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Singleton Pups: Detection and Complications

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The More You Know…

…the better prepared you can be.

At PUM, we know that our customers care about their dogs. Ethical breeding is a wonderful way to ensure continuation of exceptional lines and safeguard the health of litters, but sometimes nature has a way of throwing a curve ball: singleton pups.

Singleton Pups: An Overview.

A singleton puppy occurs when only one puppy develops in the uterus. A fairly rare occurrence, this is more commonly found in smaller breeds who tend to have smaller litters. The cause isn’t widely known; some have suggested that it may be the result of a late mating, while others have speculated that it could be due to the use of frozen semen during AI. However, it’s important to note that there is currently no scientific evidence to support these claims.

You might be thinking “what is the issue? Surely one puppy is easier for the mother to carry, deliver and care for?” Unfortunately, this is often not the case. For example, the average litter size for a cocker spaniel is between 3-7 pups, their growth develops proportionally to shared nutrients and space in utero and means they are ideally sized to fit through the birth canal without intervention. If only one puppy is present they are more than likely to be bigger than the ideal and cause complications during birth and afterwards during development.

For the wellbeing of both mother and pup it is vitally important that singleton puppies are detected; ultrasound scanning (using an Elite 5600 system for example) is the safest, most effective way to carry out the initial investigation and monitor progress throughout pregnancy. If a singleton is found at first scan (30 days) then regular subsequent scans can be used to track growth and allow owners to choose correct treatment paths for their pets (with veterinary collaboration). 

Birthing Complications: Foetal dystocia.

This can happen when natural labour is allowed to be established and the foetus is too large to naturally pass through the vaginal canal or there is a lack of hormones available. Inducing birth relies on progesterone dropping approximately 24-36 hours before the first stage of labour and oxytocin is released by the puppies to stimulate uterine contractions, therefore singleton puppies are often not able to release enough oxytocin to allow passage through the birth canal. This is why if ultrasound scans have not been performed during pregnancy foetal dystocia may only be noted when natural labour has already started. If left unassisted, the birth will be problematic for both the pup (foetal stress and possibly death) and the mother will become distressed. In some cases uterine infection can also occur.

Many singleton pups will require a caesarian section birth. When ultrasound scans have been performed and the singleton has been detected early on in pregnancy many owners will plan in advance for this procedure with their vet to ensure viability of the puppy and safety of the mother. Even if the owner chooses to wait for parturition to decide if a caesarian is necessary, very few singleton pups result in natural births because of foetal dystocia.

Singletons After Birth: Development

Due to developing in isolation without siblings, singletons will not intuitively learn habits such as bite inhibition and social skills. Often, they display inability to handle frustration and sometimes have touch sensitivity, where they may react aggressively or become anxious by unexpected contact or even as the contact is occurring. Happily, most pups will not experience any long-term health problems related to their singleton status. 

As a result of the lack of litter mates, singletons may need supplementary heat sources and extra stimulation to encourage movement and exercise. The mother may also over produce or under produce milk; if she over produces you should be looking out for signs of mastitis, in the case of under production you will need to begin supplementing feeds or consider hand rearing.


As you can see, it is not yet possible to avoid the conception of singleton pups, and the earlier you can detect one, the better you can plan to ensure the wellbeing of both pup and mother. Even when an early scan is performed it may sometimes be tricky to confirm a singleton pregnancy; this is why multiple scans throughout the process, done by a competent paraprofessional using safe and reliable equipment is such a vital component to ethical breeding practices.


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