Measure the Fence for a Pony, Not a Horse
Shetlands are commonly fenced with whatever held the horses, and that is where the trouble starts. A bottom rail or strand set to meet a horse's chest can sit above a Shetland's back, leaving a clean invitation to duck underneath. Walk the whole paddock crouched or kneeling at intervals, sighting along the lowest line. Look for places where the ground dips, where a pony has already polished the soil into a smooth slide under a rail, and where bedding or manure build-up inside the fence raises the floor and shrinks the pony's crouch.
Add a low rail or strand where clearance is more than a Shetland needs to wriggle through, and dig out built-up ground along the line so the barrier you measured is the barrier she meets.
The Push, the Rub, and the Thick Coat
A Shetland is immensely strong for her size and leans, rubs, and scratches against fencing with her whole body. Push every post at pony height, not yours, and check rails for the bow that develops where she backs up to scratch. Inspect fasteners at her rubbing height, since that is where boards work loose first.
If you rely on an electric strand, test it at several points with a proper tester rather than trusting the energiser's light. Then consider her insulation: a full Shetland coat and a long forelock can keep a strand from making honest contact, so a pony may learn the line is bluffing. Keep the strand clear of vegetation that drains it, position it where she meets it with her nose or a less insulated part of her body when she investigates, and pair it with a visible physical barrier rather than asking one strand to do the whole job.
Gates at Pony Scale
Close each gate and get down to look at its bottom edge. Gate sag that a horse owner would never notice opens a pony-sized wedge at the far corner, and Shetlands are dedicated gate investigators who push, lift with a nose, and paw at hardware. Fit a latch she cannot nose upward, add a chain low enough that the gate cannot be forced into a crawl gap, and confirm the gate cannot be lifted on its hinges. Check the ground at the gateway for the dip that constant traffic digs, and fill it before it becomes the exit.
Lead her through and watch where her attention goes. A pony studying one part of a gate is telling you which part to reinforce.
The Small Paddock Problem
Many Shetlands live in small, restricted paddocks, and a small space concentrates wear: the same corners take every rub, the same gate takes every impatient push at feeding time, and grass pressure on the other side of the fence is constant motivation. Inspect a small paddock more often than a big field, rotate any feeding station away from the fence, and keep a companion's fence line, if she has one within sight, in equally good order, since she will test hardest toward company.
Finding a Very Small Escapee
A loose Shetland can vanish into hedges and long grass that would never hide a horse, and she may not travel far before settling to graze. Keep a current photo showing her colour, mane, and size against a known reference such as a gate, so searchers judge scale correctly. If she slips under despite your checks, KinsLe's Lost Pet Alert System can send a free alert to nearby Circle of Love members, and the finder who spots her in a ditch or garden can message you directly through KinsLe.