Two different watch lists
A Mustang's health risks split by chapter of life. A horse fresh from a holding facility has lived without dentistry, trimming or worming, while a Mustang years into domestic life faces the domestic horse's problems with a body built for scarcity. Knowing which chapter your horse is in tells you what to watch first.
The newly adopted Mustang
Quarantine a new Mustang away from other horses until your vet has seen it, because respiratory infections and parasites move easily through gathered herds. A fecal test before worming tells your vet what the horse is actually carrying instead of guessing. Teeth deserve an early look: range horses can develop sharp points, uneven wear or retained caps that make eating painful, and a horse that drops wads of half-chewed hay is showing you dental trouble. Feet that have self-worn on rocky ground may be surprisingly sound, but overgrown, flared walls and thrush in soft domestic footing appear quickly once the horse stands in a paddock. Vaccination history is usually a blank page as well, so expect your vet to start a fresh schedule covering the core diseases for your region and to discuss tetanus protection early, since a range-raised horse's puncture wounds and gentling scrapes are exactly the injuries where that cover matters most.
The settled Mustang's real risk: plenty
Mustangs are survival specialists, and the same thrift that carried them through desert winters makes them gain fast on irrigated pasture and grain. The watch list becomes the easy keeper's list: a thickening crest, fat over the ribs and tailhead, and laminitis after grass flushes. Many owners are startled that the hardiest horse on the place is the one who founders first. Dry-lot turnout, hay-based feeding and regular work suit the Mustang metabolism far better than lush grazing.
Mind, gut and adjustment
Stress shows up in the gut: a newly gentled Mustang that goes off feed, paces the fence or develops loose droppings is often overwhelmed rather than ill, but a horse that stops eating entirely or shows colic signs needs a vet regardless of cause. Ulcers are a reasonable topic to raise with your vet for a horse that stays girthy, anxious or picky through gentling. Skin scrapes and rubs from first halters, blankets and saddles are common in the training months and worth checking daily.
When to call the vet
Call for colic signs at any stage, for coughing or nasal discharge in a new arrival, for rapid weight loss despite good feed — a dental or parasite problem until proven otherwise — and for any foot soreness once the horse is on domestic feed. A Mustang often has no paperwork at all, so keeping its vet exam findings, fecal results, dental notes and trim dates in its KinsLe Pet Passport builds the health history this horse never had.