chewing

VIN photo by Dr. Sophia Yin

Dogs love to chew throughout their lives, and frequent chewing is especially good for puppies, because it helps them develop strong jaws and handle a variety of food.

As the science of pet food gets more sophisticated, owners nowadays can cater to a seemingly endless assortment of their canine companions' nutritional needs — and wants. You can buy dog food tailored to specific breeds or to those with certain health conditions, such as skin problems. Dogs can even enjoy a "Mediterranean chicken and rice entrée" concocted by Spanish Michelin-starred chef, José Andrés, among other luxury offerings.

One crucial ingredient, however, appears to have gotten lost along the way: an element of challenge for the dog. That's prompting some veterinarians to ruminate on the importance of chewing — and, by extension, chews — to dog health and well-being.

"It seems like we've got really great at the nutritional side of things," said Dr. Rimini Quinn, a veterinarian with interest in behavior who practices on Australia's Sunshine Coast, north of Brisbane. "But as part of doing that, we have sort of decoupled dogs' need to chew from the need for nutrition. What have they lost?"

Quinn is among seven veterinarians who worked on new research that examined the functional significance and welfare implications of chewing in dogs. They found that chews provide myriad benefits to the animal — whether it's cleaning their teeth or calming their nerves — while conferring the mental-health benefits to owners that come with having a happy, contented pet.

Chews, of course, bring health risks like dental fractures, choking and, depending on their type, disease. While no chew is risk-free, veterinarians contacted by the VIN News Service offered some pointers on how pet owners can minimize the dangers while maximizing the upside.

Moreover, taking a zero-tolerance approach to chews can have unintended consequences: Dogs' innate desire to chew is so strong, the researchers found, they'll invariably find something to chew on — be it a shoe or a sofa, for instance — that could cause serious harm, both to the dog and their owner's bank balance.

Millennia in the making

Dogs' desire to chew is born of necessity. For tens of thousands of years, they needed to eat raw animal and plant material to survive, encouraging the evolution of a large gape (mouth size) and teeth designed for biting, ripping and crushing.

For wild dogs, feeding sessions can be lengthy affairs. Australian dingos, for instance, spend an hour or so consuming a kangaroo carcass, the researchers note.

Increasing opportunities for pet dogs to chew can mimic the kind of long feeding sessions that occur in the wild, they advise. To that end, offering a substrate that's harder than your average ready-made dog chow provides some obvious (and not so obvious) benefits to oral health.

For one, friction created by an item scraping against the teeth and gums can help prevent a buildup of plaque and tartar, warding off gum disease like gingivitis. Further, the study notes that prolonged chewing, by stimulating more saliva production, improves the pH balance in the mouth, protecting against disease, enhancing digestion and improving overall gut health.

Frequent chewing appears to be especially important during the early stages of life, since it ensures a dog's masticating (chewing) apparatus develops to handle a variety of food items. Providing pups with nothing but soft, mushy puppy food can hinder jaw development and facial strength in adulthood.

"Often, people say their puppy is always chewing on everything," Rimini said. "It's normal dog behavior to be motivated to chew from deciduous tooth eruption."

Then there's the mental-health benefits to consider. A continuous desire to chew throughout a dog's life means that being denied the opportunity can make them unhappy and anxious. The act of chewing relieves stress, whether the dog is agitated at one extreme or bored at the other.

"Chewing is a moderator," Rimini said. "Studies have shown that, depending on temperament or arousal state, it might have a different function — bringing them into that middle space, that state that's more optimal."

Choosing a chew

So what type of chew is appropriate? A bone? Rawhide? A synthetic squeak toy? And does "appropriate" differ among dogs?

It's complicated, says Rimini, noting that the allure and safety of an item can be influenced by many factors, such as its size, shape, hardness, scent, novelty value and challenge involved — all combined with the individual dog's body shape, age and experience with different chew types.

As an example of the complexity, Rimini offered, harder chews might seem appropriate for dogs with a stronger bite force, such as large brachycephalic (short-skulled) breeds like bull mastiffs or boxers. But these flat-faced breeds may have crowded or misaligned teeth, making it harder for them to chew on something solid.

There are a few basic considerations that apply when choosing a chew, namely: It shouldn't be so hard as to fracture teeth or so small or easily broken that it ends up being swallowed whole or in pieces that can cause internal obstructions.

With those goals in mind, Dr. Steven Holmstrom, a veterinary dental specialist in California, applies three golden rules.

"If it doesn't bend easily, or it breaks easily, I don't recommend it," he said. "Secondly, if you hit it on your kneecap and it hurts, it's not a good idea. And finally, if you take a look at it and say 'I'm not going to bite into this thing' and grimace at the idea, the pet shouldn't bite it either."

Chews that are safer, however, might not be as mouthwatering as that smelly raw bone from the butcher's, replete with tasty morsels of tendon, cartilage and marrow.

"Bones, in general, they're probably the most contentious of the chews, and you probably get the most variation from vets on the question: Should you give your dog a bone?" Rimini said.

Bones about bones and sticks

Natural bones provide a source of nutrition that resembles the hard, fibrous things that dogs consume in the wild, whether bones, nuts or seeds. And, since dogs tend to love bones, they're more likely to give them a long, hard chewing.

Bones for dogs present varying degrees of risk. For example, raw bones are less prone to breaking or splintering like cooked bones might. And whole raw bones are safer than cut ones, which may have harmful sharp edges.

"The more natural the bone — so if you think of a femur, the edges are kind of soft and curvy and have some cartilage on them — the better," Rimini said. "Dogs gnaw away at those ends; they get the marrow very slowly."

She added: "Yes, there are risks, but there's benefits as well. So it's a matter of weighing those up, supervising your dog and watching and learning." Still, she accepts that for many veterinarians, the dangers associated with bones are too much to bear.

Take Holmstrom in California. "I have seen a lot of fractured teeth, and bones have caused most of the fractures I see," he said, quipping: "I call feeding bones a practice builder for a veterinary dentist."

The risk of harm can be insidious, Holmstrom maintains. "The dogs could get away with it for the first two or three years of their life. Then, just like another ligament, the periodontal ligament that's holding the tooth in place, it's going to stiffen up, and there's going to be less give. Something's got to give, and it's a tooth, usually, at that point in time."

Pet owners are "walking a tightrope" with chews, agrees Dr. Crina Dragu, a veterinarian in southeastern France who commutes to work in Switzerland. Training to be a dental specialist, Dragu also is bone-averse. "If you want to give something to chew, make sure you can make an indentation in it with your fingernail," she said. "Every dentist has their own little thing that they like to say, but we all agree the item should be at least somewhat pliable."

Antlers, Dragu said, are especially risky because they are uniformly hard. "And sometimes other hard extremities of the animal, like hooves, those can do damage, as well," she said.

The consequences of broken teeth can be more severe than pet owners expect, Dragu warns. Treatment options like root canals or metal crowns are expensive. Tooth extraction could severely handicap a dog's ability to chew properly at all, especially if fractures occur on both sides of the mouth — which Dragu said isn't uncommon.

"It's very frustrating for people when they learn it after the fact, and part of the surprise comes because when you walk into a store, these kinds of items are everywhere. And there is some cognitive dissonance there, because if it's on display in a store, people think, 'How can it be bad?' "

Rimini says chews have gotten a little safer over the years as manufacturers wise up to the dangers, at least with regard to obstruction risk. "Some older chews were a little bit too smooth and regular, and they did have some esophageal obstructions with those chews,” she said. Today's chews tend to be more variable in shape.

Alternatives to bones that still offer some animal protein include pigs ears and bully sticks, the latter made from bull penises. Like many animal-based products, however, they bring a risk of infection by pathogens such as Salmonella, potentially causing diseases that can be transmitted to humans.

As for wooden sticks, which so many dogs avidly seek and play with, veterinarians have mixed feelings. Rimini said dogs typically will break sticks and spit out the pieces rather than swallow them. Still, she said, mouth injuries and dental wear are possible. Any contaminants on the stick, such as animal droppings, could cause illness, she added.

Dragu is decidedly anti-stick. "We regularly see penetrating stick injuries, where dogs will run with a stick and impale themselves on it if it catches on the ground while they run," she said. Splintered wood, she added, can become lodged in several places in the mouth or penetrate the oral mucosa, potentially causing abscesses. Dr. Christine Calder, a veterinary behavior specialist in Maine, is similarly wary. "Wooden sticks concern me," she said. "I have seen too many get stuck in the roof of a dog's mouth and splintering."

Puzzle chews: The best of both worlds?

Dragu, while advising against bones, tries to replicate their appeal through puzzle toys, which, theoretically, offer a similar challenge but without the associated injury and disease risks.

"What I try to do is fill a Kong toy, which is hollow, and fill it with stuff like peanut butter and biscuits and things. And I put it in the freezer, then give it to my dogs," she said, adding, "Let's not kid ourselves. It's probably not going to be as delicious as that disgusting bone to them, but it replicates that challenge — that there is a thing, there is a hole, and they have to suck something out of it."

Calder in Maine prefers "interactive and problem-solving" chews.

"My go-to chews are puzzle toys and lickable mats that are pre-stuffed and frozen," she said. Freezing, Calder notes, can make a puzzle last longer, and stuffing it with different items like fruit, vegetables and treats adds variety to the pet's enjoyment.

Calder advises owners to watch their dogs to make sure a puzzle isn't so challenging that it causes them frustration.

Holmstrom has "no problem" with puzzle toys, but at the moment is enamored of two squeak toys shaped like Spiderman and Captain Marvel and made of Kevlar, a strong synthetic fiber. "My dog just can't destroy them," he said. "She loves them."

To delve deeper into choice, Rimini and her fellow researchers in Australia are in the midst of a study that has involved asking hundreds of pet owners about chews. Separately, they plan a study to compare a group of dogs given chews with a control group given none, with the aim of determining how chews affect different elements of physical and mental health.

As for what a given dog should be offered to chew, for now, Rimini advises pet owners seek professional advice.

"It can be very bespoke," she said. "We do feel like it's hard to give a recipe, and we don't have a lot of that kind of information yet to be able to say absolutely what's right and what's wrong. We would always say 'Check with your vet,' because you want to make sure that it's the right thing for your dog."