Why can't my dog get pregnant?

It can be frustrating when you’ve spent time performing all the appropriate health testing and finding the perfect stud for your female dog but your bitch still isn’t pregnant. Unfortunately, there are several key moments in the breeding process where you could run into challenges. Let’s look at some of the most common barriers to getting puppies in your whelping box!

Know what kind of problem are you having

To get back on track, you need to know WHY your dog isn’t getting pregnant. Working with a reproductive specialist (a veterinarian who is a DACT, or Diplomate of the American College of Theriogenologists) is the best way to make sure you get to the bottom of what is happening, which will give you the best chance of ensuring your dog can get pregnant and carry healthy puppies to term.

Common reasons for reproductive struggles:

1. Abnormal estrous cycling

Some dogs may have absent, delayed, or irregular heat cycles. Dogs typically go into heat by 24 months of age and then experience heat intervals of 4 to 10 months after that. 

A dog who has not experienced a heat cycle by 24 months has primary persistent anestrus, which may be caused by malnutrition, genetic issues, or hormonal imbalances. A dog who has an initial heat cycle, but does not cycle in the next 18 months has secondary persistent anestrus. Aging, infections, hormone imbalances, tumors, and medications can all cause a failure to cycle. 

Some dogs will experience a “silent heat,” in which ovulation occurs, but the signs of heat, such as vulvar swelling and discharge do not occur. 

If a dog enters heat and remains in heat for six weeks or longer, they are diagnosed with persistent estrus. This can be a sign of medical conditions such as ovarian cysts or tumors.

In general, irregular heat cycles suggest that the ovaries are not functioning optimally. A reproductive veterinarian can help you figure out why with diagnostics such as a complete blood count (CBC), hormone testing, screening for viral disease or reproductive abnormalities, and vaginal cytology.

2. Failure to copulate (breed)

Sometimes, everything seems to be set up for success, but your bitch and stud fail to copulate; the female may refuse to stand, and the dogs do not tie. Failure to copulate can happen if the dogs are immature or otherwise not ready to breed, the timing of the female’s estrus is off, or if either dog is stressed. 

In some cases, medical issues such as osteoarthritis or any pain associated with mating (such as previous vaginal trauma) can increase a female’s reluctance to stand. 

3. Failure to conceive

Your bitch and stud tied - and now you wait. But not every tie leads to puppies. 

• Poor timing

Poor timing is one of the most common reasons that a tie fails to result in pregnancy. How is timing determined? Progesterone testing allows you to monitor progesterone levels to alert you to when ovulation has occurred. Approximately two days after ovulation is when the egg is first ready for fertilization.

An in-depth introduction to progesterone, and how best to measure it can be found at the WellBredVet.com. 

• Infection or inflammation

Infections of the vagina or uterus or by viruses such as brucellosis and canine herpesvirus can interfere with successful insemination and conception.

• Male infertility and sperm quality

Your male dog may have issues with fertility. A good place to get started is with a semen analysis, which can help you determine whether your dog’s sperm is healthy, active, and present in sufficient amounts to impregnate a female. 

• Age of the breeding dogs

Infertility is more common in older dogs who may be less likely to conceive. Although dogs do not experience menopause, older females may go into heat less often, have smaller litters, and have more puppies that do not survive. Older male dogs are more likely to have prostate enlargement, which can impact their fertility.

If an artificial insemination was performed on your dog, keep in mind that technique matters, and even when everything is done correctly, there is a chance that the procedure will not take (reported success rates are up to 80%). 

4. Puppy loss

Unfortunately, with some pregnancies, not every puppy will survive. There are several diseases, such as brucellosis, herpesvirus, and parvovirus, that can cause embryonic death and  resorptions, abortions or stillborn pups. There are also genetic variants, such as the Harlequin gene, that when inherited in a homozygous fashion, can cause puppies to die in utero.

Even with a successful birth, puppies can still experience high mortality rates in their first few weeks of life. Genetic and health testing before breeding can help reduce these losses.

Quick list: Tests for your breeding dogs to increase success

Good breeding starts with healthy dogs. You can work with your veterinarian to give your dogs the best chance of a successful pregnancy. They may recommend:

• Genetic tests
• Blood work
• Brucellosis testing
• Hormone assays
• X-rays/ultrasound
• Vaginal cytology 

How to find a reproductive veterinarian

If your dogs are having challenges conceiving, we recommend seeking out help from a veterinarian with a special interest in or who specializes in reproduction. A veterinarian who is also  board-certified in reproductive medicine is known as a theriogenologist. Reproductive specialists typically offer services ranging from progesterone testing, artificial insemination, ultrasound, to birthing assistance or Cesarean sections. You can find a theriogenologist at the Society for Theriogenology, or you may be able to find recommendations from fellow breeders.

Resources

VCA: Infertility in Female Dogs

Revival Animal Health: Why Won't My Dog Get Pregnant?

Cain, J. L. (2001). A logical approach to infertility in the bitch. Veterinary Clinics of North America: Small Animal Practice, 31(2), 237-245.

England, G. C. (2010). Clinical approach to the infertile bitch. In BSAVA Manual of Canine and Feline Reproduction and Neonatology (pp. 51-62). BSAVA Library.

Farstad, W., & Berg, K. A. (1989). Factors influencing the success rate of artificial insemination with frozen semen in the dog. Journal of Reproduction and fertility. Supplement, 39, 289-292.

Grundy, S. A., Feldman, E., & Davidson, A. (2002). Evaluation of infertility in the bitch. Clinical techniques in small animal practice, 17(3), 108-115. https://www.sciencedirect.com/science/article/pii/S1096286702800214