Dexamethasone

Corticosteroid Glucocorticoid

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 0.1-0.2 mg/kg (anti-inflammatory); 0.5-2 mg/kg (immunosuppressive) q12-24h (anti-inflammatory); q24h or divided q12h (immunosuppressive) Duration: Varies; taper for long-term use
Notes: Use lowest effective dose; taper gradually to avoid HPA axis suppression.
Dog IV/IM 0.1-0.2 mg/kg (anti-inflammatory); 1-4 mg/kg (shock, cerebral edema) q12-24h (anti-inflammatory); single dose or q6-8h for shock Duration: Short-term for acute conditions
Notes: For shock, administer slowly IV; monitor for hyperglycemia.
Cat PO 0.1-0.2 mg/kg (anti-inflammatory); 0.5-2 mg/kg (immunosuppressive) q12-24h (anti-inflammatory); q24h or divided q12h (immunosuppressive) Duration: Varies; taper for long-term use
Notes: Cats are more sensitive to side effects; use lowest effective dose.
Cat IV/IM 0.1-0.2 mg/kg (anti-inflammatory); 1-4 mg/kg (shock, cerebral edema) q12-24h (anti-inflammatory); single dose or q6-8h for shock Duration: Short-term for acute conditions
Notes: For shock, administer slowly IV; monitor for hyperglycemia.
Horse IV 0.02-0.1 mg/kg (anti-inflammatory); 0.1-0.2 mg/kg (shock/endotoxemia) q24h (anti-inflammatory); single dose or q12h for shock Duration: Short-term; use with caution in laminitis
Notes: Avoid in horses with laminitis risk; monitor for hyperglycemia.
Horse IM 0.02-0.1 mg/kg (anti-inflammatory) q24h Duration: Short-term
Notes: IM administration may cause local irritation.
Cattle IV/IM 0.02-0.1 mg/kg (anti-inflammatory); 0.1-0.2 mg/kg (ketosis) q24h (anti-inflammatory); single dose for ketosis Duration: Short-term
Notes: For ketosis, often used in combination with glucose; monitor for hyperglycemia.
Small Ruminants IV/IM 0.02-0.1 mg/kg (anti-inflammatory); 0.1-0.2 mg/kg (pregnancy toxemia) q24h (anti-inflammatory); single dose for toxemia Duration: Short-term
Notes: Use with caution; may induce abortion in pregnant animals.
Rabbit PO/IM/IV 0.1-0.2 mg/kg (anti-inflammatory) q12-24h Duration: Short-term
Notes: Use with caution; rabbits are prone to GI stasis and immunosuppression.
Bird/Poultry IM/PO 0.1-0.2 mg/kg (anti-inflammatory) q12-24h Duration: Short-term
Notes: Use with caution; not commonly used in poultry due to withdrawal concerns.

Clinical Indications & Species Uses

General Indications
  • Anti-inflammatory and immunosuppressive therapy
  • Management of allergic reactions
  • Treatment of shock (high-dose, short-term)
  • Cerebral edema
  • Replacement therapy for adrenal insufficiency (with mineralocorticoid)
Dog (Canine)
  • Anti-inflammatory therapy for musculoskeletal conditions (e.g., arthritis, bursitis)
  • Immunosuppressive therapy for immune-mediated diseases (e.g., immune-mediated hemolytic anemia, immune-mediated thrombocytopenia, lupus, pemphigus)
  • Management of allergic reactions and pruritus
  • Treatment of shock (high-dose, short-term)
  • Cerebral edema (with mannitol)
  • Neoplasia (as part of chemotherapy protocols, e.g., lymphoma)
  • Replacement therapy for adrenal insufficiency (with mineralocorticoid)
  • Spinal cord trauma (acute)
Cat (Feline)
  • Anti-inflammatory therapy for allergic dermatitis and asthma
  • Immunosuppressive therapy for immune-mediated diseases (e.g., inflammatory bowel disease, eosinophilic granuloma complex)
  • Management of shock
  • Cerebral edema
  • Neoplasia (e.g., lymphoma)
  • Replacement therapy for adrenal insufficiency
Horse (Equine)
  • Anti-inflammatory therapy for musculoskeletal injuries (e.g., arthritis, laminitis)
  • Management of allergic reactions (e.g., insect hypersensitivity)
  • Treatment of shock and endotoxemia (low-dose, often with flunixin)
  • Cerebral edema
  • Recurrent airway obstruction (heaves) - as adjunctive therapy
Cattle (Bovine)
  • Anti-inflammatory therapy for musculoskeletal conditions (e.g., arthritis, laminitis)
  • Management of allergic reactions (e.g., insect bites, vaccine reactions)
  • Treatment of ketosis (as a glucocorticoid to increase glucose production)
  • Induction of parturition (in combination with other agents, though not primary use)
  • Supportive therapy for respiratory disease (e.g., pneumonia) - as adjunct
Small Ruminants (Sheep / Goat)
  • Anti-inflammatory therapy for musculoskeletal conditions
  • Management of allergic reactions
  • Treatment of pregnancy toxemia (as a glucocorticoid to increase glucose)
  • Supportive therapy for respiratory disease
Rabbit & Small Mammals
  • Anti-inflammatory therapy for allergic conditions
  • Immunosuppressive therapy for immune-mediated diseases (use with caution due to susceptibility to infections)
  • Treatment of shock (rarely used)
Avian & Poultry
  • Anti-inflammatory therapy for trauma or allergic reactions (use with caution)
  • Immunosuppressive therapy for autoimmune conditions (rarely used)
Exotic & Other Species
  • Reptiles: Anti-inflammatory therapy for trauma or allergic reactions (use with caution)
  • Small mammals (ferrets, guinea pigs): Anti-inflammatory therapy for allergic or immune-mediated conditions
  • Use with caution due to increased susceptibility to infections and metabolic side effects

Pharmacology & Mechanism of Action

Drug Class: Corticosteroid | Pharmacological Group: Glucocorticoid

Mechanism of Action: Dexamethasone is a potent synthetic glucocorticoid that binds to the glucocorticoid receptor, leading to modulation of gene transcription. It induces the synthesis of lipocortin, which inhibits phospholipase A2, reducing arachidonic acid release and subsequent prostaglandin and leukotriene production. It also suppresses cytokine production (e.g., IL-1, IL-2, IL-6, TNF-alpha), inhibits inflammatory cell migration, and stabilizes lysosomal membranes. These actions result in potent anti-inflammatory, immunosuppressive, and anti-allergic effects.

Pharmacodynamics: Dexamethasone has approximately 25-30 times the anti-inflammatory potency of hydrocortisone and 7-10 times that of prednisolone. It has minimal mineralocorticoid activity, making it less likely to cause sodium and water retention. It suppresses the hypothalamic-pituitary-adrenal (HPA) axis, reduces eosinophil and lymphocyte counts, increases blood glucose via gluconeogenesis, and alters protein and fat metabolism. Its effects are dose-dependent and can be used for physiologic replacement or pharmacologic anti-inflammatory/immunosuppressive therapy.

⚡ Pharmacokinetics Summary

Absorption: Dexamethasone is well absorbed after oral administration, with peak plasma concentrations occurring within 1-2 hours. It is also well absorbed after intramuscular (IM) and subcutaneous (SC) administration, though absorption may be slower. The oral bioavailability is approximately 60-100% in dogs and cats.
Distribution: Dexamethasone is widely distributed throughout the body, crossing the blood-brain barrier and placenta. It is highly protein-bound (approximately 70-80%) to albumin and corticosteroid-binding globulin. It distributes into tissues with high concentrations in the liver, kidneys, and lungs.
Metabolism: Dexamethasone is metabolized primarily in the liver via reduction and conjugation. The major metabolic pathways involve 6-beta-hydroxylation and 20-ketosteroid reduction. Some metabolites retain weak glucocorticoid activity.
Excretion: Excretion occurs primarily via the kidneys as metabolites, with a small amount excreted in bile. In dogs, the elimination half-life is approximately 2-4 hours, while in cats it is slightly longer (approximately 3-5 hours). In horses, the half-life is approximately 1-2 hours after IV administration.
Half-Life: Dogs: 2-4 hours; Cats: 3-5 hours; Horses: 1-2 hours; Cattle: 2-3 hours
Bioavailability: Oral bioavailability is approximately 60-100% in dogs and cats; IM and SC are well absorbed.
Protein Binding: Approximately 70-80% bound to plasma proteins (albumin and corticosteroid-binding globulin).

Available Formulations & Strengths

Oral Tablet 0.25 mg, 0.5 mg, 0.75 mg, 1 mg, 2 mg, 4 mg, 6 mg (PO)
Oral Solution 0.5 mg/5 mL, 1 mg/mL (PO)
Injectable Solution 2 mg/mL, 4 mg/mL (IV/IM/SC)
Ophthalmic Suspension 0.1% (Ophthalmic)
Ophthalmic Ointment 0.05% (Ophthalmic)
Topical Cream/Ointment 0.1% (Topical)

Contraindications & Clinical Warnings

Contraindications:
  • Systemic fungal infections
  • Known hypersensitivity to dexamethasone or other corticosteroids
  • Gastrointestinal ulceration (especially in horses)
  • Corneal ulceration (for ophthalmic use)
  • Pregnancy (especially in cattle and small ruminants, may induce abortion)
  • Concurrent use of live vaccines (immunosuppression may impair immune response)
  • Cushing's syndrome (unless treating adrenal insufficiency)
Warnings & Clinical Precautions:
  • Use with caution in animals with diabetes mellitus, as it may cause hyperglycemia.
  • Use with caution in animals with renal disease, cardiac disease, or hypertension.
  • Use with caution in animals with osteoporosis or fractures.
  • Use with caution in animals with infectious diseases, as it may mask signs of infection.
  • Prolonged use may cause HPA axis suppression; taper dose gradually.
  • In horses, use with caution in those with laminitis risk; monitor closely.
  • In food animals, observe withdrawal times; extra-label use requires veterinary oversight.
  • In cats, use with caution as they are more sensitive to side effects.
  • Avoid use in pregnant animals unless benefits outweigh risks.
  • Do not use in animals with viral infections without concurrent antimicrobial therapy.

Adverse Effects & Reactions

Common:

  • Increased thirst and urination (polydipsia/polyuria)
  • Increased appetite
  • Panting (especially in dogs)
  • Gastrointestinal upset (vomiting, diarrhea)
  • Behavioral changes (restlessness, aggression)

Serious / Severe:

  • Gastrointestinal ulceration and perforation
  • Pancreatitis
  • Hepatopathy (especially in dogs)
  • Diabetes mellitus or worsening of existing diabetes
  • Cushing's syndrome (iatrogenic)
  • HPA axis suppression
  • Immunosuppression leading to opportunistic infections
  • Ligament and tendon rupture (in horses)
  • Laminitis (in horses)

Rare:

  • Anaphylactic reactions
  • Seizures
  • Cardiac arrhythmias
  • Osteoporosis
  • Growth retardation in young animals
  • Cataracts (with prolonged use)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Nonsteroidal anti-inflammatory drugs (NSAIDs) Increased risk of gastrointestinal ulceration and bleeding. High
Furosemide and other loop diuretics Increased risk of electrolyte imbalances (e.g., hypokalemia). Moderate
Insulin or oral hypoglycemic agents May reduce the effectiveness of these drugs; dose adjustment may be needed. Moderate
Phenobarbital and other hepatic enzyme inducers May increase the metabolism of dexamethasone, reducing its efficacy. Moderate
Amphotericin B Increased risk of hypokalemia and potential cardiac toxicity. High
Vaccines (live) Immunosuppression may impair immune response to vaccines; avoid concurrent use. Moderate
Anticholinesterase agents (e.g., neostigmine) May exacerbate muscle weakness in myasthenia gravis. Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Severe hyperglycemia
  • Electrolyte imbalances (hypokalemia, hypernatremia)
  • Gastrointestinal ulceration
  • Pancreatitis
  • Behavioral changes (agitation, depression)
  • Polyuria and polydipsia
  • Immunosuppression
  • HPA axis suppression

Emergency Treatment Protocol: Treatment is primarily supportive. There is no specific antidote. Monitor vital signs, blood glucose, and electrolytes. Provide symptomatic care: fluid therapy for dehydration, anti-ulcer medications (e.g., omeprazole, sucralfate) for GI protection, and insulin if severe hyperglycemia occurs. In cases of acute overdose, consider gastric lavage if oral ingestion is recent. For chronic overdose, taper the drug gradually to avoid withdrawal symptoms. Supportive care may include nutritional support and management of secondary infections.

Food Animal Withdrawal Times

🥩 Meat: 0 days🥛 Milk: 0 days🥚 Eggs: 0 days

Dexamethasone is not approved for use in food animals in many countries; however, when used extra-label, withdrawal times must be determined by a veterinarian. In the US, the FDA has established a zero-day withdrawal time for dexamethasone in cattle and swine when used according to label, but extra-label use may require extended withdrawal periods. For poultry, withdrawal times are not established; use is generally avoided. Consult the label and regulatory guidelines.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F), with excursions permitted between 15-30°C (59-86°F).

Light Sensitivity: Light-sensitive — protect from direct exposure.

Handling & Special Conditions: Protect from light and moisture. Keep in a tightly closed container. Do not freeze injectable solutions. Store ophthalmic preparations as directed on the label.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs, cats, horses, cattle, and swine in various formulations. Not approved for use in poultry or other food animals in the US.

Extra-Label (Off-Label) Use: In the US, dexamethasone is a prescription drug for veterinary use. Extra-label use in food animals is permitted under AMDUCA (Animal Medicinal Drug Use Clarification Act) only with a valid veterinary-client-patient relationship and a written or oral order from a veterinarian. Extended withdrawal times must be established. In the EU, similar regulations apply under Regulation (EC) No 470/2009.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Dexamethasone is a potent, long-acting corticosteroid used for its anti-inflammatory and immunosuppressive properties. It is particularly useful for conditions requiring rapid and potent glucocorticoid effects, such as shock, cerebral edema, and severe allergic reactions. However, its potency and long duration of action increase the risk of adverse effects, especially with prolonged use. It is essential to use the lowest effective dose for the shortest duration possible and to taper the dose gradually to avoid HPA axis suppression. In food animals, extra-label use requires careful consideration of withdrawal times. In horses, caution is advised due to the risk of laminitis. In cats, monitoring for diabetes mellitus is important. Always consider the animal's overall health status and potential drug interactions before initiating therapy.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)