The female grey tortoiseshell cat was blind and very thin with overgrown nails.
The man was spotted leaving the cat in a street in Falkirk before running away.
The 66-year-old, named locally as Iain Morrell, passed away after being airlifted to Edinburgh Royal Infirmary.
Animal welfare charities welcome change in law that comes into effect today after receiving Royal Assent.
The Scottish SPCA is investigating the 'suspicious circumstances' surrounding the incidents in North Ayrshire.
The dog was believed to be aged between five and eight-weeks-old.