Guinea Pig Dystocia

Guinea Pig Dystocia

Guinea Pig Dystocia is defined as the Inability of a Sow to deliver her litter of pups normally. Many variables can increase the risk of Dystocia. Most Dystocia in Guinea Pigs are associated with some kind of physical problem some may be due to the pup while others lie purely with the sow.

The most common cause attributed to Dystocia is when the Sow Is Bred Too Late. Female Guinea Pigs need to have their 1st litre less then 10 months of age, ideally they should be mated for the 1st time around 5-6 months of age as the Pubic Symphysis must be open to allow normal delivery of the pups.

What is the Pubic Symphysis?

The pubic symphysis in Guinea Pigs is a Fibrocartilaginous bridge that binds the Left & Right pubic bones that sit on the floor of the pelvic canal. As the Guinea Pig grows this bridge calcifies and becomes permanently fuse in Males & Unbred Females. In response to secretion of the hormone “Relaxin” the symphysis relaxes and stretches in the pregnant female allowing separation of the pubic bones. If Guinea Pigs are bred for the 1st time at greater then 6 months and certainly after 10 months of age, the pubic sympyhsis may have already fused together and will therefore be unable to open as needed leading to Dystocia.

Other Common Causes of Dystocia

Their are other common causes of Dystocia and are not limited to the following :-

  • Obesity and Uterine Inertia – Obese sows will have intrapelvic fat that can impede delivery. Uterine Inertia may occur secondary to muscle fatigue with large foetal size or positional Dystocia. Uterine Inertia may also occur secondary to pregnancy toxaemia, hypocalcaemia, or infections, as toxins produced by infection or pregnancy ketosis can weaken Uterine Musculature.
  • Pup Related Dystocia – This normally relates to Pup size. The normal neonate is approximately 10% of the Sow’s Body weight. Their are normally 2-4 pups in a litter and birth weights may reach up to 115g’s.Pup size increases as the number born decreases, therefore the risk of Dystocia is higher when the sow only gives birth to 1-2 pups. The head or pelvis of these pups may be extremely large and not surprisingly this larger size enhances the chances of a difficult delivery.
  • Foetal Malposition – This is another cause of possible Dystocia. Problems occur when only one rear leg is presented in the birth canal, when one or both forelegs point ”Backwards, Sideways (ears first) or tipping downwards” Dystocia may also develop when the back or shoulders present first at the birth opening.
  • Other Foetal Malformations – Other Foetal Malformations are rare causes of Dystocia. However conditions such as Siamese Twinning have been reported. A “Bull-Backed” abnormality has been associated with Lethal Gene of Roans which leads to a massive, short backed, arched foetus with an enlarged head.

Clinical Picture

Due to the fact that Gestation may be anything from 59-72 days Dystocia can be very difficult to detect early because of this variable gestation length paired with the sows lack of nest building and the very abrupt onset of labour.

Identify impending parturition by determining the degree of separation of the pubic bones symphysis, or measuring the distance between the two pubic bones. The symphysis opens approximately 5-7 days before delivery. The Symphysis opens approximately 1.5cm at 48 hours pre-parturition then increase further to 2-3cm at parturition. The parturition returns to normal 24 hours post-partum.

Once parturition has begun Guinea Pig pups are delivered very rapidly with normal parturition lasting at total of 30-45 minutes. Once strong Abdominal press has begun, a pup should appear within 5 minutes or less. The interval between delivered pups (rest period) should be 3-10 minutes. All pups should be delivered within 10-30 minutes. Since Neonates are relatively well developed, they have a high demand for oxygen and they will quickly deteriorate if they are still within the uterus as placental separation occurs.

A sow that has been continuously straining unsuccessfully for greater then 10-20 minutes or intermittently for greater then 2 hours is typically experiencing dystocia. The affected sow may also be found to be :-

  • weak and depressed from exertion
  • Their may also be Bloody or Green-Brown Vulvar Discharge.

Often at this stage there are mild or no contractions although though the foetus is visible or palpable within the birth canal. Sows with eclampsia or hypocalcaemia will have muscle spasms and possibly convulsions.

At this point Veterinarian Assistance is Needed Urgently

Treatment

Treatment will depend on the underlying cause. So in a timely manner this will need to be determined and the relevant action taken.

Malposition or Large Pups

In the case of malposition or Large Pups using careful direction and gentle traction however there is a risk to the sow and pup. Potential complications include :-

  • Vaginal/Uterus Tears
  • Vaginal Prolapse

If manual extraction is successful remove of the foetal membranes promptly.

Caesarean Section (C-Section)

Generally Caesarean Section will be completed although Guinea Pigs in Dystocia do not handle the stress of Anaesthesia and surgery well. This will normally only be considered when :-

  • The pup’s can not be extracted due to size or position
  • Separation of the Pelvic Symphysis is less then 2-2.5cm
  • There is no response to Oxytocin and/or Celcium.

Prognosis

The prognosis for Guinea Pigs is Guarded to Poor that require surgery.