A Queensland dog is recovering after a massive effort giving birth to her biggest ever litter.

Shadow, a Neapolitan Mastiff, managed to deliver a whopping 21 puppies this week.

The herculean effort has won her the Australian record for the largest litter.

The four-year-old dog birthed three puppies on Monday morning and then Shadow’s owner decided to take her to a vet to ensure she had the best possible care.

Veterinarian Patrycja Zimmermann said: “After four hours of no activity and a puppy that didn’t make it, her owner brought her into us expecting the worst.

“We took radiographs straight after Shadow’s arrival to see if any more puppies were on the way and made the amazing discovery of 10-plus puppies inside.

“We quickly checked the fetal heartbeats, and were praying for the best outcome for her.”

Over the next few agonising minutes, a team of 10 vets and nurses managed to find another 18 puppies that were alive thanks to an emergency caesarian.

During the birthing period, vets decided that Shadow had to undergo a procedure that would remove her female genital organs.

While that sounds drastic, it saved the dog’s life and potentially the lives of her puppies.