One feline and two canine samples had elevated mutation loads that are attributed to MSI/dMMR from loss-of-function mutations in MSH2. MSH2 is an established UC risk gene in humans [47, 48]; UC is the third most common Lynch syndrome-associated tumor [74], with increased risk of urinary bladder UC reported in Lynch syndrome patients carrying MSH2 mutations [75]. Here, MSH2 is linked to Lynch syndrome.