Parasitic worms can adversely affect a horse’s health and well-being. They can do irreversible damage to the gut and other organs and be responsible for poor body condition, colic and, in serious cases, fatalities. Whenever we rescue a horse or pony, this is one of the main problems for them. We worm all new horses immediately and undertake regular worm count tests to decide when to worm our resident ponies. Horses are usually wormed 4 times a year. If you wish to buy a wormer for a specific pony, please note this in the comments box.