Carrie Symonds has denied rumours that she and husband-to-be Boris Johnson are planning to rehome their Welsh rescue dog Dilyn.
An article in The Times suggested the Jack Russell-cross could be "quietly rehomed before the couple have their first child in early summer."
But Miss Symonds took to Twitter to deny the claims, branding the article "a load of total cr*p!"
She said in a Tweet: "There has never been a happier, healthier and more loved dog than our Dilyn."
Dilyn was adopted by Mr Johnson and Miss Symonds in September when he was 15-weeks-old.
He had been abandoned by a Welsh puppy farmer before being rescued by the animal charity Friends of Animals Wales.
Last week Mr Johnson told the Welsh Tory conference that Dilyn had brought a strong Welsh influence to Downing Street.
He said: "He is the randiest and most voluble Welsh occupant of No 10 since Lloyd George."
In February, Mr Johnson and Miss Symonds announced that they were engaged and expecting a baby in the early summer.
The couple made history as the first unmarried couple to officially live together in Downing Street when they moved in last year.