Contributors: Andrew Gardiner, Daniel Smeak

 Species: Canine   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading


  • Surgical removal of the testes through a prescrotal incision without invading the vaginal tunics.


  • Eliminate male fertility and inhibit associated behavioral responses.
  • Treatment of certain diseases influenced by male sex hormones, eg prostatic diseases Prostate disease , perianal adenomas Adenoma / adenocarcinoma and perineal hernias Perineum: rupture.
  • Treatment of testicular Testicle: neoplasia , epididymal or scrotal neoplasia.
  • Treatment of medically unresponsive orchitis Orchitis / epididymitis.
  • To prevent perpetuation of congenital problems, eg abdominally retained testicles Testicle: cryptorchidism and umbilical hernias.

  • In cryptorchid animals an inguinal and/or abdominal incision is likely to be required.
  • Severe scrotal and/or testicular trauma.
  • As part of scrotal urethrostomy procedure Urethrostomy.
  • As part of treatment of certain endocrine conditions and, occasionally, as part of treatment to control idiopathic epilepsy Epilepsy: idiopathic.


  • In "closed" castration, vaginal tunics are not entered, so ligatures are placed directly around spermatic cord and contained structures, thereby reducing risk of bleeding from incised vaginal tunics.
  • Rapid, easy technique.
  • No opening created in peritoneal cavity, so infection in region of castration is not likely to spread into peritoneal cavity.
  • No possibility of seeding local wound with tumor cells because tunics and testicle remain intact.


  • No tension must be placed on spermatic cord during clamping or ligation and extra care is required to place secure ligatures since vessels supplying testicles are indirectly ligated (ligatures are placed around tunics not directly on vessels).
  • More risk of catastrophic bleeding if ligatures are not secure.

Alternative Techniques

  • Periodic administration of anti-androgenic compounds may be a suitable alternative for some of the indications for castration.
  • Chemical sterilization by injection of zinc gluconate Zinc gluconate (for nonsurgical sterilization in the male dog) into testicle. Indicated for dogs from 3-10 months. Dose based on testicular width (Neutersol® injectable solution).
  • An alternative perineal "open" castration approach Castration , whereby incision is created just above scrotum in perineal area, can be used when technique is performed along with perineal herniorraphy to avoid repositioning dog.
  • Open castration technique, whereby the testicular tunics are entered, may alternatively be performed.
  • Castration may be combined with scrotal ablation Scrotal ablation in certain situations.

Time Required


  • 15 min.


  • 15-20 min.


Materials Required

Minimum equipment

Minimum consumables

  • Absorbable suture material for ligation and intradermal sutures Suture materials , eg chromic catgut, or polyglactin 910 (Vicryl); size 0, 2/0, 3/0 depending on size of patient.
  • For percutaneous sutures, 4-0 monofilament nonabsorbable sutures, preferred.



Dietary Preparation

Site Preparation

Ensure that both testicles are housed within scrotum before preparing site for surgery.

  • Ventral midline prescrotal area with patient in dorsal recumbency.
  • Routine surgical skin preparation including 6-10 cm of surrounding skin.
    To avoid irritating skin (and consequent self-trauma), scrotum itself should not be clipped or scrubbed; it should be draped out of aseptic field. For dogs with long hair it is acceptable to clip long hair from scrotum but do not touch clippers to scrotal skin.
  • Use routine 4-quadrant drapes to isolateprescrotal area in aseptic field Closed castration 01 - surgical skin preparation of prescrotal area.


Right-handed surgeons, stand on patient's left side to perform castration; left-handed surgeons stand on right side.

  • General anesthesia.
  • Dorsal recumbency.



Step 1 - Examine testes

  • Verify both testes are present in scrotum.

Step 2 - Exteriorize testicle

  • Advance one testicle to prescrotal area and hold in place while skin incision is made.
  • Squeeze testicle into aseptic field in prescrotal area Closed castration 02 - testicle advanced into prescrotal area.
  • Incise skin and subcutaneous tissues on midline over testicle Closed castration 03 - incision into subcutaneous tissue over the testicle.

Step 3 - Incise to tunics

  • Incise through subcutaneous tissue to reach parietal vaginal tunic of exposed testicle.
    Do not invade tunics.
  • Look for shiny, smooth surface of tunics or "bubbly" looking fat popping out of deeper layers of incision. Once either are visible, do not incise any deeper Closed castration 04 - subcutaneous tissue dissection.
  • Attempt to "pop" testicle out of wound. If not possible, incise cranial and caudal aspect of deeper tissue layer until testicle can be exteriorized from incision Closed castration 05 - exteriorized testicle with intact tunics.
  • Hold scrotum in place under drape and pull testicle up firmly to break down spermatic fascia and gubernaculum and expose at least 8 cm of cord Closed castration 06 - exposure of the cord.

Core Procedure


Step 1 - Castration

  • Gently wipe spermatic cord with a gauze sponge if necessary to retract fascial layers and strip loosely adhered fat.
  • Clamp three Carmalt forceps on cord.
    DO NOT place tension on cord while clamping.Cord should be loose so vessels within cord are not under tension. Tension on cord increases risk of vessel retraction into deeper tissues if ligatures are not secure Closed castration 07 - three Carmalt forceps clamped to the cord.
  • Cord may be cut between distal two clamps (see illustrations) or alternately, cut cord following the second ligature.
  • Place circumferential ligature under most proximal clamp around spermatic cord Closed castration 08 - application of circumferential ligature. Tighten first throw once clamp is removed. Place 4 square throws (2 square knots).
  • Insert taper needle through cord for a transfixing ligature Closed castration 09a - application of transfixing ligature so ligature lies in crushed area from second forceps Closed castration 09b - tightening of ligature over crushed tissue.
  • If cord was left intact as ligatures were placed, transect cord 0.5 cm distal to transfixing ligature.
  • Release cord under control of thumb forceps, observe for hemorrhage and replace it within wound.
  • Advance second testicle into incision, incise fascial layers over testicle but keep tunics intact Closed castration 10 - exposure of second testicle and repeat ligation sequence as above.

Step 2 - Closure

  • Close subcutaneous tissues with simple interrupted or continuous absorbable sutures.
  • Can place intradermal sutures instead of skin sutures or else close skin routinely with percutaneous sutures Closed castration 11 - final closure of prescrotal incision.




Antimicrobial therapy

  • Antibiotics should not be necessary for routine, elective castration.

Wound Protection

  • Some dogs may require an Elizabethan collar Elizabethan collar to prevent interference with skin sutures.
  • Strictly limit exercise until suture removal.

Potential complications

  • Hemorrhage from slipped or misplaced ligatures or undiagnosed bleeding disorders.
  • Scrotal hematoma from traumatic technique or poor hemostasis Scrotal hematoma.
  • Infection/dehiscence if castration was performed with poor technique or inappropriate operating standards.
  • Severe scrotal swelling 10 days after castration, scrotal ablation Scrotal ablation performed to treat problem.
  • Scrotal skin irritation if this area is clipped or scrubbed.


Follow up

  • Suture removal in 10-14 days, if skin sutures used.



Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gourley J (1998) Early neutering of cats and dogs. Vet Rec142 (9), 228 PubMed.
  • Michell A R (1998) Neutering and longevity in dogs. Vet Rec 142 (11), 288 PubMed.
  • Poole C (1998) Early neutering of cats and dogs. Vet Rec 142 (9), 227-228 PubMed.
  • Thornton P D (1998) Early neutering of cats and dogs. Vet Rec 142 (8), 200 PubMed.

Other sources of information