Why Is My Cavalier King Charles Spaniel So Small? (5 Most Common Reasons)

Are you worried about the size of your Cavalier King Charles Spaniel? You are not alone, so don’t be alarmed.

There are many factors that can affect your dog’s size, but not every deviation means your pup has a problem.

However, you should be aware that Cavalier puppies stop growing between months 12 and 15. By that time, your Cavy should be a certain height and weight.

Therefore, if your dog has less than one year, you should hold off on panicking.

In this article, I’ll cover some of the most common reasons for the size issue in Cavalier King Charles Spaniels.

Why Is My Cavalier King Charles Spaniel So Small?

If your Cavalier King Charles Spaniel is small, some of the most common reasons may be genetics, poor diet, intestinal parasites, or other health problems.

In case your dog is fed with quality food, and you don’t assume health problems, your pup might host intestinal parasites that ‘steal’ essential nutrients for growth.

During the first year of life, your pet should go through several growth stages and reach certain weight and height goals.

Maturity Not Reached

Each growth stage is characterized by certain developmental goals that your furry friend should reach. But these are not set in stone.

At some point, a Cavalier can be overweight, while in the next stage, it could be considered underweight.

So if you think your pup is smaller than it should be, height and weight deviations that occur during puppyhood can be the reason. Such delays are expected because each dog develops at a different speed.

These usually sort out after maturity, so you shouldn’t be worried if your Cavy is healthy and playful. However, if your dog hasn’t reached average or near-average size by the month 15th, maybe it’s time to visit the vet.


Genetics is a hard shell since nothing can change it. Your pups inherit a bunch of traits from their parents, and size and build shape is just one of them. That’s because 25 genes affect the growth in dogs.

The one known as IGF1 is responsible for size variation between breeds, but also variation between members of the same race. So, a smaller build is a hereditary trait and can’t be changed.

Cavalier King Charles Spaniel pups whose parents were advanced and healthy should reach the standard size. On the other hand, Cavies whose moms and dads were petite are likely to have a small build.

Improper Diet

Owners are sometimes unaware that Cavies are active, playful dogs, so they need a bit more calories than breeds that are couch potatoes.

Plus, these toy pups have quite a high metabolism rate, so they burn calories insanely fast. That’s why an average Cavalier of about 12 pounds should eat roughly 400 calories daily.

On their menu should prevail meat, as a quality source of protein and good fats, and one part should be vegetables and only a few snacks.

Cavaliers King Charles Spaniels can be underweight if their nutrition is low in nutrients and calories. That can happen if you feed your Cavy with lean meat and low-calorie vegetables.

So instead of that, opt for meaty meals and some extra snacks to help your pup get a healthy weight.

Related: Cavalier King Charles Spaniel Snoring Problems

Intestinal Parasites

Your Cavalier King Charles Spaniel is small despite having a good appetite and eating premium foods that are excellent energy and nutrient sources.

Unfortunately, it’s most likely due to some underlying issues.

You should pay attention to the symptoms that may indicate the appearance of intestinal parasites.

Several types of worms can appear in dogs, but the most common are roundworms and tapeworms. Your dog can become infected in many ways, from drinking the breastmilk of an infected mother to eating contaminated foods.

An infected Cavalier King Charles Spaniel may have worm issues since birth. These parasites can be dormant for a while, but an untreated infestation can seriously damage your pup’s health.

You can suspect worms if your Cavy looks dull and dehydrated, has cramps, and has a rare stool. In that case, your vet will give the best diagnosis and treatment.

Underlying Health Problems

Some Cavaliers may be small, but that doesn’t mean something is wrong with them.

Still, you must be able to distinguish pups with tiny musculature from underfed dogs. The latter can result from numerous diseases, some of which don’t even show symptoms.

If sick, pups in development can lag in gaining weight, and adult dogs can suddenly lose weight.

Triggers of this disorder can vary from tooth pain and illnesses that come with aging to metabolic disorders and severe conditions such as cancer or diabetes.

The symptoms of some diseases can be confusing, so a vet check is essential. By testing blood and urine and checking the general health condition of your pet, the vet can determine why your Cavalier King Charles Spaniel is small.

What’s the Average Size of Cavalier King Charles Spaniel?

The average adult Cavalier King Charles Spaniel weighs between 12 and 18 pounds by the end of month 15. As for the height, it ranges from 12 to 13 inches, depending on gender. Males are a little taller and slightly heavier, but they seem larger due to their muscular build.

Besides, you have to regularly check your pups’ health and monitor their behavior.

If the reason for being underweight is illness or poor diet, you must react in time and prevent further damage.

Before You Go

Understanding the size of your Cavalier King Charles Spaniel is crucial for its health and well-being, as well as for providing it with the appropriate care, diet, and training.

Growth chart tables can be good guidelines in assessing whether your Cavy is too small.

Read my next article to ensure your pup is in the standard size range – Cavalier King Charles Spaniel Growth Chart.

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