Image copyright PA Image caption Four breeds are banned in the UK: the pit bull terrier, Japanese tosa, dogo Argentino and fila Brasileiro

An MP has pressed Theresa May to change dangerous dogs laws to stop pit bulls being treated as "collateral damage".

Labour's Gordon Marsden said pit bull-type dogs were routinely put down due to a law which designates bull terriers as a prohibited breed and judges them on physical attributes, not behaviour.

He said the thought of the rescue dog he owned being destroyed "because her face did not fit in court is chilling".

The PM assured him the issue would be looked at "very carefully".

Raising the issue at Prime Minister's Questions, Mr Marsden highlighted a recent report by the Commons Environment Committee, which called for an overhaul of the 1991 Dangerous Dogs Act and its specific breed definitions.

The pit bull terrier is one of the four breeds banned by the act, although owners can get a certificate of exemption if a court believes the dog is not dangerous.

MPs have said the law is dysfunctional because the majority of deaths caused by dogs since then have been by non-specified breeds.

They also criticise the fact that specified breeds cannot be transferred to new owners even if they are not judged to pose any threat.

Mr Marsden referred to comments made by Environment Minister Lord Gardiner, when he appeared before the committee, about the case of a pit-bull type dog which had to be put down by Battersea Dogs and Cats Home.

Asked whether he regarded the death of the dog, even though he may have been "good-tempered", as just "collateral damage", the minister replied yes.

The Blackpool South MP told Mrs May this was unacceptable and the specific breed definition needed to be reformed as a matter of urgency.

"Hundreds of pitbull-type dogs are confiscated yearly with no impact on dog-bite numbers," he said.

Image copyright House of Commons Image caption The MP said there was no correlation between confiscations of prohibited breeds and dog attacks

"Will the prime minister ask the environment secretary to act urgently on the committee's recommendations?

"My wonderful bull terrier-type dog was rescued from the streets and to think of her being destroyed because her face did not fit in court is chilling."

Animal charities have called for changes to the way pit-bull type dogs are assessed for the purposes of the law.

At the moment, their parentage and genetic heritage are not taken into account.

Dogs are evaluated, instead, largely on their physical characteristics, measured against a 100-point scale, of which ten points are allocated to the dog's attitude and behaviour.

The PM thanked Mr Marsden for highlighting this issue and pledged a review.

"I had not looked at the detail of the report on that particular issue but I can assure him that the environment secretary is himself a keen dog owner, as indeed is the chancellor, and he will be looking at this issue very carefully," she said.