Lacerations: Specific Concerns
With regard to any laceration, our highest concern lies with the following:
Has major blood supply been compromised?
Without adequate blood supply, a laceration will not heal well... no matter what other treatment modalities are implemented. It is typical for some tissue(s) associated with a laceration to lose blood supply following injury. If these tissues are to be incorporated into primary closure of the wound, repair will ultimately fail as the affected tissue(s) devitalize (die). If closure of a wound is performed overtop of dead underlying tissue (such as muscle or bone), eventual necrosis of the dead tissue will result in abscess formation and probable wound dehiscence/ incision failure. Therefore vascularity of all associated tissues should be assessed prior to attampting any surgical repair.
Blood supply compromised at the injury site may also affect viability of tissue(s) in other areas, especially if relatively large and important blood vessels are transected (cut). All structures distal to a laceration (especially in the horse's limb) should be carefully evaluated for viability prior to formulating a treatment strategy.
Has bone been compromised?
Fractures of weightbearing bones can certainly be life-threatening to a horse. Nonweightbearing fractures don't carry the same degree of concern, although also need to be identified and treated appropriately as soon as possible. The combination of an open laceration and bone fracture can also result in osteomyelitis (infected bone) or sequestrum formation.
Clinical, radiographic and/or ultrasonographic examination may be required to rule out bone compromise following an injury.
Has a synovial structure (e.g. joint, tendon sheath, bursa, etc.) been violated?
The introduction of bacteria typically accompanies the penetration of a foreign (contaminated) object into a synovial structure. Synovial infections can be extremely challenging to resolve, especially if they have been present for awhile. Both aggressive local and systemic antimicrobial therapy is warranted in most cases, which can be life-threatening if left unresolved. Arthroscopic evaluation and debridement of synovial structures is often necessary following open injury(ies).
Synovial violation can be confirmed via the use of radiographic and/or ultrasonographic examination, although demonstration of direct communication between the synovial structure and wound is considered the definitive diagnostic test. Sterile saline is infused under pressure into the structure from an alternate location (away from the injury site). Subsequent expression of the fluid out of the wound confirms synovial involvement. Additionally, synovial fluid can be collected for analysis after the needle has been placed and before saline infusion in many cases.
Has a tendon and/or ligament been compromised? Lacerations can result in direct trauma to a tendon or ligament (such as partial or total transection, splitting, or bruising) or indirectly affect the structure via secondary infection. A combination of clinical and ultrasonographic examination of the injury site will usually identify any tendon or ligament compromise.
As a rule of thumb, tendon injuries on the front side of limbs (i.e. extensor tendons) carry a much better long-term prognosis for performance than injuries sustained to flexor tendons on the back side of the limbs. This is due to the supportive nature of flexor tendons with regard to normal limb posture and function.