Hematoma

Etiology

• Trauma.
• Kick.
• Collision.
• Fall.
• Fracture.
• Mating.
• Calving.
• Ovulation → excessive follicular hemorrhage.
• Poor platelet function in some breed lines of black Japanese cattle.

Pathophysiology

General

• Trauma → rupture of micro- and macrovasculature → local hemorrhage and inflammation → accumulation of fluids → localized swelling, pain and heat.
• Continued hemorrhage → swelling enlarges gradually → inflammatory response and organization of fluid → cessation of hemorrhage → swelling firms → gradual reduction in size and associated clinical signs.
• Open wound associated with swelling → possible infection → abscessation.

Surgery

• Surgical wounds are more likely to develop hematoma or seroma where the following factors are present:
  • Hemorrhage.
  • Tissue trauma.
  • Creation of dead space.
  • Excessive movement at wound site.
  • Hemoglobin → inhibits local tissue defences.
  • Iron → substrate for bacterial replication and virulence.

Ovarian hematoma

• Ovulation → hemorrhage into follicular cavity > normal → enlarged ovary.
  • Uneventful resolution.
• Occasionally destruction of germinal tissue → permanent unilateral loss of ovarian function.

Timecourse

• Acute trauma → swelling develops within hours.
• Continued hemorrhage → swelling enlarges over several days.
• Resolution usually:
  • Hematomas <10 cm diameter, 7-14 days.
  • Hematomas >10 cm diameter, 14-28 days.
  • Some limb hematomas never fully resolve but persist as a fluid filled swelling.