Medroxyprogesterone Acetate
17-hydroxy-6alpha-methylpregn-4-ene-3,20-dione acetate
Also known as: Depo-Provera · depo-subQ provera 104 · MPA · MAP · acetoxymethylprogesterone · medroxyprogesteroni acetas · methylacetoxyprogesterone · metipregnone · NSC-26386
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Apparent luteal insufficiency in bitches | 0.1 mg/kg PO once daily | PO | q24h | Discontinue several days prior to expected due date | 🌎 NA |
| Long-term reproductive control | 2.5-3 mg/kg IM q5 months | IM | q5 months | — | 🌎 NA |
| Adjunctive treatment of aggressive behaviors | 10 mg/kg IM or SC | IM/SC | As necessary | — | 🌎 NA |
| Young German shepherd dwarfs | 2.5-5 mg/kg initially at 3 week intervals and subsequently at 6 week intervals | IM/SC | q3w initially, then q6w | — | 🌎 NA |
| Benign prostatic hypertrophy | 0.3 mg/kg SC once | SC | Once | Effects last approximately 10 months | 🌎 NA |
| Progestin-responsive dermatitis | 20 mg/kg IM | IM | May repeat in 3-6 months if needed | — | 🌎 NA |
- Apparent luteal insufficiency in bitches: Potential benefits outweigh risks in second half of pregnancy, though fetal deformities are possible.
- Adjunctive treatment of aggressive behaviors: Works best with behavior modification. For inter-male aggression: do not exceed 3 treatments per year.
- Young German shepherd dwarfs: Has resulted in some increase in body size and adult hair coat development.
- Benign prostatic hypertrophy: Best used to maintain breeding potential for short time prior to castration; use with caution.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Behavioral disorders (reduce marking in neutered males) | 5-20 mg/kg SC or IM three to four times yearly | SC/IM | 3-4 times yearly | — | 🌎 NA |
| Feline psychogenic alopecia and dermatitis | 75-150 mg IM or SC | IM/SC | Repeat as necessary, but never more often than every 2-3 months | — | 🌎 NA |
| Progestagen-responsive dermatitis | 50-100 mg IM | IM | May repeat in 3-6 months if needed | — | 🌎 NA |
| Recurrent abortion secondary to progesterone-deficiency | 1-2 mg/kg IM once weekly | IM | q7d | Stop treatment 7-10 days prior to parturition | 🌎 NA |
| Long-term reproductive control | 2.5-5 mg PO once weekly; 25 mg injected every 6 months to postpone estrus | PO/IM/SC | q7d (PO) or q6mo (Injection) | — | 🌎 NA |
| Long-term reproductive control | 2 mg/kg IM q5 months | IM | q5 months | — | 🌎 NA |
- Behavioral disorders (reduce marking in neutered males): Use when all other drugs have been unsuccessful.
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Antipruritic and to suppress ovulation | 0.025-1 mL (3 mg/100 grams body weight) IM once every 4-6 weeks | IM | q4-6w | — | 🌎 NA |
- Antipruritic and to suppress ovulation: May cause obesity, fatty liver, polydipsia/polyuria and lethargy if used repeatedly.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Management of spring transition, prevention of estrus behavior, induction of estrous cycle synchrony, pregnancy maintenance, modification of stallion behavior | 500 to 800 mg IM | IM | Interval varies | Most injections last 2 to 3 months | 🌎 NA |
- Management of spring transition, prevention of estrus behavior, induction of estrous cycle synchrony, pregnancy maintenance, modification of stallion behavior: Will not prevent pregnancy loss and does not stop cyclicity.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Medroxyprogesterone acetate (MPA) is a potent, synthetic progestin derivative of progesterone.
Historically, it has been used in veterinary medicine for behavioral modification (e.g., roaming, inter-male aggression, spraying) and dermatologic conditions (e.g., feline psychogenic alopecia). However, its use has significantly declined due to a high risk of severe adverse effects.
Clinical Pearl: Safer alternatives (such as SSRIs, TCAs, or surgical sterilization) are now strongly preferred for behavioral issues. MPA is still occasionally utilized for specific reproductive indications, such as luteal insufficiency in pregnant bitches, short-term management of benign prostatic hypertrophy, or pituitary dwarfism in German Shepherds. Because of its profound systemic effects, the potential benefits must be carefully weighed against the substantial risks of endocrine and reproductive complications.
Mechanism of action
MPA mimics endogenous progesterone by binding to intracellular progesterone receptors, translocating to the nucleus, and altering gene transcription. It transforms the proliferative endometrium into a secretory endometrium and inhibits spontaneous uterine contractions.
- Endocrine/Reproductive: Exerts negative feedback on the hypothalamus and pituitary, decreasing GnRH → suppressing FSH and LH release, thereby inhibiting estrus and spermatogenesis. It also possesses anti-estrogenic properties and decreases plasma testosterone.
- Glucocorticoid Activity: MPA has significant intrinsic affinity for glucocorticoid receptors, leading to profound suppression of the hypothalamic-pituitary-adrenal (HPA) axis (decreased ACTH and cortisol release).
- Metabolic Effects: Induces peripheral insulin resistance, which can precipitate diabetes mellitus.
- Growth Hormone: In dogs, progestins can stimulate the mammary glands to produce growth hormone, potentially leading to acromegaly.
Safety & warnings
Contraindications
- Pre-pubescent cats or dogs
- Diabetes mellitus
- Pseudopregnant bitches
- Females in diestrus or with prolonged heat
- Uterine hemorrhage or discharge
- Pregnancy (unless specifically treating hypoluteoidism)
Adverse effects
- Increased thirst (polydipsia) and urination (polyuria)
- Increased appetite (polyphagia) and weight gain
- Depression, lethargy, and personality changes
- Adrenocortical depression (HPA axis suppression)
- Mammary changes (enlargement, milk production, neoplasia)
- Diabetes mellitus
- Pyometra / Cystic endometrial hyperplasia
- Temporary inhibition of spermatogenesis
- Permanent local alopecia, skin atrophy, and depigmentation (with SC injection)
- Acromegaly (in dogs)
Precautions
Progestagen therapy can cause serious adverse effects; safer alternative treatments should be considered first. Do not use prior to puberty as severe mammary hypertrophy or subclinical uterine/endocrine conditions may result. Because this drug can suppress adrenal function, exogenous steroids may be needed during times of stress (e.g., surgery, trauma). Prior to reproductive use, perform a thorough history, physical exam, mammary palpation, and vaginal smear to rule out diestrus, estrus, or mammary nodules.
Drug interactions
May decrease medroxyprogesterone effects
May increase medroxyprogesterone metabolism
May decrease progestin activity due to microsomal enzyme induction and increased progestin metabolism
Monitoring
- Weight
- Blood glucose (draw baseline before therapy and monitor periodically)
- Mammary gland development
- Adrenocortical function
- Clinical efficacy
Pharmacokinetics
Half-life
Distribution
Can be detected in maternal milk.
Metabolism
Hepatic metabolism (susceptible to microsomal enzyme induction).
Overdose
No specific reports on inadvertent acute overdosage were located. Overdose is expected to manifest as an exaggeration of adverse effects, including profound adrenal suppression, lethargy, metabolic derangements (hyperglycemia), and reproductive tract changes. Treatment should be supportive and symptomatic.
Available products
Formulations
- Tablets
- Injection (suspension)
Human-labeled
- Medroxyprogesterone Acetate Tablets (scored): 2.5 mg, 5 mg & 10 mg (Provera)
- Medroxyprogesterone Acetate Injection: 104 mg (160 mg/mL) in 0.65 mL prefilled syringes; 150 mg/mL in 1 mL vials; 400 mg/mL in 2.5 mL & 10 mL vials and 1 mL U-ject (depo-subQ provera 104, Depo-Provera)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Suspensions for injection should be stored at room temperature (15-30°C); avoid freezing and temperatures above 40°C. Tablets should be stored in well-closed containers at room temperature.
Client information
Important: This medication carries significant risks and is typically only used when safer alternative treatments have failed.
- Monitor closely for increased thirst, increased urination, or increased appetite. These can be early signs of diabetes mellitus, a serious potential side effect.
- Watch for any changes in the mammary glands, such as swelling, lumps, or milk production.
- In intact (unspayed) females, monitor for signs of a severe uterine infection (pyometra), which may include lethargy, vomiting, decreased appetite, or vaginal discharge. Seek veterinary care immediately if these occur.
- If given by injection under the skin, it may cause permanent hair loss, skin thinning, or color changes at the injection site.
- Your pet may experience personality changes, lethargy, or weight gain while on this medication.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.