GOOD BREEDING MANAGEMENT PRACTICES IN FEMALE DOG

GOOD BREEDING MANAGEMENT PRACTICES IN FEMALE DOG

Dr.Chandrakala Sinha,Canine Consultant.,Patna

Estrous cycle

Puberty and estrous cycling- Female dogs reach puberty, defined as the first observed heat, from 6 to 24 months of age, with an average onset of 10 to 12 months of age. Small breeds come into heat earlier than large breeds. The pubertal estrus may be a split or false heat. You may induce an early pubertal estrus by housing a young bitch with cycling females. Bitches cycle, on average, every 7 months. Some breeds cycle more frequently (German Shepherd dogs and Rottweilers may cycle as frequently as every 4.5 to 5 months) and some less frequently (Basenjis, dingos and wolf-crosses cycle yearly).

Stages

1. Proestrus

Length = 9 days average, range 0 to 17 days

Physical changes and behavior = The vulva is enlarged and firm. Vulvar discharge ranging in character from serous to serosanguinous is present. Male dogs will be attracted to the bitch but she does not stand for breeding, and often tucks her tail under tightly, sits down, or turns on the male dog.
Comparative images of the vulvas of an anestrous bitch and a proestrous bitch

Endocrinology = This is the follicular stage of the cycle. Estrogen concentrations rise during proestrus and peak at the end of this stage. Serum progesterone and luteinizing hormone (LH) concentrations are low.

2. Estrus

Length = 9 days average, range 3 to 21 days

Physical changes and behavior = The vulva may become less turgid as the bitch enters standing heat. The vulvar discharge may become straw-colored but can range from serous to serosanguinous in a normal bitch. Estrus, or standing heat, is defined by the behavior of the bitch; standing = remaining motionless as the male investigates her hindquarters, flagging = deflection of the tail laterally and muscular elevation of the vulva.

Endocrinology = Estrogen concentrations fall at the beginning of estrus. This decrease in estrogen, along with a preovulatory rise in progesterone, is necessary for appearance of breeding behaviors in the bitch, and presumably elicits the LH surge. A surge of LH is released from the pituitary on or about the first day of estrus, and causes ovulation of a primary oocyte 2 days later. Great variation in time of ovulation exists in the normal dog. After ovulation, CLs form and progesterone production begins. Measurement of serum LH is not routinely performed. However, measurement of serum progesterone concentrations easily can be performed and this data used to optimize breeding management.

3. Diestrus

Length = 60 days average, range 50 to 80 days

Physical changes and behavior = There are no characteristic physical changes or behaviors in diestrus. Small amounts of mucoid vulvar discharge may be present. Some bitches still stand to be bred early in this stage.

Endocrinology = Bitches maintain the CL for about 60 days whether they were bred or not at that cycle. Progesterone concentrations are high throughout. Diestrus ends with a decline in serum progesterone to less than 2 ng/ml. This is associated with whelping if bitch is pregnant, false pregnancy or no outward signs if she is not. The CL is the sole source of progesterone during pregnancy in the bitch.

4. Anestrus

Length = About 4.5 months average, so counting the approximately 2.5 months of proestrus, estrus and diestrus, the overall interestrous interval averages 7 months. This is a period of reproductive quiescence with no characteristic physical, behavioral or endocrinologic changes.

Breeding management

1. Ovulation timing
   Prospective methods

• Count days from estrus onset – Poor! Great variability exists between normal bitches although most bitches remain consistent as individuals; in one study evaluating 390 cycles in 102 bitches, duration from proestrus onset to ovulation did not vary significantly from one cycle to the next for a given dog.
• Progesterone assay – Progesterone begins its normal rise at the time of the LH surge that stimulates ovulation. Serum progesterone concentrations are about 2 ng/ml on the day of the LH surge, and 4 to 10 ng/ml on ovulation day. Knowing this, we can measure serial serum progesterones in a dog, and watch for the time of its rise to predict ovulation. Once progesterone begins to rise, reaching a concentration of about 2 ng/ml, ovulation will occur in 2 days.
• Luteinizing hormone (LH) assay – Because the LH peak lasts at most one day, blood samples must be drawn daily and at about the same time of day to increase chance of identifying the LH surge. This is cumbersome and expensive for the owner. One practitioners recommends freezing leftover serum from progesterone assays and running the LH test on samples believed to be indicatve of the LH surge, as a way to verify progesterone results without undue inconvenience or expensive to the owner.
• Breeding history – As far as is known, most bitches will ovulate on or about the same day of their cycle from one heat to the next.
• Change in lining of the vagina as noted vaginoscopically – In proestrus, the vaginal folds will be pink and edematous. In estrus, the vaginal folds will be white and wrinkled.

Vaginal folds during estrus
o Retrospective methods

• Diestrous smear – The abrupt transition from the complete cornification seen on cytology during estrus to the complete non-cornification seen in diestrus happens 6 days after ovulation.
• Whelping history – Gestation length is 62 to 64 days from ovulation. If good records are kept of the date of onset of heat and subsequent date of whelping, subtraction of 63 calendar days from parturition equals date and day of the estrous cycle when ovulation occurred.

1. Breeding timing

Sperm must undergo capacitation within the female tract; this requires about 7 hours. Normal sperm can remain viable in a normal female tract for up to 7 to 9 days. The ovulated oocyte is a primary oocyte which must undergo 2 meiotic divisions before fertilization can occur. This maturation process takes about 2 days. After maturation, the oocyte remains viable for 4 to 5 days.

Best conception rate occurs when the bitch is bred from 4 days before to 3 days after ovulation; best litter size is achieved when the bitch is bred 2 days after ovulation.

There are 2 possible breeding strategies:

• Breed every other day while the bitch stands
• Breed once, 2 days after ovulation

Normal canine breeding behavior

Estrus suppression

Ovariohysterectomy (OHE)

Advantages: Prevents conception, signs of heat, appearance of uterine disease, confers protection against later mammary cancer if the dog is spayed before or shortly after the first estrus.
Disadvantages: Cost, risk of anesthesia, permanent contraception, estrogen-responsive urinary incontinence, perivulvar dermatitis and obesity may be sequelae.
Progestogens – Progestogens exert negative feedback on the hypothalamus and pituitary, preventing release of gonadotropins and ovulation. The only progestogen currently approved is megestrol acetate (Ovaban – Schering). As of this writing, it is no longer commercially available. The drug can be dispensed through human pharmacies under other brand names. It can be used in 2 ways:

• Anestrus – 0.25 mg/lb po x 32 days
• Proestrus – 1.0 mg/LB PO x 8 days, begun within first 3 days of cycle
  Return to heat is extremely variable with a range of 2 to 9 months. Megestrol acetate should not be given to a bitch on her first cycle or for more than 2 consecutive cycles. If used as directed, there is no adverse effect on fertility. It is contraindicated in bitches with predisposition to progesterone-dependent disease conditions, e.g. previous pyometra, mammary nodules, or diabetes mellitus.
  Androgens – Androgens act by exerting negative feedback on the pituitary, preventing release of gonadotropins and ovulation.
  The only androgen currently approved is mibolerone. As of this writing, this drug is on indefinite backorder. Mibolerone has no progestational or estrogenic effects. Treat with 30 mcg/25# BW PO SID up to 1.8 ml daily for the length of time the dog is to kept out of heat (German Shepherd Dogs should get 1.8 ml daily regardless of body weight). Mibolerone must be started at least 30 days before the next estrus is due to begin. Return to estrus after the drug is withdrawn is variable, with an average of 70 to 90 days (range 7 to 240 days). This drug is not recommended for use in the pubertal heat, or for use in breeding bitches. No adverse effects on fertility have been reported. The drug is contraindicated in Bedlington terriers, bitches with androgen-dependent disease (e.g. perianal adenomas), or those with renal or hepatic dysfunction. Side-effects include clitoral hypertrophy and vaginitis.
  Testosterone often is used to suppress estrus in racing Greyhounds. While under racing stress, low doses (5 mg testosterone per os daily or 50 mg injectable testosterone esters monthly) suppress heat in the bitch.

Pregnancy termination

Up to 1/3 of bitches presented for pregnancy termination are not pregnant. If you choose to see a bitch immediately after a supposed breeding, be aware that absence of spermatozoa on a vaginal swab does not mean she was not bred. In general, methods that terminate pregnancy prior to day 40 of gestation result in absorption of fetuses while those after day 40 result in expulsion of fluid or tissues. Puppies passed after about day 55 of pregnancy may be alive and should be euthanized when passed.

OHE

Method: Physically remove the gravid uterus and both ovaries
Pros: 100% effective, protection against future mammary neoplasia, ovarian and uterine disease
Cons: Surgical and anesthetic risk, cost, permanent contraception, post-surgical complications

Estrogen (“mismate” shot)

Method: Estrogen slows movement of ova through the uterine tube, causes degeneration of ova, and alters the endometrium, affecting implantation
Pros: Low cost, effective if given mid-estrus to early diestrus (post-ovulation)
Cons: May induce pyometra, ovarian cystic disease and/or pancytopenia, ineffective if given at wrong stage of cycle, prolongs standing heat

Prostaglandin (PGF-2, Lutalyse)

Method: PGF-2 causes lysis of the CL with a subsequent decline in serum progesterone concentrations, and causes uterine contractions.
Pros: Effective at all stages of gestation after the fifth day of diestrus (250 mcg/kg SQ BID x 4 days), fertility unaffected
Cons: High cost, side-effects of hypersalivation, emesis and defecation, may cause early return to estrus. The GI side-effects may be minimized by concurrent administration of atropine (0.025 mg/kg SQ).

Dexamethasone

Method: Mimics normal decrease in progesterone induced at time of whelping (see Endocrine induction of parturition)
Pros: Effective after day 30 to 35 of pregnancy, can be given orally so dog need not be hospitalized (0.2 mg/kg BID x 10 days). Abuse potential minimal.
Cons: Short-term side-effects include PU/PD and vulvar discharge.

Miscellaneous

• Mifepristone (RU 486) or aglepristone (Alazine) – Blocks progesterone receptors
• Prolactin inhibitors – Bromocriptine (Parlodel – human product) or cabergoline (Dostinex – veterinary product)
• Combination therapy can be used, such as bromocriptine and prostaglandin

Pregnancy

General information

Fertilization occurs in the oviduct. The embryo enters the uterus as a morula day 8 to 12, and implantation occurs day 17 to 18. Dogs form an endotheliochorial zonary placenta with marginal hematomas containing the green pigment uteroverdin.

Gross image of a normal canine placenta

Gestation length = 62 to 64 days from ovulation. Due to variability in the time of ovulation compared to time of standing behavior in the bitch and the long time sperm are viable in the female reproductive tract, gestation length from a single breeding can range from 58 (bred late) to 71 days (bred early).

Pregnancy endocrinology – Progesterone must be present to maintain pregnancy. All progesterone is produced by the CL in dogs. No pregnancy specific gonadotropins are released.

Pregnancy management – Bitches are not handled in any different way in the first half of pregnancy. After mid-gestation, bitches should be exercised but not encouraged to jump as in agility or hunting. Diet can be altered after mid-gestation to a puppy or performance diet, with 28 to 32% protein, 17 to 22% fat, and omega-3 and omega-6 fatty acids.

Pregnancy diagnosis – This is confounded by the fact that all bitches maintain the CL and undergo a prolonged luteal phase. Endocrinologic tests and assessment of physical changes are unreliable.

• Palpation – Abdominal palpation should be performed from 28 to 35 days of gestation. Accuracy is poor in a tense or obese animal.

Demonstration of how to palpate for pregnancy

• Radiography – Less than 42 days of gestation you can see an enlarged uterus but cannot differentiate pregnancy from uterine disease. You can first see calcification days 42 to 45 from ovulation (variable number of days from breeding). Late in gestation, radiography is the best predictor of fetal number, and can be used to estimate fetal age and to assess for fetal death (chart below taken from Rendano V, et al. Vet Rad 1984;25:132).
  VISIBLE ON RADIOGRAPHS DAYS PRIOR TO WHELPING
  Mineralized fetus first observed (skull, spine, ribs) 21 (20-22)
  Scapula, humerus, femur 17 (15-18)
  Radius, ulna, tibia 11 (9-13)
  Pelvis 11 (9-13)
  13 pairs of ribs 11 (7-12)
  Caudal vertebrae, fibula, calcaneus, paws 5 (2-9)
  Teeth 4 (3-8)

Late gestation radiograph

Signs of fetal death include gas within or around fetus, collapse of the axial skeleton, overlap of cranial bones and/or failure of skeleton to calcify or fetus to grow; lack of signs of fetal death does not imply viability.

• Ultrasound – Fetal vesicles are first visible routinely day 24 to 28, and fetal heartbeats are easily visible after day 30. Fetal heart rate and movement can be used to assess fetal viability.

Mid-gestation pregnancy on ultrasound

• Relaxin – A commercial assay is available (Witness – Synbiotics). Accuracy is good after about 28 days of gestation.
• Miscellaneous – Acute phase proteins (fibrinogen), measurement of serum prolactin after challenge with naloxone
  Parturition / Dystocia Parturition

1. Endocrine induction of parturition

The fetus induces parturition. The hypothesized scheme is : Fetal ACTH causes release of fetal and maternal cortisol with subsequent decrease in progesterone secretion and increase in production and release of estrogen and prostaglandin. Dead or abnormal fetuses, or small litter size, may be insufficient to initiate labor.

Progesterone is thermogenic. As the serum progesterone concentration declines at the time of parturition, you will see a transient decrease in body temperature until other thermoregulatory systems take over. Most bitches begin labor within 24 hours of a rectal temperature drop to less than 99 degrees F.

2. Normal parturition

• Stage I = cervical dilation. This occurs secondary to increased estrogen and prostaglandins, and decreased progesterone, uterine contractions and the pressure of the fetus at the cervix. Contractions are not visible. The bitch is restless, pants and may vomit. Signs should increase in frequency and severity.
• Stage II = expulsion of fetuses. The cervix should be fully dilated. The length of this stage is variable, 6 to 12 hours on average. Abdominal contractions are strong and coordinated. The chorioallantoic sac may be seen first, then the pup with or without the covering of the amniotic sac. Puppies may present cranially or caudally. You ordinarily see passage of a neonate every 30 to 60 minutes. You should see passing of the first pup within 4 hours of labor onset, and the bitch should deliver pups at least every 2 hours thereafter. The bitch should tear away the amniotic sac and lick the neonate to stimulate respiration. If the bitch ignores the pup, tear away the sac and rub briskly with a towel. You may need to aspirate fluid from the pup’s respiratory tract.
• Stage III = expulsion of placentas. Placentas usually pass 5 to 15 minutes after each pup is born. The bitch may eat them; they have no known physiological value, and may cause vomiting and diarrhea.

2. Post-partum period

• Uterine involution
  Normal uterine involution is slow and may take up to 12 weeks; placental sites are visible histologically for up to 84 days post-partum. Administration of oxytocin to promote uterine contraction post-partum is only necessary if the pups are stillborn or not nursing.
• Lochia
  Lochia = normal vaginal discharge present for up to 3 weeks after whelping. Lochia should be sero-mucoid and odorless, ranging in color from pale brown to pale green. Lochia may be slightly hemorrhagic.
• Rectal temperature
  Slight elevation in body temperature is normal for the several days following parturition.
• Care of the neonates
  Warmth – Leave with bitch or provide an external heat source. Pups are incapable of thermoregulation until 2 to 3 weeks of age. Be careful with heating pads or heating lamps; pups are easily burned.
  Colostrum – All pups should nurse within the first 12 hours of life. Pups receive 75 to 80% of maternally derived antibodies from colostrum.
  Weight – The pups should double their birth weight by 10 to 14 days of age.
  Tails and dewclaws Dystocia

“dys” = difficult, “tokos” = birth

1. Causes Maternal
   * Obstruction of passage
   – Pelvis – congenital or acquired
   – Vagina – hypertrophy, neoplasia, developmental
   – Vulva – “infantile”
   * Abnormality of uterine function
   – Obese, debilitated, poorly exercised
   – Primary inertia = no second stage of labor seen, requires C-section
   – Secondary inertia = second stage starts but does not progress as uterine muscle fatigues. May be obstructive so be cautious with ecbolic agents.
   * Abnormality of pregnancy
   – Fetal fluid disorder
   – Herniation or torsion of uterus Fetal
   * Obstruction of passage
   – Relative oversize = birth canal too small
   – Absolute oversize = pup too big, birth canal normal
   * Developmental abnormality
   – e.g. fetal monster, hydrocephalus
   * Abnormal presentation, position, posture
   – Presentation = relation of long axis of pup to birth canal. Cranial and caudal are normal.
   – Position = relation of fetal vertebral column to birth canal
   – Posture = disposition of head and limbs
2. Determination of dystocia Questions to ask:

• Obvious malpresentation?
• First stage > 12 hours, second stage weak and intermittent > 2 to 3 hours, second stage hard > 30 minutes, > 2 hours between pups?
• Abnormal vulvar discharge? Pus, frank hemorrhage, green fluid (denotes placental separation)
• Rectal temperature decline > 24 hours ago?
• Signs of labor not progressing?
• Systemic illness in bitch?
• Prolonged gestation? Be aware that pups cannot be born prematurely and survive. Significant surfactant production occurs late in gestation, from 57 to 60 days of pregnancy. If there appears to be premature labor, treatment with betamethasone (0.5 mg/kg of maternal body weight) may enhance surfactant production in late gestation. Gestational age can be determined using ovulation data, radiographs, or serum progesterone concentrations.
• High risk pregnancy? (Previous pelvic trauma or dystocia) Presentation:
• History
• Previous disease or trauma
• Breeding dates
• History of previous whelpings
• Pups and progress at this whelping
• Temperature drop data
• Treatment thus far
• Physical examination
• General examination
• Abdominal palpation
• Digital vaginal examination
• Lateral abdominal radiographs
• Uterine monitors (WhelpWise)
  Treatment of dystocia Manipulative
  * Feathering
  * Digital manipulation
  * Instruments Pharmacologic agents
  * Oxytocin – Oxytocin acts as an ecbolic (causes uterine contraction). It may cause premature placental separation and should not be used in obstructive dystocia. Dose = 2 to 5 IU at 20 to 30 minute intervals, for no more than 3 to 4 doses if not effective. Suggested initial doses are 0.25 IU for dogs weighing less than 11 pounds (5 kg); 0.5 to 1 IU for dogs weighing 11 to 22 pounds (5 to 10 kg); 1 to 3 IU for dogs weighing 22-66 pounds (10 to 30 kg); and 3-5 IU for dogs weighing more than 66 pounds (30 kg). If there is no response to the initial oxytocin injection, progressively higher doses may be used, with an upper limit of 5 IU.
  * Calcium – Calcium increases strength of uterine contractions; oxytocin increases frequency of uterine contractions.
  * Glucose