His main subject may be terminally ill, but director John Zaritsky says Leave Them Laughing isn’t just another doc about dying.

‘I’m hoping people will get the message that this is different, funny, as well as being insightful,’ says the director, speaking shortly before the debut of his new film at Toronto’s Hot Docs. ‘I guess I’m partly nervous about it because the film is something quite different from most docs on death.’

The feature bows tonight, and follows California-based singer/comic Carla Zilbersmith, who was diagnosed with Amyotrophic Lateral Sclerosis (a.k.a. Lou Gehrig’s Disease) in 2007. She is now confined to a wheelchair and has some four years left to live. The film follows her over six weeks as she makes the most of life – singing and doing stand-up comedy – while reflecting on her failing health.

Despite the heavy subject matter, the film is often quite light-hearted. Zilbersmith and her son, Mac, ‘made it really easy on us. I’ve never had so many laughs in my entire career on any shoot, anywhere,’ says the Vancouver-based director.

In fact, he met the Canadian ex-pat because of one of her jokes, when he stumbled upon her name in Canadian national newspaper The Globe and Mail just over a year ago. ‘They had two pages of memorable quotes from the year and in the midst of this was a joke about dying that actually made me laugh,’ he recalls.

Zilbersmith had mentioned how much it ‘sucks’ to have a disease named for a baseball player because she hates baseball. She wished instead that she had ‘a basketball disease, like Wilt Chamberlain, who had sex 20,000 times and then he died.’ He found her blog, called her up and pitched what he saw as ‘a musical comedy about dying.’

Once filming began, though, he was often struck by the ‘sobering realization… that Carla was dying and we were in fact, racing against the clock trying to capture her on film.’

Zaritsky, a 30-year veteran with an Oscar on his mantle for a 1983 edition of the CBC’s the fifth estate, paid for the $450,000 film out of his own pocket, a first for him, with help from producer Montana Berg of Magical Flute Films.

‘I realized that if I’d waited for the traditional forms of funding to kick in, Carla would be too sick to do it,’ he explains. ‘Either we acted then and put money into the film or it wouldn’t get done.’