Mountainsmith K9 Review

I tested the Mountainsmith K9 dog backpack and this is my verdict.

July 06, 2023
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The Mountainsmith K9 dog pack is a saddlebag-harness combo used for backpacking with dogs. It is best known for its unique, airy design as well as its highly adjustable straps. It is not the most comfortable dog pack on the market, but it offers some of the best water resistance around.

Product Overview

Mountainsmith K9

mountainsmith k9

✅ Multiple adjustment straps

✅ Water-resistant

✅ Durable

✅ Affordable


❌ Restricts the shoulders

❌ Weight-to-volume ratio


  • Weight: 0.8 pounds
  • Volume: Small-3 liters per pannier, Medium-5 liters per pannier, Large-9 liters per pannier
  • Material: 420d HD Nylon Rip Stop PU Carbonate
  • Sizing: Small, Medium, Large
  • Number of Pockets: 4
  • Number of Straps: 3
  • Leash Attachment? Yes
  • Handle? Yes
  • Dog Tester’s Weight: 75 pounds
  • Dog Tester’s Size: Medium pack

The Mountainsmith K9 dog pack is a great choice for people looking for a pack that is water-resistant with saddlebags that can be adjusted up and down the side of the dog. It is best for hikers who want to day hike or go on shorter backpacking trips with their dog. I was pleasantly surprised with how adjustable, water-resistant, and durable this pack was at such an affordable price. Multiple connection points make it easy to modify, and I really appreciated how easy it was to put this pack on a dog as it doesn’t require them to step through any openings.

The nylon saddlebags did great during the waterproof test and held up well to scraping against rocks while scrambling. That said, this pack is one of the least comfortable that my dog has tried up until this point due to the open-air harness and how restricted shoulder movement is by the panniers.

For other dog backpack reviews, read our post on the best dog backpacks.

Performance Test Results

MOUNTAINSMITH K9 review performance score graph

How We Tested:

My dog, Prima, and I tested out the K9 dog pack while hiking in southern Colorado and Utah. We used the pack on a canyon hike which required scrambling down slick rock and hiking along a stream bed. Other conditions included road walking and hiking in spring snow.

hiker and dog wearing mountainsmith k9 in camp

Weight: 8/10

According to Mountainsmith’s website, the medium-sized K9 dog pack weighs 19.2 oz. While this would be a bit on the heavier side, it ended up only weighing 0.8 pounds on my scale, which is pretty much the same as several of the other leading competitors. Because the design of this pack does not include a robust harness or a ton of bells and whistles, it is unsurprising that it is moderately well-weighted.

dog wearing mountainsmith k9

The medium-sized Mountainsmith K9 weighs 0.8 pounds on my scale, which is comparable to several other top rivals.

Price: 9/10

One area where the K9 dog pack performs very well is cost. Compared to many other packs on the market, it is one of the easiest on the wallet. The materials are on par with competitors, and Mountainsmith has created a unique design. This could be attributed to slightly fewer features but at $35-$175 cheaper than most other dog packs. This could be an absolute steal for those who find that this pack fits their needs. Unfortunately, as this pack lacks a true harness and does not fit some dogs well, the cost savings may not be worth it for everyone.

mountainsmith k9 features close-up

At $74.95, the K9 dog pack is relatively inexpensive compared to other packs on the market.

Storage and Capacity: 8/10

The K9 dog pack offers sleek pockets that are easy to access and make it easy to organize gear; however, the weight-to-volume ratio is a bit higher than most other packs on the market. Like all dog packs, there isn’t a specific weight capacity that this pack can hold. Instead, best practice states that dogs should only carry between 10-25% of their body weight after being properly conditioned with the majority of dogs falling on the lower end of the spectrum. My dog was on the larger side for wearing a medium-sized pack, and the saddlebags offered more than enough room to fit all of her supplies. I would say that the panniers are well-sized to prevent overloading and subsequently injuring the dog.

The biggest downside is that the shape of the saddlebags causes them to stick out and catch on objects more easily than other packs my dog has used. This was especially frustrating when scrambling around in canyons, where my dog would get stuck due to the panniers sticking too far out to the side. The rectangular shape of these saddlebags also contributed to this problem.


The medium-sized pack has an adequate capacity which can hold 5 liters in each pannier.

Comfort: 5/10

The Mountainsmith website states that the K9 dog pack is “dogonomically correct” and was designed with the aid of a Colorado veterinarian. Unfortunately, they do not specify what expertise the consulting veterinarian has, such as if they are a sports medicine specialist or if there is any evidence to back this up. At the time of this writing, there is little scientific evidence backing any sort of best practice when it comes to dogs wearing packs. That said, the general consensus by veterinary professionals in the rehabilitation and sports medicine fields is that packs should not constrict the movement of the shoulders.

While the K9 dog pack sat further forward on my dog’s back than other packs I have tried, the panniers did seem to hinder normal shoulder action more than I would have liked. This, in turn, appeared to have an impact on my dog’s ability to navigate more difficult terrain. Because the pack does not have a full harness, the handle strip arched a bit over the shoulder blades, which seemed a bit awkward. The fact that there is little to no padding made it doubly so.

There are some pros to the design. The lack of harness does increase the amount of natural ventilation, and I did not notice any chaffing during use. The pack was about the middle of the road when it came to balancing the saddlebags, but it did eventually even out. While I appreciate Mountainsmith’s stab at creating a unique pack design, it didn’t appear as comfortable for my dog as the more traditional harness-and-saddlebag models on the market.


Design and Features: 7/10

Features found on the K9 dog pack include two main zipper pockets with two smaller side pockets, a metal D ring for attaching the leash, a handle on top of the harness, reflective trim, and breathable mesh lining the inside of the saddlebags. The size and shape of the saddlebags make it easy to access the entire space without having to search for items, and the smaller zipper compartments allow for some organization. However, because of the orientation of the side pocket zippers, it can be a bit more challenging to access that space. This particular pack has slightly fewer features available than some other packs out there. For example, there are not any designated spots to attach items to the outside of the pack. This does help to cut down on weight, so if you are looking for a simpler design, then this may be the pack for you.


The K9 dog pack has simpler design and fewer features that contributes to weight reduction.

Adjustability: 9/10

When it comes to adjustability, Mountainsmith has done a great job of including multiple adjustment points on the K9 dog pack. This pack has harness buckles on both sides of the pack so that the dog does not need to step through the harness unless you want them to. The strap lengths are easy to adjust using a locking mechanism that easily flips open and closed rather than fighting with friction buckles.

A unique feature of this pack compared to others I have used is the ability to adjust the height of the panniers using adjustable straps that attach to the top of the harness. Because of this, the saddlebags can be moved up or down the side of the dog. Sadly while there are a lot of modification points when sizing the dog pack, there are no options for adjusting the size of the pack itself. Overall this is one of the better packs on the market when it comes to adjustability. It would just be nice if there was a way to compact the saddlebags some when not as full.

adjusting mountainsmith k9

This pack ranks among the best on the market when it comes to adjustability as it offers several adjustment options.

Waterproofing/Resistance: 9/10

Another strength of the K9 dog pack is its water-resistant abilities. While no dog pack on the market is truly waterproof, the K9 dog pack does a better job of keeping out water than most. The nylon that the pack is made of has waterproof qualities, and only having one zipper on top minimizes water access points. The biggest problem is that the seams are not sealed, so if the pack sits in water, it will eventually soak through, such as during creek crossings.

Like all dog packs, you can minimize needing to worry about waterproofness by placing items that you do not want to get wet in a ziplock baggie or another type of dry bag. Regardless it’s nice to know that the pack will not become waterlogged during a rainstorm, which is more than can be said for almost any other dog pack you can buy.

waterproofing mountainsmith k9

From my waterproof test, I found the K9 dog pack provides one of the best water-resistant features on the market.

Durability: 8/10

With 420d HD Nylon Rip Stop PU Carbonate making up the majority of this pack, durability is not a big concern when in the backcountry. This particular type of nylon is some of the most durable on the market and is difficult to break and hard to rip. This was evident while testing this pack as my dog frequently rubbed this pack along rocks and caught it on sticks while scrambling down into a canyon in Utah. At the end of the trip, there were not any visible marks on the pack.

While the material of the pack itself is very durable, my biggest concern with this pack is the buckle adjustment points. While I love how easy they make it is to change the length of the straps, being made out of plastic, it can be expected that this will be a failure point after heavy use. This was evident after minimal use: the buckles were visibly distressed where they had rubbed against rocks. The good news is that buckles can be replaced, but it still would not be ideal if one failed while in the backcountry.

Mountainsmith did a great job overall when choosing materials for this pack. It is on par with others on the market, if not slightly more durable. The buckle durability is a bit concerning, but in general, this is a very durable pack.

dog wearing mountainsmith k9

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Bailey Bremner photo

About Bailey Bremner

Bailey (aka "PseudoSloth") is a Colorado based thru hiker and adventurer. She has thru-hiked several thousand miles including the Continental Divide Trail, Great Divide Trail, Pinhoti Trail, and several self made routes among others.

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After thru-hiking the Appalachian Trail, Chris Cage created Greenbelly to provide fast, filling and balanced meals to backpackers. Chris also wrote How to Hike the Appalachian Trail.

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