Cardiac troponin I (cTnI), a cardiac specific biomarker released into circulation following cardiac myocyte damage, is used as a non-invasive method for diagnosing heart disease in small animals. Increases following suspected myocardial injury in black-tailed prairie dogs and rabbits have been reported, although a commercially available assay has not been validated for most non-traditional species. The immediate goal of this study was to compare a cTnI ELISA from a reference laboratory to a point-of-care cTnI assay (i-STAT) in clinically healthy, subadult and adult guinea pigs of both sexes; longer-term aims are to establish reference intervals for both assays. Twenty guinea pigs were used. Six male, and six female, subadult guinea pigs were administered 20 mg/kg ketamine and 2 mg/kg xylazine intramuscularly for venipuncture, and collection was repeated on four males and six females, awake, seven days later. Eight adult males were anesthetized using isoflurane for blood collection. Samples were measured in duplicate using the i-STAT for all groups and analyzed by ELISA from the isoflurane group. Results from the point-of-care assay showed an overall median of 0.006 ng/mL (range 0-0.06 ng/mL), with medians of 0.008 ng/mL (0-0.06 ng/mL) for ketamine/xylazine (n=12), 0.019 ng/mL (0-0.05 ng/mL) for awake (n=10), and 0.007 ng/mL (0-0.06 ng/mL) for isoflurane (n=8) groups. Results from the reference laboratory ELISA are pending. Heart disease is a relatively common cause of morbidity and mortality in guinea pigs, and this information may be valuable for clinical assessment of myocardial disease in this species.