Quarantine

S3, E13: Kit's barrel racing horse, Daisy, has not been performing well since losing her foal. Ty encourages Kit to bring Daisy to Heartland to be treated by Amy, causing friction among them. Daisy turns out to have strangles, Heartland is placed under quarantine and Pegasus's health is threatened. Meanwhile, Amy is dealing with a demanding client who is having problems with her dressage horse.