What’s the most common infectious condition in dogs and cats? If you answered periodontal disease, you’re correct. Over 80% of dogs are affected by the time they’re three years old.
Periodontal disease is caused by plaque, a biofilm of bacteria and oral debris attached to the tooth and gum surfaces. Nearby tissues react to the plaque by becoming inflamed, readily absorbing bacterial toxins and pathogens, and creating bacteremia (bacteria in the blood). Usually, bacteria and periodontal toxins are eliminated quickly from the blood, but in high levels, they can cause cumulative damage to distant organs, including the kidneys, heart and liver.
At one time, it was thought that organ damage from periodontal disease was caused by oral bacteria growing in abnormal places. But new data suggests that chronic exposure to periodontal pathogens generates immune complexes of antigens and antibodies. These enter the circulatory system in sufficient amounts to cause distant organ damage.
A new field
The impact of periodontal infection on systemic diseases has been termed “periodontal medicine” and represents a new field of investigation. In humans, studies show a highly significant association between periodontitis and systemic disorders such as diabetes mellitus, pneumonia, heart disease and preterm birth. In dogs, a landmark study published ten years ago showed an association between increasing severity of periodontal disease and the severity of microscopic changes in organs such as the kidney, liver and heart muscle. A recent peer-reviewed study confirmed this finding.
Contemporary research demonstrates the association between inflammatory periodontal disease and cardiovascular disease, respiratory disease, liver disease, kidney disease, and joint disease.
Inflamed periodontal tissues present a “disease burden” to the animal. The extent of this load will likely affect the degree of pathological change in distant organs. This hypothesis was investigated in dogs with naturally occurring periodontal disease. The results revealed a link between the estimated “periodontal disease burden” resulting from plaque bacteria-associated periodontal disease, and the level of internal pathology.
The heart connection
Heart problems are the most common secondary organ side effect associated with periodontal disease.
In humans, periodontal disease is a risk factor for the development of heart disease, emboli and strokes. Veterinary research has demonstrated a correlation between chronic periodontal disease in dogs and the development of atherosclerotic changes in the heart vessels. In cases of severe periodontal disease, degenerative changes in the form of atheromas and enlargements of the smooth muscle in the wall of the carotid artery have also been found. In one study, 67% of poodles older than ten were found to have heart disease. Seven of the dogs had such severe heart failure that four died and three were euthanized. In all cases, autopsy results showed heart failure with degenerative enlargements on heart valves and enlargements in coronary vessel walls. The worst cases involving heart valves occurred in dogs with the most advanced periodontal disease.
Respiratory repercussions Respiratory disease is common. The oral cavity can serve as a direct reservoir for bacterial contamination of the lungs, with subsequent development of bacterial pneumonia. The same kind of bacteria has been isolated from alveoli sacs in the lungs and from bacterial dental plaque.
By-products of periodontal tissue inflammation enhance the adhesion and colonization of pathologic bacteria and alter the respiratory epithelium, accelerating infection.
Long-term exposure to pathogenic periodontal bacteria damages the mucociliary function and the lymphatic system in the respiratory tract, and disables the defense system in the lungs. In the same study mentioned previously, 24% of the poodles over ten years of age suffered from chronic inflammation of the windpipe and bronchi.
Liver and kidneys
Kidney disease, particularly glomerulonephritis, is believe to arise from chronic low grade bacteremia associated with periodontal disease. One study found that periodontal disease contributed to the development of microscopic damage to the kidney. In extreme cases, chronic renal failure may result.
Bacteremia associated with periodontal disease is also suspected as a cause of some liver disorders, including hepatitis and local scarring in dogs. Investigators have theorized that the by-products of gram-negative periodontal bacteria stimulate specific types of cells that lead to liver scarring. What does periodontal disease look like? Gently open your dog’s mouth and take a look at the gum line.
1. Gingivitis is defined as inflammation of the tissues surrounding the teeth. Visually, gingivitis will appear as mild redness and swelling where the gum tissue meets the tooth. There will be evidence of yellow plaque or brown tartar and a disagreeable odor. Gingivitis is reversible once plaque is removed.
2. Periodontitis is a progression of gingivitis to a loss of bone and/or periodontal ligament support. This progression is secondary to the dog’s immune response to the changes in the types and number of bacteria on and around the tooth. Eventually, a periodontal pocket forms that acts somewhat like a pocket in your pants and fills with food. Once the pocket has formed, plaque removal becomes more difficult, inflammation progresses, and support loss continues. The inflammation may result in bone re-absorption, pain, bleeding and mobile teeth. The gums will appear deeply red, there will be significant halitosis, and the teeth may be loose.
Proper diagnosis and treatment of gingivitis and periodontal disease not only keep your dog’s mouth healthy, but also lower the prevalence and complications of major systemic diseases, leading to a longer pain-free life. Call your veterinarian for an oral assessment, treatment, and prevention (see OralATP.com for more information). We constantly hear that our patients act like puppies again once periodontal disease is addressed!
Cause and effect?
Periodontal disease and distant organ disease do not implicate a direct cause-and-effect relationship. For example, dogs with periodontal inflammation are more likely to have mitral valve disease. But it may be that the cardiac problem caused the oral problem instead of the other way around. Or, there may be some underlying condition that makes the dog susceptible to both oral and cardiac disease.