When do Cocker Spaniels Stop Growing?

May 18, 2022

Any dog owner you ask will fondly remember when their cocker spaniels were puppies. This phase passed quickly as puppies grow at a very quick pace. You will see them develop on a weekly basis, especially early on.

Cocker spaniels become fully grown around 18 to 24 months old. There are a few stages to this and the exact amount of time it takes will vary from dog to dog. Let's take a look and how this breaks down.

At around one year old your cocker will be its full height. Muscles will continue to develop for another six to twelve months. Males dogs will take a bit longer to fully develop as they have more muscle mass to develop.

Physical development is only one aspect of your dog's growth. Your cocker spaniel also needs to grow mentally and emotionally. Again female cocker spaniels mature in these aspects sooner than males.

Each step of a puppy's growth brings its own new skills, experiences, and challenges. Keep reading to learn all about when cocker spaniels stop growing.

Cocker Spaniels Have to Grow in Many Ways

As previously noted cocker spaniels will grow in many ways. This includes physically, mentally, and emotionally. We will dig into what each of these aspects means.

Physical Growth

When we talk about a cocker spaniel's physical growth we are talking about their size, muscles, and weight.

The exact amounts will vary but the averages give you a decent guideline on what to expect. Most of their growth will be done by around 10-12 months old. They will continue to grow a bit after this time.

This growth rate is very similar to other dogs. Especially other smaller breeds or medium-sized dogs.

After this point, you'll notice their body begins to fill out a bit more over the next few months. This is where more muscle will develop. Particularly for males.

Your dog will develop at their pace.

So, What is the Average Size of a Cocker Spaniel?

How big your cocker spaniel pup will grow to be will depend on a variety of factors. This includes gender, type of cocker spaniel, size of the parents, genetics, or even just pure chance.

American Cocker spaniels vs English

The type of cocker spaniel you have will impact the size it will reach once fully grown. An English cocker spaniel is a bit larger than the American one with an average height of 17 and 15.5 inches respectively.

This is also reflected in their weights with the American cocker spaniel weighing 20-30 lbs on average and the English cocker coming in a bit larger at 26-34 lbs.

Male Cocker Spaniels vs Female Cocker Spaniels

So it's a bit different from American to English cocker spaniels, what about by gender? And the answer is yes. Gender also impacts the size and weight you can expect your cocker spaniel puppy to reach.

Males are unsurprisingly larger and heavier once fully grown. They stand at 16-17 inches and weigh 28-34 lbs while the females are one inch shorter and weigh two lbs lighter.

Purebred vs Mixed

If your puppy is 100% cocker spaniel you can expect it to grow to be in line with the figures above. However, if your dog happens to be a mixed breed the results can vary with the mixing breeds and genetics.

Mental and Emotional Development

It is easy to focus entirely on the physical development of dogs. It is the part which is most obvious and we see on a daily basis. Mental development is an important path your cocker spaniel will go through too.

A key stage of their maturing process.

The bulk of this happens over the first year. This is where they will begin to develop a personality. They learn what they like or don't, what is scary and where they feel most comfortable.

Your cocker spaniel will be roughly 18 months old before they reach full emotional maturity. Of course, there is no hard rule with this either and each dog will move at their own pace.

A fully grown cocker spaniel will still grow mentally over the years as its personality continues to develop.

What Does a Growing Cocker Spaniel Puppy Need?

Now that we have an understanding of how cocker spaniels develop. Let's take a look at what your puppy needs to grow up to be a happy and healthy dog. While all puppies grow there is a lot we can do to help your dog develop.

Let your Dog Rest

We have all heard the phrase "let a sleeping dog lie". There is actually a lot of truth to this. Puppies sleep 15-18 hours a day. This supports the healthy development of your pup's brain, immune system, central nervous system, and muscles.

This can be particularly challenging if you have small kids who want to play with the dog.

Solid Nutrition

Nutrition is an important factor for any dog. But particularly when it comes to puppies who need high-quality food packed with whole, fresh ingredients. Take a look at the ingredients before buying to look for fresh and whole ingredients.

Good quality food will be better for digestion, support growth, and improve your chances of having a healthy dog.

Puppy food, will have fewer carbs and be packed with protein, fats and higher concentrations of specific amino acids. Your cocker spaniel will switch to adult dog food at around 12-18 months old.

Where it is easy to drop the ball on nutrition is treats. We've all had those buy eyes looking up at us crying when we are in the kitchen. Do your best to resist the temptation when you have a cute puppy staring up at you looking for food.

Try to stick to using treats sparingly aside from during dog training or rewarding good behaviour. This can be really hard but keep in mind your cocker spaniel gets everything they need from its own food.

Regular Visits to the Vet

Taking your puppy to the vet for check-ups is a great way to monitor their progress and get a professional opinion on how they are growing.

Aim for around three check-ups in their first year so the veterinarian and check weight, height, as well as overall health. This might some like too much but its nice to have some peace of mind that your new puppy is on the right track.


All dogs need a good workout, this applies to puppies too. It can feel like a puppy has limitless energy. But, there are limits to how much a cocker spaniel should do. Too much is harmful to puppy bones, joints, tendons, and muscles. Overdoing it can lead to health issues in later life.

Typically this might be around 12-18 months depending on your dog.

Try to avoid long walks and try to stick to softer surfaces like sand or grass where possible until your dog has stopped developing. This will have less repetitive strain on their joints much like human runners.

Whatever you do, keep in mind that a cocker spaniel puppy has a lot of energy and we are responsible for making sure they don't overdo it.


It is a commonly held belief that a dog is fully grown when it reaches one year old. This is not always the case though. Your new cocker spaniel puppy has a lot of growing to do. Physically, mentally, and emotionally. That's a lot of work and this will take time.

Each dog is different and it's best not to compare your dog's journey to others. As long as your dog is happy and healthy that is all that matters. They will get there in their own time.

As with anything related to your dog make sure you speak to a vet if you are in doubt and have regular check-ups to make sure your dog is on the right path.

Allan  Noble
Hi, my name is Allan! I am the owner of Spaniel Advisor and I've got over seven years experience of owning Spaniels.  
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