Polk County Sheriff’s deputies arrested Donna Byrne Thursday for riding a horse while drunk. (Courtesy of Polk County Sheriff’s Office)

Nothing’s unusual in Florida, a sheriff department spokesman said Friday. But some things — like a woman arrested this week for allegedly riding a horse while drunk down a busy highway — are still surprising.

Around 3 p.m. Thursday, a passer-by saw Donna Byrne, 53, on the horse looking confused and possibly in danger and notified officers, according to her arrest affidavit. Sheriff’s officers found Byrne on Combee Road near North Crystal Road in Lakeland, about 35 miles east of Tampa. She smelled of alcohol and had red watery eyes. When she dismounted from the horse, she staggered from side to side.

Byrne had ridden the horse for a 10 to 15-mile stretch from Polk City, said Brian Bruchey, a spokesman for the Polk County Sheriff’s Office.

Byrne is being charged with driving under the influence while operating a vehicle — which in her case was a horse equipped with a saddle and bridle. She is also charged with animal neglect for putting the horse in danger of being injured or killed.

“We haven’t had a horse DUI that I’m aware of. We’ve had incidents of bicycle DUIs and motorcycle DUIs, so this was a different kind of thing.”

Donna Byrne, 53, is charged with a DUI for riding her horse drunk on a Florida highway. She also faces a count of animal neglect. (Courtesy of Polk County Sheriff’s Office)

Whether an intoxicated person on horseback can be charged with a DUI or DWI varies from state to state.

In 1993, an appellate court in California ruled in People vs. Fong that people riding animals on the highway are subject to the same rules as the drivers of automobiles, meaning people must ride their animals at a reasonably safe speed and avoid reckless behavior.

The issue was a hot topic in Montana in 2011, when the state’s department of transportation aired an advertisement featuring a horse picking up its owner after a night of drinking at the bar. In Montana, horseback riders can’t be arrested for driving under the influence, because state law’s criteria for a vehicle in a DUI excludes devices moved by “animal power.”

Several criminal defense lawyers in Florida interviewed by The Post are skeptical of whether the DUI charge will hold up in Florida court. Thomas Grajek, a Tampa attorney who specializes in DUI cases, said he thinks Byrne can’t be charged with a DUI because Florida law states that people riding animals on roadways or shoulders are treated as pedestrians, and are not subject to the same rules as automobile drivers. Grajek said that, if anything, someone riding a horse drunk might be charged with disorderly conduct, similarly to a publicly intoxicated pedestrian.

Officers arrested Byrne after conducting a sobriety test, during which Byrne registered blood-alcohol levels of .157 and .161, twice the state’s legal limit of .08. The horse was taken to the Polk County Sheriff’s Animal Control livestock facility, officers said.

“The road she was stopped on was a very busy road,” Bruchey said. “Of course, if somebody hit the horse, then that person would be in danger. And (Byrne) was a danger to herself.”

The Polk County State Attorney’s office could not be immediately reached for comment. Bruchey, the sheriff’s department spokesman, said the officer who arrested Byrne thought he had sufficient probable cause to consider the horse a vehicle.

“I can tell you it’s going to be interesting if (the DUI charge) goes through,” Bruchey said. “The way sheriffs look at it, the woman put a saddle and bridle on this horse and was riding it to get from point A to point B. For all intents and purposes, we look at that as a vehicle.”

Byrne’s criminal history includes five felony and ten misdemeanor charges, consisting of cruelty to animals, drug possession, probation violation and criminal traffic, officers said. She could not be reached for comment.

Read more: 

Mayor quotes Jay-Z after not guilty DUI verdict

Disney knew its property had alligators. It caught hundreds before a boy was killed.