Use of Platelet-rich Plasma in the Treatment of Desmitis of Distal Interphalangeal Joint Collateral Ligament in a Horse
Authors: Góss Geórgia Camargo , Döwich Gabriela , Machado Ingrid Rios Lima , Mozzaquatro Fabricio Desconsi , Rodrigues Ana Paula , Moreira Carneiro Ana Luísa , Leite Carla Teixeira , Duarte Claudia Acosta 
Published: March 2020

Background: Platelet-rich plasma (PRP) has been increasingly used to hasten healing of tendonitis and desmitis, allowing horse athletes to go back to practicing sports in a shorter period of time. However, its use has rarely been reported in the treatment of desmitis of the collateral ligaments of the distal interphalangeal joint (CL-DIP), which is based on the use of horseshoes and rest for at least six months. This paper describes the use of PRP as an aid in the treatment of CL-DIP in a horse athlete.Case: A male Criollo horse, 450 kg, about 15-year-old, used for team roping. The animal had a month-long history of lameness, and a visual inspection revealed an increase in volume in the lateral dorsal region of the limb proximal to the coronary band of the hoof. A specific examination of the locomotive system showed Grade III, Category 5 claudication, which became evident the beginning of the exercise and ceased after a short period. A radiographic evaluation of the distal phalanx revealed no clinically relevant changes. Therefore, and in view of the location of the increased volume, an ultrasound scan was performed, which showed an image compatible with an extensive hematoma in the region underlying the perioplic corium, while the CL-DIP presented swelling with large areas of hypoechogenicity. Considering the findings of the image, the physical examination and the history of the horse, desmitis of the collateral ligaments of the distal interphalangeal joint was diagnosed. The treatment plan consisted of rest, application of a therapeutic horseshoe, and infiltration of the lesion with platelet-rich plasma (PRP). First, however, warm compresses were applied to reduce the swelling. The PRP was obtained by collecting whole blood from the external jugular vein, subjecting it to double centrifugation, and separating the supernatant blood plasma. The end product was applied to the lesion by ultrasound-guided infiltration. The horseshoe was a model with extended side bar, i.e., an egg bar horseshoe. After 15 days of PRP infiltration, another ultrasound scan was performed, which showed improved echogenicity of the ligament. The animal was discharged, and rest and the use of the horseshoe for 6 months were recommended. However, the owner expressed interest in having his horse participate in a high level team roping event, which was slated to take place two months hence. In view of this plan, rest was recommended for a further 15 days, followed by a gradual return to the exercise until the moment of the competition, which should be interrupted if the animal displayed any sign of lameness. The animal performed well in the competition, showing no loss of performance due to locomotor changes. Discussion: Locomotor disorders in the digit region are common in Creole horses, and one of the affected structures in this area is the CL-DIP. Desmitis of this ligament is characterized by acute claudication in animals without radiographic abnormalities, and can be diagnosed based on ultrasound scans. The main cause of this disorder stems from biomechanical alterations, and therefore the main treatment is the use of a therapeutic bar horseshoe on the affected side. The prognosis varies between favorable and unfavorable, and the healing time lasts on average 6 months. In view of this lengthy period of time, one of the alternatives to hasten healing is to use PRP, which is commonly used in tendonitis of the flexor tendon and suspensory ligament desmitis. Nevertheless, this technique provides variable outcomes and its application to CL-DIP remains insufficiently described. In the case reported here, its use in association with conventional treatment was effective, enabling the horse to participate in competitive events without loss of performance due to claudication.