In Ontario, honking at a horse while driving is illegal primarily due to safety and animal welfare concerns. Horses are sensitive animals, and the sound of a car horn can startle them, potentially causing them to panic, lose control, or cause an accident. 

The law prohibiting honking at horses is part of Ontario’s Highway Traffic Act, which aims to ensure that all road users, including animals, are treated with respect and kept safe from harm. 

If a driver is caught honking at a horse in Ontario, the fine can vary, but it generally falls under “unnecessary use of horn” violations. The fine for using the horn in a manner that could startle or endanger a horse can be up to $110 or more, depending on the specific circumstances and local regulations.

To avoid fines and ensure the safety of both the animal and other road users, it’s best to remain calm and avoid honking when approaching a horse on the road. Instead, drivers should slow down, pass cautiously, and allow the rider to navigate safely.