Pregnancy and parturition in the bitch Flashcards
How long is the gestation of a dog?
65 days +/- 24 hours from LH surge
63 days +/- 24 hours from ovulation
How can we calculate gestation from the mating date?
57-73 days
LH surge = day 0
Mating can occur before that
Oestrus behaviours/mating excepted anywhere from day 0-5
Need to factor in how long the egg and sperm can survive
Always check which date an owner is basing their expected due date on
Via what methods and when can pregnancy be diagnosed?
Ultrasound – day 25 onwards
Relaxin assay – day 30 onwards
Palpation- day 30 onwards
Radiography – day 45 onwards
What is the most sensitive method of pregnancy diagnosis?
Ultrasound
Describe the feature of ultrasound for PD
In smaller dogs having them held with their front legs in the air can help drop the uterus caudally and make imaging easier
Foetal heart beats can be detected from day 25 onwards – look for the ribcage. The lungs look heterogenous like liver (no air in them). Heart rates can also be counted
- Remember other processes can cause hypoechoic lesions e.g. pyometra, gastroenteritis
What are the main benefits of ultrasound for PD?
- Rapid detection
- No sedation needed
- Assessment of foetal heart rates
- Foetal measurements possible
- Earliest reliable detection method
- Owners love getting a print out of the image!
What are the limitations of ultrasound for PD?
- Accurate foetal count not possible
- Can see false negatives (scanned too early vs missed). If negative repeat in 2 weeks
- Operator learning curve
Describe the relaxin assay for PD
Relaxin can be used from day 23, but is significantly more reliable from day 30
External lab test so delay in reporting results
Not commonly used
Describe radiography for PD and why its used from 45 days onwards
- Foetal skeletal ossification occurs from day 42 onwards. Prior to this point you will not be able to differentiate between a pregnant uterus and fluid filled one.
- Day 45 gives this time to happen
- Less widely used in practice
- Bitch may require restraint and only operator safe way to do this is to use sedation
- Can count pups but not always easy
- Expensive compared to US
How long does stage 1 of parturition take?
6-36 hours
Describe the hormonal and behavioural changes that occur in stage 1 of parturition
- Drop in progesterone and rise in prolactin
- Temp drops below 37.5°C in large dogs and 37.0°C in small dogs when about to give birth
- Restless, anorexia, milk production, infrequent uterine contractions, nesting behaviour, vulval licking
- Cervix closed but gradually opens
How long does stage 2 of parturition take?
2-12 hours
Describe stage 2 of parturition
Rupture of the allenochorion of the 1st puppy
Strong regular straining -> puppy produced within 30 minutes
Describe stage 3 of parturition
- Expulsion of placenta
- May be expelled with or after puppy
- Retained placenta unusual in dogs
- Lochia passed for approx 3 weeks
How long is the interval between pups?
Interval between pups can be 5 mins to 4 hours
When do we start to worry?
Signs of foetal distress
Maternal problems
Delays
What are the signs of foetal stress?
Meconium visible (brown-yellow coloured) Green vaginal discharge without a puppy – indicator of placental detachment
What are some maternal problems which would cause worry?
Vaginal haemorrhage
Exhaustion/collapse or other systemic disease signs
Severe pain
After how long do we start to worry?
Foetus visible in birth canal with no progression to delivery
>30 mins strong contractions without a puppy
>4h between pups
Define dystocia
Difficulty in giving birth
What are some maternal factors linked to dystocia?
Uterine inertia: Primary or Secondary
Physical obstruction of birth canal e.g. narrow pelvis
What are some foetal factors linked to dystocia?
Oversized foetus
Malpresentation
Malformation
What is primary uterine inertia?
Failure to START stage two labour
Primary uterine dystocia is associated with?
Can be associated with litter size;
50% cases <3 pups
Very large litter – myometrial stretch and inability to contract