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Why Is My Border Collie So Big (5 Reasons & What To Do)

If you’ve noticed your border collie is much larger than the average collie at the dog park, you’ll definitely be wondering why…

Not only that, but you’ve probably have a few comments here and there from other collie owners about it.

Sound familiar? Well it was for me! (I had an exceptionally large collie due to selective breeding, unbeknown to me when we got her)

Let’s run through why this might be the case for your collie.

why is my border collie so big

Border Collie: What’s the Normal Size?

When talking about size it’s necessary to have a reference point. So how big are border collies supposed to be?

Once we know their regular size according to the breed standard, we’ll know whether or not your collie is actually bigger than normal.

The following table presents the typical size range for Border Collies:

Males30-45 pounds (14-20 kg)19-22 inches (48-56 cm)
Females27-42 pounds (12-19 kg)18-21 inches (46-53 cm)

If your Border Collie falls considerably outside these limits, it might be helpful to explore some of the reasons we’ll discuss below.

5 Potential Causes of Your Border Collie’s Large Size

In most cases, unless we are dealing with an overweight collie, it will be their genetics behind the large size. Still, there are other reasons that we’ll include below too.


Genetics often play a vital role in determining the size of a Border Collie. If the parents or grandparents were larger than usual, those genes might be passed down to your pup.

Additionally, some breeders might engage in selective breeding, focusing on specific size traits. This deliberate breeding could contribute to your Border Collie’s larger size, and it’s something beyond your control.


According to VCA Hospitals, around 25-30% of all dogs are obese. So this is a real issue common to our furry friends!

Not only that, but collies are a breed prone to obesity, especially as they age…

The type and amount of food you feed your Border Collie can have a significant impact on their size. A diet that’s too rich in calories or protein, especially during the puppy phase, might lead to rapid growth and a bigger dog.

Conversely, overfeeding an adult dog can cause them to gain weight, making them appear larger. Proper nutrition, tailored to the specific age, activity level, and health status of your dog, is crucial to maintaining an ideal size.

Top 5 Food for Border Collies
Healthy Low-Calorie Treats for Collies (Product)

Lack of Exercise

Border Collies are known for their intelligence and energy, requiring regular physical and mental stimulation.

If a Border Collie doesn’t receive enough exercise, they can easily gain weight, contributing to a more substantial appearance.

Regular walks, play sessions, agility training, and mentally stimulating activities are essential for keeping your Border Collie in top shape. A well-exercised dog is generally a happy and healthy one!

Neutering or Spaying

Spaying or neutering your Border Collie can cause changes in their metabolism, often resulting in weight gain if their diet and exercise regimen aren’t adjusted accordingly.

Some research suggests that dogs spayed or neutered at a young age might grow taller, as the sex hormones play a role in closing the growth plates in bones.

Being aware of these potential changes can help you make informed decisions about your dog’s health and care.

Underlying Health Issues

Some medical conditions, such as Hypothyroidism or Cushing’s disease, might cause weight gain or an increase in size.

Hypothyroidism slows the dog’s metabolism, leading to weight gain, while Cushing’s disease can lead to similar effects. It’s essential to have regular veterinary check-ups to ensure your Border Collie is in good health.

Early detection of any underlying issues allows for proper treatment and helps in maintaining your dog’s ideal size and overall well-being.

Overweight Vs. Big: Understanding the Difference

It’s essential to distinguish between an overweight Border Collie and one that’s naturally big.

A Border Collie might be big due to genetics, or it could be overweight, which involves an excess amount of body fat. The distinction is crucial, as being overweight can pose serious health risks.


An overweight Border Collie will show signs of difficulty in performing physical activities that they once enjoyed, and might even display labored breathing. You’ll notice the lack of a visible waistline, and their ribs, spine, and hip bones will be difficult to feel due to the excess fat.

Naturally Big

Conversely, a big but healthy Border Collie will exhibit an ideal body condition. You can easily feel their ribs under a thin layer of fat, they’ll have a visible waist when looked at from above, and their abdomen will show a graceful tuck when viewed from the side.

Understanding whether your Border Collie is just big or overweight is essential. If your dog falls into the overweight category, it could be a sign of a health issue that requires attention, while a naturally big Border Collie might just be displaying their unique genetic traits.

Should I Be Concerned About My Border Collie’s Size?

A big but healthy Border Collie isn’t usually a concern.

But overweight can lead to health issues like diabetes, heart problems, and joint pain.

It’s important to establish which of the two your collie is. And if you suspect that their larger size is infact due to being overweight, it’s best to consult your vet with a tailored plan.

OR, if you think you know what the cause is (perhaps there is an obvious reason like being fed too many table scraps every day) then make some necessary changes and analyze her weight over 2-3 weeks.

What Can I Do About My Large Border Collie?

Understanding your Border Collie’s size and taking appropriate steps are essential. Here’s what you can do:

If Your Border Collie is Overweight:

You’ll need to take proactive measures to help your Border Collie lose weight. This usually means:

  • Adjusting Their Diet: Reducing calorie intake is often necessary. This could involve selecting a lower-calorie dog food or reducing portion sizes.
  • Increasing Exercise: More physical activity can help burn off excess calories. This might include longer walks, more playtime, or additional training sessions.
  • Consult Your Vet: It’s wise to work with a veterinary professional to create a customized diet and exercise plan that suits your Border Collie’s specific needs. They can provide guidance on the safest and most effective methods for weight loss.
  • Make Changes Gradually: Remember, abrupt shifts in diet or exercise can be stressful for your dog. Any adjustments should be made gradually and with care, under the guidance of a professional.

If Your Border Collie is Naturally Big:

If your Border Collie is simply larger due to genetics and not overweight, there’s no need for significant changes. Continue to provide:

  • A Healthy Diet: Ensure that your dog’s meals are balanced and appropriate for their size and activity level.
  • Ample Exercise: Regular exercise is vital for a naturally big dog, just as it is for any dog. Continue to engage in regular walks, play sessions, and other activities that your Border Collie enjoys.

By understanding your Border Collie’s unique size and needs, you can ensure they remain healthy, active, and content, whether they are naturally big or need assistance in managing their weight. 🐶

Last Thoughts

Border Collies come in various sizes, and a larger-than-average dog might be perfectly normal. Understanding the difference between being big and being overweight is key to keeping your canine companion healthy.

Remember, your oversized Border Collie might just be a larger-than-life bundle of joy! Maintain regular vet check-ups, proper nutrition, and exercise to ensure their happiness and well-being.

If you’ve got questions or concerns, don’t hesitate to consult with a veterinary professional. After all, every dog is unique, and what matters most is their overall health and happiness. 🐶


Before making any decisions that could affect the health and/or safety of your dog, you should always consult a trained veterinarian in your local area. Even though this content may have been written/reviewed by a trained veterinarian, our advice to you is to always consult your own local veterinarian in person. Please read our full dislcaimer if you have any questions.