Drains in Wound Management of Small Animals

Drains are essential tools used to direct fluid out of a wound or body cavity to facilitate healing. 

1. Passive Drains

These techniques rely on natural forces rather than external pressure to function.

• Mechanism: They utilize gravity or capillary action to draw fluid from the wound or cavity.

• Common Types:

  • Penrose Drains: Soft, flat drains made from latex; they are the most commonly used passive variety.

  • Tubular Drains: Firmer passive drains can be constructed using red rubber or silicone tubes.

• Critical Requirement: These must be placed in gravity-dependent locations to ensure they function correctly.

2. Active Drains

These systems are more advanced and rely on mechanical forces to move fluid.

• Mechanism: They use negative pressure to actively pull fluid from the wound.

• Equipment: Red rubber or silicone drains are used within a closed system, maintained by intermittent low-pressure pumps or handheld rechargeable devices.

• Negative-Pressure Wound Therapy: Based on active drainage theory; it is used to remove purulent debris and significantly speed the closure of open wounds.

• Key Advantage: Active, closed-drain systems decrease the likelihood of ascending infection, which is a common complication associated with passive drains.

3. Monitoring and Removal

Drains must be managed carefully to ensure they do not become a source of further infection.

• Clinical Evaluation: The draining fluid should be evaluated via cytologic examination.

• Removal Criteria: Drains should remain in place until the fluid being removed decreases in quantity and no longer appears purulent.