The chest is, without doubt, the determining factor as to whether a terrier may follow its intended quarry underground. Too large and he/she is of little use for underground work, for no matter how determined the terrier may be, this physical setback will not be overcome in the nearly-light situations it will encounter in working foxes. It may be thought the fox is a large animal - to the casual observer it would appear so. However, the bone structure of the fox is finer than that of a terrier, plus it has a loose-fitting, profuse pelt which lends itself to flexibility. I have not encountered a fox which could not be spanned at 14 inches circumference - this within a weight range of 10lbs to 24lbs, on average 300 foxes spanned a year. You may not wish to work your terrier. However, there is a Standard to be attained, and Spannability is a must in the Parson Russell Terrier..

How to span?

               With so many variations of hand size a more precise statement of average hand span is required. The way I find easy to explain is to take a round object of four and a half inch diameter, place your two thumbs and index fingers together forming a circle - this is your span. 

Some will not be able to cover the entire distance, others will have an overlap. Either way, when spanning the person will bear in mind their +or -- factor and be able to gauge the four and a half inch diameter, which is approximately 14 inches circumference. This size of chest in a terrier of 12inches --14inches height will look and be balanced, allowing heart and lung room, with the flexibility to follow its quarry in underground work. Regarding the shape of the chest -- this should not of course be round (barrel-chested), rather the shape of an egg in profile, large end uppermost, allowing free movement of the forelegs. Too large a chest will put out the elbows causing poor movement, so it is not only from a working point that the chest should be of the correct size.

Where to span?

               Approach the terrier with its full knowledge of being handled -- do not grab or suddenly place hands. With the terrier on the ground, not more than the forelegs off the floor, place hands in a direct line down around the chest directly behind the elbows. The lifting of terriers off the ground, sometimes to chest height, and in extreme cases higher, causes distress and tenseness.

              I cannot recall any guidelines for spanning apart from the average hand size, which of course does not exist! This method is what evolved with the working and judging of terriers. I find it works well with practice and a little forethought. Maybe there is a better idea?