Trauma and Ischemia: Quantifying the "Hit"

In trauma medicine, we often rely on physical exam findings (mucous membranes, pulse quality) and basic labs (lactate, PCV/TP) to estimate how badly a patient is injured.

cfDNA offers a molecular perspective: it quantifies exactly how much tissue has been crushed or starved of oxygen.

The Mechanism: Necrosis

* Trauma (Blunt Force): When a dog is hit by a car, muscle and organ cells rupture. This is direct mechanical necrosis.
* Ischemia (GDV/Torsion): When a stomach twists, blood flow is cut off. Cells starve and die. This is ischemic necrosis.

Both events release massive plumes of cfDNA into the blood.

The Troia Study: GDV

A pivotal study by Troia et al. (2018) looked at dogs with Gastric Dilatation-Volvulus (GDV).
* Findings: Dogs with GDV had median cfDNA levels of ~3,500 ng/mL, compared to ~1,300 ng/mL in healthy controls (using their specific assay).
The Surprise: Interestingly, while cfDNA was high, it did not* predict survival as well as Lactate or Procalcitonin.

Why? Because cfDNA measures the injury (necrosis), while lactate measures the response (perfusion/shock). A dog can have a lot of dead stomach tissue (High cfDNA) but be hemodynamically stable after surgery (Low Lactate) and survive.

The Clinical Use Case

So why measure it?

It is valuable for Polytrauma.

A dog arrives with no external wounds but was rolled by a car.
* Low cfDNA: Suggests the internal organs escaped major crushing injury.
* Sky-High cfDNA: Suggests significant occult tissue destruction (liver fracture, splenic rupture, or severe muscle crush) even if the ultrasound is equivocal.

It serves as a "whole-body damage assessment" that flags patients needing intensive monitoring for delayed complications like kidney failure or DIC.