Could chemical sterilization be an affordable solution to keeping stray dog populations under control? Raffaella Leoci, DVM, PhD, is a researcher at the University Bari Aldo Moro in Italy and a specialist in pet reproduction. She is the lead author of two articles published in Acta Veterinaria Scandinavica on chemical sterilization of dogs using calcium chloride, which identified the most effective concentration and the optimal solution. In this guest post she tells us why she thinks use of calcium chloride sterilization could be the answer to stray overpopulation.

Pet overpopulation is a serious problem across much of the world. In some regions such as where I live, the number of stray dogs is not under control and many dogs are killed by car accidents or suffer from serious illnesses.

Italian law includes a no kill policy and stray dogs are captured, microchipped, neutered and taken to dog shelters where they live the rest of their lives. Some are released because of overcrowded shelters. Unfortunately, the existing trap/neuter programs are unsuccessful and the dog population continues to grow.

These are grave issues with serious health and welfare implications for both humans and dogs. Surgical castration is not a solution: it is too expensive and time consuming. My priority was to find an alternative method that was safe, effective, inexpensive and easy to perform to prevent canine reproduction – and also prevent the suffering that dogs experience from life as a stray.

I have been studying various methods of nonsurgical sterilization since 2007, including ultrasound. Several years ago, I partnered with Parsemus Foundation – a U.S. based nonprofit organization with an interest in nonsurgical methods – to investigate the use of calcium chloride dihydrate (CaCl₂) as a chemical castrating agent. CaCl₂ is a commonly available salt used for various medical applications.

The first published reports of using CaCl₂ to sterilize animals date back to 1977 and 1978 with the work of L.M. Koger and researchers at Washington State University, Pullman. But the procedure was neglected for decades until researchers Kuladip Jana and P.K. Samanta in India began exploring its use in companion animals. Their research provided good indications that calcium chloride could indeed be an ideal chemical sterilizing agent. Their short term studies in dogs and cats have been published over the past decade.

But more information was needed to clarify whether CaCl₂ could be used on a wide scale as a nonsurgical sterilant. What is the best concentration and solution? What were the long-term effects? We also needed to better understand the safety and welfare implications and the impact on canine behavior. Our research projects were the first to study large numbers of dogs over a long time period (12 months) and evaluate different solutions of CaCl₂ in an attempt to find the optimal solution.

We found that a 20% concentration of CaCl₂ in an alcohol solution (called “Calchlorin”) met all our requirements – azoospermia over the 12 month study and a significant drop in testosterone and associated sex-linked aggressive and mating behavior.

The procedure was also safe, quick and easy to administer. The dogs even showed little reaction to the intratesticular injection. This makes sense since afferent nerve endings are located on the skin and capsule of the testis. There may be slight pain sensation when the needle pierces the skin, but the dogs are unlikely to experience pain from within the testis.

Though basic attention needs to be given to proper technique, the procedure, if correctly performed, requires no medical recovery and carries no risk of secondary infections – providing a great improvement over the welfare implications of surgical castration.

The use of CaCl₂ could be particularly important for large scale canine neutering programs. In many developing countries or resource-limited areas, mass sterilization programs are often prohibitively expensive. An alternative method to surgical sterilization that is effective, easy to administer, safe, and affordable would offer immense benefits, allowing animal welfare organizations, public health programs, and governments to reach further with limited resources. Our research supports the use of CaCl₂ as an excellent alternative to surgical castration.

The next steps in evaluating the impact of CaCl₂ sterilization is gathering data from the field to evaluate its performance in a variety of environmental conditions with varied practitioner skill levels, dog sizes and temperaments. I look forward to the use of CaCl₂ sterilization to improve the health and welfare of stray dogs in my hometown and around the world.