Three years into the $4.1 million deer-vasectomy program meant to reduce Staten Island’s herd, the horny animals are causing more car crashes than ever.

Lusty bucks and frisky does running rampant on the borough’s roads led to 103 accidents in 2018 — an all-time high — and injured 17 people, according to the NYPD.

The crash data reflected a 4 percent increase over the 99 deer-caused accidents reported in 2017 — and a 232 percent vault over the 31 collisions tallied in 2015, the year before Mayor de Blasio launched the world’s first attempt to control wild deer by sterilizing only males.

“At some point we have to confront the reality that it’s simply not working,” City Councilman Joe Borelli (R-SI) told The Post.

Borelli, whose South Shore district logged more deer-caused crashes than any other last year, said he spots deer carcasses frequently.

“The truth is that just about every single one of them will die in an accident that can also injure a person and damage property,” Borelli said.

The Sanitation Department picked up 291 dead deer last year, almost all from Staten Island roads — more than double the 141 carcasses gathered in 2016.

The city says the accident numbers are misleading. “It’s an increase in more accurate reporting, not necessarily an increase in collisions themselves,” City Hall spokeswoman Jane Meyer told The Post, pointing to the NYPD’s addition of a “deer” category to its accident-report forms in 2016.

White Buffalo, the environmental firm that has given more than 1,400 of the borough’s randy bucks the snip, estimated the herd size at 1,884 last spring, a total touted by the Parks Department as an 8 percent drop from the previous year.

But locals say they’re seeing more deer than ever as the costly vasectomy program wraps up its third and final season.

“This is a years-long — maybe even decade-long — process,” said Meghan Lalor of the Parks Department.