When your pack arrives, adjust it to fit your individual dog. The panniers should hang as vertically as possible to keep the weight centered low on the dog’s shoulders. The bottom of the pack should be no lower than the dog’s elbows nor forward of the front legs. The belly strap(s) should be snug, but not overly tight. The chest strap must not be too high on the neck region nor so low that it interferes with the swing of the front legs. If your pack has an adjustable backpiece, you can taper the width of the rear portion of the pack to conform with your dog’s waist.
The most important consideration of pack fit is the comfort of your dog. Freedom of movement is paramount, so adjust the pack anywhere it seems to hamper the natural way your dog moves.
Acclimating Your Dog
Your dog needs a chance to get used to the pack. Allow him to sniff and investigate the new gear, but discourage mouthing or gnawing of the pack–he should learn that the pack is a work tool, not a chew toy. Let the dog wear the empty pack around the house for an hour or so, making sure that no nibbling or worrying at the pack takes place. Better yet, go on a vigorous walk with your dog wearing the empty pack, and give lots of praise and attention. Soon your dog will associate the pack with exercise and accomplishment.
Once the dog is used to the feel of the pack, stuff both sides with crumpled newspaper to expand the sides without adding appreciable weight. It will probably take some time for your dog to understand that the pack makes him considerably wider: the first doorway is likely to cause a bit of confusion when a pannier collides with the door jamb!
After this initial adjustment period is well underway, you can begin adding weight. As mentioned before, a healthy dog can carry one-fourth to one-third of their weight. However, these weights must be achieved gradually as the dog builds strength: don’t load them up on the first day! Start with perhaps a tenth of their weight (e.g., eight pounds for an eighty-pound dog). This weight ratio will not tax the dog, but it will allow him to get a feel for the swing of the pack and an idea of what dogpacking entails.