While most people choose to have their dog spayed or neutered to control pet overpopulation, an oral contraceptive for dogs can sometimes be an option to prevent unwanted litters of puppies. However, the availability of these products is limited and these drugs are associated with potential side effects.
Dog Contraceptive Products
Two oral birth control products are available for dogs. Both require a prescription through a veterinarian, and most veterinarians do not carry these products.
Cheque Drops (Mibolerone)
According to ScienceDirect.com, Cheque Drops is an androgenic steroid and oral contraceptive that must be given to bitches on a daily basis for thirty days prior to coming into heat to be effective. Predicting the beginning of a bitch's cycle can be difficult, so it is challenging to know when to start the thirty day course of treatment. This can lead to prolonged use of the medication, and a greater possibility of experiencing some of the numerous side effects. Veterinarians do not recommend using Cheque Drops until after a bitch has had her first full season.
Cheque Drops have been known to cause a host of health issues including (but not limited to):
- Liver damage
- Body odor
- Personality changes
- Weight loss
According to an article in the 4th International Symposium on Non-Surgical Contraception Methods of Pet Population Control, Cheque Drops was formerly made by the Upjohn company, but was discontinued in 1990 and is no longer on the market. However, a generic version can be obtained from veterinary compounding pharmacies through a special order from that pharmacy and a prescription from your vet.
In the United States, the Drug Enforcement Agency (DEA), has also classified this as a class III controlled substance due to its human abuse potential and risk of dependence.
Ovaban (Megestrol acetate)
Ovaban works via a different mechanism than Cheque Drops, and is part of a class of drugs known as progestins. According to Dr. Dawn Ruben, this medication is similar to the natural hormone progesterone. It can be used to delay estrus, for treatment of false pregnancy, and for some skin and behavioral disorders.
Like Cheque Drops, Ovaban should not be given to a dog until she has completed her first heat cycle. According to the Alliance for Contraception in Cats and Dogs, administration must start at the beginning of the heat cycle, during the portion termed proestrus. The drug is only administered for a short window of time, and will delay the heat for four to six months. Repeated use for more than two consecutive heat cycles is not recommended.
Reported side effects include:
- Development of pyometra
- Mammary gland enlargement and cancers
- Diabetes mellitus
- Adrenal gland suppression
- Behavioral changes
- Weight gain
- Delayed birth and fetal defects when administered to pregnant animals
This product is no longer available under the name Ovaban, but generic products are still being manufactured.
When Surgery Isn't An Option
Surgical sterilization is almost always the best option for prevention of pregnancy in dogs. Some of the situations in which an oral contraceptive for dogs may be a reasonable alternative are outlined in the chapter Clinical Use of Progestins in Bitches and Queens: A Review in Recent Advances in Small Animal Reproduction (2000), Concannon P.W., England G., Verstegen III J., et al. (Eds.).
These situations include:
- When a reversible form of contraception is preferred
- When a dog has a serious medical condition and anesthesia is deemed too risky
- When a delayed breeding or estrus is desired
- When appropriate surgical facilities or personnel are lacking
Cannot Use Human Birth Control Pills for Dogs
Due to the difference in hormones and the reproductive cycle, human birth control pills do not work to prevent contraception and pregnancy in dogs. Human birth control pills can even be toxic to dogs, but fortunately, a dog would have to eat a very large number of these to cause a serious problem.
The biology of canine reproduction is not the same as that of humans. According to Ernest Ward, DVM, bitches come into "heat" twice a year, on average. This is more formally called being in estrus. A dog can only become pregnant when she is in the estrus portion of her cycle, in contrast to a woman's monthly cycle.
Future Options in Birth Control for Dogs
A significant amount of research funding has been directed toward non-surgical solutions for pet overpopulation. However, since these projects are focused on stray populations, almost all of these products are intended to be given as a single injection. According to Mushtaq A. Memon, BVSc, PhD, DACT and Megan Cathey, DVM, in an article for DVM360.com, both male and female contraceptives are being studied, including Gonazon, Suprelorin, acyline, ChemSpay, Neutersol, EsterilSol, and contraceptive vaccinations.
If you decide that your pet has need for birth control pills, take time to consult your veterinarian about all the options. With careful attention to your dog's heat cycle, these medications can be used to safely prevent pregnancy.