Although spaying and neutering are the only 100 per cent effective methods of birth control for dogs, different methods of chemical contraception are available. This can come in handy for breeders who breed their dogs infrequently, as any unintended pregnancy puts the health of the female dog at risk, and produces a litter of unplanned puppies that could potentially end up in a shelter. Female dogs have the option of several oral contraceptives, but birth control for male dogs is usually injectable.
Marketed under several different brand names, zinc gluconate neutralised with arginine is the only non-surgical pet birth control approved by the U.S. Food and Drug Administration. Injected directly into each testicle, the drug prohibits the production of sperm, and also decreases the incidence of male hormonal behaviours. Canine gonadotrophin releasing factor immunotherapeutic (CGRFI) is a vaccine-like injectable that is used to treat non-cancerous enlarged prostate in young dogs, but because a side effect is sterility, it is also used off-label as a birth control.
According to Ark Sciences, which manufactures zinc gluconate under the name Esterilsol, the injectable contraceptive is 99.6 per cent effective when properly administered, and 97.7 per cent of dogs displayed no undue stress upon injection. Zinc gluconate remains active in the dog's system for at least six months. Since sterility is only a side effect of CGRFI, studies have not been performed with contraception as the focus, but side effects only last as long as the drug is in the system, which is about six months after injection.
Zinc gluconate is made for use in dogs three to 10 moths of age, but has been used off-label in older dogs with no harmful effects. CGRFI is strictly for dogs over 1 year old. Any dog receiving an injectable contraceptive should be healthy, active and free from any chronic condition. Some veterinarians run a routine blood panel before performing the injection, just to verify kidney and liver function.
Side effects of either drug are rare, with only 3.9 per cent of dogs showing any signs of complications. Reactions were limited to localised irritation at the injection site, mostly mild, with rare cases developing into infection. Any substance injected into the body can cause a systemic reaction in very rare cases, so your vet will likely check kidney and liver function at yearly check-ups, and you should report any changes in your dog's health or habits to your veterinarian.
The only permanent birth control method for male dogs is neutering, in which the testicles are fully removed. If temporary contraception is all that is needed, various implants are available that are impregnated with time-release medication and implanted under the dog's skin, and remain effective for up to a year. Many methods of birth control are not approved for use in all countries, so ask your veterinarian what options are available in your area.