Labrador and Collie cross Bella and Irish setter-English spaniel Archie should both have been "snipped" but weren't able to due to the lockdown.
Despite the best efforts of owner Mary Killing, 51, to keep the pair apart they ended up mating and Bella got pregnant.
Between July 26 and July 27, Mary, a mum-of-five, watched in astonishment as her 15-month-old pooch gave birth to 16 pups.
While one of the animals sadly died, the incredible birth is still one of the largest single deliveries ever.
Mary, who's from the small Irish village of Crecora in Limerick, said: "The neutering appointment was cancelled during the lockdown as it was not considered urgent.
"We tried keeping Bella and Archie apart, we tried nappies, Vick's VapoRub and we separated them for a couple of days.
"It wasn't to be though."
The litter began arriving at the Killing family home late on July 25 and finally ended with the 16th pup in the early hours of July 26.
It is thought to be the largest ever delivered in Ireland, with eight boys and eight girls arriving in just a few hours.
Mary said: "I was in absolute shock. The vet had told us she was going to have eight to 10 puppies.
"So having 15 was quite phenomenal. It's a record I think."
Mary said she was watching Game of Thrones when Bella started panting heavily and gave birth right there on her lap.
She then moved the pup on to a large duvet to deliver the rest.
Mary said: "We had to get a suitcase the following morning to put them into to count them as they were wriggling all over the place.
"It was just phenomenal. We were in awe."
Mary has been able to care for the pups, as she has been working in her role with the University of Limerick from home.
She said: "It's been tough, it's been hard work."
The family are keeping one of the litter, first-born Walter – named by 11-year-old Isaac after Where's Wally because he kept hiding.
The rest of the pups are going to family and friends, including one to her eldest son Josh, 24.
Mary is not charging for the dogs and is only asking they are loved and treated like a member of the family.
They are due to go to their forever homes this weekend.