Lead foreign body arthropathy in a horse.

This research article investigates a case of joint disease in a Quarter Horse that was caused by a metallic foreign body, specifically a lead sphere, in the metacarpophalangeal joint.

Introduction

• The article investigates a case of degenerative joint disease that occurred in a Quarter Horse gelding. The disease was linked to the presence of a lead-based foreign object within the horse’s metacarpophalangeal joint.

Diagnosis and Procedure

• An arthroscope, an instrument used to visually examine a joint internally, was used to both evaluate the condition of the joint and remove the foreign object.
• The arthroscopy revealed a yellow discoloration of the articular cartilage and synovium, and blunting and proliferation of the synovium. These are all signs of joint disease and inflammation.

Foreign Body Identification

• The foreign body was identified as a lead sphere, which was unexpected as lead is not commonly found within the bodies of horses.

Synovial Examination and diagnosis

• A microscopic examination of the inflamed synovial tissue (synovitis) also revealed accumulation of hemosiderin, a pigment that is significant in iron storage, and areas of mild mineralization.
• An additional pigment was also noticeable outside the cells (extracellular) within the synovial tissue.
• Upon examination of these findings, the horse was diagnosed with lead arthropathy, a rare condition resulting from the dissolution of intra-articular lead within a joint.

Effects of Lead Arthropathy

• Lead arthropathy causes chronic signs of pain, restrictions in motion, joint effusion (swelling due to excess fluid), and the excessive growth and division of synovial cells (synovial proliferation).