Kidney: trauma in Cats (Felis) | Vetlexicon
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Kidney: trauma

ISSN 2398-2950

Contributor(s) :


  • Kidneys are relatively protected by surrounding sublumbar muscles and ribs.
  • Cause: most injuries from road traffic accidents (RTA)/hit by car (HBC).
    In all cases of traumatic injury warn owner of potential complications at time of injury.
  • Signs: degree of injury determines pathophysiology, signs and management.
  • Diagnosis: imaging techniques.
  • Treatment: severe trauma requires urgent fluid replacement and possible nephrectomy.
  • Prognosis: good in mild cases; guarded if trauma is severe.

Presenting signs

  • RTA/HBC.
  • Ballistic or penetrating injury.
  • Dysuria.
  • Discolored urine.

Acute presentation

  • Shock due to renal hemorrhage.

Cost considerations

  • Monitoring, supportive care and surgery can be costly.

Special risks

  • Patient may require emergency surgery but this may be complicated by other factors associated with recent trauma Trauma: overview:
    • Hypovolemia (hemorrhage).
    • Respiratory trauma.
    • Arrhythmia (cardiac trauma).
  • Ensure patient has adequate blood pressure support during surgery to prevent further damage to kidneys.



Road traffic accidents

  • Surrounding structures (sublumbar muscles and ribs) can cause damage.
  • Kidney 'whiplashed' about its hilar structures to collide with these structures.

Ballistic injury

  • Cause direct renal damage.
  • Compromise renal blood supply.

Penetrating injury

  • May cause direct renal damage.
  • Secondary infection can result in renal complications.


  • Subcapsular hematoma.
  • Parenchymal rupture.
  • Renal crushing.
  • Avulsion of vessels/ureter.
  • Variable hemorrhage and hypovolemia.
  • Urine leakage and retroperitonitis.


  • Severe injuries acute (within hours).
  • More chronic signs may develop over days-weeks.


Presenting problems

  • Shock.
  • Sublumbar distension and pain.
  • Retroperitonitis.

Client history

  • Trauma.
  • Discomfort.
  • Dysuria.
  • Discolored urine.
  • Non-specific signs:
    • Anorexia.
    • Depression.
    • Vomiting.
  • Collapse.

Clinical signs

  • Pain on dorsal abdominal/retroperitoneal palpation.
  • Signs associated with shock  Shock /hypovolemia:
    • Weakness.
    • Tachycardia.
    • Pallor.
  • Guarded abdomen, abdominal extension or renal mass.

Diagnostic investigation


  • Abdominal radiography Radiography: abdomen  may show evidence of retroperitoneal hemorrhage or perirenal hemorrhage (apparent enlarged renal silhouette).
  • Abdominal fluid may be present if damage to lower urinary tract   →   uroabdomen.
  • Always examine entire radiograph and perform thoracic radiography Radiography: thorax to check for other potential injuries.

2-D Ultrasonography

  • Useful to assess perirenal and retroperitoneal hemorrhage or damage within parenchyma Ultrasonography: kidney.
    Particularly valuable when ascites obscures radiographic detail

Contrast Radiography

  • Intravenous urography Radiography: intravenous urography may be required to identify
  • Contrast leakage (urinary tract rupture).
  • Non-opacification of kidney (hypovolemia or pre-existing functional damage).




Confirmation of diagnosis

Discriminatory diagnostic features

  • History.
  • Clinical signs.
  • Renal function tests.

Definitive diagnostic features

  • Radiography.
  • Urography (degree of urine leakage).
  • Ultrasonography.

Gross autopsy findings

  • Check for signs of trauma, eg road traffic accident:
    • Drag marks.
    • Claw damage, bruising/hemorrhage in skin/subcutis/muscles/body cavities and other organs.
  • Check for bone fracture.
  • Retroperitoneal hemorrhage may be seen, with subcapsular hematoma, tears in the renal tissue itself, with hemorrhage.
  • Associated ureter avulsion, bladder rupture or splenic/hepatic rupture may be seen.
  • Trauma may be iatrogenic from biopsy or other surgery.

Histopathology findings

  • Hemorrhage with hemosiderin if old lesion.
  • Parenchymal dissociation.
  • Inflammation and fibrosis will depend on age of lesion.


Initial symptomatic treatment

Minor trauma

  • Careful monitoring of renal function Renal function assessment and urine output.
  • Intravenous fluid therapy to maintain renal perfusion and output.

Severe trauma

  • Urgent blood volume replacement if substantial hemorrhage to maintain renal perfusion.
  • Blood transfusion may be required.
  • Possible nephrectomy Ureteronephrectomy if hemorrhage cannot be controlled or kidney function will not be maintained.
    Ensure that contralateral kidney is functioning adequately BEFORE nephrectomy.


  • Urine output to ensure kidney functioning.
    Urine output does not ensure both kidneys are functional.

Subsequent management


  • Renal function parameters to ensure that renal function persists.




  • Guarded if severe trauma - nephrectomy may be necessary.
  • Good if mild trauma.

Expected response to treatment

  • Adequate renal output maintained.

Reasons for treatment failure

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Streeter E M, Rozanski E A, LaForcade-Buress Ad, Freeman L M, Rush J E (2010) Evaluation of vehicular trauma in dogs: 239 cases (January-December 2001). JAVMA 235 (4), 405-408 PubMed.
  • Boysen S R, Rozanski E A, Tidwell A S et al (2004) Evaluation of a focused assessment with sonography for trauma protocol to detect free abdominal fluid in dogs involved in motor vehicle accidents. JAVMA 225 (8), 1198-1204 PubMed
  • Vinavak A & Krahwinkel D J (2004) Managing blunt trauma-induced hemoperitoneum in dogs and cats. Comp Contin Educ Pract Vet 26 (4), 276 VetMedResource.