Calcium Chloride Male Sterilization

Nonsurgical sterilant for male animals:
Calcium chloride in alcohol

What is it?

A low-cost nonsurgical neuter shot for male dogs, cats, and other animals. Coverage of calcium chloride sterilant in the Wall Street Journal.

Not patented — and thus available in the U.S. and every country with access to the two ingredients (calcium chloride dihydrate, and pharmaceutical-grade or food-grade pure ethyl alcohol). Can be ordered by veterinarians from a reputable compounding pharmacy (“20% (w/v) Calcium Chloride Dihydrate, USP in Ethyl Alcohol 190 proof, USP”) or can be prepared under sterile conditions.

Keep in mind that successful use of calcium chloride sterilant is dependent on proper technique and follow up. For best results, educate yourself on all aspects of its use, understand the potential for complications, and start slowly. At this time, this method is not suitable for large scale neuter clinics or training sessions, or in settings that do not allow follow-up observations and treatment.

Parsemus Foundation’s role

Spreading the word, after having funded research (2014 Italian study) to improve the level of evidence so veterinarians and rescue groups can make a fully informed decision about whether it is appropriate in their context. Collecting data from early adopters to evaluate use in varied settings.

Disclaimer: The information on this website is for informational purposes only to promote broader  understanding and knowledge of calcium chloride neuter. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your veterinarian.

Checklist for considering use

  • Determine whether you are seeking hormone-preserving sterilization, or behavior-changing neuter. Calcium chloride sterilant has hormonal effects similar to surgical castration (“neuter”), which is what most shelters and rescue groups are seeking. If hormone-sparing sterilization is desired, calcium chloride should be administered into the epididymis instead (see below), or another method (such as vasectomy) should be used.
  • Read the instruction sheet and tips at SpayFIRST!, and watch the instructional video to determine whether calcium chloride could be similarly applicable in your situation.
  • Read the peer-reviewed publication of dog study results from Italy.
  • Watch the videos and absorb the background information on this website.
  • Read the position statement and explore the resources and more conservative viewpoints at the Alliance for Contraception in Cats & Dogs.
  • Decide on sourcing. Your options are ordering “20% (w/v) Calcium Chloride Dihydrate, USP in Ethyl Alcohol 190 proof, USP” from a trusted compounding pharmacy; or obtaining and mixing ingredients individually (not advisable for veterinarians in countries with the above more quality-controlled option).
  • Know possible complications: Take a look at photos of possible complications to decide whether you are prepared for these lesions (and prepared to explain them to clients) that resolve uneventfully if properly treated, but look awful and may occur especially during your learning curve. Calcium chloride injection is highly technique-dependent; the most experienced practitioners report complication rates less than 1 in 100, but new users may experience rates as high as 1 in 5, especially if any of the recommendations in the SpayFirst video are not followed.
  • Be able to conduct follow-ups. If a complication occurs, it needs to be addressed immediately so it does not become serious. Provide directions to owners on observing their pet and reporting any issues. Hold strays until you are sure there are no problems.
  • START SLOWLY, and follow best practices, including informed consent, proper technique as shown in the Spay FIRST! video, systematic follow-up, and organized record-keeping.
  • Before extensive use, explore the regulatory situation in your city/state/country, and seek input from local thought leaders and veterinary board/authority. The American Veterinary Medical Association maintains a state-by-state listing of veterinary authorities in the U.S.
    •  Veterinarians within an organization – present a plan to your organization’s board so the board can explore pros and cons and set policy with full board support. Your board may wish to seek legal input on issues around compounding and standard of practice if calcium chloride is not yet being used widely in your area. Parsemus Foundation can provide resources and links.
    • Private veterinarians – consider teaming with a municipal program to gain experience, avoid undue personal exposure, and assure full community buy-in.


Still hungry for more? Watch the first of two presentations on calcium chloride at the Alliance for Contraception in Cats & Dogs 5th International Symposium, June 2013:

Calcium chloride presentation at ACC&D 5th International Symposium, June 2013 from the Parsemus Foundation on Vimeo.

Want even more background info? View the second presentation, ACC&D Getting Involved in Field Testing Session on Vimeo. The talk, titled “Could your organization use Calcium Chloride? Nuts and Bolts,” begins at 37:54. It is part of the panel presentation “Getting involved in field testing of non-surgical sterilants: Lessons learned, and what organizations and veterinarians should consider when getting involved” at the Alliance for Contraception in Cats & Dogs 5th International Symposium on Non-Surgical Methods of Pet Population Control.

For tips on nonsurgical neuter in context and best practice, see the Animal Grantmakers 2014 Conference – Ruth Steinberger Spay/Neuter Presentation from the Parsemus Foundation on Vimeo.

Published papers

Published papers since 1977: Publications 1977-Present are available on PubMed (often abstracts only) and listed/linked in this downloadable bibliography. Recent papers (2011 Jana cats, done using older formulation; 2014 Leoci dogs) were supported by Parsemus Foundation and are available open access, full text, free online. Also available is an unpublished paper on the use of calcium chloride in adult male goats.

An independent review of the data

The scientific advisory committee of the Alliance for Contraception in Cats & Dogs has produced an extensive independent review of the data through November 2014. This organization considers the use of calcium chloride sterilant as “experimental”.

Interested in sterilizing while preserving hormones?

Parsemus Foundation is also interested in furthering research on epididymal injection of calcium chloride (vs. testicular injection) for hormone-preserving sterilization — useful for health reasons in large dogs, and also as a nonsurgical alternative to vasectomy in both humans and animals. Testicular injection of calcium chloride is for nonsurgical neuter (eliminating or greatly reducing hormones). But — injected into the epididymis instead of testes, could calcium chloride sterilize while preserving testosterone production, providing an ultra-low-cost nonsurgical alternative to invasive surgical vasectomy?

Pilot studies from the U.S. in the 1970’s, and studies of other sterilants and in other species, indicate yes. Immature sperm leave the testes and travel to the epididymis where they mature and are stored until needed. Injection of calcium chloride into the epididymis can stop sperm transit without affecting the production of testosterone (which is made in the Leydig cells in the testes). A recent study by Leoci and colleagues confirms that sterility can be achieved with an intra-epididymal injection of calcium chloride in dogs, with no drop in serum testosterone. However, the procedure required ultrasound guidance and took as long as castration. Intraepididymal use of calcium chloride may be best for dogs whose owners do not wish to have any change in behavior or anatomy.

For further information on hormone-preserving options (including epididymal injection and vasectomy), see our hormone-sparing male sterilization page.

Need more help?

Read through all the material and still have some questions? Do not hesitate to contact us at and we will do everything we can to assist.