Development of Injectable and Oral Contraceptive Technologies and Their Assessment for Wildlife Population and Disease Management
Diazacon as an Induced Infertility Agent
diazacholesterol) is a cholesterol mimic that inhibits cholesterol
production and blocks steroid hormone formation. The compound was originally
developed by the G.D. Searle Co. for use as a cholesterol-reducing agent
in humans. Although the drug was successful in reducing cholesterol
levels, its use was discontinued because of side effects.
Diazacon was later studied as a reproductive inhibitor for use in control
of pest birds. It was thought that since eggs contain cholesterol, lowering
cholesterol might inhibit reproduction. More importantly, 20,25 diazacholesterol
may have the ability to block production of hormones necessary for reproduction
such as estrogen, progesterone, and testosterone.
Tests showed 20,25 diazacosterol to be effective in reducing reproduction
in pigeons, blackbirds, starlings, and sparrows. The product was subsequently
registered for pigeon population control under the tradename Ornitrol.
In some instances, good results were seen, in others, results were less
than optimal. One problem with pigeons is that they breed year round
(especially in warm climates). Long-term treatment with high doses of
Ornitrol not only became expensive but sometimes muscle tremors developed
in the birds.
Diazacon has the same hormone-inhibiting
effect in mammals as in birds, and has been shown to limit reproduction
in different types of rats. The most promising uses of diazacon would
logically be in animals (birds or mammals) that have a limited breeding
season. Animals in areas where increased population is a problem could
be treated prior to the breeding season without the need to treat throughout
To date, diazacon has been studied in Japanese quail, ring-necked doves,
and brown-headed cowbirds. Studies have shown significant differences
in absorption and effectiveness of diazacon among bird species studied.
In Japanese quail, diazacon effectively lowered cholesterol and reproductive
hormone production in both sexes for several months following treatment.
In female Japanese quail, egg-laying, fertility, and hatchability of
eggs decreased significantly after one week of treatment and remained
significantly reduced for several months. In ring-necked doves, cholesterol
levels were significantly reduced for several months after treatment.
Studies in brown-headed cowbirds showed a significant reduction in cholesterol,
although subsequent studies are needed to determine the optimal dose
and how long the effect lasts. Currently, diazacon absorption and effectiveness
are being studied in American crows and in waterfowl.
A Preliminary Field Trial of Diazacon Use in Prairie Dogs
A small study was undertaken to test whether diazacon would be effective
in prairie dogs. Due to delays in obtaining the proper permits, treatment
began later than planned. Even so, the average number of young as a
proportion of adults at treated sites compared to control sites was
reduced by about 59%. These results suggest that , at least in animals
with a single breeding season, diazacon has potential for use as a fertility
Goals and Objectives
Immunocontraception (Technical Discussion)
Development (Technical Discussion)
Design (Technical Discussion)