Vet science Chapter 11 (preventative health)

Cellular and Vascular Response to Injury

  • Cellular Extravasation and Pus Formation:

    • White blood cells exit the lumen of the blood vessels to migrate directly to the site of tissue trauma or infection.

    • At the target site, these cells phagocytose ("eat") foreign pathogens such as bacteria.

    • Following the neutralization of pathogens, the accumulated dead cells and debris are excreted in the form of pus.

  • Vascular Dynamics Post-Injury:

    • Step One (Initial Response): Immediate vasoconstriction occurs at the site of injury.

    • Subsequent Response: Following initial constriction, the vasculature undergoes vasodilation in order to flush out the affected area.

Granulation Tissue and Scar Dynamics

  • Vascularity and Healing Viability of Scars:

    • Granulation tissue and scarring function efficiently and effectively during the primary (first-time) healing event.

    • Re-injury or rupture of an existing scar at the exact same location yields an extremely poor ("garbage") prognosis for healing.

    • Etiology of Poor Secondary Healing: Scar tissue possesses a deficient vascular supply (marked paucity of blood vessels) and remains structurally thin compared to undamaged tissue.

  • Visual Characteristics of Granulation Tissue:

    • Normal Appearance: Healthy, normal granulation tissue exhibits a distinct "bubblegum pink" color.

    • Acceptable Variance: A reddish coloration is marginally acceptable, but the tissue will distinctly not be skin-colored.

  • Hypergranulation:

    • Pathological overproduction occurs when granulation tissue fails to halt its proliferative phase, continuing to expand unabated.

Mechanical Injury and Internal Tissue Necrosis

  • Definition of Mechanical Injury:

    • Any physical or structural insult that results directly in tissue necrosis (tissue death).

  • Intestinal Telescoping (Intussusception):

    • Characterized by segments of the intestines telescoping into adjacent segments in an inside-outside fashion.

    • Pathology: Uncorrected telescoping leads inevitably to tissue ischemia and necrosis.

    • Surgical Intervention: Irreversibly damaged segments cannot self-resolve; necrotic portions must be surgically excised (cut out), and the viable remaining tissues must be reconnected.

  • Internal Mechanical Pathologies in Veterinary Medicine:

    • Intestinal Torsion: Twisting of the intestines, potentially precipitating severe colic in equine species.

    • Displaced Capo Mesa: Organ displacement observed in large animal medicine where internal organs fold or displace upon themselves.

    • GVBs (Gastric Dilatation-Volvulus): Pathological rotational and distension disorders of the stomach compromising visceral perfusion.

    • Classification Criteria: Any internal phenomenon that physically restricts, strangulates, or compromises internal organ viability qualifies as an internal mechanical injury.

Classification and Presentation of Contusions

  • Definition of a Contusion:

    • A contusion is classified as any bruise on the body characterized by subsurface tissue trauma while the overlying external skin remains intact and undamaged.

  • Anatomical Distribution:

    • External Contusions: The most common presentation, occurring in peripheral tissues beneath intact dermal layers.

    • Internal Contusions: Tissue bruising occurring deep within internal visceral organs.

    • Pulmonary Contusion: An internal contusion characterized specifically by bruising of the lung tissue.