There has been an alarming increase of pets surrendered to the Ottawa Humane Society over the last year, the organization says, because owners can't afford the animals.

In the last year, the humane society has seen a 20 per cent jump in the number of animals surrendered for financial reasons.

It told CBC News the most popular case is an owner bringing a pet in after an expensive visit to the veterinarian.

Bruce Roney, executive director of the Ottawa Humane Society, said more pet owners need to avoid impulse pet buys. (CBC)

"Often these are emergency situations, a dog that is ill or has been hit by a car," said Bruce Roney, the humane society's executive director. "These are very costly things for [the humane society] to take these animals, perform the surgeries and then re-home them."

Now the organization is warning pet lovers to avoid making impulse decisions and think about the costs that come with owning a pet.

"They're thinking, 'free kitten'," Roney said. "They don't realize that, that kitten is going to cost them - just for routine care - about 900$ a year."

Basic care for dogs is even more expensive, according to Roney, at about $1,100 per year. It also costs an added couple hundred dollars for spaying or neutering a pet and some pet surgeries can cost thousands.

Pet insurance, which runs about $30 per month, is one way to avoid the high cost of pet care.