Controversies in ovulation timing (Proceedings) - Veterinary Healthcare


Controversies in ovulation timing (Proceedings)


The investment in time a veterinarian makes in providing ovulation timing can be challenging. This is easily offset by training technical personnel to counsel breeders correctly about breeding management and details of the bitch and dog reproductive physiology. Prepared handouts are invaluable. After the initial consultation and examination, follow up visits for ovulation timing do not require office calls which could disrupt the normal busy flow of a practice catering to sick patients. Once a patient-doctor-client relationship has been established, bitches can be presented for ovulation timing appointments with technicians. It is perfectly reasonable to have a receptionist or technician receive the dog from the breeder, walk it into the treatment area for sample acquisition, and return it to the client within a matter of moments, without involvement of the veterinarian. Some breeder clients insist on staying with their dogs throughout any procedure, these clients can be taught to restrain their bitches properly for vaginal cytology, vaginoscopy, and/or venipuncture. Technicians can be taught to obtain and perform vaginal cytologies in a matter of minutes; these results can be relayed to the breeder client immediately. Vaginoscopy is a skill that is also readily taught to qualified technicians, with immediate interpretation possible. In house progesterone kits offer results in 15-30 minutes. The results of progesterone assays sent out to a commercial laboratory are subsequently relayed to breeder clients by telephone. Thus, the time investment by a busy veterinarian is minimal once proper technical training of staff has occurred and practice management has been structured. The fees charged for such services should be fair: they should cover the veterinary clinic costs adequately for technician time, laboratory costs and interpretive skills. However, they need to be affordable enough that breeder clients will return a bitch 3-6 times during a cycle for completion of ovulation timing. An average ovulation timing in a California practice (vaginal cytologies, serial progesterone assays and vaginoscopies) costs approximately $200-$300.00. If the client and bitch have never been seen at the practice, an initial office call for physical examination and establishment of the patient-doctor-client relationship is necessary. It is of utmost importance that the breeder relay to the practice what type of breeding is being planned: natural, fresh artificial insemination, chilled extended semen that is shipped, or frozen semen, as arrangements for the latter two need to be made well in advance. Clinic costs can be contained by reducing unnecessary office calls, performing all vaginal cytologies in house, having technicians perform sample acquisition and run tests, and bartering with commercial veterinary laboratories on the cost of progesterone assays.

Reproductive Physiology

Sound knowledge of the bitch reproductive cycle is essential, as individual bitches will have interesting variations of normal, be presented at variable times during their estrous cycle for evaluation, and sometimes exhibit pathologic variations in cycles. Each of these scenarios requires veterinary interpretation. Controversies in ovulation timing arise in interpretation of the normal events of the bitch reproductive cycle, as they relate to the optimal way to predict or identify the fertile period. The normal canine reproductive cycle can be categorized into 4 phases, each having characteristic behavioral, physical and endocrinologic patterns. Considerable variation exists within the normal range of events in the reproductive cycle. The clinician must differentiate between bitches with normal estrous cycles but unexpected patterns and those with true abnormalities. Detection of individual variation within the normal range of events in a fertile bitch can be crucial to providing effective counseling concerning breeding management. Evaluation of the estrous cycle for true abnormalities is an important part of the workup of the apparently infertile bitch.

The interestrous interval is normally 4 to 13 months, with 7 months the average. The anestrus phase of the estrous cycle is marked by uterine involution and endometrial repair. The normal bitch is not attractive or receptive to male dogs. No overt vulvar discharge is present, and the vulva is small. Vaginal cytology is predominated by small parabasal cells, with occasional neutrophils and small numbers of mixed bacteria. The endoscopic appearance of vaginal mucosal folds is flat, thin and red. The physiologic controls terminating anestrus are still under investigation, but involve the spontaneous deterioration of luteal function and the decline of prolactin secretion. It has been shown that the administration of dopamine agonists shortens the interestrous interval, which in some instances is associated with inhibition of prolactin release (prolactin is luteotrophic). The natural termination of anestrus is induced by an increase in the pulsatile gonadotropin-releasing hormone (GnRH) induced secretion of pituitary gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH). Hypothalamic GnRH secretion is itself pulsatile, its intermittent secretion a physiologic requirement of gonadotropin release. Mean levels of FSH are moderately elevated, and those of LH slightly elevated during anestrus. At late anestrus, the pulsatile release of FSH increases, causing proestrous folliculogenesis. Estrogen levels are basal (2-10 pg/ml) and progesterone levels at nadir (<1 ng/ml) at late anestrus. Anestrous normally lasts from 1 to 6 months.


Click here