RECOGNIZING THE SIGNS OF A HEAT CYCLE & WHeN TO BReeD A BROOD BITCH
Whether you’ve been a dog breeder for a couple of years or for 10 years, you know that you can only breed a bitch when she is in season, or during her heat cycle. However, not all breeders realize that individual vari- ations in the timing of a bitch’s reproductive cycle could throw off the breeding schedule and cause failure to conceive. In general, females have two heat cycles a year that are about six to seven months apart and that last about two to three weeks. The estrous cycle consists of four phases: proestrus, estrus, diestrus and anestrus. Proestrus and estrus are the phases most familiar to breeders because this is when a
bitch is swollen, bleeding and other dogs are inter- ested in her. “Not all bitches have a regular cycle,” explains Cheryl Lopate, MS, DVM, DACT, a board-certified small-animal reproduction specialist at Reproductive Revolutions in Wilsonville, Oregon. “Sometimes there is little bleeding or swelling in the first days of proestrus, making it easy for a breeder to miss the signs, or sometimes a bitch’s proestrus is shorter than normal. Both could affect the ability to deter- mine the beginning of the fertile period. “On the other hand, some bitches may have a prolonged proestrus or prolonged estrus that lasts up to three to four weeks. Breeding these bitches too early will result in failure to conceive.” In contrast, “some bitches have a prolonged anestrus, in which they fail to enter estrus at all,” she says. “This can be caused by many things, includ- ing prior spay, delayed puberty, parasites, nutrition, ovarian hypoplasia, immune-mediated ovarian inflam- mation and progesterone-secreting cysts. It also may be caused by silent heat or failure of a novice breeder to notice a heat cycle because the bitch is fastidiously clean or not bleeding much.” The hormonal changes that occur in females during their reproductive stages relate to their ability to get pregnant. In the bitch, progesterone is a reproductive hormone that increases in the bloodstream just before ovulation. Progesterone rises due to lutenizing hormone being released from the pituitary gland, first in lower amounts and finally in a big surge that induces ovulation. Thus, progesterone testing is key to knowing the appropriate time to breed. If you know when the bitch is ovulating, or when the eggs are released from the follicles, this tells you the fertile window to optimize the chance of pregnancy and having a full-size litter. It also allows for the calculation of an accurate due date.
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