A five year-old Quarter Horse mare presented to the Cornell University Equine Hospital on 9/18/2009 for evaluation of severe left forelimb lameness. The patient had dozens of porcupine quills removed from the palmar aspect of both distal front limbs near the level of the fetlock on 9/5/2009, and had become progressively lame on the left forelimb. Severe effusion of the left front digital flexor tendon sheath and fetlock joint were the most significant physical exam findings. Ultrasonography of the left forelimb revealed multiple quills in the digital flexor tendon sheath, superficial digital flexor tendon and palmar aspect of the fetlock joint. Cytology of the fluid obtained from the digital flexor tendon sheath and fetlock joint were consistent with septic and aseptic inflammation, respectively. A total of 16 quills were removed during tenoscopy of the tendon sheath and arthroscopy of the fetlock joint. The patient was discharged five days post-operatively.