There are two different criteria for OutFox® Field Guard sizing: one for breeds with average head shapes and muzzle lengths and one for breeds with short snouts/wide heads. See below for detailed information.

* In the sizing charts below, breed examples are only rough guidelines: please always take the required measurements for your dog for exact sizing.

Regular Sizing

For breeds with average head shapes and muzzle lengths, sizing is based on head length: Measure from the base of the skull straight to the end of the nose while keeping the tape taut so that the contours of the face are not factored into the measurement.  See How to Measure Head Length video.

Please note:  Pointy-eared dogs do fine in regular-sized Field Guards.


Dog Type Field Guard Size Designed to Fit Breed Examples Head Length
XXS XXS tiny breeds Chihuahua, Miniature Dachshund, Maltese, Yorkie
(custom order for dogs under 8 lbs)
5-6 1/2″”
XS_spaniel XS toy breeds Cairn Terrier, Fox Terrier, Jack Russell, Miniature Dachshund, Norwich Terrier, Westie, Whippet 6 1/2-8″
S_beagle S small breeds Basenji, Beagle, Border Collie, Brittany Spaniel, Sheltie,
Fox Terrier, Jack Russell
8-9 1/2″
M_icon2 M medium breeds Australian Shepherd, Bull Terrier, Dalmatian, Greyhound , Labrador, Vizsla, Wheaton Terrier 9 1/2-11″
L large breeds Doberman, Large German Shepherd,
Large Labrador
Guardian Dog, Bloodhound, Weimaraner
11-13 1/2″
CUSTOM ORDER    for head lengths over 13 1/2″
or head circumference over 25″

These breed examples are only a rough guideline: please measure your dog’s skull length for exact sizing.

Wide Head/Short Snout Sizing

For breeds with short snouts or wide heads, sizing is based primarily on head circumference. By OutFox definition, a wide head is one that is shorter (horizontally) than it is tall; in other words, the length of the muzzle is less than the height of the head. Additionally, wide heads include those of breeds who have full, furry heads, which would require a Field Guard with more airspace around the head. Unlike regular sizing, head length is an additional parameter but is not crucial in determining the proper size Field Guard for short snout/wide head sizing (see the note below).
Head circumference: Measure the circumference loosely around the largest part of the head: go gently over the ears with the measuring tape held loosely around the head. If the ears stand up, do not measure up and over the ears. Please reference the red line in the illustration below.  See How to Measure Head Circumference video.
Head length: Measure from just behind the ears to the end of the snout (or the part of the head that protrudes the farthest—some Bulldogs’ lower jaws protrude farther than their noses). Please reference the blue line in the illustration below.

Please Note: Measurements for head circumference and head length do not always correlate as shown on the sizing chart. For short snout/wide head breeds, head circumference is most important. If, for example, your dog’s head circumference necessitates a size Small but the head length necessitates a size Medium, please always order the size based on head circumference (a Small in this case). If you have any questions or concerns about choosing the right size, feel free to contact us before you place your order.

Dog Type Field Guard Size Head Circumference Breed Examples Head Length
XS-short XS-Short 15″-17″ Boston Terrier
King Charles Spaniel
Shih Tzu
5-6 1/2″
S-Short S-Short 17″-19″ French Bulldog
King Charles Spaniel
6 1/2-8″
M_Short M-Short 19″-22″ Boxer
English Bulldog
Pit Bull
8-9 1/2″
L_Short L-Short 22″-25″ Large Boxer, Large English Bulldog, Large Pit Bull
Small Rottweiler
9 1/2-11″