Calcium Chloride Instructions to Veterinarians

Preparing the alcohol solution of 20% calcium chloride dihydrate for chemically castrating stray dogs and feral cats 

Chloretum Calcium Bottle4 gr of pharmaceutical grade CaCl2 [dihydrate] is brought to a final volume of 20 ml with 95% pharmaceutical grade ethanol.

Prepare the solution:

Insert a sterile needle in the stopper of the vial which contains 4 grams of CaCl2.

This needle should stay in the vial until you are finished drawing out all the fluid you need. Its function is two-fold: firstly to prevent pressure built up while adding the alcohol and secondly to draw the solution from the vial.

Inject 20 ml of ethanol through a different needle into the vial and then remove this needle.

Determine dosage as per this table:

Testicular WidthDose per testicle
10-14 mm and sexually mature adult cats0.25 ml (if testis feels overly full, STOP before full dose)
15-18 mm0.5 ml
19-22 mm0.8 ml to 1 ml (continue to fullness)
23-24 mm1 ml to 1.5 ml (continue to fullness)
25-26 mm1.5 ml to 2 ml (continue to fullness)
27 mm and above2 ml and up (continue to fullness)


Draw the proper amount in each syringe through the needle that remains in the vial.
Remove the syringe and attach a different needle. Every injection should be made with a fresh needle.

Always pull 0.2 ml of calcium chloride over the maximum recommended dose. Up to 10% of dogs require up to 0.2 ml more calcium chloride in order to achieve a firm feeling upon injection. This includes large and small dogs as elongation of the testicle may change the required volume significantly.


This video shows the use of compounded calcium chloride dihydrate for non-surgical castration of male dogs. Technique modified from earlier research by Kuladip Jana, Prabhat K Samanta and Raffaella Leoci.

Instructions on properly injecting CaCl2 in alcohol are available at in EnglishSpanish and Mandarin.

Before you start using Calcium Chloride please read the following cautions (English) (Spanish).

The Alliance for Contraception in Cats & Dogs provides information on current research related to Calcium Chloride and other non-surgical sterilants (ACC&D).