Thirty-six canine flexor digitorum profundus tendons were repaired using 5-0 polyglycolide-trimethylene carbonate monofilament (Maxon) or polydioxanone monofilament (PDS2). All the tendons healed without rupture or formation of gaps of more than 2 mm. Mechanically, all tendon repairs had sufficient tensile strength to enable active mobilization. Polyglycolide-trimethylene carbonate (Maxon) repairs were initially superior in gap and ultimate strength to polydioxanone (PDS2) repairs. However, the gap and ultimate tensile strength of polyglycolide-trimethylene carbonate (Maxon) repairs had decreased significantly at day 14, whereas polydioxanone (PDS2) repairs maintained their strength throughout the 28-day observation period.