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Megestrol Acetate

Prescription
Synthetic progestational agent
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
4 available
Formulations
2

Mechanism of action

Synthetic progestin that suppresses gonadotropin (FSH/LH) release from the anterior pituitary; has anti-estrogenic, glucocorticoid-like, and appetite-stimulating properties

At a glance

Class
Synthetic progestational agent
Schedule
Prescription
Storage
Below 25°C, protect from light

Dosing

🐕

Dog

Estrus suppression/postponement, behavior modification (aggression)
Dose
0.5–2 mg/kg
Route
PO
Frequency
SID for 8 days (estrus suppression), then reduce
Max dose
40 mg
Duration: Short-term only (1–2 estrus cycles max); not for long-term use
🐈

Cat

Estrus suppression, miliary dermatitis, eosinophilic granuloma (last resort), spraying behavior
Dose
2.5–5 mg/cat
Route
PO
Frequency
SID for 5 days, then weekly for maintenance
Max dose
5 mg
Duration: Short-term only; maximum 2 consecutive cycles
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Tablet — 2

Strength
5mg
Available in India
Strength
20mg
Available in India

Storage

Below 25°C, protect from light

Safety

Absolute contraindications — do not use

  • Pregnancy
    May cause masculinization of female fetuses or prolonged gestation
  • Uterine disease (pyometra)
    Progestins promote pyometra development
  • Mammary tumors
    Progestins stimulate mammary tumor growth

Use with caution

  • Diabetes mellitus
    Causes insulin resistance and can induce diabetes, especially in cats

Adverse effects

Common
Weight gain
Polyphagia
Lethargy
Personality changes
Serious
Pyometra
Mammary hyperplasia/neoplasia
Diabetes mellitus (especially cats)
Adrenocortical suppression

Monitoring parameters

Blood glucoseMammary gland examinationBody weightSigns of pyometraAdrenal function
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Interactions

No documented interactions.

Brands

International

Ovaban
Schering-Plough
Megace
Bristol-Myers Squibb

India

Megestol
Sarabhai
Megahit-V
Virbac India

FAQs

Frequently asked questions

What is Megestrol Acetate?
Megestrol Acetate is a synthetic progestational agent used in pets. Synthetic progestin that suppresses gonadotropin (FSH/LH) release from the anterior pituitary; has anti-estrogenic, glucocorticoid-like, and appetite-stimulating properties
What is Megestrol Acetate used for in pets?
Megestrol Acetate is used in veterinary medicine for: Estrus suppression/postponement, behavior modification (aggression); Estrus suppression, miliary dermatitis, eosinophilic granuloma (last resort), spraying behavior.
What is the Megestrol Acetate dose for dogs?
For dogs, Megestrol Acetate is typically dosed as follows — Estrus suppression/postponement, behavior modification (aggression): 0.5–2 mg/kg PO SID for 8 days (estrus suppression), then reduce. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
What is the Megestrol Acetate dose for cats?
For cats, Megestrol Acetate is typically dosed as follows — Estrus suppression, miliary dermatitis, eosinophilic granuloma (last resort), spraying behavior: 2.5–5 mg/cat PO SID for 5 days, then weekly for maintenance. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
What are the side effects of Megestrol Acetate?
Common: Weight gain, Polyphagia, Lethargy, Personality changes. Serious (call your vet immediately): Pyometra, Mammary hyperplasia/neoplasia, Diabetes mellitus (especially cats), Adrenocortical suppression.
Does Megestrol Acetate need a prescription?
Yes. Megestrol Acetate is a prescription medication and should only be administered under veterinary supervision.
When should Megestrol Acetate not be used?
Do not use Megestrol Acetate if: Pregnancy; Uterine disease (pyometra); Mammary tumors.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

References

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

  • Plumb's Veterinary Drug Handbook
  • Withrow & MacEwen's Small Animal Clinical Oncology
  • Merck Veterinary Manual
  • NRC Nutrient Requirements of Dogs and Cats
  • Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

  • ASPCA Animal Poison Control Center Guidelines
  • AAHA Diabetes Management Guidelines
  • ASPCA Poison Control Guidelines
  • RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

  • EPIC Study (J Vet Intern Med 2016)
  • JVIM FAT CAT Study

Regulatory & approvals — 1

  • CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

  • Washington State University VCPL MDR1 Database
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