A Keswick Ridge meat cutter says three of the roughly 50 deer that have been brought into his store this year have featured an overbite deformity that is known by some as "dork deer."

Evan Brewer has only been running B & E Meat Cutting for two years, but he grew up hunting and butchering animals.

But with all the deer he'd seen, he never spotted one with an overbite. That is, until a customer brought one in this season.

I've heard everything from in-breeding to spraying, to just a rare birth defect. - Evan Brewer, meat cutter

"The first time you see one, you think maybe it's just a one-in-a-million type thing," Brewer said.

"But when you get three in one year, it kind of makes you wonder."

The condition is formally called mandibular brachygnathia, or underdevelopment of the lower jaw.

Brewer was curious, so he posted photos on the business's Facebook page and hunters chimed in with possible theories and photos of their own "dork deer," as they are called in the community.

"I've heard everything from in-breeding to spraying, to just a rare birth defect," Brewer said.

The Department of Natural Resources did not respond to requests for an interview on Monday.

Ugly but tasty

Derek Donahue is an avid hunter who shot one of these deer in the same area, outside Stanley, four years ago.

Derek Donahue harvested this deer four years ago outside Stanley. (Derek Donahue) "It wasn't underweight, it didn't look to be in distress or nothing over it," he said.

"It was actually a little bit heavier than most of them are."

In fact, Donahue said that somehow, it was one of the tastiest deer he'd ever hunted.

But he hasn't seen one since, and when he asked fellow hunters about them, they didn't seem to know anything about it.

Shawn Ripley also shot a deer with mandibluar brachygnathia this year. It was the first one that B & E Meat Cutting saw this year.

Ripley confirmed that other than a little abnormality in the deer's behaviour, there was nothing different other than the jaw.

"I just assumed it was, you know, an abnormal jaw growth and never thought anything of it," he said.

On the rise

No experts were available for comment, and no large-scale studies of the deformity have been conducted in New Brunswick.

The lower jaw is severely under formed, leaving the top jaw hanging far over the bottom. (Derek Donahue) However, a study in Montana showed that the percentage of deer with jaw issues has increased between 1995 and 2011.

The deformity is widely believed to be due to congenital hypothyroidism, but it is not known what might be causing the thyroid difficulties.

Theories include genetic mutations due to inbreeding, pesticides and random occurrences.