The Ultimate Puppy Harness Guide (2025): Everything New Dog Owners Need to Know

Bringing home a puppy is exciting, chaotic, and a little overwhelming. One of the most important items you’ll buy in the first week? A puppy harness that actually fits, supports safe training, and keeps them comfy on every walk.

While it may be tempting to clip a lead to a collar, vets and trainers alike recommend starting with a harness – especially for young, growing dogs. In this guide, we’ll walk you through everything you need to know about finding the best puppy harness, how to size it correctly, and which features truly matter.

Why Puppies Need a Harness (Not Just a Collar)

Puppies are curious explorers with delicate bodies. A collar puts direct strain on the trachea and neck muscles – which can cause long-term damage if your pup pulls or lunges suddenly. A harness, on the other hand, distributes pressure evenly across their chest and shoulders.

Benefits of using a puppy harness:

• Better control: Ideal for unpredictable movements during early training
• No pressure on neck: Reduces risk of choking or throat injury
• Safer walks: Particularly important for small or toy breeds
• Helps with pulling: Many no-pull harnesses offer front D-rings for redirection

For active breeds like Cockapoos and Labradors, a good harness is essential to manage that puppy energy. And for smaller pups like Dachshunds or Chihuahuas, it’s even more important to avoid strain on fragile frames.

At Bailey & Coco, we design harnesses with these needs in mind – balancing control, safety, and comfort with adorable styles.

Already familiar with the basics? You might enjoy our earlier post: Best Puppy Harness by Bailey & Coco, which shares our original size guide and design features. This post expands on it with fresh insights for 2025.

Next, let’s look at the most important features to consider when choosing a harness for your puppy...

What to Look for in the Best Puppy Harness

With so many styles and brands on the market, how do you know which puppy harness is actually worth it? While some may look cute, the wrong design can cause discomfort, make training harder, or even allow your pup to wriggle free mid-walk. Here's how to separate the fluff from the function.

1. Adjustable Fit

Puppies grow fast. Choose a harness with adjustable straps around the neck and chest so it can grow with your dog. Look for at least three points of adjustment for the best fit.

2. Soft, Breathable Materials

A good harness should be made from lightweight materials like mesh or padded nylon. It should feel comfortable on your puppy’s body and not rub under the armpits. Bonus points for quick-drying fabric after muddy adventures.

3. Secure Buckles and Clips

Make sure the harness features sturdy, quick-clip buckles for easy on/off. This saves time and stress – especially when your pup is wriggly or excited to go out.

4. No-Pull Training Options

Look for a harness with a front D-ring in addition to the back clip. This allows you to attach the lead at the chest, helping to discourage pulling during walks.

5. Handle for Extra Control

A top handle is a game changer for young pups. Whether you need to quickly lift them over a puddle or hold them back from another dog, it gives you fast, safe control in unpredictable situations.

6. Reflective Safety Details

Even if you only plan daytime walks, reflective stitching or panels are important for visibility in low light. Safety first – always.

All of these features come together in our bestselling Bailey & Coco Puppy Harnesses, designed specifically for dogs aged 8 weeks and up.

In the next section, we’ll show you how to turn that great-fitting harness into a training tool your puppy will respond to – including tips to stop pulling and help them feel confident on the lead.

Lead Training Tips Using a Harness

Even the best harness won’t magically stop your puppy pulling – but it will give you the tools and control to teach them. Here’s how to use your puppy harness to build lead confidence step-by-step.

1. Introduce the Harness Slowly

Don’t expect your puppy to love the harness right away. Let them sniff it. Put it near their food bowl. Clip it on for short periods around the house. Always use positive reinforcement – treats and praise go a long way.

2. Use a Front D-Ring for Training

Attaching the lead to the front D-ring gently steers your pup back toward you when they pull. This discourages lunging and encourages better walking habits. Over time, you can transition to the back clip as their behaviour improves.

3. Practice in Low-Distraction Environments

Start indoors or in a quiet garden before attempting the pavement. Let your pup get used to the feeling of the harness and lead without too many distractions. Short sessions are better than long, overwhelming ones.

4. Reward Calm Walking

Every time your pup walks calmly beside you, mark it with a cheerful “yes!” and offer a treat. This builds positive associations with good leash behaviour. If they pull ahead, stop walking. No progress = no reward.

5. Keep Sessions Short and Positive

For young puppies, even a 5-minute walk can be enough. End on a positive note, with plenty of cuddles and encouragement. Gradually increase duration as their attention span grows.

Remember: pulling, biting the lead, or freezing mid-walk is totally normal for young pups. Stay calm, be patient, and trust the process.

If you’re struggling with pulling or reactive behaviour, consider booking a few sessions with a qualified trainer who uses force-free methods. Pairing their guidance with a proper no-pull puppy harness can transform your walks completely.

Next up, we’ll walk you through how to measure your puppy properly and choose the correct size for their breed and age.

How to Measure Your Puppy for the Right Fit

Finding the right harness isn’t just about features – it’s also about fit. An ill-fitting harness can cause rubbing, slipping, or escape risks. Here’s how to measure your puppy like a pro.

1. Neck Measurement

Wrap a soft measuring tape around the base of your puppy’s neck, where a collar would naturally sit. Make sure it’s snug but not tight – you should be able to slip two fingers underneath.

2. Chest Girth

This is the most important measurement. Wrap the tape around the widest part of your puppy’s chest, just behind the front legs. Write down the number in centimetres or inches – depending on your harness brand.

3. Weight Range (Optional)

Some harness brands offer sizing based on weight brackets. Use this only as a guide – chest measurement is always more accurate.

4. Try It On and Adjust

Once your harness arrives, try it on and adjust each strap. You should be able to slip two fingers under every part of the harness without it being loose or baggy.

5. Watch for Fit Issues

If your pup slips a leg out, resists walking, or the harness shifts to one side, the fit may need adjusting. Never use a harness that allows escape or causes discomfort.

We recommend starting with an XS or S size for most puppies, but always check the brand’s size guide. Our full puppy size chart is available in our original blog post here.

Once you have accurate measurements, use our dog harness collection to find the perfect style and fit.

In the next section, we’ll break down sizing recommendations by breed to give you a helpful starting point based on your puppy’s type.

Puppy Harness Sizes by Breed

If you’re not sure where to start with sizing, this breed-based guide can help. Below are average harness sizes for popular UK puppy breeds – based on customer data and real-world testing.

• Dachshund Puppy: XS (Neck: 22–30cm, Chest: 30–40cm)
• French Bulldog Puppy: S (Neck: 30–45cm, Chest: 40–55cm)
• Cockapoo Puppy: S-M (Neck: 28–40cm, Chest: 35–55cm)
• Cocker Spaniel Puppy: S (Neck: 30–40cm, Chest: 35–50cm)
• Labrador Puppy: M-L (Neck: 40–55cm, Chest: 50–70cm)
• Golden Retriever Puppy: M-L (Neck: 40–60cm, Chest: 50–75cm)
• Chihuahua Puppy: XS (Neck: 20–28cm, Chest: 28–35cm)

💡 Tip: If your puppy is between sizes, size up and tighten the straps for a snug, secure fit. Adjustable harnesses like ours will give you more flexibility as your pup grows.

We also recommend checking our full dog harness collection for styles that are specifically tailored for growing breeds. Each product includes sizing info and recommendations by weight and age range.

Coming up next: the most common mistakes new puppy owners make when choosing and using a harness – and how you can avoid them!

Common Mistakes New Owners Make (and How to Avoid Them)

Choosing your first puppy harness can feel overwhelming – and it's easy to make the wrong call. Here are the top 5 mistakes we see new dog parents make, and how to steer clear of them.

1. Buying Too Big “So They Can Grow Into It”

A loose or oversized harness is more dangerous than a snug one. Puppies can slip out of poor-fitting gear. Always buy the correct size for their current measurements and upgrade later.

2. Ignoring Fit Around the Chest

Chest girth is the most important measurement, but many people focus only on the neck. A bad chest fit causes chafing, twisting, or escape – especially on high-energy pups.

3. Choosing Style Over Function

Cute is important – but not at the expense of safety. Avoid fashion harnesses with thin straps, buckles in awkward places, or no front clip. Your harness should support your pup, not just your feed aesthetic.

4. Not Adjusting the Straps Correctly

Even the best harness won’t perform if the straps are left too loose. Take time to fit it snugly and evenly on both sides. Most returns happen because of incorrect adjustment, not sizing.

5. Skipping Training and Blaming the Harness

A harness supports good behaviour – it doesn’t create it. Consistency, rewards, and short sessions are key. Your harness is a tool, not a magic fix.

Want help choosing the right one? Explore our most-loved options in the Bailey & Coco harness collection – we’ve got real reviews, detailed size info, and features designed for happy pups and stress-free owners.

Thanks for reading! You now have the confidence to pick the perfect harness for your puppy’s first adventures. 🐾