclivity for eating anything they can get their mouths on, many dogs are nonetheless treated for ingesting chocolate every year.
However, there are also many, many dogs who eat chocolate (with or without their owner’s knowledge) who are perfectly fine, no treatment necessary. If chocolate is so bad for dogs, why are these candy-consuming canines fine?
Because, as with all things, the dose makes the poison.
The components of chocolate that are toxic to dogs are theobromine and caffeine. These two chemicals are, structurally, almost identical, and both belong to a group of chemicals called methylxanthines.
Part of what makes methylxanthines so dangerous to animals is how slowly they process them, in particular, theobromine. While dogs reach peak serum (the non-cell part of blood) levels of caffeine after 30-60 minutes and eliminate half of an ingested dose in 4.5 hours, they don’t reach peak serum levels of theobromine until after 10 hours and take 17.5 hours to eliminate half of it.
While they’re in the blood, methylxanthines have a few effects. Primarily, they inhibit the activation of adenosine receptors. These receptors are generally responsible for making us feel sleepy, and decreasing the activity of our bodies. Methylxanthines inhibit these sleepy feelings and act as stimulants.
An aside: Grapefruit’s effects on theobromine metabolism
The enzyme responsible for metabolizing theobromine is a member of the cytochrome P450 family. If you’ve heard of these enzymes its likely because you take a medication that is similarly affected by them (such as Viagra, Cialis, Erythromycin, Xanax and many others) and you’ve been warned to stay away from grapefruit juice. This is due to compounds in grapefruit interfering with the P450 enzymes. Without properly functioning enzymes, medications aren’t broken down as they should be, and overdoses can occur. These compounds aren’t exclusive to grapefruits: they’re also found in pomelos, bitter oranges and Seville oranges that are used to make marmalade. Luckily dogs don’t often consume the fruits that harbour these compounds, however, if Marmaduke ever eats a jar of marmalade as well as some chocolate, he would be in serious trouble.
So, what does this mean for your dog who ate a chocolate bar? It means they will feel nauseous and probably vomit, they’ll have a high heart rate, diarrhea, show signs of hyperactivity and, if they consumed a high dose of methylxanthines, tremors, seizures and possibly death.
What exactly is a high dose of methylxanthines however depends on your dog.
According to the ASPCA mild effects of theobromine poisoning can be seen at a dose of 20 mg/kg. Severe signs begin at about 40 mg/kg and seizures can begin at 60 mg/kg. A median lethal dose (LD50) is the dose of a toxin required to kill half of a sample population. It’s a common way of measuring a lethal dose of a substance in toxicological research, and for theobromine, the LD50is 100-200 mg/kg.
Notice that because all of these doses are given per kilogram of dog, what’s a low dose of theobromine for a German Shepard could be an exceptionally large dose for a chihuahua.
To illustrate my point, allow me to introduce three dogs. First, we have Baci, a 5-year-old, 7-kg Maltipoo. She’s considered a small dog by all reasonable metrics.
Next meet Chanelle, a 10-year-old Golden Retriever who is solidly medium-sized at 25 kg.
Last, we have Jupiter, a 5-year-old Malamute/German Shepherd cross who is quite large at 50 kg.
I’ve run some numbers to see how each of these dogs would fair if they ate the same amounts of chocolate. You can see my results in the chart below and can replicate my calculations easily using one of the online chocolate toxicity calculators.
(Green = <20 mg/kg, yellow = 20-40 mg/kg, red = 40-60 mg/kg, black = >60 mg/kg)
So, we can see that while Jupiter will probably be fine if he scarfs down 1/3 cup of cocoa powder (the amount in your average recipe for brownies), Chanelle would likely be sick, and Baci would be facing seizures and possibly death.
It’s easy to see, when you start playing with the numbers, how so many dogs can eat chocolate-containing foods and be totally fine. Chanelle could easily consume ½ cup of chocolate ice cream, or a chocolate pudding cup, or a chocolate cupcake and not even show the slightest sign of being sick!
An aside: What about mulch made from cocoa bean shells?
In recent years cocoa-bean-based mulch has gained popularity as an attractive alternative to traditional mulch. It can be good for your garden, contributing nutrients and preventing weed growth, but it can be really bad for your dog. With up to 32 mg of theobromine per gram, cocoa bean mulch can be a more potent source of theobromine than even pure unsweetened baking chocolate. If you can’t guarantee that a dog won’t munch on your mulch, you’re better off sticking to the traditional mulches, which come with the bonus of being much cheaper!
Even if your dog doesn’t get sick from eating small amounts of chocolate however, it’s still best that they avoid it. One study found that repeated theobromine exposure led to the development of cardiomyopathy (a chronic disease of the heart muscle that makes it harder for the heart to pump blood) in dogs.
An aside: There may also be a genetic component to dogs’ ability to metabolize theobromine
Dogs with a particular variant in their CYP1A2 gene (the variant is 1117C>T) lack the ability to properly metabolize and break down some substances, including lidocaine, naproxen and theobromine. This has important implications in their veterinary treatment and could explain why some dogs get sick after eating very little chocolate.
So, what should you do if you suspect your dog has eaten chocolate? You have a few options. You can check an online calculator (like this one) to see if your dog is likely to exhibit symptoms, or call animal poison control (1-888-426-4435 in Canada and the U.S.). Keeping in mind that such resources are not substitutes for veterinarian care, you should monitor your dog closely no matter what they say, looking for symptoms like a fast heart rate, vomiting or tremors.
If your dog ate an unknown amount of chocolate; is exhibiting symptoms; is pregnant (theobromine can cross the placenta and affect the puppy); or has other health complications, you should take them to a vet right away. Symptoms may not develop until up to two hours after ingestion, but veterinarian anti-chocolate treatments are most effective if performed as soon as possible after ingestion.
And what exactly do they do to cure a dog of theobromine poisoning? Gastric decontamination. The first step is to empty the stomach (if the ingestion was recent enough). This is often done with a drug called apomorphine which is administered through the eye so that it is quickly absorbed.
Next a vet will administer activated charcoal, a finely powdered material capable of binding a variety of drugs and chemicals. Activated charcoal is most effective if given immediately after ingestion of the toxin and is usually given by mixing it with wet dog food (beware: it will turn your dog’s poop black). In some cases, repeat administrations of charcoal are necessary, but in others just one dose will do it.
Beyond these steps, a theobromine-poisoned dog will just be given medicines to manage their specific symptoms, such as Diazepam for seizures or hyperexcitability, beta blockers for high heart rate, Atropine for low heart rate or others.
Before you go: a note on cats
As it turns out, cats are actually more susceptible to theobromine poisoning than dogs, but we don’t ever hear about a cat getting sick from eating chocolate. Why is that?
Mainly because cats don’t eat as indiscriminately as dogs. Dogs are known for eating just about anything they can find (including joint butts, a practice that places them at risk for cannabis poisoning), whereas cats tend to be picky eaters. In part this is explained by the fact that cats lack the ability to taste glucose.
If all chocolate tasted like 100% dark chocolate, you likely wouldn’t eat much of it either.
Take-home message: • Chocolate is poisonous to dogs mostly because of its theobromine content, which dogs are unable to metabolize effectively. •The amount of chocolate a dog can eat without showing symptoms varies drastically with their weight • If your dog eats chocolate, you should monitor them closely and seek veterinary attention if they show any symptoms, or if they are very young, pregnant or have other health concerns.
Special thanks to Rachel Malkani MSc. CDBC and veterinary PhD candidate, and to Henry for inspiring this article by, as you may guess, eating chocolate.
Take-home message: – THC is very dangerous to most companion animals – Medical cannabis has only a few uses in humans, and even fewer in animals – Cannabis, hemp or CBD treats, food or supplements are not approved or regulated by Health Canada. They are illegal and could be quite dangerous for your pets.
While medical marijuana has been available to varying degrees for decades, with recreational marijuana legalized this week in Canada, discussions about what (if anything) cannabis can treat seem to be at an all-time high (see what I did there?)
Discussions of treating medical problems with cannabis are not limited to humans. If cannabis may benefit humans, it may similarity benefit companion animals like dogs or cats. Considering that some of the major ailments cannabis is touted to treat are prime concerns for pet owners (anxiety, arthritis, pain) it makes sense for pet owners to be curious about cannabis.
Cannabis can be very dangerous for pets
When discussing cannabis and companion animals, it’s important to define a few terms.
Tetrahydrocannabinol or THC is the main psychoactive component of cannabis. As most pet owners aren’t interested in getting their furry friends high, the vast majority of pet-marketed cannabis products are free, or almost free, from THC. Which is good, because THC is quite dangerous for animals.
Since it’s difficult to study cannabis (due to it’s soon-to-expire illegal nature) we lack recent numbers on the dose based effects of THC in dogs. Early studies report intoxication effects in dogs with doses between0.25 and 0.5 mg/kg of body weight. If your average German Shepard is about 30 kg, they would show THC’s effects after ingesting 7.5 – 15 mg, or about a 10th of your average “special” brownie.
Though cannabis intoxication and adverse effects have been reported in other animals like cats, horses and ferrets, it’s much more common in dogs. Why? Because dogs like to eat. As Dr Sarah Silcox, the President of the Canadian Association of Veterinary Cannabinoid Medicine explained to me, “edibles, in particular, are very attractive to dogs, and if left within reach of pets, will often be gobbled up quickly.”
While it’s not likely that pets will die from cannabis exposure (through smoke or edibles) there can still be serious effects, especially if left untreated. Fluffy and Rover probably won’t get a kick out of the intoxicating effects of cannabis, given that they can’t understand what’s happening. Pets may experience significant anxiety, agitation or lethargy. Smoke of any kind can cause respiratory distress and potentially lung cancer to pets who inhale it regularly, due to the polyaromatic hydrocarbons created during incomplete combustion. Cats in particular are at risk of developing malignant lymphomas when exposed to secondhand cigarette smoke, a risk that may transfer to other types of smoke. .
So what’s with all the cannabis products for pets then?
Pet treats, foods and supplements in general feature no THC. They instead contain a different cannabinoid found in cannabis: cannabidiol or CBD. CBD is not toxic to animals like THC, and it does not cause the same psychoactive effects.
This study of 16 dogs with osteoarthritis showed a significant decrease in pain after treatment with CBD oil, but similar studies, or studies looking at cannabis to treat other conditions are seriously lacking.
Dr Silcox mentioned many anecdotes of positive effects of CBD products on pets, and this survey have found that that well over half of all owners polled who have used cannabis products on their pets felt it helped. But anecdotes are never evidence enough. We need good, large, controlled studies to properly evaluate the potential benefits and risks of cannabis products on cats, dogs and other pets.
For pain treatment however, the evidence for cannabis hasn’t looked wonderful. This 2015 review found evidence for use of low dose cannabis for neuropathic pain, but not for other pain. This 2018 Cochrane review states that the use of cannabis for “chronic neuropathic pain might be outweighed by their potential harms.”
Second, as Dr Silcox wrote, there is a “concern that that pet owners will attempt to medicate their pets with cannabis products and without appropriate guidance, put their pets at risk of adverse effects.” When we give our pets, children or ourselves any medication we first check dosage information, but the problem is that it isn’t available in any well researched, accurate or well-defined way for most species.
Third, pet owners may use cannabis in lieu of other evidence-based treatments, putting their pets at risk or hurting their quality of life. We don’t really know what cannabis can or should be used for in animals, but that hasn’t stopped many owners from using it for things like pain, anxiety management and diabetes management. My fear, simply put, is that owners will choose cannabis over NSAIDS, over other pain killers, over insulin, and even over euthanasia. I hope that no animals are suffering as a result of receiving cannabis as an alternative treatment to conventional veterinary medicine, but my fear is that it’s already happening and will begin to happen more with legalization.
Whether they work or not, they’re illegal and unregulated.
Until October 17th, 2018 all products containing plant-derived cannabinoids (which includes THC and CBD) fall under the Controlled Drugs and Substances Act. But even after the 17th, it isn’t open season for cannabis products. The new Cannabis Act will regulate the approval and sales of cannabis products, meaning that anything sold legally will need to be approved by Health Canada.
Health Canada currently has no products approved for veterinary or animal use. So CBD and cannabis products currently have, as Dr Silcox explains, “no regulatory oversight to ensure their quality, safety, or effectiveness. While they are marketed to treat a range of ailments, these health claims are unsubstantiated by Health Canada, the products are not approved, and as such, are not compliant with Canadian law.”
Now, that could soon change. With legalization around the corner, studies on cannabis and its effects are about to become a lot more feasible. With more evidence we will be able to hash out which CBD claims have merit, and which are baseless.
With entire conferences being held on veterinary use of cannabis we can hopefully expect some answers soon. In the meantime, a few things remain really important.
If you have a dog, you don’t need me to tell you how important food is to their happiness. But even if you realize how much your dog loves food (the speed with which they gobble it up is a good clue) you may not realize how complex dog foods can be. More than 36% of households in the U.S. have a dog, and all of these dogs need to eat. The pet food industry in America is worth more than 30 billion dollars, but how can we tell what’s best to feed our furry friends when every package shouts that their brand is the best? Let’s take a look at the science.
The history of dog food
Prior to 1860, dogs and cats were largely fed the leftovers of their human handlers. But in 1860, James Spratt brought the first commercial pet food to market in the form of a biscuit. At the time, little was known about the nutritional requirements of cats and dogs, so they were fed the same foods. Until the mid-1930s, pet food was not sold in the same places as groceries, due to fears that it would carry germs to nearby groceries. Nevertheless, Spratt’s biscuits proved popular amongst pet owners due to their convenience and low cost. In 1908 Milk-Bone began producing their famous biscuits, and in 1922 the first canned dog food was marketed under the name “Ken-L-Ration”.
Until the invention of the extrusion process, canned dog food comprised more than 90% of the dog food market (except the years during WWII when rationing of metal and meat forced manufacturers to make dry foods).
Extrusion is the technique used to make the vast majority of dry commercial dog foods today. Ingredients are ground into powders and combined with water to form a paste, which is shaped into kibble pieces. These pieces are then cooked at high pressures (20-30 bars) and temperatures (100-150˚C). The first commercially available extruded dog food was Purina Dog Chow, which became the best-selling dog food in the U.S. within a year of its release. Extruded pet foods are still the most popular option amongst pet parents, in part due to their convenience, safety and low cost, and in part due to their benefits to dogs’ dental health (the mechanical abrasion from chewing hard pellets helps to clear dogs’ teeth of plaque and sediment).
As we’ve learned more about how to best feed our furry friends, commercially available dog foods have become better tailored to canine needs in all stages of their life. Commercial dog foods are regulated by a few different bodies in the U.S. and Canada. The Association of American Feed Control Officials (AAFCO) is the primary organization in charge. They set the standards for what claims are evidence-based, and they publish regulations and nutritional profiles that manufacturers must heed. The National Research Council (NRC) is also involved in publishing nutritional recommendations, as is the Food and Drug Administration (FDA) which regulates the safety of ingredients and the veracity of claims made on packaging.
The claims that do get made on pet food packages, however, can be really confusing, so let’s go over some basics.
How to read food packages
Just like you and I, pets need energy from their food in order to function. But unlike human food packages, which express energy in calories, pet foods express energy in terms of kcal of metabolizable energy per pound of food. Metabolizable energy is the energy contained in the food that is actually absorbed by your dog. It’s determined through feeding trials, in which animals are fed the diet and their urine and feces are collected and analyzed for their energy contents. If displayed, the metabolizable energy is your first tool for evaluating a type of dog food.
Sadly, not all pet foods include the metabolizable energy of the product on the package. Many instead choose to display the proximate or guaranteed analysis. These are similar to the nutrition facts displayed on human foods, but don’t actually provide as much information. The guaranteed or proximate analysis displays the percentage of the product, by mass, that is made of crude protein, fat, fibre and moisture. Other nutrients may appear, but only these four are mandatory.
The moisture content of a particular macronutrient can give a food the appearance of having more or less than it truly does. An example is shown below comparing a wet and dry dog food. On first glance, the wet food appears to contain much more protein than the dry one, but when calories provided by protein is calculated instead of the mass provided by protein, they are almost identical. These analyses are your second tool for evaluating a kind of dog food, but neither it nor metabolizable energy alone gives you the whole picture.
If you’re wondering what the difference between a proximate and guaranteed analysis is, the answer lies in the recipe for the pet food. Some foods are made with a “fixed formula”, which means that the ingredients of the food do not change between batches, while other foods (commonly lower budget ones) are “variable-formula” diets, meaning that the ingredients will change according to the market prices of available ingredients. The nutrition, however, will not change. If your dog is quite picky, choosing a fixed-formula diet can avoid any changes in the flavour of their food, but if, like most dogs, your pet is willing to eat anything they can get their mouth around, they are unlikely to notice the changes from batch to batch..
Your third tool for evaluating dog food is the Ingredient list. They can be useful for comparing the components of a food, but don’t actually tell you much about the amounts of certain ingredients in a food. This is, again, due to moisture in the ingredients. Like in human food, pet food ingredient lists put the most abundant ingredient by weight first, but just because an ingredient is the heaviest doesn’t mean it is contributing the most energy. Ingredient lists can be scanned for things your dog dislikes, or is allergic to, but do not tell you the main ingredient in a food.
It’s also important to not panic when looking at ingredient lists. Many foods are supplemented with vitamins and minerals, but instead of recognizable names like “vitamin K” the scientific name of a compound (menadione sodium bisulfite complex) may appear. Ingredient names you can recognize may put your mind at ease, but supplementation with vitamins and minerals helps ensure that your pet is getting everything they need to thrive.
The most powerful tool owners have when evaluating pet foods are statements of nutritional adequacies. Excluding treats, all pet food labels must feature such a statemen. This is regulated by the AAFCO, and usually takes the form “complete and balanced nutrition for all _____” where the blank will be filled in with the type of dog this food is for (e.g. adult dogs, dogs of all sized, nursing mothers, etc.)
These claims mean that the product has either been formulated to meet the AAFCO’s nutrient profiles for dogs or has been shown in a feeding trial to meet the nutritional needs of dogs. An alternative statement, “intended for intermittent or supplemental use”, is displayed when a food does not meet the complete nutritional requirements, and thus cannot alone sustain a dog in good health. If a food states that it is formulated to meet your dog’s nutritional needs, you can be confident that it will.
Statements that certain ingredients can cure, treat, or prevent a certain medical condition are not permitted on dog food (this includes claims that a food is “hypoallergenic”), but nonspecific claims like “promotes healthy skin” are.
Other statements that may be seen on dog food labels include the terms natural, organic or human grade. While natural does have an AAFCO-regulated definition (all ingredients must be derived solely from plant, animal or mined sources), organic and human grade do not. These are simply buzz words used for marketing purposes.
The last tool you have for evaluating a brand of dog food is the feeding instructions. While a generic brand of dog food may seem cheaper, it’s possible that the ingredients used to make it are less digestible than those used to make more expensive foods. This will be reflected in the feeding instructions, as more of the cheaper food will need to be fed to your dog to meet their nutritional requirements. The cost may, in the end, be the same as if you fed your pet the lower quantity of the more expensive food.
Pet food labels are confusing, especially when it has taken most of us most of our lives to become literate in human food labels, but with a little bit of investigating it is possible to ensure that your dog is being fed a healthy diet. If you ever need some help, talk to your veterinarian, they are after all, the expert.