Dystocia Part 1 – Labour Stages & Diagnostics

Now most female canine patients are spayed; it comes as no surprise reproductive emergencies are not as common.

One area of confusion seems to be not knowing how to determine a true dystocia emergency from the process of normal partuirition, especially when having discussion over the phone with an owner who’s pet is going through the process.

Another concern is what diagnostic pathway to follow to determine the cause of dystocia, especially for reasons other than obvious physical abnormalities (for example, fetopelvic disparity and fetal malposition).

Often, once we decide to go down the medical treatment pathway, whether the result of findings or owner/financial constraint, no one is confident as to what medication should be used and how often drugs can be given safely.

This series of articles will address these issues in a step-by-step manner. Hopefully, by the end, you will be confident in the diagnosis and management of dystocia.

1. Labour stages

Before moving on to the signs of dystocia, let’s go through the signs of labour.

First stage labour

First stage labour is characterised by panting, tremoring, nesting behaviour, a drop in core temperature, usually a drop by almost 1°C 24 hours before second stage labour and a drop of progesterone to below 2mg/ml.  

The duration of first stage:

• Dogs: approximately 6 to 12 hours
• Cats:  approximately 6 to 24 hours

Second stage labour

Second stage labour is landmarked by the water breaking, visible abdominal contractions, and the allantoic/amniotic sac or fetal parts visible from the vulva.

If vulval discharge is present, it should be clear. Excessive amount of bright red haemorrhage, green or black discharge before delivery or purulent material can indicate a pathological process requiring immediate veterinary attention.

The duration of second stage:

• Dogs: approximately 3 to 6 hours
• Cats:  approximately 6 to 24 hours

Third stage labour

Third stage labour is when passage of all the placenta has occurred, generally within 15 minutes after passing a puppy or kitten.

2.  Clues

Now we understand the normal progression of parturition; a few clues exist in the history that could suggest dystocia may be present.

Some breeders will often know the ovulation timing of the patient, especially if AI was performed. Tests such as progesterone levels, luteal hormone (LH) levels, cytology, and vaginoscopy are some ways where it can help time the ovulation.

The normal gestation length should not be any longer than 66 days from the LH surge or, if the ovulation history is unknown, 72 days from the last known breeding.

History of prior dystocia is a warning, as most animals with prior parturition difficulties are more likely to develop dystocia again.

The same goes for animals that have previously required a caesarean. Their risk of requiring future caesareans is high, with possible further risk of uterine rupture if dystocia happens again.

3. Intervention signs

Owners often telephone after the failure of the normal progression of the delivery of a puppy/kitten. The signs that always require immediate intervention are:

• More than 4 hours have passed from the rupture of the first chorioallantois
• More than 2 hours between delivery
• More than 30 minutes of strong abdominal contraction and no delivery
• Presence of green or black discharge before delivery
• A large amount of bright red haemorrhage
• An abnormal amount of pain during contractions
• The collapse of the bitch or distracted mothering

Any of these signs require immediate presentation to the veterinarian. Delivery of stillborn puppies is also an indication where veterinary attention indicated.

Finally, if owners are concerned, it is best to advise veterinary assessment rather than try to convince them everything is okay based on what they describe over the telephone.

4. Diagnostics

Once the bitch presents to the clinic, a few basic diagnostic checks need completing to determine the status of the bitch/queen and the fetuses.

Physical examination

The first is a thorough physical examination, starting with the bitch or queen:

• Demeanour, hydration status, vital signs, mucous membrane colour, capillary refill time, and temperature are important.
• Pregnancy anaemia is not uncommon; however, for patients with a haemorrhagic discharge, it is important to know their cardiovascular status.
• Thorough abdominal palpation should be carried out to assess comfort level and palpation for the presence of fetuses. Palpating fetuses can be difficult and cannot confirm if no fetuses are present.
• A digital vaginal examination should be performed. The feathering response, also known as the Ferguson reflex in human medicine, is the neuroendocrine reflex where the self-sustained cycle of uterine contractions initiated by firm pressure on the dorsal aspect of the vestibulovaginal wall. If this is absent, the patient is unlikely to progress with the parturition unaided.
• Palpation of fetuses in the canal can help decide whether surgical management is required. Obvious fetal malposition, malposture or malpresentation, or fetopelvic disparity, will be indications of caesarean. Abnormal pelvic diameter is also another reason to not proceed with medical management. To confirm these suspicions, abdominal radiography is required.
• Radiographs will also help determine the number of fetuses to be expected, the signs of fetal death (presence of gas surrounding the fetus) and aforementioned fetomaternal abnormalities. I always repeat radiographs after the expected number of neonates is passed to make sure I have not miscounted at the start.

Ultrasound

Panel 1. Heart rate ranges to help indicate stress of fetuses

• Dogs:

Normal – 180 to 220 beats per minute (bpm)

Stressed – 160bpm

Real concern – less than 160bpm

• Cats:

Normal – more than 220pbm

Fetal stress – less than 180bpm

The second important diagnostic tool is ultrasound.

Fetal heart rates are good indicators of fetal stress. Some heart rate ranges that can help provide information about the status of the fetuses are detailed in Panel 1. These ranges vary between sources but are good guidelines.

Ultrasounds can also help visualise the maturation status of the fetuses. At-term fetuses should have normal hepatic, renal, and intestinal development. Intestinal peristalsis should be evident in at-term fetuses.

Other diagnostics

Other diagnostics may be indicated for patients, depending on the status of the bitch/queen:

• If the patient is stable, but dystocia is present, a minimum database would include PCV/total protein, electrolytes, glucose, ionised calcium, lactate, and acid-base balance.
• Serum ionised calcium levels are important, as they influence the strength of contractions and how much supplementation is required.
• Hypoglycaemia needs to be ruled out as a cause of dystocia, especially when large litters are involved.
• If the patient is unstable or systemically unwell, include complete blood count, blood smears, and biochemistry.
• Physiological pregnancy anaemia can be present. The presence of a regenerative response can help differentiate this from acute haemorrhage.
• Abnormal leukocyte panel, especially with the presence of degenerative left shift, can indicate the presence of an infection, especially if toxic changes are present in the neutrophil.

Part two will briefly look at the medical management of dystocia and when surgical intervention is required.