What might cause a pregnant dog to miscarry?

What might cause a pregnant dog to miscarry?

Health & Safety

Making the decision to breed from your dog is not a choice to undertake lightly, and as well as thinking very hard about the decision itself, there is a lot of planning to be done beforehand to ensure that you give your dog and her litter the best possible start in life.

While most canine pregnancies go off without a hitch, problems can and sometimes do occur along the way, and some of the more serious threats to pregnant bitches can actually lead to miscarriage of the whole litter. This is not something that can always be foreseen ahead of time, regardless of how vigilant you are – but there are a range of factors that can increase or contribute to your dog’s chances of having a miscarriage, some of which can be prevented or avoided.

In this article, we will look at some of the most common factors that can cause or contribute to a pregnant bitch miscarrying. Read on to learn more.

The age of the dam

Bitches should be fully mature but not approaching old age in order to have the best chance of a successful pregnancy, and breeding from a dam that is too young is apt to lead to problems with carrying the litter and delivering it – and even in successful pregnancies, may result in smaller litter sizes and smaller puppies.

Prospective dams should be a minimum of two years old before breeding (and even older for some large, slow-growing breeds like the Newfoundland), because it takes time for a dog to mature physically and emotionally enough to carry and care for a litter. Additionally, some serious health problems like hip dysplasia don’t always become apparent for the first time until dogs are around two, and waiting until at least this time to breed can help you to ensure that your dam doesn’t pass on such a condition to her pups.

Breeding from dogs that are too old also has implications for the viability of the litter too, and dams should be fully mature and grown, but not heading towards their senior years.

The health of the dam and sire

Both the dam and the sire should be in peak condition and good health in order to breed, and a dam that is not quite 100% is apt to be too weak to manage a pregnancy, increasing the risk of miscarriages and other problems.

Hereditary health conditions

Most pedigree dog breeds have certain hereditary health conditions that are prevalent enough within the breed’s gene pool as to pose a risk to future populations, and some of these can lead to spontaneous abortion or miscarriage before the litter is even born.

If you do wish to breed from your dam, your first move should be to find out what hereditary health conditions pose a risk to the breed, and ensure that both the sire and the dam are tested where possible to confirm their status before going ahead.

Congenital health defects

Congenital health defects can arise in dogs of any breed, but much like hereditary health conditions, some breeds tend to be more at risk than others. Never breed from a dam or sire with a known congenital defect – even if they outgrew it or it was corrected – and find out if there are any testing schemes in place for your dog’s breed to identify congenital defects prior to breeding to reduce the chances of miscarriage.

Sexually transmitted infections

Sexually transmitted infections affect dogs as well as people – and brucellosis is by far the most common of these. Brucellosis doesn’t usually produce any symptoms or problems in dogs affected by it, but does greatly increase the chances of your bitch spontaneously miscarrying after conception.

Both the potential dam and sire should be tested for brucellosis prior to breeding, to prevent this from happening.

Other infections during pregnancy

If a pregnant bitch picks up another type of infection during pregnancy, this can have implications not only for her own health, but that of her litter too. Bacterial, viral and fungal infections are all a risk, and even if your dam weathers a minor ill while pregnant with no problems, you should still ask your vet to monitor your dam carefully to ensure that the puppies are coping ok.

Making sure that your bitch is vaccinated and up to date with her boosters can help to avoid some of the most serious canine health conditions, and you should keep a close eye on your bitch’s health during the pregnancy and act quickly if she seems to be coming down with something.

Hormone imbalances

Hormonal imbalances while pregnant can compromise the health and viability of the litter and lead to miscarriages or still births, which cannot always be prevented or identified ahead of time.


High stress levels can directly contribute to your dam miscarrying, so it is important to keep her safe, comfortable and happy, and feeling secure in her home. Avoid having lots of visitors or strangers around that your dog doesn’t know, and keep her bed and nesting box in a quiet area of the home.

Avoid stress, upset and things that might frighten your dam while she is pregnant, and take care to stick to her normal routine as much as possible.

Injury or trauma

An accident or injury can of course directly damage the developing litter too, as well as leading to stress and shock. If your dam has an accident, even if she appears to be fine, ask your vet to check her out and ensure that the pups are doing well too.

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