Is calcium chloride used to desex male dogs and cats in Australia?

Calcium chloride (Calchlorin®, CaClCa) can be used as a non-surgical castration technique in male cats and dogs but is not currently being used for this purpose in Australia. The chemical was first investigated as a method of sterilisation in the 1970s, with recent field and experimental trials conducted in the past decade in India, Italy and the US. Calcium chloride has been used overseas in some low-cost spay and desexing programs focussing on mass population control and the reduction of unowned animal populations [1]. The benefits of chemical castration are its relatively low cost and that it does not require surgery or general anaesthesia. This is useful in countries with limited access to sterile operating theatres, potentially allowing many more animals to be castrated than under surgical desexing programs. However, surgical desexing performed by a veterinarian under sterile surgical conditions and with the animal anaesthetised is considered the gold standard of care [2]. This is because surgical desexing has low post-operative complications, sterilisation is permanent, and it has the flexibility to be used for all types of dogs and cats [3].

How does calcium chloride desex male dogs and cats?

When used as a chemical castration agent, calcium chloride is injected directly into both testes whilst under sedation. The chemical is injected until each teste feels ‘full’. This injection causes the testes to atrophy (waste away) resulting in sterility and a decrease in testosterone production [4]. One study has shown that calcium chloride combined with ethyl alcohol successfully sterilised male dogs for 12 months, however studies have not been performed beyond this time [1].

What are the limitations of calcium chloride as a castration method?

• No research has been conducted on the long-term effects of calcium chloride on dogs or cats, including the permanency of the sterilisation beyond 12 months.
• No research has been conducted on the safety and efficacy of calcium chloride on puppies and dogs under 16 weeks of age.
• No research has been conducted on the animal welfare implications of this method of desexing, including rate and severity of post-operative complications.
• It is currently recommended only for use in smaller dogs (testes less than 2.4cm diameter) and cats as the effects of testosterone reduction and sterilization become more variable in larger dogs due to the administration method of the injection [1].
• This technique is currently considered experimental by the Alliance for Contraception in Cats and Dogs, therefore veterinarians opting to use it are recommended to view the procedure as experimental and obtain appropriate regulatory approval, including chemical registration for this purpose [5].
• If the procedure is not performed correctly, or any calcium chloride is incorrectly injected under the skin rather than directly into the teste (even when withdrawing the needle), infection and abscesses are likely [1].
• Not all states in Australia recognise chemical castration in legislation as a viable method of desexing, with some defining desexing of a dog or cat as a ‘means to surgically remove its gonads for the purpose of making it permanently incapable of reproducing’ (e.g. Queensland Animal Management Act 2008).

The RSPCA supports further research and investigation into alternatives to surgical desexing methods including immunological and chemical sterilisation as well as legislative reform to recognise alternatives to surgical desexing. Due to the experimental nature and potential risks of calcium chloride [6] as a method for non-surgical desexing, surgical castration remains the method of choice for companion animals in RSPCA shelters.