Is it possible that my neutered dog impregnated my female?

So, my Male Newfoundland has been neutered for some time now, and our female mastiff was NOT fixed.She got mounted by a Golden Retriever on accident and got pregant, or so we thought...but now we are a little worred. Rosie (the English Mastiff) just jas a 12 pup liter. She's light tan with only the slightest black aorund her nose (i mean slight, its barely there). The Golden retriever was golden red....all her puppies are black with white spots on their chests....Here is where is gets weird. Gunner ( the Newfoundland) is black with a white marking on his chest...but he's been fixed.I know alot of people are going to ask for how long he's been fixed cause in some rare cases about a month after the procedure he could still impregnate a female, but he's been fixed for about a year.So my question is: Is it possible that his sperm stayed active for that long? or is it possible for the Golden retriver to still be the father? and lastly, can a neutering prodedure fail?I should also make it known that the only time she was not watched for more than a couple minutes was the one time she was knotted with the golden retriever. She was never knotted with any other dog, unless it was the Newfie.Our Newfoundland was sick at the time and had messed in the kitchen (where they sleep) so we let the dogs outside to clean it. It was the first and only time during her entire heat (or any other time as a matter of fact) that she was not watched. The also happened to be the time that she was found knotted. A neighbors dog smelled her stench and came onto our property.We were going to spay her right after her heat, but her being pregnant it was not an option.So you can give us crap for the puppies, but our intentions were never to just breed randomly.Thank you very much.Both the Newfoundland and the English Mastiff are purebred papered Dogs.

No - impossible that your Newfie mix tied with your female to produce offspring.It was the Retriever. Best have the female spayed after she's weaned the litter.

No the Newfy didn't impregnate the mastiff. My guess is there was another dog involved as well as the Golden Retriever.If the GR had access to the Mastiff, what's to say other male dogs didn't have the same access.Now you have a litter of 12 cross bred puppies to rehome. May I suggest you spay the Mastiff as soon as the vet will do the surgery so there is no repeat performance of a huge cross bred litter. How on earth will you rehome all those puppies?ADD: @ Alison, you are incorrect. The testicles are not 'squeezed' in a neuter. They are removed by pushing them higher up into the abdomen and they are tottaly removed through the incision. In most cases the scrotum remains but there are no testicles remaining.

There is a slight small possibility. When they neuter dogs they basically squeeze their testicles they do not actually remove them like people assume. So yes 1% chance. Very very rare like someone winning the a billion dollar lottery but it has happen.

See, that is where you are wrong. Spaying her after she tied would have been the BEST decision you made. I hope you will do it now so no more unplanned litters end up happening. Who cares if both of the dogs are papered? The puppies are still mutts so it doesn't matter WHO the father is. When you place an ad to give them away call them Mastiff mixes (the "English" was dropped many years ago).