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Ovaban Tablets

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

Ovaban Tablets

This treatment applies to the following species:
Manufacturer: Intervet/Schering-Plough Animal Health


Veterinary (for Use In Dogs Only)

Ovaban Tablets Caution federal Law Restricts This Drug To Use By Or On The Order Of A Licensed Veterinarian.

nada #91-603, Approved By Fda


Each tablet contains megestrol acetate in a dried yeast base. Two strengths are available: 5 mg tablets, 20 mg tablets.

General Considerations

Megestrol acetate is a tasteless, odorless, crystalline powder with a melting point of about 217°C and a molecular weight of 384.5. It is a potent oral progestogen with marked anti-estrogenic properties and more active in the Clauberg assay than progesterone given subcutaneously.1

Megestrol acetate is rapidly metabolized. In dogs given the recommended oral dose for 8 days, the drug (as metabolites) was recovered from feces and urine. An average of 50% of the total dose was excreted by the last treatment day and 90% within an additional 15 days.2

Toxicity Studies

Megestrol acetate at 0.1 to 0.25 mg/kg/day orally in dogs for 36 months did not produce any gross abnormalities. Histologically, cystic endometrial hyperplasia was observed at 36 months. These uterine changes were reversed when dosing ceased and the dogs were observed for an additional 15 months.

In another study, megestrol acetate was administered orally at the rate of 0.5 mg/kg/day for 5 months. At this observation period, no abnormalities were noted except signs of mild uterine hyperplasia which regressed at the final observation period which was 4 months from cessation of treatment.

Additionally, dogs were treated with 2 mg/kg/day for 64 days. Uterine biopsies were taken at day 32 and day 64. Uteri were found to be normal at day 32. At day 64, signs of early cystic endometritis were evident. No other abnormalities were observed.

Cox3 compared several progestogens in dogs and determined megestrol acetate did not produce cystic endometrial hyperplasia at the recommended doses.

Burke4 reported studies in dogs that show no effects on conception, litter size, mortality, or sex ratios following megestrol acetate at recommended dosage for 32 days.

Megestrol acetate at 0.25 mg/lb. for 32 days did not affect the dam or litter when administered during the first half of pregnancy, however, reduced litter size and livability resulted when the dose was given during the last half of pregnancy.

Ovaban Tablets Indications

OVABAN (Megestrol Acetate) is recommended for the postponement of estrus and the alleviation of false pregnancy in the dog.

Postponement of estrus: Treatment regimens for the postponement of estrus depend on the stage of the estrus cycle when therapy is initiated.

Proestrus treatment: An 8-day course of OVABAN is recommended for dogs in proestrus. Vaginal bleeding and vulvar swelling will usually disappear in 3 to 8 days. The time until the next estrus occurs is dependent on the timing of the dose and will vary with individual dogs. In clinical studies, return to estrus ranged from 2 to 9 months with the majority recurring in 4 to 6 months.

Treatment should be initiated during the first 3 days of proestrus for best results. Examination of vaginal smears is strongly recommended prior to OVABAN therapy to confirm detection of proestrus.

Once Therapy Is Started, The Dog Should Be Confined For 3 To 8 Days Or Until Cessation Of Bleeding, Since Dogs In Proestrus May Accept A Male. Once Bleeding Stops, Male Dogs Should Not Be Attracted.

Anestrus treatment: A 32-day course of OVABAN therapy is recommended for dogs in anestrus. The dog will remain anestrus as long as therapy is continued.

The next estrus may occur any time after cessation of treatment. In clinical studies, there was a range of 2 to 9 months, though most dogs returned to estrus in 4 to 6 months.

Alleviation of false pregnancy: OVABAN can be administered to alleviate the physical and nervous symptoms of false pregnancy. Remission of symptoms will usually occur in 3 to 8 days. For best results, treatment should be initiated at the first signs of false pregnancy.

Ovaban Tablets Dosage And Administration

OVABAN Tablets are palatable and may be given intact or crushed and mixed in the food. It is recommended that the full dosage regimen be completed to produce the desired effect. In addition, OVABAN Tablets should not be administered for more than two consecutive treatments.

Postponement of Estrus

Proestrus treatment: Administer 1 mg per pound of body weight per day for 8 days.

Anestrus treatment: Administer 0.25 mg per pound of body weight per day for 32 days.

Alleviation of false pregnancy: Administer 1 mg per pound of body weight per day for 8 days.


OVABAN Tablets must not be used in dogs when there is evidence of uterine disease, or in the presence of disease in any of the reproductive organs.

OVABAN Tablets should not be used in dogs prior to or during their first estrus cycle.

OVABAN Tablets must not be used in pregnant dogs. It should be established that there was no exposure to a male dog during the previous heat period.

OVABAN Tablets must not be used in dogs with mammary tumors. Growth of some mammary tumors may be stimulated by exogenous progestogens.

Should estrus occur within 30 days after cessation of treatment with OVABAN Tablets, mating should be prevented.


Clinical studies indicate the full dosage regimen must be completed to produce the desired effect.

OVABAN Tablets should not be administered for more than two consecutive treatments.

Side Effects

Oral doses of megestrol acetate are well tolerated. Occasionally, the following transient progestational side effects were noted in clinical studies; mammary enlargement, lactation, listlessness, increased appetite, and temperament change. In clinical studies, confirmed cases of pyometra occurred in 0.6% of the cases.

How Supplied

OVABAN Tablets, 5 mg (NDC 0061-0867-05) and 20 mg (NDC 0061-0509-05), are available in bottles of 100 tablets.

Store Between 2° And 30°c (36° And 86°f).


1. David A, et al. Anti-ovulatory and other biological properties of megestrol acetate. J Reprod Fertil. 1963;5:331-346.

2. Chainey D, et al. The excretion of megestrol acetate by beagle bitches. Vet Rec. March 7, 1970.

3. Cox JE. Progestogens in bitches: a review. Small Anim Pract. 1970; 1 1:759-778.

4. Burke TJ. Megestrol acetate for estrus postponement in the bitch. J Am Vet Med Assoc. 1975;167(August)285.

Schering-plough Animal Health

Schering-Plough Animal Health Corp., Union, NJ 07083. All rights reserved.

Made in Canada

Rev. 1/00


Copyright ©



100 Tablets 5 mg

1988, 1989, 1993



100 Tablets 20 mg

1989, 1993



Nac No.


29160 INTERVET LANE, P.O. BOX 318, MILLSBORO, DE, 19966-0318
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Every effort has been made to ensure the accuracy of the Ovaban Tablets information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2017 North American Compendiums. Updated: 2017-11-28