Severe periodontal disease: Take a moment to lift the lip

Philadelphia — Dr. Colin Harvey, BVSc. FRCVS, Dipl. ACVS, Dipl. AVDC, is an expert in oral, dental and periodontal diseases of dogs and cats and the relationship of those diseases to systemic health. He is currently professor of surgery and dentistry at the School of Veterinary Medicine of the University of Pennsylvania in Philadelphia, as well as the director of the Veterinary Oral Health Council (VOHC). Dr. Harvey recently spoke with DVM Newsmagazine about treatment of severe periodontal disease and shared his insights about dealing with the special needs of afflicted animals.

Dr. Colin Harvey

DVM: Will you describe the characteristics of severe periodontal disease in dogs and cats?

Harvey: The major characteristic of severe periodontal disease is the reaction of the body to plaque and calculus buildup. The longer extensive buildups are present, then the more likely it is that there will be not just gingivitis – inflammation of the tissue – but a more harmful response where the body's own tissues are melting away as a result of the inflammation. That is the problem with severe periodontal disease. If you eliminate the plaque and calculus, then you can stop the inflammation. Meanwhile, there may not be a mechanically stable tooth in place.

But the local immune response is different between individuals so that one dog may have a lot of calculus buildup on it's teeth and have very little signs of infection, while another dog may have a lesser amount of calculus present, but the teeth may already be loose.

This points to the need for, and the value of, a routine visual examination which I hope would be done any time a pet comes in for any reason. It takes only a moment to simply lift the lip to see what's going on with the upper teeth – those are more likely to be severely affected in animals with periodontal disease. It gives you an excellent sense of what's going on in the mouth. If what you see is disease and a lot of calculus then, clearly, there is need for some professional intervention. If not, then there's no further need beyond opening the mouth. But the critical point is to get the process started no matter the reason for the animal being on the exam table.

DVM: How can chronic medical conditions complicate the treatment of periodontal disease?

Harvey: There are clearly some conditions that will adversely affect the health of the mouth. For example, in chronic renal failure the increased urea level in the blood affects urea levels in saliva. When the urea in the saliva breaks down to ammonia, this causes the nasty smell in the mouth which you find in dogs that have severe renal disease. But this can also be severe enough to cause chemical burning of the tissues in the mouth. Further, the chemically difficult environment suppresses the local defense mechanisms and makes mouth tissues that are much less able to fight off infection. And in diabetic animals, the elevated blood sugar means there's more substrate in the mouth for bacteria to feed on.

There's also a danger that periodontal disease may mask a primary medical problem. Particularly in middle-aged or older dogs with halitosis, it's critical to look at the overall health of the dog before starting to treat the periodontal disease. If people have a sense from their own dental treatment of what's going to happen to their pet, then that needs to be expanded to include a discussion about anesthesia and how to manage it. The first requirement for veterinarians is to justify the preoperative tests that are necessary. If I'm going to put an animal under anesthesia, particularly if it's middle-aged or older or if it's showing any kinds of symptoms like polydipsia, polyphagia, not eating, losing weight or throwing up, then it's an easy decision.

The health of the dog is the major determinant of what we can do, how long we have to do it, how involved the anesthesia will be and what kind of support we need to provide during that anesthesia. And in some dogs that means we look to extraction as a way of dealing with oral infections in the most dependable manner. We have to consider the whole patient rather than just what would be best for likelihood of healthy retention of the teeth.

DVM: What is the best way to approach the treatment of severe periodontal disease? Do certain breeds have special needs that should be considered?

Harvey: There are two aspects to professional treatment. One is cleaning, including scaling and polishing to remove the plaque and calculus that are causing periodontal disease. Then for severe disease there is surgery or some other procedure to stabilize the tooth sufficient to allow it to be maintained.

It's not inherently easy to figure out what to do to retain a tooth. Radiographs are essential. If you're going to treat a tooth that is severely diseased, then you need to know how much of the root is still in place, how much of the bone around the tooth is healthy and whether endodontic disease is present. You want to be sure that the work you're going to do will produce a more healthy bone and soft-tissue combination around that tooth. We're not looking for some quick result here. We're looking to retain that tooth over the remaining life span of the patient.

I like to think in terms of triaging teeth. There are 42 teeth in the mouth of the dog, and what I hope is that veterinarians pay attention to the most severely affected teeth first, particularly in older dogs or dogs that have systemic problems where we might have concerns about anesthesia. So if we only have a half an hour under anesthesia, we know at the end we've dealt with what's going to be most beneficial to the dog. And we haven't lost the opportunity to do something good because we use an identical approach with every patient – always starting at the top right of the mouth and going all the way around.

We have a particular problem when treating toy breeds with periodontal disease. The epidemiological evidence is very clear that small dogs are more likely to be affected than larger dogs. But, as a result of the selected breeding that produced the smaller dogs, the amount of bone in the bodies of the toy breeds genetically down-sized more than the teeth. That means there's less bone around the teeth in toy breed dogs, so the same amount of inflammation will have a proportionately more serious effect in toy breeds than in larger dogs. And the impact may be more severe because the jaw may not have enough strength to resist fracture. The classical problem is a 15-year-old Yorkshire terrier or other toy breed with plaque and calculus, and the dog is anesthetized for a combination extraction/scaling procedure. But as the lower jaw is pulled down to insert the endotracheal tube, the traction is enough to cause a pathological fracture, usually around the first molar tooth. So it's important that veterinarians are careful when they're handling the jaws of older toy breed dogs with severe periodontal disease. It's good to pay special attention to the small and toy breed dogs early on and get owners to understand the value of disease prevention.

DVM: Are there any strong indicators or studies showing that periodontal disease affects other body systems?

Harvey: There are two studies in dogs that have looked at microscopic changes in the heart, liver and kidneys. They found that with more severe periodontal disease there is an increase in inflammatory or degenerative changes in those organs compared to less severely affected dogs. There is also evidence of an increase in C-reactive protein, which is produced by the liver in response to stress or inflammation anywhere in the body.

In dogs that were anesthetized for periodontal treatment and then were re-examined the C-RP level was reduced, suggesting that the periodontal treatment eliminated a cause of C-RP production. That's as close as we've come to proving a cause-and-effect relationship. It would take a large-scale and expensive study to actually prove this cause-and-effect relationship, but the association does infer that periodontal disease is a risk factor for microscopic scarring in the distant organs.

It's very easy to get caught up in hyperbole in statements like "Periodontal disease causes heart disease," or "Periodontal disease causes renal disease," and have that repeated to the point where it becomes hugely overstated. Many dogs have some degree of periodontal disease and some measurable abnormality associated with periodontal disease. A much smaller number of dogs have severe periodontal disease and may have had it long enough that daily bacteremia (shedding of bacteria into the bloodstream) as a result of chewing may have triggered some distant change in the body's tissues.

It's difficult to maintain perspective because people want a simple statement, and it just doesn't work that way yet. If indeed there is a cause-and-effect relationship, then it's worth our while to do something that's pretty easy to do anyway (preventive care) and has a big benefit. Preventing the accumulation of dental plaque and calculus is a habit that we accept for the health of our own teeth, and we can do this for our dogs whether its daily brushing, rubbing the teeth with a cloth, by giving dental treats, feeding a dental diet or using other products with proven dental efficacy – just look for the VOHC Accepted Seal.

Linda Marie Wetzel is a freelance writer in Cleveland, Ohio.