A heartbroken mum has blamed an animal hospital for the death of her beloved two-year-old dog.

Devastated Emma Houson said family pet Cassie died because a swab used in a routine speying operation was left inside her, causing infection to the animal’s kidney and bladder that was only discovered more than a year later.

Miss Houson also alleged that, unknown to her, vets at PDSA PetAid hospital in Wakefield Road, Bradford, had failed to remove the dog’s womb during the procedure in September 2011. Cassie, a Staffordshire bull terrier, died on Monday at the Lorne Street hospital, hours after she underwent a second operation to remove her womb and the swab.

The dog’s infected kidney was also removed, said Miss Houson, and her bladder was treated.

However, Cassie failed to recover after the operation and suffered a seizure and heart attack.

Despite last year’s operation, Cassie began experiencing problems earlier this year. Miss Houson said the vet booked Cassie in for a second operation because they thought the dog still had some of her womb.

Miss Houson, 24, of Argent Way, Holme Wood, said: “They discovered the whole womb was actually left in there.

“They then found a swab, and that had infected her kidney and bladder. They told me they had removed a kidney and tried to clean up the bladder.”

At 1.20pm Miss Houson was told Cassie was in recovery but was critical. The news of Cassie’s death came at 5.30pm.

“I have a five-year-old girl who is devastated about it,” said Miss Houson.

“Cassie was part of the family, she was a lovely dog. I am really angry. It was a simple operation it’s not like she has been run over in an accident.”

Miss Houson, who says she was charged £30 for the first operation, added that Cassie had been with the family since she was eight weeks old.

She has also lodged a complaint with PDSA and said: “I would like this investigating.”

A PDSA spokesman said: “The loss of a family pet is always upsetting and PDSA extends its sympathies to Cassie’s owners.

“Due to strict confidentiality rules set out by the Royal College of Veterinary Surgeons, we cannot provide detailed comment on individual cases. However we would encourage any pet owner who has a specific complaint about PDSA’s charitable veterinary services to contact us with full details, so thatthe matter can be investigated.”