Can Dogs Get Pregnant by Two Dogs?

Planning on the patter of tiny paws? 

A female dog comes into heat twice a year. If you are planning on a litter of puppies, then timing is everything, especially if the female is to mate with a stud dog. However, Mother Nature may have other ideas. Her priority is to perpetuate canine kind and she's not fussy about who father's the litter. 

Imagine then, the scenario where a purebred female from a rare breed escapes while in heat. Those jangling hormones are going to send her looking for a mate… but it might not be the breed you had in mind. What are the implications for any subsequent purebred mating and any puppies born?

YES!

Mother Nature has some aces up her sleeve when it comes to dogs and pregnancy, so let's take a look at what these are.

Two factors conspire to give the female the greatest chance of falling pregnant. These are:

• Sperm can remain viable in the female reproductive tract for around 7 days

• The female doesn't have to ovulate on the day she is mated to fall pregnant

Long story short, there's a lot of flexibility in the timing of fertilization. This gives scope for two (or more) lots of sperm to lurk in the female reproductive tract to fertilize an egg.

To understand this better let's look at a female dog's estrus, or heat, cycle.

• She comes into estrus or 'heat' twice a year

• Each season lasts approximately 3 - 4 weeks

• The first 7 - 10 days the female's vulva enlarges, she bleeds, but she won't stand for a dog

• The middle 5 - 10 days the female ovulates. This is when she will stand to be mated and may fall pregnant

• The last 7 - 14 days she slowly comes out of heat

• Ovulation can occur at any time during that middle period

• Unfertilized eggs can survive for around 48 hours

If two male dogs mate with the female on the same day, it's a straight swimming race between the sperm as to which reaches the ovum first and fertilizes it. 

If different males mate with the female on different days, she can fall pregnant by both of them. This is because the sperm survive for days in her tract, and are ready and waiting when she does ovulate.

Once the deed is done, there is no undoing the mating other than to abort those fetuses and wait for her next season. If your purebred girl was caught by the local stray, there's nothing you can do to selectively destroy his semen. When the plan was to have a pedigree litter you have two choices: 

• Accept a mixed litter of puppies, some purebred, some crossbred

• Abort the litter with two injections of Alizin, and then wait for her next heat

In the general scheme of things, if the girl is healthy enough to undergo pregnancy, then being pregnant by two dogs of a similar or smaller size to her is unlikely to cause problems. 

The issue comes if there is a size mismatch between the mother and father, where the father is much bigger. This can mean the pups in the womb are larger than the female is designed to carry, which could make it difficult to give birth. 

Likewise, if the father was a breed such as a Bulldog, with a big head, this raises the possibility of dystocia (difficulty giving birth) and a cesarean may be necessary. 

One parting thought: Do you adore Cavapoos and love Labradoodles?

The hybrid dogs are the result of matings between different dog breeds, so why not go with the flow and see what delightful mix the happy accident brings forth!

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Sophie is a purebred Curly-coated Retriever. Her owner mates Sophie to a show-champion sire in the expectation of producing a litter of outstanding puppies. However, the day after the mating Sophie escapes and stands for the neighborhood stray. In a flap, the owner contacts the local vet who confirms her worst fear: Sophie can fall pregnant to two dogs. Worse still, there's no way to selectively eradicate the stray's sperm in preference to the stud dog. 

After some soul searching, the owner realizes that all the puppies have an equal right to life, regardless of their pedigree, and she lets the pregnancy progress. Sophie gives birth to a delightful litter of healthy pups, and happily, they all find homes.