When we think of dogs-with-jobs our minds tend to go straight to police, search and rescue, drug-sniffing and guide dogs. But therapy dogs are the unsung heroes of the working dog world! These four-legged therapists undergo detailed training to help comfort, support and encourage people suffering from a variety of mental health issues. They work in all kinds of conditions — from hospitals to group homes — to bring their special brand of assistance to those who need it most. Let’s take a closer look at how these four-legged heroes are helping humans.
If you have avoided having poinsettias in your home because of small children or animals, you’re not alone. But despite the commonly held belief that poinsettias are toxic, they aren’t. This myth seems to have originated in 1919 with a misattributed poisoning of a child and perhaps persisted because several members of the same family as the flower are quite toxic.
These leaves, however, aren’t meant for your salad, so eating even a couple can give you an upset stomach or cause vomiting. This is the reaction commonly seen in dogs and cats, but since these symptoms are mild, oftentimes no veterinarian care is required, although you should contact your vet if your pet is sick for more than a few hours.
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.
Female dogs opt for less yoga-like squatting postures than their male companions, who can sometimes be seen with their leg so far in the air they seem about ready to topple over. It turns out that the height to which male dogs raise their leg has a lot to do with their body size, where they are, and who’s around.
All canines use urine to mark their territory, but some do it more than others. All male dogs, big and small, raise their leg to pee or scent-mark much more frequently in the fall than in the summer, likely because it is mating season. Accordingly, the frequency of their urination increases whenever there is a female dog or a male competitor present. Males will sometimes even raise their leg when their bladders are empty, performing what is called a raised-leg display. Females mark their scent much more often when near their nest or den, and males mark theirs more frequently on unfamiliar objects and places.
The height to which they raise their leg also seems to have to do with getting a mate, defending territory, or intimidating other males. Male dogs raised their legs higher when near the edges of their territories, or when they were with their mates. But proportionally, littler dogs raised their leg much higher than their big friends. Perhaps this is their way of making themselves seem larger, like a bettawith its fins or a cat with its fur.
All we know for sure is that they look pretty silly to us.
In the late 1940’s both Soviets and Americans began investigating the expanse of space by sending animals up, up and away. It began with fruit flies in 1947, grew to include monkeys in 1949 and mice in 1950, but no animal actually entered orbit until November 3rd, 1957, when Laika, a Soviet trainedstreet dog, made history.
Sputnik 1 was the first satellite to orbit the Earth, but Sputnik 2 (or more appropriately Muttnik) was the first satellite to reach orbit with a creature aboard.
Laika was found on the streets of Moscow, which meant she was already adapted to survive extreme cold and hunger. She was chosen because she was calm, sweet, and, as a female, could pee with her leg down (this made designing her space suit much simpler). She underwent training like any cosmonaut: centrifuges, confined spaces, loud noise exposure, acclimatization to nutrient gel food and fitting for a space suit. However, unlike modern cosmonauts, her return was never planned for.
According to the Sovietsthe plan was to euthanize Laika with medicated food just before reentry. Sadly this humane method didn’t pan out. Laika’s vital signs stopped after 5-7 hours in orbit.
The Sputnik 2 mission was planned hastily, as then Soviet leader Khrushchev wanted its launch to coincide with the 40th anniversary of the October Revolution. The vessel was built in only about 4 weeks. After news of Laika’s launch spread, the Soviet government alternatively claimed that she had died from a lack of oxygen or been euthanized early. Years later, one of the mission’s scientists admitted Laika had died by overheating due to a mechanical problem in the spacecraft, a much less desirable way to go.
Laika’s flight spawned outrage from animal rights activists the world over. But it also piqued the curiosity of an American army physician, Duane Graveline. His desire to understand how the Soviets had received the biophysical data from Laika led him to research space’s effects on the human body and help develop the technologies that allowed NASA to send astronauts (which he later became!) to space.
Dogs are dichromates whereas humans are trichromates. That means that our eyes contain 3 different types of cone cells, each of which are responsible for detecting a unique colour (for a description of both rods and cones, click here). That’s why every colour you can think of is a combination of the 3 primary colours.
But dogs only have 2 types of colour-sensing cone cells, and instead of them sensing red, blue or yellow, they’re tuned to violet and yellow-green. This means that dogs have less sensitivity in their green, yellow and red detection than humans. But conversely, humans have less sensitivity in their blue and purple detection than dogs.
And cats? Well they are a bit of a mystery. We know that they have at least two types of cone cells, one tuned to violet and one to green. But there have been studies the showed evidence of a third type of cone cell, one sensitive to light at 500 nm (greenish-blue to us). Other studies have rejected this finding, and yet others have found evidence of a cone cell sensitive at 610 nm(red to us). Currently, it’s believed they have vision similar to rhesus monkeys, called photopic trichromatic vision. In essence, they likely see similar colours to us, but not quite in the same clarity or saturation.
Cats’ and dogs’ vision systems evolved to help them hunt. They’re better at seeing movement than still objects; they see best in low light rather than bright; and they have larger visual fields (up to 270° compared to the 180° of humans!)
Cats and dogs also have evidence of their previous nictitating membranes, or third translucent eyelids, in the corners of their eyes. These would once have allowed them to maintain their sight on prey when hunting without their eyes drying out.
So when you throw a red ball into a green field, Rover sees a yellow ball being thrown into a white or gray field. Those colours just aren’t that different, so don’t be too surprised when he can’t find the ball that’s obvious to you!
Given the breadth of commercially available dog foods it can be tricky for dog owners to make informed decisions on how to feed their pets. Add into the mix the wealth of websites and books advocating for specialized dog diets and feeding your dog well can seem like a monumental task.
In a previous article I addressed what owners are able to know about a type of food, and what they aren’t, based on the package.
There is, however, a lot more nuance to the world of dog food than could be covered in one article. From vegan diets to how to feed nursing moms, there are a lot of questions I’ve left unanswered, so let’s try to answer a few.
How to Feed Dogs Throughout Their Lives
Dogs, much like humans, have different energy and nutritional requirements during different stages of life.
Pregnant dogs require slightly increased levels of protein, although only for the last few weeks of gestation, since 75% of fetal weight is attained in this time.
Foods for growing puppies also need to be slightly higher in protein, to accommodate their rapid growth. Larger breeds will grow over a longer period of time (~15 months) than their toy-sized counterparts (~9 months), so you can expect to be feeding them puppy chow longer.
You do not, however, want to continue feeding milk to growing dogs. Their ability to digest dairy products falls with age, as the lactase activity in their intestines decreases. Your dog may love cheese, but more than a small bit will leave him pretty unhappy.
As dogs age, their metabolic rates will naturally slow down, as will their activity levels. With this should come a reduction in their caloric intake. Specially formulated senior pet foods will generally be lower in calories while still containing all the essential nutrients, and some will also contain compounds to help dogs suffering from arthritis.
While it is a common myth that protein consumption can worsen the condition of dogs with renal disease, this is not true. Older dogs tend to be more affected by renal issues, and they actually have a slightly increased protein need to account for the age-associated losses of the body’s protein reserves.
Dogs with jobs (like these ones) will need to have their nutrition adjusted according to the energy they expend throughout the day. Sled or search-and-rescue dogs will require an increased portion of fat in their diets to supply fuel for their longer-term aerobic exercise, whereas dogs who engage in brief stints of intense exercise, like greyhounds, require more carbohydrates in their diets to fuel their anaerobic respiration.
Should dogs eat grain-free?
It’s commonly said that dogs are unable to digest carbohydrates. This is just not true. Dogs have evolved over the 14 000+ years since their domestication to have quite different digestion than their wolf ancestors.
In 2013, researchers compared the genome sequences of 12 wolves with those of 60 dogs and found that the regions selected for since the domestication of dogs fell into two categories: those which alter the nervous system (and therefore potentially behaviour) and those which alter starch digestion.
As humans switched to a predominantly agriculture-based lifestyle, they created more permanent settlements, near which food scraps and waste would be disposed of. An early adaptation allowed wild dogs to digest these starch-rich castoffs and helped them to thrive in this new ecological niche.
However, in all mammals (including humans) carbohydrates are a non-essential nutrient. The glucose required by the body can be synthesized from amino acids and fats through gluconeogenesis. So, it is possible to meet the nutritional requirements of dogs, and yourself, without eating carbohydrates, but it’s not necessary. While dogs do not have amylase in their saliva as humans do, their pancreases produce enough amylase and other enzymes to break down carbs quite well.
Many dog foods market themselves as grain-free, a statement that is often misinterpreted as carbohydrate-free. Grain-free diets are not necessarily even low in carbs, never mind carb-free. Grains are a common source of carbs, but they are not the only one. The fruits and vegetables included in your pet’s food contribute necessary vitamins and minerals, as well as carbohydrates.
The term “filler” is thrown around a lot when talking about grains in dog foods. As grains contribute protein, amino acids, fibre and vitamins, referring to them as filler (i.e. nutritionally useless) is simply wrong. Dietary fibre provided by carbohydrate-rich foods like grains and legumes helps ease bowel movements in dogs just as it does in humans. Further, grain-free diets tend to replace the metabolizable energy lost with the exclusion of grains with increased fat content.
While gluten intolerance is increasingly common in humans, food allergies in dogs are considered quite rare. Grain allergies make up only 1-2% of these already rare allergies, so the risks of your dog being intolerant of the grains in their food is quite small.
Should dogs follow the raw diet?
A growing number of pet owners are advocating for feeding their animals some variation of the BARF (Biologically Appropriate Raw Food) diet. Numbers vary, but one study found that 8% of dog owners in the U.S. and Australia currently feed raw meat and/or bones as their dog’s main meal. Many proponents of these diets will draw connections between their pet dogs and their wolf ancestors, but as discussed, 14 000 years of evolution have left domestic dogs with very different digestive systems than their wolf ancestors.
There are two main problems arising from feeding dogs bones and raw meat (whether it makes up all or only some of their diet): bacterial contamination, and nutritional deficiencies. Atleastfivedifferentstudies have found that both commercial and home-prepared raw diets are commonly contaminated with bacteria like Salmonella and E. coli. This is especially true of, but not limited to, diets containing raw chicken.
If raw foods are left sitting in dog bowls, the risks get even higher. Traditional methods of cleaning pet bowls are unlikely to completely remove bacterial contamination, and the quantity of bacteria present on food increases rapidly as it sits out.
The bacteria found on raw meats are not only a risk for dogs however. Severalstudieshaveshown that dogs fed raw diets shed bacteria in their feces. Any person who comes into contact with these feces, whether by cleaning it up or just encountering some inevitable residue on the dog itself, is at risk of bacterial infection. This is especially hazardous when dogs are in contact with the young, elderly or immunocompromised, such as therapy dogs who visit care homes or hospitals.
The problem of nutritional inadequacy is a major one when it comes to both raw and cooked home-prepared dog food. One study found that of 95 raw meals reportedly fed by German pet owners, 60% were deficient in at least one essential vitamin or mineral. A different study found that 35% of veterinarian-recommended, long-term homemade recipes for dogs were nutritionally deficient, and yet another study found that 86% of published dog diets were deficient in various minerals, and 55% were deficient in protein.
Part of the problem is that while human meals have a considerable amount of leeway in terms of substitutions, specially formulated dog diets do not. One study showed that a majority of owners do not strictly stick to recommended homemade diets. Swapping one type of protein for another, or even just buying a different leanness of ground beef can alter the entire nutritional profile of the food and cause imbalances.
If you are feeding your dog a BARF diet, there are some specific things to be careful of. Care should be taken when giving dogs bones (particularly poultry bones) to ensure that they don’t choke, and raw fish should never be given to dogs. Many fish contain thiaminase that can destroy dietary thiamine (vitamin B1) and cause a nutritional deficiency.
Can dogs be vegetarian or vegan?
Perhaps surprisingly, yes!
But having a vegan dog is more difficult than going vegan yourself.
As I explained above, dogs can digest carbohydrates and grains quite well. So, the main issue with excluding meat and/or animal products is in nutritional, not caloric, deficiencies.
Dogs who are eating vegetarian or vegan may face vitamin deficiencies, just like their human vegan counterparts. To combat this, commercial vegan dog foods will often be supplemented with vitamins that are difficult or impossible to find non-animal sources for, like vitamin B12, taurine and vitamin A.
One study analyzed 12 commercial vegetarian dog foods and 86 homemade vegetarian diets and found many of them to be nutritionally bereft. Home prepared diets, regardless of their vegan status tend to be nutritionally lacking, so you can imagine that cutting out an entire food group doesn’t fix this problem.
If you really do want to transition your dog to a vegetarian or vegan diet, I would highly, highly, recommend talking to veterinarians and canine nutritionists, to ensure that your pet is getting all that they need to stay healthy.
In the end, every dog is a unique creature with unique needs, likes, dislikes and health situations. The best option for every pet owner is to talk to their veterinarian about what is best for their particular dog.
That, and remember to keep the chocolate, onions, garlic and grapes away from man’s best friend.
Want to cuddle cats but can’t stand the coughing? Want to romp with Rover but avoid the red eyes? Allerpet markets itself as the product for you! Sadly, though, it doesn’t work.
Allergic reactions occur when your immune system comes into contact with an allergen to which it is hypersensitive. In the case of cats, these allergens can be a few different things. The two biggest culprits are the proteins Fel d 1, secreted by cats’ sebaceous glands (which are found over their entire body) and Fel d 4, found in cats’ urine and saliva. Dogs also produce multiple proteins in their hair, dander, saliva and urine, and those can trigger allergic reactions.
The allergens produced by sebaceous glands are present in dander (animal dandruff) and tend to be the most annoying to allergy-suffering pet owners. Dander is made of microscopic skin flakes and can float in the air for hours, just waiting to be inhaled by an unsuspecting human. It can quickly spread to every surface an animal has contact with and readily collects on soft items like beds and couches. The amount of dander an animal gives off increases with their age, hence why some pet owners are fine for years before they develop allergies to their companions.
One study estimated that 26% of European adults are sensitized to cats and 27% to dogs. Cats’ reputation as allergy-enhancers comes from their ability to spread their allergens much more effectively than their canine counterparts. Cats tend to have access to entire homes and to stay inside 24/7, whereas dogs may be contained to an area of the house and often leave for walks or visits. Dogs are usually bathed more often than cats, which removes some allergens whereas cats spend a significant portion of their day grooming themselves, during which the allergens from their saliva are spread throughout their fur, and released into the air along with dander.
So what can you do If you’re allergic to your fluffy best friend? One product, Allerpet, is marketed as a “pet dander remover” to “people with allergies to pets.” It’s a damp wipe that can be applied to pets of all kinds while they sit in your lap, and its maker claims that it can cleanse your pet of dander and other allergens, thereby restoring your ability to play with them sneeze free.
Their website states that “Allerpet products have been recommended by Allergists & Veterinarians for over 25 years!” and that they are “recommended by veterinarians for all pet allergies,” which leads me to question if these veterinarians have read the studies testing the product, since they’re not very positive.
A 1995 study compared weekly washings with distilled water and weekly treatments with Allerpet. Researchers sampled the Fed d 1 protein given off by each cat twice a week for eight weeks and concluded that there was no significant reduction in allergens. Similarly, a 1997 study compared brushing and wiping cats with either Allerpet, water or nothing on a cloth and found no difference between the amounts of allergens removed by these methods. They concluded that, while wiping a cat is easier than washing one, wiping with Allerpet, water, or nothing is five times less effective than washing a cat.
Allerpet contains ingredients similar to conventional shampoos (although it is much more expensive), as well as aloe vera which is actually toxic to cats and dogs and which can irritate guinea pigs intensely. Since the concentrations of the ingredients aren’t known, it’s impossible to know if the aloe in Allerpet could really pose a risk to pets. Since the animal product industry has relatively little oversight in North America, it’s possible that this product is being marketed for animals on which it was never tested.
Even if this product did work for dander, the allergens present in animals’ urine and saliva would still be present, ready to cause your runny nose. Reviews of it on Amazon are littered with stories of its failure to relieve allergy symptoms, as well as a few cases of it making cats vomit and giving dogs hives. Anecdotes are not evidence, but taken with the evidence that Allerpet doesn’t work, they’re enough to make me wary of even trying this product on my pets.
Sadly, truly hypoallergenic breeds are a myth. No cat or dog breed is completely allergen free, but there are various breeds that produce fewer allergens. Since dander attaches itself to hair, an animal that sheds less or is hairless will likely spread fewer allergens throughout your home. In the same vein, an animal that’s physically smaller has fewer sebaceous glands with which to produce allergens, so will likely trigger fewer allergies.
So if snuggles with Fluffy cause you to sneeze, there are a few things you can do. Most importantly, skip the pseudoscientific products. Consider a low-shedding small cat or dog for your next rescue. Install a HEPA air filter or two around your house. Wash your companion regularly (so long as they aren’t a rabbit or chinchilla). Keep them out of the bedroom, vacuum lots, and ask your doctor about allergy shots or prescription medicines.
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.