Cabergoline
**Cabergoline** is a synthetic ergot derivative primarily used in veterinary medicine for its potent prolactin-lowering effects. * **Key Indications:** Treatment of pseudopregnancy (false pregnancy), estrus induction/synchronization, pregnancy termination, and management of mastitis in dogs and cats. * **Clinical Advantages:** Compared to older dopamine agonists like bromocriptine, cabergoline is much better tolerated, possessing greater receptor specificity, a longer duration of action, and a significantly lower incidence of vomiting. * **Off-label uses:** Has shown some efficacy in treating pituitary-dependent hyperadrenocorticism (Cushing's disease) in dogs and persistent egg-laying in psittacines. * **Cost Consideration:** Can be expensive for large dogs, but generic tablets are available. It often requires compounding by a pharmacist for accurate veterinary dosing.
Mechanism: Cabergoline is a highly specific, long-acting **dopamine D2 receptor agonist**. * **Mechanism:** It binds with high affinity to **D2 receptors** on lactotroph cells in the anterior pituitary gland. * **Pathway:** **D2 receptor activation** โ inhibition of adenylyl cyclase โ decreased intracellular cAMP โ direct suppression of **prolactin** synthesis and secretion. * **Reproductive Impact:** Because prolactin is luteotropic in dogs and cats (it maintains the corpus luteum during the second half of pregnancy), suppressing prolactin leads to a drop in progesterone. This mechanism is responsible for its ability to terminate pregnancy, resolve pseudopregnancy, and induce estrus.
Dosing by species
- Estrus induction ยท 5 micrograms/kg PO once daily induces fertile proestrus in 4-25 days. ยท PO ยท q24h ยท 4-25 days
- Estrus induction ยท 5 micrograms/kg PO once daily until an induced proestrus is pronounced for 2 days or until onset of estrus ยท PO ยท q24h ยท Until proestrus is pronounced for 2 days or onset of estrus
- Estrus induction ยท 0.6 micrograms/kg PO once daily. Make a 10 micrograms per mL solution by dissolving commercial tablets in warm distilled water (One 0.5 mg tablet (500 micrograms) per 50 mL of distilled water.) Give the appropriate dose for the patient within 15 minutes of preparation and discard the remaining solution. Continue until day 2 after the onset of the first signs of proestrus, or until day 42 without signs of proestrus. ยท PO ยท q24h ยท Until day 2 after onset of proestrus, or up to 42 days ยท 81% (22 of 27) of dogs treated at this low dose showed proestrus between days 4 and 48.
- Pseudocyesis (pseudopregnancy) ยท 5 micrograms/kg once a day PO for 5-10 days. ยท PO ยท q24h ยท 5-10 days
- Pseudocyesis ยท 5 micrograms/kg once a day or every other day SC ยท SC ยท q24h or q48h ยท Not specified ยท Likely needs to be compounded.
- Pseudocyesis ยท 5 micrograms/kg PO once daily for 4-5 days; occasional failures can be handled by repeating treatment and extending duration to 8-10 days. ยท PO ยท q24h ยท 4-5 days (up to 8-10 days) ยท Additional protocols for treatment failures include combining cabergoline with metergoline (500 micrograms/kg PO twice daily), or cabergoline with bromocriptine (10-30 micrograms/kg PO twice daily).
- Adjunctive treatment of mastitis after puppies weaned ยท 5 micrograms/kg PO daily. ยท PO ยท q24h ยท Not specified
Routes of administration
Contraindications
- Pregnancy (unless abortion is desired)
- Hypersensitivity to ergot derivatives
- Uncontrolled hypertension (in humans)
- Nursing mothers
Adverse effects
- Vomiting (infrequent, alleviated by food)
- Coat color changes (in dogs treated >14 days)
- Postural hypotension (reported in humans)
- Dizziness (reported in humans)
- Headache (reported in humans)
- Nausea (reported in humans)
Drug interactions
- Hypotensive Drugs ยท Concomitant use may cause additive hypotension due to cabergoline's hypotensive effects.
- Metoclopramide ยท Use with cabergoline may reduce the efficacy of both drugs and should be avoided. ยท major
- Phenothiazines (e.g., acepromazine, chlorpromazine) ยท Use of cabergoline with dopamine (D2) antagonists may reduce the efficacy of both drugs and should be avoided.
- Domperidone ยท Antagonizes the therapeutic effect of cabergoline ยท major
- Phenothiazines (e.g., Acepromazine) ยท May antagonize cabergoline effects due to dopamine receptor blockade ยท moderate
- Hypotensive agents ยท Additive hypotensive effects ยท moderate
Monitoring
- Clinical efficacy (resolution of pseudopregnancy, estrus induction, etc.)
- Adverse effects (vomiting, behavioral changes)
Overdose
Overdose information is not available for dogs or cats, and remains very limited for humans. * **Potential Signs:** It is postulated that cabergoline overdoses could cause severe hypotension, nasal congestion, syncope, or hallucinations. * **Treatment:** Treatment is basically supportive and primarily focuses on supporting cardiovascular function and blood pressure.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.