title: Intra-articular use of a platelet-rich product in normal horses: clinical signs and cytologic responses.
abstract: OBJECTIVE
  (1) To report the clinical and synovial effects of a platelet-rich product (PRPr) in normal equine joints, (2) to assess the persistence of platelets within synovial fluid after intra-articular injection, (3) to compare responses to different preparations of that product, and (4) to evaluate a gravity filtration system for PRPr preparation in horses.
  
  
  METHODS
  Experimental.
  
  
  METHODS
  A platelet-rich saline product (PRPr) was prepared from 7 normal horses using a proprietary preparation device and was divided into 3 treatments: resting, CaCl2 -activated (23 mM, final), and bovine thrombin-activated (10 U/mL, final). Each horse had 3 concurrent randomly assigned intra-articular PRPr treatments administered in their metacarpophalangeal/metatarsophalangeal joints; the fourth limb was injected with saline (0.9% NaCl) solution as a control. Clinical assessments, cytologic analysis of synovial fluid and hemograms were performed at 6, 24, 48, and 96 hours after injection. PRPr composition and growth factor content were analyzed.
  
  
  RESULTS
  The gravity filtration system produced a moderately concentrated PRPr. At 6 and 24 hours, when compared to control values, all PRPr treatments caused a significant increase in synovial WBC concentration (P < .0059) and neutrophil percentage (P < .0005). Bovine thrombin-activated PRPr injection consistently caused increased effusion scores and periarticular signs. At all time points, the synovial WBC concentration after thrombin-activated PRPr was significantly greater (P < .001) than for the control, CaCl2 -activated or resting PRPr. Intact platelets could be observed in synovial fluid for up to 5 days after intra-articular PRPr injection.
  
  
  CONCLUSIONS
  Resting and CaCl2 -activated PRPr may be safely used to treat equine joints, but bovine thrombin activation is not recommended at 10 U/mL. A PRPr can be prepared using a gravity filtration system, eliminating the need for centrifugation.
authors: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA. jamietextor@gmail.com
authors: Jamie A
authors: JA
authors: Textor
authors: Fern
authors: F
authors: Tablin
mesh_terms: D000818:Animals; D002122:Calcium Chloride; D006736:Horses; D007270:Injections, Intra-Articular; D053657:Platelet-Rich Plasma
chemical_list: D002122:Calcium Chloride