Visiting Vet: Anesthesia for dental work

When you’re as old as Zeus, maybe not.

Yogi shows off his puppy teeth. Courtesy Juliana Mannino.

I loved Greek mythology when I was a student, the stories that distilled the essence of so many human struggles. From the vanity of Narcissus to the hopeless toil of Sisyphus, I found them fascinating. But I wasn’t thinking along such literary lines when little Zeus, an elderly Jack Russell terrier, arrived for his annual physical. “I’m concerned about him,” his owner said. She had noticed Zeus had been moaning more over the past few months, and occasionally pawing at his mouth, though he was chewing and eating normally

“Let’s take a look,” I said optimistically. Zeus had other ideas. Usually a cooperative, albeit nervous, patient, he channeled Cerberus when I tried to open his mouth. I wanted to examine, tooth by tooth, looking for any abnormalities, but the best I could do was pull back his gums and see the hunks of calculus caked on his teeth. Dental calculus is the name for that hard, crusted-on stuff that develops when plaque accumulates and hardens. Brushing won’t remove it. It needs to be scaled off, either with hand instruments or an ultrasonic scaler. You or I just go to the dental hygienist, but Zeus wasn’t going to listen to me if I said “Open wider, please,” or “Turn this way.”

Now I could devote an entire column to the controversy between (mostly lay) people who insist that thorough dental cleanings can be done on pets without anesthesia, and the vast majority of veterinarians who, after years of sticking our hands in animals’ mouths, recognize the fact that for the majority of our patients, they need to be comfortably sleeping if we want to do anything more than a cursory dental scaling. If Zeus had a broken, loose, or infected tooth, as I was concerned he might, he was going to need help from Lethe, Hypnos, and Morpheus if I was going to be able to treat him effectively. However, I am a believer in the old medical adage “There’s no such thing as routine anesthesia.” Although we had cleaned Zeus’ teeth under anesthesia many times before throughout his life without complications, he was a senior citizen now. And I couldn’t be sure what was causing his moaning. Maybe something besides dental disease was going on. I advised thorough preoperative blood tests. “As long as the lab work is all normal, then we can proceed with anesthesia and see what’s going on in his mouth,” I concluded.

Only the lab work wasn’t all normal. Two liver tests were elevated. Not so high as to set off alarm bells, but high enough to give me pause. I had seen a number of elderly dogs with liver cancer recently, so we decided our next step would be radiographs. When the films were developed, sure enough, right between the liver and spleen was a roughly circular density about the size of a small apple. Was it a tumor? Well, maybe, but I could also see that Zeus had eaten an Olympian meal recently. His tummy was full of food. Sometimes food and fluid can pool in a portion of the stomach, leading to the appearance of a circular mass in just that spot. “We need to fast him overnight and retake the x-rays,” I sighed. A few days later, we repeated the films with his stomach empty. Everything looked perfectly normal. The suspected “mass” had just been a bowl of breakfast.

Now what? I suggested we proceed with a bile acids test, which is a more sensitive and specific indicator of liver disease. Whereas our initial tests just suggested nonspecific liver inflammation or damage, the bile acids test could help assess if the liver was functioning properly. Bile is a substance stored in the gallbladder in the liver, then released into the intestines to aid with digestion. Bile acids are then reabsorbed from the gut and transported back to the liver, where the liver cells remove them from the blood, “recycling” them for future use. If Zeus’ liver was functioning normally, he should have normal bile acids levels in his blood both before and after eating. Since he was already fasted that morning, we proceeded with this test. We drew a pre-meal sample, fed him a mound of delicious food, waited two hours, drew a post-meal sample, then sent everything off to the big laboratory. If pre- and post-meal levels were normal, that would give us a greater degree of confidence that Zeus’ liver was functioning adequately and we could proceed with anesthesia for dental work.

Only his bile acids were not normal. Both pre- and post- meal bile acids were elevated. Not so high as to completely preclude possible anesthesia, but high enough to tell us something wasn’t right. Again, now what? Usually I can listen to all the nonverbal cues my patients give me, put those together with the tale the diagnostic tests tell, and find the end of the story. This time, I was stuck in the labyrinth. Severe dental disease can sometimes cause liver problems, so it was conceivable his mouth was the major source of his troubles. It was also possible he had liver disease completely independent of his mouth … and I still didn’t know for sure why he was moaning.

“If you want more definitive answers, I can refer you for abdominal ultrasound and ultrasound-guided liver biopsy,” I offered. “Or I can prescribe oral antibiotics and medication to support his liver and recheck blood work in two to four weeks.” Considering Zeus’ age, and not wanting to put him through too much, we settled on the latter option.

It felt like we had opened Pandora’s box when we started testing, but this case shows the importance of doing preoperative screening, especially in older patients. Remember that the last thing to fly out of Pandora’s box was Hope. We hope Zeus responds to medication, his liver function improves, and by proceeding with any necessary dental or other medical care, we can help him be happy and healthy.