Dental chews help dogs' teeth stay cleaner longer
I LOVE my job as a companion animal vet, but there's one area where I'm envious of equine vets: estimating the age of an animal. I'm often asked to guess the age of a dog - typically when a stray animal has been rescued. Unfortunately, this is more difficult than you might expect.
In contrast, it's relatively easy to accurately tell the age of a horse by examining its teeth. Horses' teeth grow at a steady rate throughout their lives, and they are worn down in a predictable way by grazing and chewing food. Of course there is some variability, and it is not always easy, but compared to other species, it's a doddle.
It's easiest to accurately age a horse up till five years of age: the adult teeth erupt in a predetermined order, pushing out the deciduous, so-called "milk" teeth at the more-or-less the same age in every horse. From five to eight years, a horse's teeth wear down in a predictable way, with the appearance then disappearance of the 'seven year hook' in the top corner incisor teeth.
When a horse gets older than eight, ageing becomes less accurate, but it's still possible to assess the wear, to look for certain grooves and channels, to look at the angle of the teeth, and by a combination of these aspects, to come up with a reasonable estimate of a horse's age.
It's much more difficult with dogs. As with horses, the initial eruption of the adult teeth provide an accurate guide, but this happens much more quickly in dogs: the milk teeth have been replaced by the adult versions by seven or eight months of age. From this age onwards, there are no specific dental markers of a dog's age. Vets still use dogs' teeth to estimate the age, but it's less of a science, and more of a 'guestimate'.
In most areas of pet care, recent developments in science are bringing improvements and making life easier. Interestingly, when it comes to guessing the age of a dog, the reverse is true. When estimating the age of a dog, one of the main parameters that's used is the severity of dental disease. In the past, there was more-or-less a direct correlation between age and dental disease. As dogs get older, there's a gradual accumulation of tartar, with progressive recession of the gums. As time passes, some teeth loosen and fall out. Traditionally, it was possible to look at a dog's mouth and to be reasonably confident about making an age assessment. With the advances and improvements in dental care for dogs, this has now changed.
This week, I met a seventeen year old dog called Toby. Ever since he was a puppy, his owner has diligently cleaned his teeth with a toothbrush, after every evening meal. Toby has never minded this being done: it's part of his daily routine, and he sits quietly until it's finished. It takes less than a minute every day, but the effect on this teeth is astonishing. Toby has the clean, healthy teeth of a two year old, and none of them are missing. If I was asked to age Toby based on his dentition, I would call him "a young adult". Obviously, at the age of seventeen, he has other give-away signs of age, including a grey muzzle, early cataracts in his eyes and some muscle wasting. But still, I would guess him at around twelve years, and even then, I'd comment on his unusually healthy mouth for his age.
While it's logical to brush a dog's teeth every day, very few owners are committed enough to actually do this. Perhaps it's because the teeth are hidden behind the lips, so it's easy to conveniently forget about them, or more likely, it's just that people are too busy to do everything that they really ought to do in the ideal world. Most owners do worry about the condition of their pets' teeth. and rightly so: 80% of dogs over the age of three years have gum disease caused by the build up of plaque and tartar. Daily brushing prevents gum disease, which is why Toby has such a healthy mouth.
This is where science has come to the rescue: it's now possible to buy dental chews and specially designed foodstuffs for dogs that provide a way for dogs to keep their teeth clean and healthy without any effort on the part of the owner. It isn't as simple as just 'giving a dog a bone', or buying a random chew from the pet shop. Veterinary dentists have developed specially formulated and shaped dental chews that have been designed to rub against the parts of the teeth where tartar accumulates. If dogs are given these chews regularly, studies have shown that their teeth stay cleaner for longer. The latest commercially available chew to be released is called a Dentaflex: it only needs to be given twice a week for it to be effective.
I'm pleased for dogs that these products have been developed: if dogs have healthy teeth, they live for longer, they have less discomfort in their mouths and sweeter-smelling breath. But there is one down side: it's now much more difficult to tell the age of a dog.
From now on, vets may need to qualify their age assessment of dogs, saying something like:
'Assuming that this dog has not had regular preventive dental care, my estimate of this dog's age is...'