Canada Post employees interact with thousands of dogs on the job every year. The majority of those instances are friendly and leave tails wagging. But the postal service says about 500 end with workers being bit.

With warmer weather on the way and the COVID-19 pandemic keeping people at home ordering packages, Canada Post is set to launch an awareness campaign Monday aimed at helping both canines and letter carriers stay safe.

"Dogs hate the mailman" is an old cliché, but when things go wrong it can have a devastating impact. About 150 carriers are injured each year, according to Canada Post.

"We've had somebody bitten on the face by a dog before. Or the dog might nip you in the calf … or in the arm," explained Jan Simpson, national president of the Canadian Union of Postal Workers (CUPW).

"Those kind of injuries might require you to go to hospital and get stitches and be off for a little bit of time as your body heals."

Postal staff working in Hamilton, Burlington, Niagara and Norfolk County were bit by 60 dogs and one cat between 2015 and 2019, according to records provided to CBC News under Access to Information laws.

Thirty-one of those injuries were considered disabling.

People love their dogs, and owners are likely to insist their particular pet would never bite someone, but it's impossible for postal workers to know if a pooch is just excited to make a friend or over-protective of its home.

"Most of our people are dog owners and we've worked with our unions and local safety teams to ensure customers understand that when a dog is running loose towards a mail carrier ... they have no idea if they are just friendly and playful or otherwise," explained Canada Post spokesperson Jon Hamilton.

Canada Post is asking animal owners to keep their doors closed when the mail is being delivered and to give staff some space when they're out in the community — both to maintain physical distancing and to decrease the risk of someone being bit.

Bites can stay with someone

The CUPW is asking anyone with a dog to keep it on a leash when they're outside and to make sure screen doors are locked.

That's because the effect of an animal attack can last longer than a hospital visit, according to Simpson.

Canada Post is asking people and their dogs to keep their distance from carriers. (Ryan Remiorz/Canadian Press)

Many letter carriers keep the same route for decades, but an aggressive dog can change that in an instant.

When someone returns to work after recovering from a bite and they run into the same pet "right away you feel the hesitation and the memory of what happened," she said. "Sometimes they might actually have to change their route because they have that memory or PTSD almost from a dog bite."

Carriers have a few different strategies to protect themselves, including putting a dot on a package of mail to identify a home where a potentially dangerous dog lives when they leave for vacation.

They're also equipped with dog spray for "extreme cases where they could be physically harmed," said Hamilton.

Anyone who's carrying spray is told by a supervisor how to use it and, if an animal is sprayed, their owner is notified.

"We work with the dog owner to ensure we can deliver safely going forward," said Hamilton. "The dog owners are usually just as devastated when an incident occurs."

Cats, birds and bears too

Most of the conversation around bites focuses on dogs but, as the records obtained by CBC indicates, cats can be culprits too.

Those nips and scratches seem to happen when someone is pushing mail through a slot in a door, said Simpson, who has also heard of birds and spiders as other natural hazards for workers.

"We all know pets are part of our families, but letter carriers are part of the community … and we just want to be able to be safe and do our work," she pointed out.

In northern communities and British Columbia, bears can also present a threat, she said.

Right now teeth and claws aren't the only danger.

Lea Duck, a letter carrier with Canada Post, wears a mask as she delivers mail in downtown Vancouver. The Canadian Union of Postal Workers is asking people to wipe down their mailboxes and doorknobs to keep carriers safe from COVID-19. (Ben Nelms/CBC)

Postal workers have been deemed essential during the pandemic, which introduces a range of opportunities for exposure.

The CUPW is asking people to wipe down their mailboxes, door knobs and railings to keep carriers safe.

"We talk about being an essential service or an essential workplace," said Simpson. "But we also have to make sure the health and safety of these workers is also essential, not just their labour."