canine estrus breeding and management .pptx

MVSc, BVSc & AH syllabus topic
On canine reproduction

1. INTRODUCTION Average age of puberty Male dog 10 month (5 month to 2 year) B itches 6 to 10 month (4 month to 2 year ) Smallest breed bitches cycle earlier in life than the large and giant breed bitches.

2. CANINE ESTROUS CYCLE Bitches are monoestrus and nonseasonal They do not cycle continuously and do not cycle in response to season. Each cycle is at least 5 month in duration

3. Estrous cycle consist or four stage 1.Proestrus 2.Estrus 3.Diestrus 4.Anestrus PROESTRUS ANESTRUS DIESTRUS ESTRUS PREGNANCY 9 DAYS (2-25) 9 DAYS (2-21) 60 -100 DAYS 65 DAYS 4.5 MONTHS CONTI …

4. CANINE ESTROUS CYCLE 9 DAYS 9 DAYS Arbitrary Plasma Concentrations Days from Proestrual bleeding Estrogen LH Progesterone 2 4 6 8 10 12 14 16 18 20 DIESTRUS PROESTRUS 9 days ESTRUS 9 days ESTRUS OVULATION CONTI…

5. The reproductive cycle of the bitch, classified as monoestrus , is unique in several aspects.   1. Each cycle is at least 5 months in duration;   2. The follicular phase, period of sexual receptivity and luteal phase are longer than those found in most other domestic animals.   3. Pregnancy occurs within the normal diestrus phase rather than prolonging it.   4. A long period of relative ovarian inactivity termed anestrus arises between cycles whether the bitch is pregnant or not.

6. Proestrus Proestrus defined as the “Period of increased follicular activity preceding estrus” begins when vaginal bleeding is first seen and ends when the bitch allows the male dog to mount and breed.   The duration is on an average 9 days but can vary from 2 to 3 days to as long as 25 days.   Early proestrus behaviour includes an increase in playful, teasing activity but the female discourages any mounting attempts made by the male.   As proestrus progresses the female becomes more receptive by increasingly seeking males, playing and teasing.

7. Vaginal bleeding begins as Diapedesis of erythrocytes through the endometrium and Subepithelially as capillaries rupture within the endometrium.   Some dogs cease vaginal bleeding as proestrus proceeds into estrus . In these bitches the bloody discharge fades and becomes transparent to straw coloured .   Changes in color of the vaginal discharge are inconsistent, as some bitches have a bloody discharge throughout proestrus , estrus, and into diestrus while others bleed little or only at the beginning of proestrus .   Early through late proestrus is associated with a swollen and turgid vulva that could impede intromission by a male.   As proestrus proceeds into estrus the vulva softens.

8. Estrus   The estrus phase includes the time during which the bitch allows a male to mount and breed. The duration is on an average 9 days but may vary from 2 days to 18-20 days. Bitches in estrus attract males over long distance due to presence of potent pheromones and show receptivity to the male ,elevating the perineum ( lordosis ). Pressure placed on or near their lower back causes the tail to be held off to one side (flagging).   The vaginal discharge appears straw coloured .   The vulvar swelling is reduced and it becomes soft and flaccid.  

9. Ovulation   Early estrus (standing heat) is associated with the final maturation of developing follicles. Ovulation is spontaneous in bitches and occurs 48-72 hrs (2 to 2½ days or 3 days) after LH surge initiation. Greatest ovulation occurs 24 to 72 hrs after the LH peak. Plasma progesterone rises prior to ovulation Follicles will start luteinsation before ovulation.  

10. The number of ova released depends on breed of bitch with smaller breeds ovulating 2-10 ova and larger breeds ovulating 5-15 ova.   Ovulations do not occur as a single spurt (jet/spray) but continue to occur over a period of 12-96 hours.   Ovulated oocytes are primary oocytes and require 2 more days to mature and form secondary oocytes .   Following oocyte maturation the bitch remain fertile for 2- 4 days or longer.

11. DIESTRUS   This is the period following mating and is the phase of progesterone dominance following estrus and begins with the cessation of standing heat (estrus) and ends when progesterone levels return to basal levels (<1 ng /ml).   The duration ranges from 56-65 days in pregnancy and 60-100 days in non pregnant bitch.   The corpora lutea regress sooner in pregnancy probably due to effects of prostaglandins (fetus stimulates synthesis and secretion of prostaglandins).   The bitch no longer attracts males and the vulva returns to normal anestrus size.    

12. ANESTRUS   Anestrus begins with whelping and ends with proestrus and is the phase of the female reproductive cycle in which the uterus involutes.   In the non-pregnant bitch no demarcation between diestrus and anestrus is clinically detectable.   The duration of anestrus varies depending on breed, health, age, time of year, environment, and other factors.   A typical bitch has an anestrus of 4.5 months.

13. ENDOCRINOLOGY   Proestrus / Estrus   During early proestrus the 2-3 mm follicles selected by increased LH continue to grow after the LH surge become 9-12 mm by the time of ovulation.   The Bitch in proestrus is under the influence of estrogen, which is synthesised and secreted by the developing ovarian follicles. Estradiol concentrations reach peaks during proestrus causing significant vaginal epithelial cell proliferation and cornification.   Peak levels are achieved 1-3 days prior to LH peak after which it begins to decrease returning to basal levels within 5-20 days Decreasing plasma estradiol concentrations are associated with and stimulate onset of estrus.   LH and FSH levels decline to near nadir levels (lowest point) during mid and late proestrus probably due to oestrogen and inhibin negative feedback.  

14. LH Surge and Ovulation   * During the preovulatory LH surge, LH levels peak 1-3 days after peak in estrogen O ccurs during the last 2 days of proestrus or the first 2 days of estrus ) and last for 1 day . Progesterone concentrations are low throughout proestrus (<0.5 ng /ml) except during last 24-72 hours when progesterone levels start rising (1 ng /ml, the concentration required for induction of the behavioural changes typical of estrus) while estrogen levels are decreasing The progesterone is secreted by follicles which undergo luteinization , prior to ovulation and development of CL.    

15. CANINE ESTROUS CYCLE 9 DAYS 9 DAYS Arbitrary Plasma Concentrations Days from Proestrual bleeding Estrogen LH Progesterone 2 4 6 8 10 12 14 16 18 20 DIESTRUS PROESTRUS 9 days ESTRUS 9 days ESTRUS OVULATION CONTI…

16. The decreasing estrogen and increasing progesterone concentrations bring about 2 major events The bitch becomes receptive to the male (effect on secretion of pheromones)   • Strong positive feedback to the hypothalamus and pituitary leading to initiation of LH surge.  

17. Corpus Luteum Formation/ Luteal Phase   Following ovulation the corpus luteum thus formed is capable of synthesising and secreting progesterone.   Peak levels of progesterone (15 to 60 ng /ml) are achieved 20-30 days after ovulation (2-3 weeks after beginning of diestrus ). All non pregnant healthy bitches that have passed through estrus are “ Pseudopregnant ” in the sense they have a functioning corpus luteum despite lack of pregnancy ( Pregnancy recognition system does not exist in the bitch ).    

18.   Therefore, corpora lutea function throughout a normal gestational period regardless of the presence or absence of a fetus(s) ( progesterone assays cannot be used for diagnosis of pregnancy ). Luteal phase ends abruptly in the pregnant bitch (approximately 65 days after fertilization) as a part of onset of parturition.   However luteal phase slowly wanes in the non pregnant bitch lasting for an additional 10 to 30 days.

19. LH and Prolactin as Luteotrophic Hormones   Both LH and prolactin are luteotrophic within 2 weeks after ovulation and remain so throughout pregnant and non-pregnant luteal phases. In fact, prolactin is one of the key hormones of diestrus and is an important luteotrophic factor in canines by day 25 . Prolactin concentrations are low during anestrus , proestrus and estrus. As progesterone concentration decline in the latter half of diestrus , prolactin concentrations increase.    

20. An inverse relationship appears to exist between serum concentrations of progesterone and prolactin immediately prior to parturition as well as during pregnant and non-pregnant diestrus .   Administration of dopamine agonists after day 25 not only reduces but also permanently or transiently suppresses luteal function fully, causing abortifacient lowering of progesterone concentrations and shortening of luteal phase.

21. Conventional methods of breeding Behavioural or physical changes Changes in vaginal fluid Vaginal cytology

22. Straight forward Inexpensive reliable. Day 5 of PE 10-20 min contact. Rept. every third day Breed when bitch is willing . Continue to breed every third forth day till Refusal . BREEDING BASED ON BEHAVIOUR

23. Changes in vaginal fluid Proestrus - Serosanguinous (composed of serum and blood) to straw coloured Estrus - Tan-coloured (yellow brown colour)

24. BREEDING BASED ON VAGINAL CYTOLOGY Vaginal exfoliative cytology has proved to be a very useful tool for accurately monitoring the stages of estrous cycle in the bitch. The technique is used widely in managing canine breeding programs and understanding its applications and limitations increases its value.

25. Parabasal Cells Parabasal cells are healthiest and smallest of vaginal cells. They are round or slightly oval in shape with large vesiculated nucleus, relatively small amount of cytoplasm. Seen in anestrus Large nucleus Conti…

26. Intermediate Cells Vary in size - slightly larger or twice the size of parabasal cells. Cells have smooth, oval to rounded irregular borders, vesiculated nucleus which is smaller than those found in parabasal cells. Nucleus smaller than parabasal cells Intermediate cell Conti..

27. Superficial Intermediate Cells Superficial intermediate cells have angular, sharp, flat cytoplasmic border typical of superficial cells but the nucleus is still vesiculated nucleus vesiculated Conti..

28. Superficial Cells are the largest cells identified on vaginal cytology. Cells have sharp, flat, angular cytoplasmic borders and small pyknotic fading nuclei or no nuclei Conti..

29. Anuclear Squames or Cornified cells These are large, dead, irregular vaginal cells with no nucleus. These cells represent the end of the process that began with healthy round parabasal cells. Conti.. CORNIFICATION the process in which body tissues, such as nails, hair, and skin in humans, and horns in animals, become dry and hard  

30. When the smear shows >80% of superficial or cornified epithelial cells, the female should be bred. Breeding should be done once every second, third or fourth day of estrus until the bitch refuses to breed. Based on cytology studies ovulation were found to occur 2.4+ 0.39 days after 80% of vaginal epithelial cells were superficial and keratinized. Conti..

31. OVULATION TIMING IN BITCHES AN AID TO MODERN BREEDING MANAGEMENT

32. Ovulation timing tools - the aid to modern breeding management GOAL OF OVULATION TIMING IS TO DETERMINE THE LH SURGE To test breed apparently infertile bitches For AI using extended chilled or frozen thawed semen Could be used to accurately predict the time of whelping (65 1 day after LH surge) To determine the appropriate time for making pregnancy diagnosis or elective c-section

33. BREEDING BASED ON VAGINOSCOPY CANINE VAGINOSCOPY The changes in the vaginal mucosa during different stages of the estrous cycle is as follows

34. Anoestrus vaginal mucosa is relatively flat, dry and red in appearance . onset of proestrus mucosal folds are greatly enlarged, edematous, and pink or pink/white in color, with serosanguinous fluid in crevices formed by the folds. late proestrus or early estrus , Begins a progressive shrinking of the folds that is accompanied by pallor. (result of an abrupt withdrawal of the “water-retaining” edematous effect of estrogen) over the next several days in estrus Mucosal shrinkage occurs and causes minor and then gross wrinkling of the mucosal folds ( crenulation of the mucosal folds), that by day 3 or 4 after the LH surge become distinctly angulated.

35. A) Proestrus – pink fluid, edematous glossy folds. B)Onset of estrous – pale colour , onset of wrinkling of mucosa. Occurs just before LH peak. C)Mid oestrus - pale creamy colour , marked wrinkling (shrinkage) and angular mucosal profiles. D and e) Diestrous - mucosal folds are rounded with pale patches, sometimes close to forming rosette.

36. The onset of the peak fertile period can thus be detected by observing the onset of mucosal shrinkage without excessive angulations, whilst gross shrinkage of entire mucosal folds with obvious angulation is characteristic of the fertilization period . Matings or inseminations should be planned to coincide with the fertilization period , about four days after first detecting mucosal shrinkage, and at the onset of the period of obvious angulation of mucosal folds. The termination of the fertilization period can be detected by observing a decline or cessation of mucosal shrinkage, a flattening and thinning of the mucosa .

37. BREEDING BASED ON HORMONE ASSAY 1.LH ASSAY 2. PROGESTERONE

38. 1.LH ASSAY peak level to 4-40 ng / ml (occur during the last 2 day of proestrus or first 2 day of estrus ) Because duration of the LH peak averages about one day in bitches, samples must be drawn daily, at about the same time of day.     Mating or insemination should be planned between 4 and 6 days after the LH surge. LH ASSAY

39. 2.Correlation of serum progesterone conc. with specific reproductive events in the bitch SERUM PROGESTERONE ( ng /ml) EVENT LESS THAN 1.0 ANOESTRUS OR PROESTRUS 1.0-1.9 OVULATION MINUS 3 DAYS, RECOMMEND RECHECK 2.0-2.9 OVULATION MINUS 2 DAYS 3.0-3.9 OVULATION MINUS 1 DAY 4.0-10.0 OVULATION DAY - OVULATION PLUS 2 DAYS IS OPTIMAL BREEDING DAY 10.0-19.0 Fertilization period

40. The ovaries of a bitch can be identified using real- time diagnostic B-mode ultrasound. With careful and repeated examination it is possible to monitor follicular growth and to detect the time of ovulation. Ovarian Ultrasound Examination

41. Follicular phase of the ovarian cycle. Multiple thin-walled hypoechoic follicles are noted .

42. Ovulation: The ovarian follicles do not collapse . The corpora hemorrhagica are isoechoic to the ovarian parenchyma as compared with the previous follicles.

43. Optimal breeding day Natural/AI using Fresh and Extended chilled semen 2 days after ovulation AI using Frozen semen -3 to 4 days after ovulation No single test will pinpoint breeding time absolute accuracy, but combination of test will be useful in finding fertile period BEHAVIOUR . Is best method

44. Aberration of estrus cycle SPLIT HEAT Proestrus bleeding starts with vulvar swelling Not proceed to estrus , not receptive No treatment is required Second heat occurs 2 to 10 weeks later. Short interestrous interval : Interval from first cycle to next cycle is less than 4 month. No chance of pregnancy