In this article, Stefano Romagnoli, DVM, MS, PhD, DECAR, University of Padua, Padua, Italy, explores, among other things, why ovulation timing is important and how it can be applied in breeding bitches.
Canine breeding is increasing in popularity worldwide, and subsequently, reproduction problems are becoming increasingly common. The following are the most common veterinary reproduction concerns presented to the author:
1. Ovulation Timing
Identifying the day of ovulation in the bitch is becoming increasingly important in small animal practice, not only for maximizing fertility but also for proper management of canine parturition, high-risk pregnancy management, and cycle manipulation with hormone therapy (Table 1). The most practical way to identify canine ovulation is to perform vaginal cytology every 2 to 3 days starting from the onset of proestrus and then running progesterone assays once vaginal epithelial cells reach ≥50% superficial cells. Serum progesterone is typically <1.0 ng/mL in early proestrus, around 2.0 (±0.5) ng/mL on the day of luteinizing hormone (LH) surge, and 4-10 ng/mL at the time of ovulation. Canine ovulation may take up to 2 to 3 days; oocytes then require an additional maturation period of 48 to 72 hours before fertilization is possible.1 Canine oocytes are viable for up to 170+ hours postovulation, but because of the time required for canine oocytes to mature, the optimal breeding time is 2 to 4 days postonset of ovulation. Conception can occur, albeit with likely a small litter size, if the bitch is bred as early as 7 days before or as late as 5 days after ovulation.
Table 1: Reasons to Time Ovulation in the Bitch
|Maximize conception rates and litter size
||Breed on days 2 and 4 postovulation with fresh or fresh-chilled semen or on day 3 and/or 4 postovulation with frozen semen
|Predict date of parturition
||Due date is 63 days (+/- 1 day) from ovulation; ovulation must be properly timed using vaginal cytology and serum progesterone assay
|Evaluate proper breeding management in the diagnostic investigation of fertility cases
||Bitches bred outside their optimal fertile window will have questionable fertility
|Choose the right time for hormonal administration
||Progestogen treatment or estrus-inducing drug administration should be avoided during the 2-month diestrus window to avoid overdosing or lack of efficacy respectively
From ovulation timing to pyometra, urinary incontinence, and ovarian remnant syndrome to benign prostatic hyperplasia, this article shares what you need to know. View now.
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