The Gay Dog (1954)

From the pen of Peter Rogers and starring Wilfred Pickles (fan of) in his first film, along with Megs Jenkins, Petula Clark and minor roles for Peter Butterworth, Jon Pertwee and Noel Dyson.

The gay dog in question being a racing greyhound belonging to the Gay family, which is a regular winner but the family can never get a decent bet on it, until they dream up a plan to put it about that the dog had finally had it and was no longer a good racer, so the odds went up at the dog track and they could lay heavy money on it.

Just the sort of film I enjoy with gentle humour and a lot of fun.

That's interesting "gay dog" in the fifties meant womanizer. Not in the 70s though.

That's right - same as "he's a queer fellow", referring to someone who is odd.