Monday, July 22, 2013

Three things I learned: periodontal disease in companion animals or, does my pet really need a dental?

Phil. Former sufferer of severe periodontal disease.
This is an icky subject very close to my heart. No, I don't have a festering abscess in my armpit (that would be both icky and close to my heart). I DO however live with a dog who had serious, severe periodontal disease. Phil did not have the ideal start in life and had bad dental disease when I met him: he could bleach my hair with a yawn. Several dentals and multiple extractions later he is a new man.


This post refers to the sensational ASAVA webinar given by veterinary dentist Gary Wilson, of Advanced Animal Dentistry. He talked about periodontal disease (ie disease of the structures supporting the teeth - gingiva, periodontal ligament and alveolar bone). We all know it is caused by plaque (a combination of bacteria + food + saliva). Its by far and away the most common disease we see in companion animal practice (although often not the reason animals are presented for examination as many owners don't look in their pet's mouth). 

It is well established that periodontal disease leads to bacteraemia, which can lead to the release of endotoxins and inflammatory mediators and antigen-antibody complex formation. Such complexes can lodge in the heart, liver and kidney and can lead to chronic renal insufficiency which we see so often in our feline patients.

So what did I learn? 

That factors which predispose dogs and cats to periodontal disease include: proximity to salivary glands (e.g. the parotid duct is adjacent to the carnassial and if saliva pools it can contribute to plaque in this region); soft-food diet; overcrowding of teeth; rotated teeth (as often seen in brachycephalic breeds); retained deciduous teeth; systemic disease; malocclusions; slab fractures or damage to the surface of teeth; trauma; open-mouth breathing and FUR. Hair caught in the gingival sulcus becomes entrapped in teeth. Grooming dogs with long fur around the face is therefore important for their dental health. Even schnauzers!
Molars from a small dog with severe dental disease. Note that despite having three roots, each tooth came out whole. That isn't normal! You should need to section these teeth before removing, but check the size of the granulomas on those root tips. These were not happy teeth. In fact, they practically jumped out of the dog.

Severe dental disease in a dog presented for vaccination (i.e. not for dental disease - this was an incidental finding). Note the marked gingival recession and entrapped fur.

I also learned that bone loss seen with dental disease is associated with osteoclast stimulation rather than direct destruction by bacteria, although antibiotics are still indicated to remove the inflammatory stimulus (as are extractions!).

Finally, I learned that bacteraemia associated with dental procedures lasts for approximately twenty minutes, which is a good argument for avoiding performing invasive surgery at the same time as dental procedures.

Upper and lower retained canine teeth in a poodle. Note again entrapped fur, food matter and other not-so-nice scented crud. 
Although I try to limit myself to three things, I could not help but also learn that while we tend to see chronic gingivitis, acute, severe gingivitis can occur but is easily differentiated from gingivostomatitis as it only involves the gingiva which is 1-2mm thick. 

We perform dental examinations and procedures often (you can see why), so it was nice to get a "fresh" perspective on a not-always-fresh topic. I was glad that Dr Wilson mentioned that xylitol, present at low concentrations in many dental rinses for dogs, must be avoided in dogs with liver disease - and at high concentrations (found in chewing gum, artificial sweetened foods etc) it can prove fatal.

Dental work is one of the most rewarding and important things we can do to keep pets healthy. Once he had had his festering teeth removed Phil certainly got a new lease on life.

[Phil would also like to thank Dr Christine Hawke, of Sydney Pet Dentistry, for extracting his more challenging teeth].