Back: Measure length of pet's back from the base of the neck to the base of the tail. See below for estimating by breed.
Neck: Measure the circumference of pet's neck for a snug fit. No need to add inches as you would with a collar.
Chest/Girth: Measure girth around the broadest part of the chest and add 2".
Note: If the dog has a stout build, select one size larger.
Recommended Sizing by Breed:
X-Small: Maltese, Chihuahua, Pomeranian, Toy Poople, Yorkshire Terrier and similar breeds.
Small: Australian Terrier, French Bulldog, Dachshund, Pug and similar breeds.
Medium: Beagle, Bichon Frise, Cocker Spaniel, Corgi, Jack Russell Terrier and similar breeds.
Large: Austrailian Shepherd, Border Collie, Bulldog, Dalmation and similar breeds.