A dog fight in the skies appears to be escalating after the Canadian Transport Agency announced it will look into health complaints about allowing pets in passenger areas of planes.

Anger by asthma and allergy sufferers has been flying high ever since Air Canada recently announced it would allow pet owners to carry dogs and cats under 10 kilograms with them onto planes, rather than delegating them to the cargo hold.

West Jet has let pets on board for years. Guide dogs will always be allowed but pet owners say being able to carry all pets on board is a big convenience.

The federal government has hired an allergy doctor to write a report about the health effects of dogs and cats on allergic people, so it can better make a decision on whether to ban pets in the cabin.

"I think it's a good idea because I have a small animal so if I wanted to travel, I would want it on board and not stuck in the back in the cargo," one pet owner told CTV News.

But people suffering from allergies say bringing a pet on board isn't fair to them.

"It would be a very uncomfortable flight for me. My head would get stuffed up. I'd be coughing and sneezing," said Elaine Newton.

People suffering from allergies now have a major organization on their side. The Lung Association is leading a campaign to get pooches out of the passenger cabin.

"It's a public health issue for air passengers and crew who may have asthma or severe pet allergies," said spokesperson Cameron Bishop.

At least one respirologist says pets in the skies can be dangerous for some people's health.

"Having (at pet) at 40,000 feet is a huge deal and it really becomes a safety issue," said Dr. Thomas Kovesi, a pediatric respirologist at the Children's Hospital of Eastern Ontario in Ottawa.

The airlines say they can come up with ways to minimize the risks by limiting the number of pets in the cabin to four on big planes, and two on smaller ones. It says those with sensitivities can call ahead and book a seat as far away as possible.

But Kovesi says limits to the number of animals on board aren't enough, and airlines need to make a choice.

"The airlines have to ask themselves which are more important: people or pets? And pets are important, but I think people are more important," he said.

Airlines mostly implement their own policies on whether pets should be treated as cargo:

• American Airlines allows up to seven pets in the cabin at a time, but pets may also travel in the cargo hold.
• Air France, Alitalia and KLM allow small pets under a certain weight to travel in the cabin.
• European Union rules require they carry documentation of all shots and have a microchip implanted.
• Delta Airlines allows dogs, cats, and birds.
• Cathay Pacific requires all pets travel in the cargo hold.