Testicles, sometimes referred to as balls, are either of the two sexual organs that produce sperm in dogs and other male mammals. People often talk about the testicles “dropping” at different ages – but what does this mean? When does it become a problem?

Where are they before they ‘drop’?

Initially when a male puppy is born, their testicles are inside their body. They actually originate from around the puppy’s kidneys! However, the testicles need to be kept in a cooler environment so need to descend from within the body to be outside in the scrotum of the dog. Temperature of testicles needs to be lower than the body temperature to optimise sperm production. Having testicles remain inside the body, called cryptorchidism, can increase chances of certain cancers too.

When should they drop?

After birth over a period of approximately two weeks, the testicles start descending (dropping) into the scrotum through a narrow channel called the ‘inguinal canal’. This is why your veterinary surgeon or registered veterinary nurses will usually have a feel of this area in your puppy when they come in for their health check and vaccinations.

The process of their testicles descending can take a little longer in some dogs. But if both testicles haven’t dropped after around 6-8 months old it may be the case that they never will. Your vet will discuss the next action but this likely means surgery to go and find the missing testicle/testicles!

As an aside, people often think that the testicles “drop” at puberty. But in dogs (like many mammals including humans), the testicles are normally in the scrotum long before puberty begins. The apparent “descent” in adolescence is simply due to rapid growth of the testicles and relaxation of the muscles around them; their increasing weight causing them to hang lower.

What happens when dogs are sexually mature?

Some people want to neuter their dogs when their testicles have descended. Decisions regarding the age of neutering are often based on the age at which the dog is estimated to reach sexual maturity. We don’t always want to rush to neuter every male dog.

It is understood that male dogs may reach puberty between 6 months and 2 years (quite the range) of age. However sexual and skeletal maturity varies from dog to dog depending on their breed. Small breeds grow quicker and reach their adult size much quicker than large and giant breeds who continue to grow for up to 1.5-2 years.

We like to wait for dogs to reach maturity first because exposure to gonadal (reproductive) hormones is necessary for the healthy maturation of a muscular-skeletal system; we want them to be fully mature in their body before we do anything.

Undesirable sexual behaviour and why people neuter

In one study from the UK public identified that most respondents supported routine neutering of dogs (88% for male dogs). One reason for doing so was for a positive impact on behaviour. Male dogs can often hump, their training can get less successful and they can express other undesirable sexual/hormonal related behaviour when they reach sexual maturity. Indeed, in this study 21% of male dogs were neutered to prevent sexual behaviour in the future and 19% because they had started to show sexual behaviour. This teenage phase can be a tricky time for owners. So we recommend getting help and support from a positive behaviourist if you are struggling and your veterinary team. 

What can go wrong?

There are a few eventualities that can happen when our dogs’ testicles start to descend. The best scenario is that they drop into the scrotum successfully and we have no further issues. 

However, sometimes along the way things can go wrong. On occasion the testicles don’t even start their journey and remain tucked up in the abdomen meaning one or none of the testicles are present in the scrotum. Sometimes they do start, but for whatever reason stop somewhere along the way, and never make it to the scrotum. This can be the case of both testicles or more often just one. In these cases, your veterinary team will support you in the best course of action for your dog. But usually this involves opening up their abdomen and trying to find the missing testicles or testicles! Sometimes, they are sitting in the inguinal area (groin) and we can feel them easily, these also need to be removed.


The physical age testicles can descend is usually before around 8 weeks old. But the age that they actually start displaying sexual behaviour can vary massively between dogs. If your dog has both or one testicle missing by 6-8 months then you need to start the conversation with your wonderful veterinary team about when the right time to go and retrieve it is!

Further reading: