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Why Is My Australian Shepherd So Big: (5 Reasons)

As an Australian Shepherd parent, you might find yourself looking at your companion and wondering, “Why is my Aussie so big?”

Your dog might be towering over other Australian Shepherds, or they might be a tad bulkier, raising some eyebrows.

This guide will help you unravel the mystery behind your Australian Shepherd’s size, distinguishing between a dog who is just big versus one who might be overweight.

why is my australian shepherd so big

Australian Shepherd: What’s the Normal Size?

First things first, let’s establish the baseline. Australian Shepherds are medium-sized dogs with a robust and athletic build.

According to the American Kennel Club (AKC):

  • A male Australian Shepherd typically weighs between 50-65 pounds (23-29 kg) and stands about 20-23 inches (51-58 cm) tall at the shoulder.
  • Females usually weigh between 40-55 pounds (18-25 kg) and stand about 18-21 inches (46-53 cm) tall.

Of course, individual dogs can vary slightly from these ranges, but if your Aussie is considerably above these limits, they would be considered ‘big’.

5 Potential Causes of Your Australian Shepherd’s Large Size

Let’s explain the most influential factors over an Aussie’s size.


Genetics play a crucial role in your Aussie’s size. If your dog’s parents or grandparents were larger than the breed average, those genes might be passed down to your pup.

Breeders might also opt to breed only large Aussies with other large Aussies, which would be considered selective breeding.

Additionally, if your Australian Shepherd is a mix, they could have inherited size traits from the other breed in their lineage. The genetic factor is something that you cannot control.


The type and quantity of food you feed your Aussie can significantly impact their size. A diet that’s too high in calories or protein can lead to rapid growth in puppies, which might result in a bigger dog.

Similarly, overfeeding an adult dog can cause them to gain weight, making them larger.

The nutritional needs of Australian Shepherds can vary based on their age, activity level, and health status, so it’s essential to provide a balanced diet suited to their individual needs.

Lack of Exercise:

Australian Shepherds are a highly active and energetic breed. They need daily exercise to maintain a healthy weight. If they don’t get enough physical activity, they can easily gain weight, which contributes to their larger size.

Regular walks, play sessions, and mentally stimulating activities can help keep your Aussie in top shape.

Neutering or Spaying:

Spaying or neutering your Aussie 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 than those who are not, as the sex hormones play a role in closing the growth plates in bones.

Underlying Health Issues:

Some medical conditions can cause weight gain or an increase in size. Hypothyroidism, for instance, is a condition where the thyroid gland doesn’t produce enough hormones, slowing the dog’s metabolism and leading to weight gain.

Other conditions like Cushing’s disease can also cause similar effects. It’s essential to have regular veterinary check-ups to ensure your Aussie is in good health.

Remember, a larger-than-average size or slight weight gain in your Australian Shepherd isn’t necessarily cause for concern. However, significant weight gain can lead to health problems, so it’s important to keep an eye on their size and take action if necessary.

Overweight Vs. Big: What’s The Difference?

An overweight Australian Shepherd has an excess amount of body fat, while a big Aussie may simply be taller or have a larger frame due to genetics.

It’s important to know the difference because if your Aussie is in fact overweight, this poses a health issue that should be addressed, compared to if your Aussie is just naturally big.


An overweight Aussie might have difficulty performing physical activities they once enjoyed, show signs of labored breathing, and may lack a visible waistline. Their ribs, spine, and hip bones will be hard to feel because of the excess fat.

Naturally big:

On the other hand, a big but healthy Aussie will display an ideal body condition: you can feel their ribs easily under a thin layer of fat, they’ll have a visible waist when viewed from above, and their abdomen will tuck up when seen from the side.

Should I Be Worried About My Aussie’s Size?

A larger-than-average Australian Shepherd isn’t inherently a problem as long as they’re healthy, active, and not overweight.

If your Aussie is simply big, their size shouldn’t be a cause for concern. However, if your dog is overweight, it can lead to several health issues like diabetes, arthritis, heart disease, and a reduced lifespan.

If you’re worried about your Australian Shepherd’s size, it’s always a good idea to consult your vet. They can assess your dog’s body condition score, a quantitative measurement of their body fat, and provide guidance on diet and exercise.

What Can I Do About My Large Australian Shepherd?

If your Aussie is overweight, you’ll want to take steps to help them lose weight.

This usually involves adjusting their diet to reduce calorie intake and increasing their exercise.

Consult your vet for a customized diet and exercise plan that suits your dog’s needs.

Remember, abrupt changes in diet and exercise can be stressful for your dog. Any changes should be made gradually and under the guidance of a professional.

If your Aussie is just naturally big and not overweight, no action is needed other than to continue providing a healthy diet and ample exercise.

Last thoughts

Australian Shepherds are a diverse breed, and size can vary. A larger-than-average Aussie might be perfectly normal, but it’s crucial to understand the difference between being big and being overweight.

Regular vet check-ups, balanced nutrition, and exercise are key components in maintaining your Aussie’s health, no matter their size.

Remember, every dog is unique, and what matters most is their overall health and happiness. Your giant Aussie might just be a big bundle of love!


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.