Dexamethasone
Dexamethasone is a potent, long-acting synthetic glucocorticoid with anti-inflammatory and immunosuppressive activity and minimal mineralocorticoid effect. Veterinary applications span inflammatory and immune-mediated disease, selected endocrine uses and diagnostic adrenal suppression testing. Dexamethasone sodium phosphate is a water-soluble ester used in injectable products, while other dexamethasone formulations have different solubility and duration characteristics.
Group
Glucocorticoid
Mechanism of Action
Dexamethasone enters cells and binds cytoplasmic glucocorticoid receptors. The activated receptor complex modifies nuclear gene transcription, reducing expression of inflammatory cytokines and enzymes and increasing anti-inflammatory proteins. These changes suppress inflammatory-cell recruitment, vascular permeability and immune activation. Negative feedback on hypothalamic–pituitary signaling reduces ACTH and endogenous cortisol secretion, forming the basis of dexamethasone suppression testing. Sodium phosphate is converted to active dexamethasone after administration.
Dose Rates
Dog
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Inflammation | 0.07–0.15 mg/kg | IV, IM, PO | Every 12–24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dose expressed as dexamethasone; select a preparation labelled in dexamethasone equivalents. IV use requires a suitable soluble formulation. |
| Immunosuppression — Initial | 0.125–0.25 mg/kg | IV, IM, PO | Every 24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dose expressed as dexamethasone; select a preparation labelled in dexamethasone equivalents. IV use requires a suitable soluble formulation. |
| Pulse immunosuppression | Reference only | PO | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; 0.5 mg/kg daily for 4 consecutive days, repeated every 28 days. Cycle-dependent protocol. | |
| Low-dose suppression test | 0.01 mg/kg | IV | Once | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| Low-dose suppression test | 0.015 mg/kg | IV | Once | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Alternative laboratory protocol. |
| High-dose suppression test | 0.1 mg/kg | IV | Once | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| Alternative high-dose suppression test | Reference only | IV | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; The source also cites 1 mg/kg in dogs; confirm the laboratory protocol before using this tenfold alternative. | |
| Shock or spinal injury | Reference only | IV | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Historical 2.2–4.4 mg/kg IV regimen: efficacy is questionable and risks may be high; routine high-dose use is unsupported. | |
| Isonicotinate anti-inflammatory regimen | Reference only | IM | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dexamethasone-21-isonicotinate 0.03–0.05 mg/kg IM. Different ester basis; retained outside generic dexamethasone calculation. | |
| Addisonian crisis — Initial | 0.1–0.2 mg/kg | IV | Use soluble dexamethasone sodium phosphate with strength interpreted on the stated dexamethasone basis; dexamethasone does not cross-react with the cortisol assay. | |
| Addisonian crisis — Initial | 0.2–0.5 mg/kg | IV | Once | Alternative initial regimen using dexamethasone sodium phosphate; transition to oral glucocorticoid replacement when feasible. |
| Addisonian crisis — Maintenance | 0.05–0.1 mg/kg | IV | Every 12 h | Temporary parenteral replacement while vomiting or inappetent; transition to oral prednisone when tolerated. No mineralocorticoid activity. |
Cat
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Inflammation | 0.07–0.15 mg/kg | IV, IM, PO | Every 12–24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dose expressed as dexamethasone; select a preparation labelled in dexamethasone equivalents. IV use requires a suitable soluble formulation. |
| Immunosuppression — Initial | 0.125–0.25 mg/kg | IV, IM, PO | Every 24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dose expressed as dexamethasone; select a preparation labelled in dexamethasone equivalents. IV use requires a suitable soluble formulation. |
| Inflammation — Initial | 0.1–0.2 mg/kg | PO | Every 24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Alternative oral regimen, mixed with food. |
| Inflammation — Maintenance | 0.05 mg/kg | PO | Every 48–72 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| Pulse immunosuppression | Reference only | PO | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; 0.5 mg/kg daily for 4 consecutive days, repeated every 28 days. Cycle-dependent protocol. | |
| Low-dose suppression test | 0.1 mg/kg | IV | Once | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| High-dose suppression test | 1 mg/kg | IV | Once | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| Shock or spinal injury | Reference only | IV | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Historical 2.2–4.4 mg/kg IV regimen: efficacy is questionable and risks may be high; routine high-dose use is unsupported. | |
| Isonicotinate anti-inflammatory regimen | Reference only | IM | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dexamethasone-21-isonicotinate 0.03–0.05 mg/kg IM. Different ester basis; retained outside generic dexamethasone calculation. |
Horse
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Inflammation | 0.04–0.15 mg/kg | IV, IM | Every 24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| Inflammation | 5–20 mg/animal | IV, IM | Every 24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Alternative fixed-dose product regimen; do not combine with the weight-based alternative. |
| Equine asthma | 0.05–0.1 mg/kg | IV, IM | Every 24 h | Up to 3 days; Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| Equine asthma | 0.165 mg/kg | PO | Every 24 h | Up to 3 days; Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Short oral course. Longer courses require a separate taper. |
| Equine asthma taper | Reference only | PO | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; 0.165 mg/kg daily for 7 days, then half that dose daily for another 7 days. | |
| Isonicotinate anti-inflammatory regimen | Reference only | IM | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dexamethasone-21-isonicotinate 0.01–0.04 mg/kg IM; do not calculate with dexamethasone-base strengths. | |
| Dexamethasone suppression test | 0.04 mg/kg | IM | Once | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Use the sampling times specified by the laboratory protocol. |
| Equine asthma | 0.05 mg/kg | PO | Every 24 h | Up to 7 days; Studied during continuing antigen exposure; environmental control remains important. |
| Sodium-phosphate asthma taper | Reference only | IM | Dexamethasone sodium phosphate regimen: 0.1 mg/kg daily for four days, 0.075 mg/kg daily for four days, then 0.05 mg/kg daily for four days, with environmental control. Interpret the product strength on its explicitly stated active basis. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Inflammation | 0.04–0.15 mg/kg | IV, IM | Every 24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan |
| Inflammation | 5–20 mg/animal | IV, IM | Every 24 h | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Alternative fixed-dose product regimen; do not combine with the weight-based alternative. |
| Isonicotinate anti-inflammatory regimen | Reference only | IM | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Dexamethasone-21-isonicotinate 0.01–0.04 mg/kg IM; do not calculate with dexamethasone-base strengths. | |
| Ketosis | 0.01–0.04 mg/kg | IV, IM | Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan | |
| Insect bite or sting adjunct | Reference only | IV | The additional source prints 2 mg/kg IV or IM every 4 hours, far above its other glucocorticoid regimens; the dose is unresolved. Epinephrine is the immediate treatment if anaphylaxis develops. | |
| Ketosis | 5–20 mg | IV, IM |
Sheep
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Induction of parturition | 0.15 mg/kg | IM | Every 24 h | Up to 5 days; Do not use in: Concurrent NSAID treatment without a specific risk-assessed plan; Use for 1–5 days during the final week of gestation. |
Mouse
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anti-inflammatory therapy | 0.6 mg/kg | IM |
Rat
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anti-inflammatory therapy | 0.6 mg/kg | IM |
Gerbil
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anti-inflammatory therapy | 0.6 mg/kg | IM |
Hamster
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anti-inflammatory therapy | 0.6 mg/kg | IM |
Guinea Pig
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anti-inflammatory therapy | 0.6 mg/kg | IM |
Chinchilla
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anti-inflammatory therapy | 0.6 mg/kg | IM |
Pig
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Glucocorticoid therapy | 1–10 mg | IV, IM |
Reptile
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Adjunctive septic shock therapy | 0.1–0.25 mg/kg | IV, IM | Dexamethasone sodium phosphate regimen; adjunctive treatment only. |
Llama
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anaphylaxis adjunct | Reference only | IV | The additional source reports 2 mg/kg IV as adjunctive therapy; its unusually high amount is inconsistent with the other supplied glucocorticoid regimens and is retained as an unresolved reference. |
Indications
- Treatment of clinically significant inflammatory and allergic disease in dogs, cats, horses and other veterinary species.
- Immunosuppressive treatment of selected immune-mediated disorders, including immune-mediated cytopenias and inflammatory skin, joint or neurologic disease.
- Control of airway inflammation in horses with equine asthma.
- Short-term glucocorticoid support in selected patients with adrenal insufficiency, particularly when parenteral treatment is required.
- Diagnostic low- or high-dose dexamethasone suppression testing for assessment of the pituitary–adrenal axis in appropriate veterinary patients.
- Adjunctive treatment of bovine ketosis in selected cases.
- Induction of parturition in cattle within an appropriate obstetrical protocol.
Contraindications
- Use cautiously with infection, ulcers, diabetes, renal disease, pregnancy or impaired wound healing.
- Dexamethasone isonicotinate suspension must not be given IV.
- Do not apply ophthalmic corticosteroids to an ulcerated cornea or an uncontrolled ocular infection.
Interactions
- NSAIDs increase gastrointestinal injury.
- Do not mix alkaline dexamethasone solutions with acidifying solutions.
Adverse effects
- Polyuria, polydipsia and polyphagia
- Adrenal suppression, hyperglycemia and hepatopathy
- Gastrointestinal ulceration and secondary infection
- Delayed healing; possible equine laminitis
Toxicity
Excess or prolonged exposure causes iatrogenic hyperadrenocorticism and adrenal suppression; abrupt withdrawal after prolonged treatment can cause adrenal insufficiency.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Dexamethasone 0.25 mg | Tablet | 0.25 mg / tablet | PO |
| Dexamethasone 0.5 mg | Tablet | 0.5 mg / tablet | PO |
| Dexamethasone 0.75 mg | Tablet | 0.75 mg / tablet | PO |
| Dexamethasone 1 mg | Tablet | 1 mg / tablet | PO |
| Dexamethasone 1.5 mg | Tablet | 1.5 mg / tablet | PO |
| Dexamethasone 2 mg | Tablet | 2 mg / tablet | PO |
| Dexamethasone 4 mg | Tablet | 4 mg / tablet | PO |
| Dexamethasone 6 mg | Tablet | 6 mg / tablet | PO |
| Dexamethasone polyethylene-glycol solution 2 mg/mL Give IV slowly; soluble sodium phosphate is preferred for IV use. | Injection | 2 mg / mL | IV, IM |
| Dexamethasone oral solution 0.1 mg/mL | Oral Liquid | 0.1 mg / mL | PO |
| Dexamethasone oral solution 1 mg/mL | Oral Liquid | 1 mg / mL | PO |
| Dexamethasone powder 10 mg/15 g | Powder | 10 mg / 15 g | PO |
| Dexamethasone sodium phosphate 4 mg/mL The source describes this presentation as equivalent to 3 mg/mL dexamethasone base. Salt-labelled product is not auto-linked to the base regimen. | Injection | 4 mg / mL | IV, IM |
| Dexamethasone isonicotinate suspension 1 mg/mL Depot ester; never IV. | Injection | 1 mg / mL | IM |
| Glucortin-20 2 mg/mL Interchemie werken De Adelaar B.V. Contains dexamethasone 2 mg/mL as sodium phosphate, explicitly expressed as dexamethasone equivalents. | Injection | 2 mg / mL | IV, IM |
| Dexamethasone sodium phosphate ophthalmic solution 0.1% Ophthalmic solution only; not an injectable preparation. Confirm the label’s salt-equivalent basis before interchange. | Other | 1 mg / mL | TOPICAL |
| Dexamethasone phosphate ophthalmic ointment 0.05% Ophthalmic ointment; not interchangeable with systemic formulations. | Other | 0.5 mg / g | TOPICAL |
Monitoring and Administration
Sodium phosphate is the preferred water-soluble IV form. Polyethylene-glycol solutions require slow injection because rapid injection can cause hemolysis, hypotension or collapse.
Monitor clinical response, glucose, infection and CBC during prolonged treatment; taper when indicated.
For canine/feline low-dose suppression testing, obtain baseline, 4-hour and 8-hour cortisol samples.
Equine suppression sampling differs between source protocols (17 and 19 hours versus 24 hours); use one validated laboratory protocol.
Protect from light. Sodium phosphate diluted in saline or 5% dextrose has a reported 24-hour use period. Formulation-specific stability must not be transferred to unrelated mixtures.
0.05 mg/kg (example: 25 mg per cow) during the final 1–2 weeks of gestation. The source does not explicitly specify the route for this regimen and cites an ambiguous PGF2-alpha combination amount; route and combination must be resolved before calculation.
For canine low-dose dexamethasone suppression testing, collect baseline, four-hour and eight-hour cortisol samples; feline testing uses a different dose. Use the laboratory’s species-specific interpretation. Dexamethasone has a long biological effect, so alternate-day administration may still suppress adrenal function.