The state's RSPCA is slashing adoption fees - that can cost up to $420 - for about 1,000 loveable dogs, cats, guinea pigs and rabbits to $29 over the weekend, in an effort to clear the shelters across the state.

At such a low price, the animal welfare group is set to lose money after ensuring all anxious adoptees are desexed, microchipped, vaccinated and checked for behaviour and health issues.

"The $29 fee is nowhere near what it costs to prepare an animal for adoption, but if we can get hundreds of pets into permanent homes then that's a really worthwhile investment," RSPCA Victoria CEO Liz Walker said on Monday.

Contrary to common opinion, the stockpile of pets is not the result of unwanted Christmas gifts.

Many of the hopeful adoptees are kittens, found roaming after the warm summer months which is peak mating season.

Ms Walker said research indicated price had no effect on the level of care afforded to re-homed animals as long as pets were carefully matched to owners' needs.

"We monitor adoption promotions carefully and have found that the price someone pays to acquire an animal has no impact on return rates and no negative impact on the animal's welfare," she added.

Australian Associated Press