Estrus contains the oil-soluble 17β-cyclopentylpropionate ester of estradiol. It provides estradiol-17β believed to be most potent of the naturally occurring estrogens, in the form of the cyclopentylpropionate ester, a highly fat-soluble derivative with a profound estrogenic effect. Comparative studies have demonstrated that estradiol cypionate produces estrogenic effects which are qualitatively the same as those produced by other estradiol esters.
Estrus has a wide range of usefulness in veterinary practice inasmuch as it offers all of the functional activity of natural estrogenic substances with the advantage of a prolonged action. For use in cows and heifers for the following conditions:
To induce estrus in the absence of a follicular cyst.
To aid in the treatment of retained corpus luteum.
To expel purulent material from the uterus in pyometra of cows.
To induce expulsion of retained placenta and mummified fetus.
Dosage and Administration
Administer by intramuscular injection using proper aseptic techniques. Average doses in cattle may be repeated, if necessary, in one week.
3-5 mg (3-5 mL)
10 mg (10 mL)
10 mg (10 mL)
Persistent corpus luteum
4 mg (4 mL)
10 mg (10 mL)
3 mg (3 mL)
Repeat in one week, if necessary
As with all products of this nature, a complete examination to determine the status of the reproductive tract should be undertaken prior to administration of this drug. Pregnancy may be the prime reason for either anestrus or the persistence of the corpus luteum. Since pregnancy may be terminated by estrogens, Estrus is contraindicated when a desired pregnancy exists.
Cautions: In the case of prolonged persistence of the corpus luteum in cows, thorough examination should also be made of the uterus to determine the presence of endometritis or a fetus. Use of appropriate antimicrobial agents, in addition to Estrus, should be considered if endometritis exists.
In the absence of normally developing follicles on the ovaries, estrus may be produced, but ovulation may not accompany estrus.
Because it is impossible to determine exactly if and when ovulation may occur in treated females during an induced heat period, it may help to have the female bred frequently throughout the induced heat periods in order to improve the possibility of conception. Repeat breeding will improve the chance of conception only if ovulation occurs.
Adverse Reactions: Prolonged estrus, precocious development, genital irritation, follicular cysts and a reduction of milk flow may occur following estrogen therapy, frequently as a result of overdosage. If any of these are observed, the dosage should be reduced accordingly. In the event of a hypersensitivity reaction following administration, immediate appropriate therapy should be initiated.
Warnings: In cattle, Estrus should be used only for therapeutic purposes in animals intended for breeding.
Store at room temperature (15-30°C). Keep from freezing. Protect from light.