An emergency vet had to stitch up the hole – then safely deflate him back to normal. Picture: YouTube screenshot

London - Trevor the sausage dog always was a bouncy chap – but when his owners came downstairs one day, he really did look like a balloon.

The dachshund had filled up with gas after suffering a puncture to his windpipe, which saw him swell up each time he breathed in.

An emergency vet had to stitch up the hole – then safely deflate him back to normal.

Owner Fran Jennings, 49, from Lymm, Cheshire, said: "We came down one day and found Trevor in a bad state – he was three times the size he should’ve been. We took him to the vets and they had never seen anything like it."

Michelle Coward, of Beech House surgery in Warrington, diagnosed the four-year-old dog with subcutaneous emphysema – an abnormal collection of air under the skin.

"Every time he took a breath, the inhaled air escaped through a hole in his windpipe around the muscles and fatty tissue under the skin, and X-rays showed it was worsening," she said.

"Surgery was the only way to repair the injury... I have never seen a case like this before and it was a new surgery for me."

Thankfully, the operation was a success and Trevor made a speedy recovery, with no expectation of long-term impact on his health. The cause remains a mystery.