Isaac Barber-Axthelm helps Niki Fadden examine the back molars of a dairy cow.
Student Niki Fadden spent the summer of 2013 working on a research project that investigated the dental health of local dairy cows. She chose the project because there wasn’t much research on the subject and she was curious. “I wanted to see what their teeth looked like, if they had dental problems, and what kind,” she says.
For the study, Fadden arranged to work with three local dairies; two were conventional dairies, where all the cows are indoors and fed a mixed ration, and one was an organic dairy where the cows are pasture-fed. When a cow died or was euthanized, Fadden travelled out to the dairy to collect its head; just the head. This created quite a stir amongst the dairy employees. “I severed the heads myself,” she says. “Lots of times they came out to watch me.” Apparently, they had never seen a young woman with a knife disarticulate a cow head and stuff it in a trash bag. “I said, ‘You think this grosses me out? This is nothing.’”
Back at the Veterinary Teaching Hospital, Fadden froze the heads, ran them through computed tomography (CT) and took radiographs. Then, working with Drs. Mecham and Bildfeld, she performed gross exams in necropsy.
“We wanted to compare the three different diagnostic types for looking at dental pathology,” she says. “Our thought was that maybe imaging would show a lot more of the pathology than you can see in a gross exam. I wanted if an oral exam in a cow would provide you a picture of what is actually going on. It turns out it does.”
In the course of this investigation, Fadden discovered that there were a lot of transverse ridges on the cow’s teeth. “You would think that their teeth would be relatively flat with all the grinding they do, but they can develop sharp points like horses do,” she says. “In a horse, those are normally floated down. But they don’t float cow teeth – it is not common.” This led Fadden to another question: Is it possible to develop a system for floating cow teeth?
“Through the CT images, I went in and looked at every single tooth and measured the dentin thickness over the pulp. The average was about 4-5 mm. It is not enough for floating; you would end up frying their tooth and damaging the pulp.”
She made another discovery: “Something interesting we found was that cows can develop hooks on their very back molars. Some of the girls we looked at, their hooks were so bad, they were puncturing the gingiva.” This could be a concern to farmers if the hooks cause ulcers and effect the cows ability to eat. “If they can’t eat, then they can’t produce milk,” says Fadden.
Fadden also found that the hooks were composed of pure dentin and enamel, and therefore could be corrected with floating.
The discovery of the dental hooks last summer resulted in another research opportunity for Fadden this summer. “Since hooks are the only dental pathology we found that you can correct, I wanted to know how often hooks occur,” she says. So she went back to the same three dairies and examined the teeth of one hundred cows on each farm. “I wanted to get a good representative age sample of the population so I grouped them by lactation number, which basically represents the numbers of babies they have had and is also an indicator of age.” She also randomized the samples to make them as statistically valid as possible.
Her research yielded some interesting results: nearly one third of the cows had hooks. “Some of them were pretty large,” she says. “In general, of course, the older cows had more, but even the three and four year-olds had hooks.”
