Government-backed plans to bring in a law to stop people who attack police dogs and horses from claiming self-defence have been derailed.
Environment Secretary Michael Gove had supported the so-called "Finn's law", debated in the House of Commons.
It is named after police dog Finn, who needed surgery when he was stabbed in October 2016.
But Conservative MP Sir Christopher Chope announced his objection to the proposed Animal Welfare (Service) Bill.
The Bill was tabled by Conservative MP Sir Oliver Heald and would have progressed further towards becoming law if Sir Christopher, who has a reputation for derailing private members' bills, had not objected.
The rules in Parliament mean it only requires one MP to shout "object" to block a bill's progress once time for debate has concluded at 14:30 on a Friday.
Sir Oliver said he was "disappointed" following the debate, but said he was "hopeful" upon the Bill's return to the Commons on 6 July.
Speaking prior to the debate Mr Gove had offered his full support.
You may also be interested in:
Finn's handler PC Dave Wardell, from Hertfordshire, said the dog - now retired - saved his life when a robbery suspect they were pursuing turned on them with a knife in 2016.
Finn was stabbed in the chest and head but did not let go until reinforcements arrived, and was initially thought unlikely to survive.
But while the suspect was charged with ABH in relation to wounds to PC Wardell's hand, he faced only criminal damage charges over the injuries to Finn.
The bill, if passed, would amend a 2006 Animal Welfare Act to address concerns about defendants' ability to claim they were justified in using physical force to protect themselves from a service animal.