Methylprednisolone Acetate: veterinary dose and monograph

At a glance

Drug class

Anti-inflammatory

Also known as

Depo-Medrol, Solu-Medrol (sodium succinate)

Species with doses

Dogs, Cats and Horses

General dose range

0.5–2 mg/kg IM long-acting (weeks) — check the species tables for the indication

Routes

IV, IM, PO, Intra-articular

Last reviewed

1 October 2026

Indications

• Feline atopy / allergic asthma (long-acting depot)
• Equine joint inflammation (intra-articular)
• Allergic dermatitis (single depot dose in cats)
• Anaphylaxis / septic shock (Solu-Medrol IV high dose)
• Spinal cord trauma (Solu-Medrol high-dose protocol — controversial; falling out of favour)
• Inflammatory immune-mediated disease (oral tablets, off-label vs prednisolone)

Methylprednisolone Acetate dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Acute / immune-mediated disease (Solu-Medrol IV): Plumb’s p.817: for methylprednisolone tablets or sodium succinate, take the prednisolone dose for the condition and divide by 1.25 (5 mg prednisolone ≈ 4 mg methylprednisolone) — anti-inflammatory ≈0.4–0.8 mg/kg/day, immunosuppressive ≈1.6 mg/kg/day or more. Taper to the lowest effective dose. The 0.5–2 mg/kg range reflects that conversion across anti-inflammatory to immunosuppressive indications. Papich 5e: oral tablets 0.25–0.5 mg/kg q12–24h; sodium succinate emergency use 30 mg/kg IV then 15 mg/kg in 2–6 h (efficacy debated).
• Spinal cord trauma — SODIUM SUCCINATE ONLY (high-dose protocol): SODIUM SUCCINATE ONLY — the acetate depot must never be given IV or at this dose. Papich 5e (emergency use): 30 mg/kg IV, then 15 mg/kg IV 2–6 h later. Plumb’s p.817: current evidence does NOT support high-dose glucocorticoids for spinal cord trauma, head trauma, haemorrhagic/hypovolaemic shock or sepsis; significant GI-haemorrhage risk.
• Depot acetate (IM): Papich 5e: methylprednisolone ACETATE 1 mg/kg (or 20–40 mg/dog) IM every 1–3 weeks. Plumb’s p.817 (label): 2–120 mg IM (average 20 mg) by size and severity, repeated weekly or as the condition requires. Intralesional: 10–40 mg total (Scott 1982).
• Oral tablets: Papich 5e: 0.25–0.5 mg/kg q12–24h PO (label 0.22–0.44 mg/kg); taper to the lowest effective dose; long-term maintenance 0.3–0.5 mg/kg every other day. Adrenal-insufficiency replacement 0.2 mg/kg/day.

Cats

• Depot acetate (IM): Papich 5e: methylprednisolone acetate 10–20 mg/cat IM every 1–3 weeks. Plumb’s p.817 (label): up to 20 mg (average 10 mg) IM, repeated weekly or as the condition requires. Repeated depots raise the risk of diabetes mellitus and congestive heart failure — use the lowest effective frequency.
• Oral tablets: Papich 5e: 0.25–0.5 mg/kg q12–24h PO (label 0.22–0.44 mg/kg), tapering to the lowest dose that controls the disease. Plumb’s p.817 (label): cats 5–15 lb 2 mg/day, over 15 lb 2–4 mg/day, divided.

Horses

• Intra-articular joint inflammation: Papich 5e: 40–240 mg total per joint, average 120 mg, with sterile technique. Plumb’s p.817: 100 mg IA (McClure 2002). Refer to the package insert for intrasynovial directions; repeated injections risk cartilage damage.
• Systemic anti-inflammatory (acetate IM): Papich 5e and Plumb’s p.817 (Depo-Medrol label): methylprednisolone acetate 200 mg total IM, repeated as necessary. Caution in laminitis-prone horses.

Contraindications

Untreated systemic infection (bacterial / fungal / viral). Diabetes mellitus (worsens hyperglycaemia). Active GI ulceration. Concurrent NSAIDs (additive ulceration). Vaccination response will be blunted. Diabetic remission attempts in cats — corticosteroids antagonise insulin sensitivity. Pregnancy near term (potential fetal adrenal suppression).

Species-specific warnings

Dogs: Equivalent to prednisolone at 0.8× the dose. Chronic use → iatrogenic Cushing's. NEVER combine with NSAIDs.

Cats: Depo-Medrol 10–20 mg per cat IM/SC q3–6 weeks is a long-standing atopy / asthma standard — but DIABETES precipitation risk; check fructosamine.

Horses: Intra-articular use → potential laminitis at high doses. Repeated intra-articular causes cartilage degeneration.

Adverse effects

• Polyuria / polydipsia / polyphagia (chronic dosing)
• Iatrogenic hyperadrenocorticism (chronic)
• GI ulceration (combined with NSAIDs)
• Diabetes / insulin resistance (cats especially)
• Wound healing delay
• Increased infection susceptibility
• Adrenal axis suppression — taper after >2 weeks of therapy
• Intra-articular: post-injection arthropathy / cartilage degeneration with repeated use

Drug interactions

• NSAIDs: additive GI ulceration — DO NOT combine routinely
• Insulin / oral hypoglycemics: corticosteroids antagonise — increase insulin requirement
• Diuretics / amphotericin B: additive hypokalaemia
• Live vaccines: blunted response — defer 2 weeks
• Cyclosporine: corticosteroids reduce cyclosporine clearance
• Phenytoin / phenobarbital: induce CYP3A4 → faster steroid clearance

Pregnancy and lactation

Cross placenta; high doses near term can suppress fetal adrenal axis or precipitate parturition. Equine: high-dose steroids can induce abortion in mares. FDA Category C.

Monitoring

• Blood glucose at baseline + 2 weeks (especially cats — diabetes risk)
• Body weight, abdominal contour, water intake
• CBC, biochemistry, urinalysis every 3 months on chronic therapy
• Cortisol / ACTH stim test if iatrogenic Cushing's suspected
• Wound healing / infection signs
• For chronic equine intra-articular use: joint film at 6 / 12 months to detect cartilage degeneration

Toxicity and overdose

Chronic high-dose: iatrogenic Cushing's (panting, alopecia, abdominal distension, hepatomegaly, calcinosis cutis). Acute adrenal crisis on sudden withdrawal after >14 days. GI ulceration with NSAIDs. Steroid-induced laminitis in horses with depot doses (controversial mechanism). Diabetes precipitation in cats.

Management: Acute overdose: usually well tolerated — supportive. Chronic side effects: taper slowly (over weeks). Adrenal crisis: dexamethasone IV + fluids + glucose. Steroid-induced laminitis: standard equine laminitis care.

Clinical pearls

• Feline allergic asthma flare: Depo-Medrol 20 mg SC q3–4 weeks gives convenient long-acting control — but check fructosamine every 6 months for diabetes precipitation
• Equine joint injection for OA: 40–80 mg Depo-Medrol intra-articular gives 6–8 weeks of comfort — limit to 3–4 repeats per joint per lifetime due to chondrotoxicity
• Spinal cord trauma high-dose protocol: 30 mg/kg IV within 8 h → 15 mg/kg IV at 2 + 6 h → evidence is mixed; many specialists no longer use
• Cat with refractory dermatitis: try methylprednisolone Depo before moving to cyclosporine — cheaper, simpler, fewer monitoring requirements
• NEVER use Depo-Medrol in a diabetic patient — long action means glycaemic disruption for weeks
• Always counsel owner on PU/PD before steroid therapy — sets expectations and detects early Cushing's

Mechanism of action

Intermediate-acting glucocorticoid. Binds cytoplasmic glucocorticoid receptor → translocates to nucleus → suppresses pro-inflammatory gene transcription (NF-κB, AP-1 pathways) and induces anti-inflammatory gene expression (lipocortin, IL-10). Anti-inflammatory potency ~5× cortisol; mineralocorticoid activity minimal vs cortisol. Acetate ester (Depo-Medrol) crystallises at injection site → slow release over 3–6 weeks; succinate (Solu-Medrol) is water-soluble for rapid IV action.

Formulations and products

• Depo-Medrol 40 mg/mL injection (acetate ester, long-acting IM/IA)
• Solu-Medrol 62.5 mg/mL injection (sodium succinate, IV)
• Methylprednisolone 4 mg / 16 mg tablet

Storage

Vials 15–25 °C protected from light. SHAKE Depo-Medrol vial before drawing — particle suspension. Solu-Medrol act-o-vial reconstitution per label.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other anti-inflammatory drugs

• Isoflupredone Acetate
• Ketoprofen
• Mavacoxib
• Meloxicam
• Nimesulide
• Phenylbutazone
• Piroxicam
• Prednisolone

Frequently asked questions