From ANIMAL PEOPLE, October 2012: (Actually published on November 1, 2012.)
Thank you for your September 2012 article “Trial of calcium chloride to fix dogs succeeds in Nepal,” bringing attention to calcium chloride dihydrate nonsurgical sterilization, which I believe has the potential to help dog welfare organizations make their funding go further, and to spare dogs the trauma of transport and surgery.
I am writing with a few corrections and clarifications. Most importantly, it is alcohol, not lidocaine, that has been determined to be the most effective base for calcium chloride. Lidocaine has been used as the base by Kolkata veterinary researchers P.K. Samanta and Kuladip Jana, who have diligently pursued developing calcium chloride sterilization for over a decade with very little support.
. Excited about their results but mindful of the scientific principle that results should be independently reproducible, we funded an independent study in Italy to try to replicate the results and, if successful, look at what formulation might be best. The study confirmed that indeed, calcium chloride in lidocaine renders dogs infertile and is well-tolerated, as Jana and Samanta have published in papers pertaining to multiple species, including cats and dogs, since 1998.
. However, the study by Italian veterinarian Raffaella Leoci also produced a surprising result: All of the dogs in the alcohol-base group were still sperm-free after one year, but some dogs in the lidocaine-base group had a few sperm return.
. This underscores the importance of doing long-term studies: since all the lidocaine-group dogs were still sperm-free at the 6-month time point, we never would have known that sperm might return if the study had not run a full year.
. The study produced a further result: the alcohol base was even better tolerated than lidocaine, resulting in no or very minimal swelling. These results were presented by Dr. Leoci in August 2012 at the First International Conference on Dog Population Management conference in York, United Kingdom, and will be published next year. Samanta and Jana have acknowledged the improvement that alcohol brings and are now adding alcohol to their formula.
. Second, some clarifications are needed regarding the campaign in Nepal that you described. As you correctly pointed out, we were intrigued when our colleagues at the Greenbaum Foundation told us they had passed along the information about calcium chloride nonsurgical sterilization to the groups they fund. The organization Devoted Radical Environment Animal Movement Society in Nepal had tried it and had been very happy with the results. But the reported use was part of an anti-rabies vaccination campaign, not a spay/neuter campaign. Female dogs were vaccinated only, since there is no nonsurgical sterilant available for females.
. We sent DREAM a long list of questions through the Greenbaum Foundation, and we shared their resulting report at the York conference. However, it is important to note that we were not in Nepal to witness the campaign firsthand. We are grateful to the Greenbaum Foundation for sharing the information and making it freely available.
. Several elements increase our confidence in the genuineness of the report, including the photos, the honest recounting of follow-up–for example acknowledging the reality of recapturing street dogs, rather than trying to paint an overly rosy picture to tell the funder what the funder wants to hear–and the mention of sterilizing the solution in an autoclave. We had not mentioned autoclave sterilization, but it is a logical technique, and has been used in some of the published studies. However, we don’t work in Nepal and have no way of knowing the complexities of local alliances or the effectiveness and reliability of different organizations. The field report is available on our website. Readers who have more experience in the area can draw their own conclusions.
. Third, a few more small corrections need to be made. Dr. Samanta published his first dog study in 1998, but had actually begun work on the subject before then. And the pilot study in cats from Turkey was presented at the 2010 Alliance for Contraception in Cats & Dogs conference and is complete. So far as we know, there is no ongoing work on calcium chloride in Turkey, just in India, Italy, and the U.S., where a recent pilot study was done. We expect that a year from now there will be experience in a number of countries, as many of the delegates at the U.K. conference were intrigued to learn of this new tool for humane dog population management.
_______________ Regulatory status
. Finally, let me offer a clarification about regulatory status. Our understanding is that in most countries, veterinarians have significant leeway in the practice of veterinary medicine, and have the ability to provide treatment that, in their judgement, is consistent with doing the “greatest good” for the animal and the community. That extends to using compounded drugs, in certain circumstances, when there is no commercially available drug for that indication on the market. Typically a veterinarian can get a drug made by a compounding pharmacy if there is a justification for its use and documentation of safety testing in peer-reviewed veterinary literature, he or she keeps records, and meets various other requirements.
. In countries with a functioning veterinary drug regulatory body, it is advisable for veterinarians to consult with the regulatory body. So, to clarify, the reason calcium chloride can be used for sterilization is not because it is used in human medicine (10% calcium chloride in saline injection is used, for instance, to treat hypocalcemia), but because there is evidence of safety in the peer-reviewed literature and, except in nations where Esterisol or Infertile is available, there is no other drug commercially sold. Regulations vary by country. Any organization considering using calcium chloride to spare dogs the trauma of transport and surgery may wish to consult with the Alliance for Contraception in Cats & Dogs, which has prepared a literature review and position statement on calcium chloride dihydrate, and can refer people to knowledgeable veterinary regulatory consultants.
. Thank you again for bringing greater visibility to the recent progress on calcium chloride dihydrate nonsurgical sterilization. This sterilant will never attract pharmaceutical support, since it is easy to make from simple ingredients, can’t be patented (documentation that it works was first published in 1977), and will never make anyone a lot of money. But animal advocates are in a unique situation, precisely because calcium chloride dihydrate is so easy to make, or to have made by a reputable compounding pharmacy. We hope animal advocates will find the the large body of published literature pertaining to calcium chloride dihydrate gathered on our website, and the resources and information on regulatory status we have posted, useful in making an informed decision.