Methylprednisolone

Methylprednisolone is a synthetic glucocorticoid used for inflammatory and immune-mediated disease. Oral preparations support systemic treatment, soluble sodium succinate provides a parenteral option, and acetate suspensions provide prolonged depot or local effects. Its veterinary applications include dermatologic, respiratory, hematologic and musculoskeletal disorders, with the formulation determining the clinical delivery role.

Group

Glucocorticoid

Mechanism of Action

Methylprednisolone binds intracellular glucocorticoid receptors and alters transcription of inflammatory and immune-response genes. Reduced cytokine and mediator production limits leukocyte recruitment, vascular permeability and immune-cell activation. These effects produce anti-inflammatory or immunosuppressive activity according to exposure. Acetate and sodium succinate formulations ultimately supply the same active glucocorticoid but differ in release characteristics.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Inflammatory or immune-mediated disease — Initial	0.25–0.5 mg/kg	PO	Every 12–24 h	Taper to the lowest effective amount and frequency once stable.
Inflammatory or immune-mediated disease — Initial	0.22–0.44 mg/kg	PO	Every 12–24 h	Separate reported label range; taper according to response.
Historical emergency steroid treatment	Reference only	IV		Sodium succinate 30 mg/kg initially, followed by 15 mg/kg after 2-6 hours. Benefit in spinal trauma or shock is questionable and gastrointestinal bleeding risk is high; not routine emergency treatment.
Chronic anti-inflammatory maintenance — Maintenance	0.3–0.5 mg/kg	PO	Every 48 h
Depot anti-inflammatory treatment	1 mg/kg	IM	Every 168–504 h	Acetate suspension only; reported fixed alternative is 20-40 mg/dog.
Depot anti-inflammatory treatment	20–40 mg/animal	IM	Every 168–504 h	Acetate suspension only; fixed-dose alternative.
Broad depot acetate label alternative	Reference only	IM		2-120 mg/animal, average 20 mg, with repeat at about weekly intervals or according to response. The broad size-dependent label range is not a universal starting amount.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Inflammatory or immune-mediated disease — Initial	0.25–0.5 mg/kg	PO	Every 12–24 h	Taper to the lowest effective amount and frequency once stable.
Inflammatory or immune-mediated disease — Initial	0.22–0.44 mg/kg	PO	Every 12–24 h	Separate reported label range; taper according to response.
Historical emergency steroid treatment	Reference only	IV		Sodium succinate 30 mg/kg initially, followed by 15 mg/kg after 2-6 hours. Benefit in spinal trauma or shock is questionable and gastrointestinal bleeding risk is high; not routine emergency treatment.
Depot anti-inflammatory treatment	10–20 mg/animal	IM	Every 168–504 h	Acetate suspension only; monitor for diabetes, cardiac decompensation and herpesvirus reactivation.

Horses

Use / stage	Dose	Route	Schedule	Instructions
Depot anti-inflammatory treatment	200 mg/animal	IM	Once	Acetate formulation.

Indications

Treatment of selected inflammatory or allergic skin and airway disorders in dogs, cats and other veterinary patients.
Immunosuppressive treatment of selected immune-mediated disorders, including cytopenias, inflammatory joint disease and immune-mediated dermatoses.
Treatment of selected steroid-responsive intestinal or neurologic inflammatory disease.
Local treatment of selected noninfectious synovitis, osteoarthritis-associated synovial inflammation or other focal inflammatory lesions with an appropriate injectable formulation.

Contraindications

Use cautiously with diabetes, active infection, gastrointestinal ulceration, impaired wound healing or pregnancy.

Interactions

NSAIDs increase gastrointestinal ulceration and bleeding.
May antagonize insulin and impair glycaemic control.

Adverse effects

Polyphagia, polydipsia and polyuria
Adrenal suppression, hyperglycaemia, hepatopathy and secondary infection
Delayed wound healing

Toxicity

Excessive exposure causes iatrogenic hyperadrenocorticism and immunosuppression; abrupt withdrawal after prolonged treatment may cause adrenal insufficiency.

Preparations

Preparation	Form	Strength	Route
Methylprednisolone 1 mg tablet	Tablet	1 mg / tablet	PO
Methylprednisolone 2 mg tablet	Tablet	2 mg / tablet	PO
Methylprednisolone 4 mg tablet	Tablet	4 mg / tablet	PO
Methylprednisolone 8 mg tablet	Tablet	8 mg / tablet	PO
Methylprednisolone 32 mg tablet	Tablet	32 mg / tablet	PO
Methylprednisolone 20 mg/mL injection Depot acetate salt retained separately; do not use IV.	Injection	20 mg / mL	IM
Methylprednisolone 40 mg/mL injection Depot acetate salt retained separately; do not use IV.	Injection	40 mg / mL	IM
Methylprednisolone sodium succinate 125 mg vial Unreconstituted vial; no final mL concentration is assumed.	Injection	125 mg / vial	IV, IM
Methylprednisolone sodium succinate 500 mg vial Unreconstituted vial; no final mL concentration is assumed.	Injection	500 mg / vial	IV, IM
Methylprednisolone sodium succinate 1000 mg vial Unreconstituted vial; no final mL concentration is assumed.	Injection	1000 mg / vial	IV, IM
Methylprednisolone sodium succinate 2000 mg vial Unreconstituted vial; no final mL concentration is assumed.	Injection	2000 mg / vial	IV, IM
Methylprednisolone 16 mg tablet	Tablet	16 mg / tablet	PO
Methylprednisolone 24 mg tablet	Tablet	24 mg / tablet	PO
Methylprednisolone acetate 80 mg/mL suspension Depot suspension; not for IV use.	Injection	80 mg / mL	IM

Monitoring and Administration

Monitor glucose, hepatic and renal parameters, infection and adrenal function when indicated.

Taper sustained systemic treatment according to response rather than stopping abruptly; depot injections cannot be withdrawn after administration.

Equine intra-articular acetate: 40-240 mg per joint, average 120 mg, using aseptic technique. Use an appropriate joint formulation and aseptic technique.

Sodium succinate reconstitution and use periods are product-specific; the published guidance describes up to 48 hours at room temperature. Acetate suspension must not be injected IV.

Monitor cats for diabetes, volume expansion or congestive heart failure after depot injection; injection-site alopecia and latent herpesvirus reactivation are reported.

Canine adrenal-replacement amount is 0.2 mg/kg/day, but route is missing in that entry; the dose is retained without an inferred route.

Approximate systemic potency conversion from prednisone/prednisolone is to divide its milligram amount by 1.25 for methylprednisolone; this does not convert depot kinetics or route. Label weight-group oral totals are dogs 5-15 lb: 2 mg/day, 15-40 lb: 2-4 mg/day, 40-80 lb: 4-8 mg/day; cats 5-15 lb: 2 mg/day and over 15 lb: 2-4 mg/day. These daily totals are divided 6-10 hours apart and must not be repeated whole at every interval.

Local intralesional acetate treatment uses 10-40 mg total of 20 mg/mL suspension to undermine the lesion; a dedicated local-procedure route is required. Equine intra-articular alternative is 100 mg/joint. Do not inject local steroid into an infected site. High-dose treatment for hypovolaemic/haemorrhagic shock, head or spinal trauma and sepsis lacks supporting evidence.