Contributors: Susan Rackard, Prof Walter Renberg, Richard Meeson

 Species: Canine   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading


  • Fractures occur when the forces acting on a bone exceed its ultimate strength.
  • The type of fracture occurring is dependent on the magnitude, rate and direction of the force applied to it, and also the shape, size and structure of the bone involved.
  • Separation of the fracture fragments, and therefore the degree of instability, is dependent on the severity of the fracture and any restraining forces from surrounding tissues and their attachments.
  • Signs: vary according to site, type, degree of instability, severity of fracture, whether 'open' or 'closed'.
  • Treatment: coaptation, external or internal fixation may be necessary - dependent upon site, type, severity of fracture Fracture: internal fixation Fracture: external fixation.
  • Prognosis: dependent upon site, type, severity, method of repair,age and co-morbidities.

Presenting Signs

  • Functional compromise.


  • History of trauma or suspected trauma Trauma: overview, however minimal or apparently non-traumatic can occur in pathological or fatigue fractures.
  • Pain.
  • Swelling.


  • Dependent upon site.
  • Instability.
  • Crepitus - dependent upon distraction of fracture fragments (ends).
  • Signs of predisposing condition.

Acute Presentation

  • Shock Shock.
  • Collapse.
  • Bleeding ± wounds.

Age Predisposition


  • Young animal <12 months (skeletally immature).


  • More commonly, but not exclusively middle-aged and older.

Cost Considerations

Special Risks

  • The more severe the fracture, the greater the causal forces (usually), and the associated damage to surrounding tissues and other systems.
  • Forelimb fractures more likely to have associated thoracic trauma Thorax: trauma.



  • Direct trauma, eg road traffic accident (most common), gun shot.
  • Compression, eg fall from height.
  • Shearing forces, eg trapped limb.

Predisposing Factors





  • Fractures are caused when the force applied the bone exceeds the ultimate strength of the bone.
  • Fractures can be separated into 6 broad groups:
    • Oblique.
    • Transverse.
    • Comminuted.
    • Spiral.
    • Segmental.
    • Associated with the growth place (physis) (Salter-Harris classification ).
  • Fractures may be:

    Either Open - skin wound communicating with fracture site.

    Or Closed - overlying skin is intact.

  • Fractures may be:
    Either Complete (most common) - total disruption of bone continuity.
    Or Incomplete (rare) - partial continuity of bone maintained, eg Greenstick fracture (young animals), fissure fracture (adults).
  • Relative displacement of fracture fragments:
    • Distraction/avulsion - pull of tendon/ligament/muscle attachments separate bone fragments.
    • Compression - compressive force shortens bone, eg vertebra.
    • Depression - concave deformity of bone, eg skull, from applied force.
    • Impaction - fractured bone ends driven into one another.
  • Type depends upon:
  • Size and direction of the force applied.
  • Bone structure.
  • Bone shape.
  • Site.


  • Torsion → spiral fractures.
  • Shearing/tension/bending → transverse fractures.
  • Compression/bending → oblique fractures with/without comminution.
  • High energy stress, eg RTA or ballistic often → severe comminution and damage to surrounding tissue.
  • A combination of the above forces are usually acting in any one instance → variable fracture patterns.

Bone structure and shape

  • Both the bone structure and shape affect the manner in which a fracture occurs.
  • Cross-sectional area, length and the shape of the bone as it relates to the neutral axis. As such, a bigger dog's femur will fail at a higher load than a smaller dog's femur.


  • The type of stresses acting on a bone will vary according to the site of the bone, eg:
    • Vertebrae/Long bone metaphyses - compression.
    • Patella/Traction epiphyses - tension.
    • Humeral condyle - shearing.
    • Long bone diaphyses - bending.
    • Tibia/humerus - torsion.
  • Exposure/degree of protection by surrounding tissue affects fracture incidence/type, eg distal limbs have little covering tissue to absorb external forces → high incidence of limb fractures in general trauma, eg road traffic accident and risk of comminution and being open in nature.


Presenting Problems

  • Dependent upon bone involved.

Client History

  • Loss of use.


  • History of trauma.
  • Pain.
  • Swelling.
  • Soft-tissue injuries.


  • Dependent upon site.
  • History of predisposing condition - see Predisposers.

Clinical Signs

  • Signs of other tissue damage.

    It is almost impossible for a bone to fracture without considerable damage occurring to adjacent soft tissues - always examine whole animal carefully - always check for thoracic and abdominal trauma.

  • Site dependent, eg:
    • Limb Femur: fracture - acute onset lameness, limb shortening +/- deviation.
    • Spine Spine: fracture luxation - neurological signs, pain.
    • Jaw - eating abnormalities, facial distension, blood tinged saliva, dental malocclusion, hypersalivation.
    • Tail - abnormalities of function and carriage deviation Limber tail syndrome.
    • Ribs - signs of thoracic involvement.
    • Pelvis Pelvis: fracture - urinary tract injury, lameness/inability to stand.
  • Instability.
  • Crepitus - dependent upon distraction of fracture/fragments or interposition of soft tissue.
  • Signs of predisposing condition - see Predisposers.

Diagnostic Investigation


  • Full case assessment:
    • Major body systems: cardiovascular, respiratory and neurological:
      • Assess other injuries, eg neurological function Neurological examination , vascular integrity, cardiovascular compromise/signs of cardiovascular shock, respiratory compromise.


  • Two views under general anesthesia or deep sedation - including both proximal and distal joints.
  • Visualization of fracture site; classification of fracture type; involvement of associated tissues in multiple injuries.
  • Stressed - in some cases eg hock, carpal fractures.
  • Involvement of associated tissues in multiple injuries, eg ligament rupture.
  • Trauma cases should have thoracic radiographs Radiography: thorax.
  • May be useful to have contralateral limb region as comparison in young animals with open physes, comminuted fractures to establish original limb length, and in regions with complex or unfamiliar anatomy such as the tarsus or carpus.

Gross Autopsy Findings

  • Gross evidence of fracture.
  • Associated soft tissue trauma.

Differential Diagnosis

  • Dependent upon bone affected.
  • Neoplasia.
  • Luxation.
  • Joint disruption.
  • Sepsis (joint or foot).


Initial Symptomatic Treatment

Stabilize patient


  • Either If possible, support/splint affected bone (if distal) to elbow/stifle in order to restrict fracture movement/reduce pain/prevent further tissue damage or hemorrhage.
    Or Restrict movement, eg cage rest.

Standard Treatment

General considerations

  • Choice of treatment should take into account.
  • Patient status:
    • Age.
    • Size.
    • General health.
    • Expected lifestyle.
    • Other injuries, eg nerve damage.
  • Fracture site.
  • Fracture type and severity.
  • Available equipment and implants.
  • Surgical expertise.
  • Cost.
  • Open fractures will require urgent debridement, but not necessarily immediate fracture surgery.
  • The aim of fracture repair is to rapidly restore function of the bone.
  • Urgency of fracture repair varies according to site: spinal fractures may require immediate decompression; intra-articular fractures/growth plate injuries should be stabilized within 48 hours. Diaphyseal fractures within 5 days.

Early orthopedic repair in a stable patient reduces the incidence of post-operative complications.

Specific considerations

Conservative management

  • May be chosen in cases where the fracture cannot be repaired, eg fracture of a caudal vertebra, or where the fracture does not cause loss of function, eg isolated rib fracture, ischial fracture.

    High risk of 'false joint' formation, non-union, limb deformity if chosen inappropriately.

  • Analgesia and monitoring essential.


  • Always take post-operative radiographs (orthogonal views).

Subsequent Management


  • Repeat radiograph every 4-6 weeks to assess healing progress in adults (2-4 weeks in young).
  • Assess return of function 2 weeks post-operatively, and 4-weekly thereafter.




  • Early orthopedic repair in a stable patient reduces the incidence of post-operative complications.
  • It is important that neurological injury be identified before fracture treatment and ideally would be assessed prior to opioid analgesia in the early stages of initial triage assessment - prognosis will be affected:
    • Neuropraxia - good prognosis.
    • Plexus avulsion - guarded prognosis.
    • Nerve severence - poor prognosis.

 Conservative management

  • Site-dependent.
  • Almost always malunion Fracture: healing.
  • High risk of non-union, limb deviation, limb shortening/deformity, 'false joint' formation Fracture: healing.
  • External coaptation best for fractures below the elbow and stifle due to the conformation of the canine limb. Most appropriate for fractures with inter-digitation, minimally displaced fractures, ideally when a paired bone (fibula, ulna) also intact. Often better option in young due to reduced healing time and therefore coaptation time. Regular monitoring essential to minimize soft-tissue injuries with the coaptation.

External/internal fixation

Expected Response to Treatment

  • Conservative management - gradual return of function over >6 weeks. Often normal function never achieved owing to deformity, non-union or malunion.
  • External fixation. 
  • Internal fixation. 

Reasons for Treatment Failure

Further Reading


Refereed papers

Other sources of information

  • Tobias K & Johnston S  (2011) Veterinary Surgery: Small Animal. 1st edn. W B Saunder & Co. pp 565-571, 647-656.
  • Fossum T W (1997) Small Animal Surgery. St Louis: Mosby Year Book.
  • Piermattei D & Flo G (1997) Handbook of Small Animal Orthopaedics and Fracture Repair. 3rd ed. Philadelphia: W B Saunders & Co.

Other Sources of Information