Birth Control Alternatives (In Pets)

Neutering, ovariohysterectomy (spaying) of females or castration
of males, remains the most effective, least expensive, safest,
and permanent method of birth control for pets. The procedures
are well tolerated by dogs and cats and are routinely performed
in most veterinary hospitals, and both dogs and cats can have
the surgery as young as 6 to 8 weeks of age.

The only valid reason to avoid neutering as a birth control
method is that the pet has value as a breeding animal. A
valuable breeding animal has desirable physical and behavioral
traits for its (pure) breed. This animal should have undergone
appropriate testing and found not to have evidence of any known
genetic defects. In addition, the owner of that pet must be
willing and able to take responsibility for managing breeding,
whelping or queening, weaning, socializing, and placing the
offspring produced. Breeding dogs and cats is not a financially
rewarding undertaking-much the opposite! Financial setbacks are
common, raising pup-pies and kittens can be quite time
consuming, and finding desirable homes for the offspring is a
major responsibility.

The pet overpopulation problem is a gigantic and serious reality
in the United States that underscores the need for responsible
breeding. Breeding animals should be neutered for health reasons
when their reproductive careers are complete. Neutered animals
have the same capacity to perform as hunting, herding, and guard
animals. Breast cancer is at least as common in dogs and cats as
in people, and spaying a female before her first “heat”
virtually eliminates risk of breast cancer in dogs and cats.
Spaying between the first and second cycles dramatically
decreases the risk of breast cancer. Obviously, spaying also
eliminates risk of diseases of the ovaries or uterus, which are
relatively common. Prostate and testicular diseases are also
common, and neutering of males decreases the risk of these
problems as well. Neutered animals should be fed approximately
25 per cent fewer calories to prevent obesity; otherwise, their
physique remains normal. Urinary incontinence occasionally
occurs in spayed female dogs. This condition is treatable.

Alternatives to neutering for temporary birth control in pets
are few. Most products available in the United States are not
licensed for use in pets or are not recommended for pets
intended for breeding. None have current application to the
male. Birth control in females is accomplished by pre-venting
estrous cycles or interrupting pregnancy establishment. Estrous
cycles can be prevented in bitches or queens by appropriate
administration of commercially available veterinary progestin or
testosterone compounds. Progestin compounds work to prevent
estrous cycles by keeping the female in a “pregnant-like”
condition. Unfortunately, the administration of progesterone to
an intact (unspayed) bitch or queen can cause uterine wall
disease, leading to the later development of a severe and
potentially life-threatening uterine infection called “pyometra”
or infertility. Progesterone medications can also cause or
contribute to the development of serious diseases (diabetes,
growth hormone disorders) and anatomic problems (mammary masses,
gallbladder disorders). Therefore, we do not recommend the use
of progestogens to prevent estrous cycles. Testosterone-like
compounds prevent estrous cycles in bitches by keeping the
female in an anestrus-like (no ovarian activity) condition.
Behavioral side effects (aggression), tearing of the eyes,
malodorous skin, liver problems, and sub-fertility during
subsequent estrous cycles are common consequences of the use of
testosterone compounds. Clearly, these are not ideal compounds
for use in valuable breeding animals.

Methods for preventing estrous cycles by administering synthetic
hormones with fewer side effects or immunizing the animal
against egg membranes or endogenous hormones have not been
perfected to the point where they are commercially available.
Methods for preventing pregnancy by interfering with egg travel
in the fallopian tubes or embryo implantation in the uterus with
estrogen compounds are not recommended because of their
potential for causing life- threatening bone marrow suppression
(the bone marrow is the sole source of red and white blood cells
and cells that help clotting, called platelets). Estrogens may
also promote later development of pyometra, clearly undesirable
in an animal intended for breeding. Application of newer human
birth control agents, such as carbergoline and mifepristone, in
pets is limited by availability in the United States, but these
agents have the best promise for providing effective birth
control with minimal side effects.

The best current nonpermanent method for preventing pregnancy in
the bitch or queen is simply to prevent breeding (copulation) by
confining the individual indoors, away from intact (un-neutered)
males. Bitches should be let into an enclosed yard only with
direct supervision or on leash for the entire time when
copulation could occur. This could be as long as 3 weeks. A
veterinarian can determine when the bitch’s cycle is complete by
performing vaginal cytology. Queens must be kept isolated from
toms during their entire period of receptivity, as they ovulate
after copulation.

The above is general veterinary information. Do not begin
any course of treatment without consulting your regular
veterinarian. All animals should be examined at least once every
12 months.