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Estrus (Canada)

This page contains information on Estrus for veterinary use.
The information provided typically includes the following:
  • Estrus Indications
  • Warnings and cautions for Estrus
  • Direction and dosage information for Estrus


This treatment applies to the following species:
Company: Rafter 8

Estradiol cypionate injection, USP (1 mg/mL)

DIN 02299283


Veterinary Use Only


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.

Active Ingredient

estradiol cypionate (Cyclopentylpropionate ester) (USP) 1 mg /mL.

Preservative: chlorbutanol (Ph.Eur.) 0.5% w/v as preservative.

Estrus Indications

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)

Retained placenta

10 mg (10 mL)

Persistent corpus luteum

4 mg (4 mL)

Mummified fetus

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.


Frequently, cows with a follicular cyst may be more inclined to be anestrual than nymphomaniac. Many cows will recover spontaneously from anestrus (if due to follicular cysts) in less than 60 days postparturient. In cases of anestrus due to follicular cysts, estrogens are not usually indicated. Frequently, anestrus or follicular cysts have developed in association with a marked loss in body condition due to disease or high milk production.

Anestrus in conjunction with a persistent corpus luteum probably reflects some interference with normal function of the uterine endometrium. As indicated earlier, pregnancy must be considered as a cause of the persistence of the corpus luteum. Prolonged maintenance of the corpus luteum has also occurred following hysterectomy or experimental induction of endometritis. It is doubtful that corpora lutea are retained indefinitely in cattle with normal uterine function. It has been demonstrated that some estrogen esters will cause regression of the corpus luteum in cycling, pregnant or hysterectomized cattle. The response of the corpus luteum of pregnancy may differ with different estrogen esters.

In the absence of a pregnancy or a detectable uterine malfunction, repeated rectal palpations will be required to establish a diagnosis of persistent corpus luteum. Although some estrogen esters may produce luteal regression, treatment with prostaglandins should be considered. The proper diagnosis of anestrus without frequent rectal palpation is difficult since normal ovarian cycles can occur without accompanying estrus. It has been reported that such “silent heat” is more frequent at the first postpartum estrus.

Regression of the corpus luteum as in cattle following treatment with some estrogen esters may not be noticed in all species; for example, in swine, a persistent corpus luteum may be a sequel of estrogen therapy The induced estrus in cows or heifers may not be fertile. Regular cyclic activity may not follow an induced estrus.

WARNINGS: KEEP OUT OF REACH OF CHILDREN. 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.

Rafter 8 products Inc., 87 Skyline Crescent N.E., Calgary, AB T2K 5X2


Presentation: 10 mL.

CPN: 1219020.1

Telephone:   403-291-3640
Order Desk:   800-461-8615
Fax:   403-250-2703
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