Canine Chemical Castration (Zeuterin)

Canine Chemical Castration (Zeuterin)

spacer-green.gifWhat is Zeuterin? 

Zeuterin.jpg

Zeuterin™ (pronounced "zū-tur-in") Injectable Solution for Dogs  (zinc gluconate neutralized by arginine)  Zeuterin™ injectable solution is a prescription product used to sterilize male dogs. Zeuterin™ is given as a single injection into each testicle.

spacer-green.gifWhat happens when my dog is injected with Zeuterin™?

The effectiveness of Zeuterin™ was demonstrated in a field study. In this study, 99.6% of the 224 dogs injected became sterile. Zeuterin™ may not kill the sperm present at the time of injection in dogs. As with castration or a vasectomy, you should keep your dog away from females in heat for at least 60 days after the injection.

Unlike surgical castration, dogs treated with Zeuterin™ become sterile without removal of the testicles and, therefore, the male hormone, testosterone, is not completely eliminated. Zeuterin™ may not prevent diseases associated with male hormones, such as prostatic disease or testicular or perianal tumors in dogs. As with surgical castration, Zeuterin™ may not eliminate male behavior such as roaming, marking, aggression, or mounting in dogs.

spacer-green.gifCan the procedure be performed on any male dog?

Zeuterin™ is contraindicated and the procedure will not be performed in dogs that have the following conditions:

  • Undescended testicles (cryptorchid).
  • A disease or malformation of the testicle (including fibrosis of the testicles or epididymides).
  • A history of allergic reaction to any of the components of the drug.
  • Pre-existing scrotal irritation or dermatitis.
  • Infected bite wounds.
  • Testicular cancers of any kind.
  • Transmissible venereal tumor.

spacer-green.gifWhat is the procedure for chemical castration?

We will perform a routine physical exam before the sterilization procedure paying particular attention to the testes and scrotal region.

Patients are then provided a light sedative prior to the procedure and will also receive an injection of an antiinflammatory/pain control medication.  Each testicle is individually measured so that the correct dose of Zeuterin can be administered.  The scrotum is then cleaned and Zeuterin is administered into each testicle with a very small needle. 

spacer-green.gifWhat are the possible side effects after a Zeuterin™ injection?

Zeuterin™ may cause some side effects. Local and systemic reactions were observed in the field study.


Local reactions included testicular swelling (normal reaction to the injection), pain (dogs may resist sitting or may sit with both hind legs open), biting and licking at the scrotum, swelling of the prepuce and irritation, dermatitis, ulceration, infection, dryness or bruising of the scrotum.

Systemic reactions included an increase in the white blood cell count, vomiting, anorexia (loss of appetite), lethargy (tiredness or abnormal attitude), and diarrhea.

Most reactions were seen within the first 7 days after the injection. Pain was most commonly seen in the first 2 days. Vomiting was most commonly seen on the day of the injection (within 1 minute and 4 hours after the injection). You should withhold food for 12 hours prior to injection to help prevent vomiting.

Mild, temporary swelling of the testicles is an expected reaction to the injection which you will notice within
24 - 48 hours after the injection. Your dog's testicles may remain slightly enlarged but non-painful for a few months after the injection.

To minimize the occurrence of adverse reactions, such as scrotal irritation, inflammation or infection, it is critical that you closely monitor your dog's activity post-injection and that you take all precautions necessary to prevent injury to the testicles and to prevent your dog from licking or biting the scrotal area. For the first few days after injection:

  • Restrict your dog's exercise to leash walking.
  • Do not allow your dog to run, jump, or engage in play activity.
  • Do not allow your dog to lay on hard or wet surfaces.
  • Do not allow your dog to lick or bite the scrotal area.

You should contact your veterinarian immediately if you notice that your dog is biting or licking the scrotal area or if you see any signs of redness, discharge or broken skin in the scrotal area.

spacer-green.gifHome Care Information

As with castration or a vasectomy, you should keep your dog away from females in heat for at least 60 days after the injection.
Unlike surgical castration, dogs treated with Zeuterin™ become sterile without removal of the testicles and, therefore, the male hormone, testosterone, is not completely eliminated. Zeuterin™ may not prevent diseases associated with male hormones, such as prostatic disease or testicular or perianal tumors in dogs. As with surgical castration, Zeuterin™ may not eliminate male behavior such as roaming, marking, aggression, or mounting in dogs.

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