Reasons for Small Canine Litters

A male dog should be producing approximately 10 million sperm per pound of body weight to successfully impregnate a female dog. A 70-pound male Lab should be producing 700 million sperm. While some assume the female dog is the cause of a small litter, this is not true. There are many different factors that can cause a small litter -- from the type of breed to the age of the male dog, or even the embryos themselves.

  1. Female Dogs: Health

    • Certain health issues can result in smaller litters. For example, thyroid deficiencies can result in fewer eggs being released, thus resulting in a smaller litter. The genetic background of the female dog also is important, because genetics play a huge role in breeding. Inbreeding in dogs can result in smaller litter sizes. Other diseases and illnesses that can affect litter size include Pelger-Huet anamoly, dystocia and T-strain mycoplasma.

    Female Dogs: Age

    • The age of the breeding dogs can affect litter size. This does not necessarily only point to older dogs, however. Generally, either the youngest dogs and the oldest dogs will produce the smaller litters, but this is not a guarantee. For many dogs, the first litter is small,but the following litters increase in size. By the time the female is approximately 5 years old, litter size will begin to decrease again.

    Male Dogs

    • It is not always the female dog that is the cause of the small litter. Health issues in males, such as a thyroid deficiency, can result in a decreased sperm count. These low sperm counts can translate into smaller litter sizes in an impregnated female dog. Furthermore, as a male sire ages, he produces less viable sperm naturally, though this tends to be more toward 6 years of age and older.

    Breed

    • Smaller breeds tend to produce smaller litters, just as larger breeds produce larger litters. For example, a Labrador may produce a litter of five to 10 pups while a Yorkshire terrier may only produce a litter of two to five pups. Though five pups are possible for smaller dogs, such as the Yorkie or the Chihuahua, a study on litter size by the Crown Partners and Royal Canin found that 80 percent of all litters produced by these breeds generally produced only four puppies or fewer.

    Embryos

    • The embryos also can be the cause of a smaller litter. It is always possible that more embryos were present at some point of the pregnancy, but were reabsorbed for any number of reasons. For example, issues during development can result in the death an embryo, causing absorption to occur. These developmental issues may be the result of trauma to the mother, genetics, exposure to illnesses or infections, or vaccinations.

    Nutrition

    • Nutrition of a pregnant female is incredibly important. During the last three weeks of pregnancy, pups gain approximately 75 percent of their birth weight. This translates into greater nutritional requirements for the mother. If these nutritional needs are not met, pups can die, resulting in still born pups and a decrease in the number of surviving puppies.