Dog Reproduction and Estrous Cycle

Study Notes

Estrous Cycle of Dogs

Consists of four stages: Anoestrus, Pro-oestrus, Oestrus, and Meta-/Dioestrus.
Pro-oestrus lasts approximately 10 days, where females exhibit hormonal changes.
Oestrus follows, also lasting about 10 days, characterized by receptiveness to mating.
The Luteal Phase lasts around 2 days, which involves hormone production from the corpus luteum.
Anoestrus usually lasts about 4.5 months, a period of reproductive inactivity.

Gestation Period

The average duration of gestation in dogs is approximately 64 days.

When to Seek Veterinary Assistance

Weak straining persists for over 2-4 hours.
Strong straining lasts more than 20-30 minutes without progress.
No progress occurs 2-3 hours after fetal fluid release.
If a puppy is due to be born in 2-4 hours but no green discharge appears.
Post-delivery, if the queen has no discharge or it is red-brown for more than 2-4 hours.
Failure to expel after more than 12 hours in the second stage of labor.

Transabdominal Ultrasound (US) for Fetal Monitoring

Normal fetal heart rate is between 180-240 beats per minute (bpm).

Reproductive Phases

Anoestrus: Dominated by oestrogen, lasts 4.5 months.
Pro-oestrus: Approximately 10 days, prepares the reproductive system for mating.
Oestrus: Also lasts about 10 days; the period of receptivity to mating.
Luteal Phase: Lasts around 2 months, characterized by high progesterone levels.
Average Gestation Period: Approximately 64 days from conception.

Indicators for Veterinary Intervention

Weak straining persisting for more than 2-4 hours may indicate complications.
Strong straining for over 20-30 minutes requires immediate attention.
If no activity has occurred 2-3 hours post-passing of fetal fluids.
The presence of a puppy within 2-4 hours of green discharge or red-brown in queens.
If more than 2-4 hours have elapsed since the last puppy and more are expected.
More than 12 hours in the second stage of expulsion signals a potential issue.

Transabdominal Ultrasound and Fetal Monitoring

Normal fetal heart rate: 180-240 bpm.
Heart rate below 180 bpm indicates fetal distress.
Heart rate drops below 150 bpm at full term is concerning.

Immediate Veterinary Intervention Measures

Oxytocin: Used to start or continue labor, contraindicated in obstructive dystocia.
A recorded body temperature exceeding 39.5°C is a sign of potential complications.
If the placenta has not been expelled within 4-6 hours, intervention is necessary.

Clinical Signs of Approaching Parturition

Reddened or enlarged teats may indicate hormonal changes.
Increased heart rate is commonly observed as parturition approaches.
Significant increase in appetite and weight gain during pregnancy.
Relaxation of perineal tissue and vulva is noted as a sign of impending labor.

Plasma Relaxin and Pregnancy Confirmation

At 25 days gestation, abdominal palpation can detect pregnancies as early as Day 21-32.
Puppies can be balloted starting at 30 days of gestation.
Ultrasonography can confirm fetal heartbeats between 24-28 days.

Pseudopregnancy

Occurs naturally in all entire non-pregnant bitches; also seen in queens after sterile mating.
Characterized by elevated prolactin levels.
Typically resolves after 'parturition' or simulated birthing behavior.

Predictions for Parturition Timing

Based on progesterone level exceeding 1.8 ng/mL as an indicator:
- +1 day prediction accuracy: 67%.
- +2 days: 90%.
- +3 days: 100%.
Notable drop in body temperature can signify imminent parturition.
Progesterone levels above 5 ng/mL are relevant later in pregnancy.

Description

Explore the key stages of a dog's estrous cycle, including anoestrus, pro-oestrus, oestrus, and meta/dioestrus. Understand the average gestation period and important signs of when to get involved during the birthing process. This quiz will help solidify your knowledge on canine reproduction.