Cabergoline

Dopamine receptor agonist (ergot derivative) Prolactin inhibitor

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 5-10 µg/kg (0.005-0.01 mg/kg) q24h Duration: 5-7 days for pseudopregnancy; 3-5 days for lactation suppression
Notes: For pseudopregnancy, treatment is continued until clinical signs resolve. For lactation suppression, treatment is given for 3-5 days.
Cat PO 5-10 µg/kg (0.005-0.01 mg/kg) q24h Duration: 3-5 days
Notes: Off-label use; monitor for adverse effects.
Horse PO 0.5-1 mg per horse (approximately 1-2 µg/kg) q24h Duration: 3-5 days
Notes: For lactation suppression in mares. Adjust dose based on response.

Clinical Indications & Species Uses

General Indications
  • Prolactin inhibition for various reproductive disorders
Dog (Canine)
  • Treatment of pseudopregnancy (false pregnancy)
  • Suppression of lactation
  • Treatment of pituitary-dependent hyperadrenocorticism (as an adjunct, off-label)
  • Treatment of prolactinoma (rare)
Cat (Feline)
  • Suppression of lactation (off-label)
  • Treatment of hyperprolactinemia (rare)
Horse (Equine)
  • Suppression of lactation in mares
  • Treatment of hyperprolactinemia (e.g., associated with pituitary pars intermedia dysfunction, off-label)

Pharmacology & Mechanism of Action

Drug Class: Dopamine receptor agonist (ergot derivative) | Pharmacological Group: Prolactin inhibitor

Mechanism of Action: Cabergoline is a long-acting ergot derivative that acts as a potent and selective agonist at D2 dopamine receptors. By stimulating D2 receptors on lactotroph cells in the anterior pituitary, it inhibits the release of prolactin. This reduces serum prolactin levels, leading to decreased lactation and regression of prolactin-dependent tissues. In dogs, it also has an antiprolactinemic effect that terminates pseudopregnancy and suppresses lactation. In horses, it inhibits prolactin secretion, which is useful for treating hyperprolactinemia and suppressing lactation in mares.

Pharmacodynamics: Cabergoline has a high affinity for D2 receptors and a low affinity for D1, serotonin, and alpha-adrenergic receptors. Its effect on prolactin suppression is dose-dependent and long-lasting. In dogs, a single oral dose can suppress prolactin for up to 7 days. In horses, it effectively reduces prolactin levels within hours, with effects lasting for several days. It also has some central effects, including anti-Parkinsonian activity, but these are not clinically exploited in veterinary medicine.

⚡ Pharmacokinetics Summary

Absorption: Cabergoline is well absorbed after oral administration. In dogs, peak plasma concentrations are reached within 1-2 hours. Food does not significantly affect absorption.
Distribution: Cabergoline is widely distributed in tissues. It crosses the blood-brain barrier to a limited extent. In dogs, the volume of distribution is approximately 2-3 L/kg. It is not extensively bound to plasma proteins (about 40-50%).
Metabolism: Cabergoline undergoes extensive hepatic metabolism, primarily by hydrolysis to an inactive acid derivative. The major metabolite is 6-allyl-8β-carboxy-ergoline, which is inactive.
Excretion: Cabergoline is excreted mainly in feces (about 60%) and urine (about 20%). The elimination half-life is long, ranging from 63-68 hours in dogs and approximately 24 hours in horses.
Half-Life: Dogs: 63-68 hours; Horses: ~24 hours; Cats: ~24 hours (estimated)
Bioavailability: Oral bioavailability is approximately 60-70% in dogs.
Protein Binding: 40-50%

Available Formulations & Strengths

Oral Tablet 0.5 mg, 1 mg (PO)
Oral Solution 0.5 mg/mL (PO)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to cabergoline or other ergot derivatives
  • Pregnancy (unless termination is intended, as it may cause abortion)
  • Lactation in animals intended for breeding (unless suppression is desired)
  • Severe hepatic impairment
  • Cardiovascular disease (especially hypotension)
Warnings & Clinical Precautions:
  • Use with caution in animals with renal or hepatic disease.
  • May cause hypotension; monitor blood pressure in at-risk animals.
  • In horses, use with caution in pregnant mares as it may cause abortion.
  • Do not use in animals with a history of psychotic disorders (rare in animals).
  • Safety in breeding males has not been established.
  • In food animals, not approved; extra-label use is subject to withdrawal times.

Adverse Effects & Reactions

Common:

  • Vomiting
  • Nausea
  • Anorexia
  • Lethargy
  • Diarrhea

Serious / Severe:

  • Hypotension
  • Cardiac arrhythmias
  • Hallucinations (rare)
  • Seizures (rare)
  • Hepatotoxicity (rare)

Rare:

  • Fibrotic reactions (e.g., pleural effusion, pericardial effusion) with long-term use
  • Allergic reactions

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Dopamine antagonists (e.g., metoclopramide, phenothiazines) May reduce the prolactin-lowering effect of cabergoline. Moderate
Antihypertensive agents Additive hypotensive effects. Moderate
Macrolide antibiotics (e.g., erythromycin) May increase cabergoline plasma levels. Mild
Other ergot alkaloids Increased risk of ergotism (vasoconstriction). High

Overdose & Toxicity Management

Signs of Toxicity:

  • Severe vomiting
  • Hypotension
  • Hallucinations
  • Agitation
  • Seizures
  • Cardiac arrhythmias

Emergency Treatment Protocol: Treatment is symptomatic and supportive. Induce vomiting if recent ingestion and animal is conscious. Administer activated charcoal to reduce absorption. Provide intravenous fluids for hypotension. Monitor cardiac function and treat arrhythmias as needed. Use dopamine antagonists (e.g., metoclopramide) to counteract central effects if severe. There is no specific antidote.

Food Animal Withdrawal Times

Not approved for food animals. Extra-label use in food animals requires extended withdrawal periods; consult FARAD (Food Animal Residue Avoidance Databank) for specific recommendations.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F)

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

Handling & Special Conditions: Protect from light and moisture. Keep in tightly closed container.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; approved for human use (Dostinex) and available as a generic.

Extra-Label (Off-Label) Use: In the US, cabergoline is not FDA-approved for veterinary use; it is used extra-label under AMDUCA. For food animals, extra-label use is prohibited unless a valid veterinarian-client-patient relationship exists and withdrawal times are established.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Cabergoline is a valuable drug for managing reproductive disorders in small animals, particularly pseudopregnancy in dogs. It is generally well-tolerated, but gastrointestinal side effects are common. In horses, it is used off-label for lactation suppression. Due to its long half-life, dosing is once daily. It is important to rule out pregnancy before use in intact females. For food animals, its use is limited due to lack of approval and potential residues. Always follow legal and ethical guidelines for extra-label drug use.

References & Literature

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