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Glossary of Breeding Terms

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Quite often, we are asked "what do you mean by that" when we are talking about breeding, owning, etc with our dogs. So, here is a list of common terms that we use in the dog breeding world. Knowing what these mean may help you to understand the whole process more!


  • Bitch - This is the term for a female dog.

  • Dam - This is the name given to the mother of a litter or female in a mating pair.

  • Stud - The stud is an intact male dog that performs the breeding.

  • Sire - The father of the litter.

  • Litter - This is a group of puppies that are born from the same pregnancy.


  • Heat cycle - This is a period in the bitch's reproductive cycle in which she will be able to mate to produce puppies. It's characterized by a bloody discharge, the release of eggs for fertilization and a period of active willingness to breed. This usually lasts up to 28 days in total.

  • Ovaries - These are reproductive organs that release ovum for fertilization during a bitch's heat cycle.

  • Eggs - This is the common term for reproductive cells that are created when ovum are released from the ovaries and are fertilized by sperm. A fertilized egg is known as a zygote and develops into an embryo once it implants in the uterine wall.

  • Sperm - These are minute organisms produced by the male that fertilize the bitch's eggs and deliver the stud's DNA.

  • Vulva - This is the opening to the bitch's reproductive tract. The vulva swells considerably at the beginning of the heat cycle and then softens to facilitate breeding.

  • Penis and testicles - These are the stud's reproductive organs designed to produce and deliver sperm.

  • Gestation - This term applies to the entire period of pregnancy. A dog's gestation period is generally about 63 days.

  • Tie - This term is used to describe the swelling near the base of the dog's penis that temporarily binds the dog to the bitch during intercourse. As the swelling develops, the bitch's muscles clamp down around it to hold the organ in place. This helps to ensure proper delivery of semen, and though not completely necessary for producing a litter, it does increase the chance for fertilization.

  • Uterus - This is organ wherein the embryos attach and grow throughout the pregnancy.


  • Whelp - This is a term used to describe a newborn pup.

  • Whelping - This is the act of giving birth, and it is also simply known as "labor."

  • Whelping box - This is a prepared box in which the bitch gives birth.

  • Contractions - These are spasms of the uterus that are designed to propel the pup along the birth canal toward delivery.

  • Water bag or Sac - This is the thin yet durable membrane or "birth sac" that surrounds each puppy in utero. Nearly all pups are born in this protective sac which must be broken immediately after the pup is born or it will suffocate.

  • Umbilical cord - This is the fleshy cord that is attached between a pup's abdomen and the placenta. It must be severed after the pups' birth either by the mother chewing the cord or by cutting it with sterilized scissors.

  • Placenta - This is the organ that attaches each embryo to the uterine wall. It supports each pup's growth and development by delivering oxygen and nutrients, and also by carrying waste away via the umbilical cord. When a puppy is born, its umbilical cord is still attached to the placenta. The placenta may be delivered with the pup, or it may take a few minutes longer to be delivered with the next contraction.


  • Line breeding - This term refers to a planned breeding between family members used to secure desirable qualities in the progeny. Line breedings include breedings between grandparent/ grandchild, uncle/niece, aunt/nephew half-brother/half-sister and breedings with relatives even further apart.

  • Inbreeding - These are breedings between closely related individuals including mother/son, father/daughter and full-brother/full-sister. Such breedings are typically undesirable and may produce congenital defects in the pups.

  • Outcrossing - A breeding between two non-related dogs.

  • Dual Sire- This is a pregnancy resulting in the use of two fathers (each egg can be fertilized by a different male). Either by AI or naturally done. The purpose of this would be to increase the ability to produce puppies complimenting their chosen sires during one breeding. This should only be done with proper education and the willingness to DNA parentage test each and every puppy to determine the sire. 

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