Antibiotic (over) use in Veterinary Dentistry

[Dr. Jeff]

Here's some interesting and useful thoughts from vet dental specialist Fraser A. Hale, DVM, FAVD, from 2004 regarding "preventative" anti-biotic use:

"Those who know me know I have several pet peeves. One of the biggies is the inappropriate use of antibiotics and it is on this subject that I have chosen to rant in this issue of The CUSP.

What follows is my opinion. There are others with differing opinions.

In general, antibiotics are vastly over used in veterinary dentistry, often to the detriment of the patient. They are often used in an attempt to treat undiagnosed dental disease and this simply does not work.

Consider how antibiotics work. If the drug is in high enough concentration around the bacteria, the drug either prevents bacterial reproduction (bacteriostatic) or actually kills the bacteria (bactericidal). In order for this to happen, the drug must come into contact with the offending bacteria for a sufficiently long time.

In the case of endodontic disease, the bacteria are living inside the hollow pulp chamber – an area once occupied by living pulp tissue, but now simply a hollow chamber full of necrotic pulp, food debris and bacteria. Since there is no blood flowing into the pulp chamber of a dead tooth, there is no way for the antibiotics to reach and affect the bacteria....

...In the case of periodontal disease, the cause of the problem is bacteria living in the dental plaque and within the porous calculus on the crown and root surfaces. Antibiotics can reduce the bacteria count in the surrounding soft tissues and may even have an effect in reducing the bacteria count within the plaque film, but antibiotics cannot remove the calculus or the plaque film and so the infection recurs as soon as antibiotic treatment stops. Again, by far the most important step is to remove the source of the infection by doing a thorough oral hygiene procedure to remove all plaque and calculus. While it is important to clean the crowns, it is far more important that the subgingival areas (gingival sulcus and periodontal pockets) are cleaned thoroughly.

From my perspective as a referral service, I see cases that are complex and have often been ongoing for some time. The history often includes several spins of the Antibiotic Wheel of Misfortune. The primary-care practitioner saw an oral problem and without a proper assessment and diagnosis, decided to try Drug A. When that did not work they tried Drug B (still no diagnosis!) and finally Drug C and D together. After weeks of ineffective drug therapy (with potential side-effects and the attendant cost), the animal is referred for assessment, diagnosis and treatment. This is backwards. It should be diagnosis first, then treatment.

As the oral cavity is home to dozens (if not hundreds) of species of bacteria, culture and sensitivity testing may have very limited value. The results with tell which of the harvested bacteria grow best under specific laboratory conditions and what antibiotics they are sensitive to (again, in vitro). The bacteria that grow in the lab may not be the ones causing disease in the mouth and in vitro sensitivity is not a reliable predictor of response to therapy. For the vast majority of cases, the time and money spent on culture and sensitivity would be better spent doing a proper dental and radiographic examination followed by surgical/mechanical removal of the source of infection.

Certainly, some animals have rampant oral infection (periodontal or endodontic) and require antibiotic therapy as part of the treatment plan, but the most important thing to do is to remove the source of the problem through any or all of root canal therapy, periodontal therapy or extraction.

Some clinics like to have a pre-operative antibiotic protocol. I feel this is bad medicine. The routine or reflex use of antibiotics is the reason we have so many resistant bacteria and why antibiotics are becoming more and more expensive as the pharmaceutical industry struggles to keep up with the evolution of the pathogens. My preference would be to do a proper pre-operative assessment on each patient and decide, based on the specifics of each case, if pre-operative antibiotics are appropriate.

The American Heart Association and American Dental Association have had recommendations for antibiotic use for many years. Though there have been some changes over the years, the recommendations have been fairly consistent. If a patient has a heart murmur or any prosthetic device (artificial heart valve, knee, hip...) then a dose of penicillin the morning of treatment and for 24 hours post treatment may be prescribed.

Personally, I dispense antibiotics only rarely. If I see an animal with a seriously infected mouth or with some serious compromise, I will give a pre-induction injection IV of ampicillin Na+. If after surgery I feel there is still deep-seated infection of soft tissues or bone, I will dispense seven to fourteen days of antibiotic, but more than 60% of my patients are sent home without antibiotics...

Dr. Hale then discusses specific anti-biotics and concludes with:

"Conclusion:

Antibiotics are for the treatment of clinical infection. They are not a vaccine against infection. In fact, giving pre-operative or “preventative” antibiotics may do far more harm than good, in that the drug will reduce the numbers of sensitive bacteria, reducing the competition for the resistant ones. The net result is an increased risk of infection with a resistant organism.

When dealing with a confirmed or suspected oral/dental infection the protocols should be:

1. Get an accurate assessment of the problem.
2. Remove the source of the problem (root canal treatment, periodontal surgery, extraction...).
3. Only in cases of residual infection following thorough assessment and appropriate mechanical/surgical treatment to remove the source of the infection should antibiotics be dispensed."

The bottom line is that anti-biotic overuse is rampant in vet dentistry and most important is to improve balance and his #1 conclusion that context is key.

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