Reproduction Drugs

Gonadorelin / Buserelin

Category: GnRH agonists.

Mechanism: Stimulate anterior pituitary LH and FSH release → ovulation/luteinization.

Indications: Ovulation induction, anovulatory follicular cysts in cattle, estrus synchronization.

PK: Not specified in lecture.

Adverse effects: Not specified for intermittent use.

Distinction: Act on the PITUITARY, unlike hCG, which mimics LH at gonadal receptors.

Deslorelin

Category: GnRH agonist.

Mechanism: Initially stimulates LH/FSH; sustained stimulation → GnRH receptor downregulation → gonadotropin suppression.

Indications: Ovulation induction; sustained-release implant for contraception in dogs.

PK: Sustained-release implant; specific half-life not stated.

Adverse effects: Not specified.

Distinction: Short-term stimulation = ovulation; sustained-release = contraception.

FSH

Category: Gonadotropin.

Mechanism: Stimulates follicular growth and estrogen production.

Indications: Superovulation in cattle; estrus induction protocols in anestrous bitches/queens.

PK: Not specified.

Adverse effects: Excessive/prolonged gonadotropin treatment may cause cystic endometrial hyperplasia (lecture example).

Distinction: FSH = FOLLICLE DEVELOPMENT, while LH triggers ovulation.

LH

Category: Gonadotropin.

Mechanism: LH surge triggers ovulation and luteinization.

Indications: Ovulation induction in reproductive protocols.

PK: Not specified.

Adverse effects: Excessive/prolonged gonadotropin dosing may produce adverse reproductive effects, including lecture example of cystic endometrial hyperplasia.

Distinction: LH = OVULATION; FSH = FOLLICULAR GROWTH

hCG

Category: Human chorionic gonadotropin; LH-mimicking gonadotropin.

Mechanism: Mimics LH → induces ovulation and supports luteal function.

Indications: Controlled breeding in mares, cryptorchidism diagnostic stimulation, canine ovulation induction.

PK: Rapid absorption after injection; plasma peak ~6 HOURS.

Adverse effects: Not specified.

Distinction: Direct LH-like gonadal action, rather than stimulating pituitary LH secretion like GnRH agonists.

Cloprostenol / Dinoprost / Tromethamine

Category: PGF₂α prostaglandin agents / luteolytics.

Mechanism: CL regression (luteolysis) → P4 decreases.

Indications: Estrus synchronization, pregnancy termination; dinoprost in the lecture's cattle synchronization protocol.

PK: Species-specific formulations/dosing; detailed kinetics not provided.

Adverse effects: Not specified.

Distinction: Destroy the CL / lower progesterone. Lecture does not differentiate these drugs pharmacologically.

Progestins

Category: Progesterone-like steroid hormones.

Mechanism: Suppress preovulatory LH surge → prevent ovulation.

Indications: Estrus synchronization, cycle-timing control, contraception and pregnancy maintenance.

PK: Not specified.

Adverse effects: Cystic endometrial hyperplasia noted among reproductive steroid-hormone risks.

Distinction: Progestins suppress ovulation, unlike GnRH/LH/hCG ovulation-induction treatments.

Estrogens

Category: Estrogenic steroid hormones.

Mechanism: Promote estrogenic reproductive effects and estrus behavior.

Indications: Estrus induction, certain ovarian dysfunction treatments, sometimes synchronization.

PK: Not specified.

Adverse effects: Cystic endometrial hyperplasia noted among reproductive steroid-hormone risks.

Distinction: Promote estrus-related effects, whereas progestins suppress the LH surge.

Oxytocin

Category: Peptide hormone / uterotonic.

Mechanism: Uterine smooth-muscle contraction + mammary myoepithelial contraction.

Indications: Parturition and milk letdown.

PK: Not specified.

Adverse effects: Not specified.

Distinction: Uterine contractions + milk ejection, not direct luteolysis or ovulation induction.

Melatonin

Category: Hormone / seasonal reproductive modulator.

Mechanism: Regulates reproductive seasonality.

Indications: Seasonal breeding management in sheep and goats.

PK: Not specified.

Adverse effects: Not specified.

Distinction: Controls SEASONAL breeding patterns, rather than immediately triggering ovulation.

Dexamethasone

Category: Glucocorticoid / corticosteroid.

Mechanism: Corticosteroid receptors → altered gene expression → decreased proinflammatory cytokines; can mimic fetal cortisol signaling.

Indications: Induction of parturition in cattle; corticosteroids also used for reproductive inflammation.

PK: Not specified; timing and dosage critical.

Adverse effects: Fetal growth retardation, immunosuppression, metabolic disturbances.

Distinction: Mimics fetal cortisol signaling to induce parturition, not ovulation.

Mineralocorticoids

Category: Corticosteroid class (no individual agent named).

Mechanism: Corticosteroid receptor-mediated regulation of fluid and electrolyte balance, with tissue-remodeling effects.

Indications: No specific reproductive protocol provided.

PK: Not specified.

Adverse effects: Not separately specified.

Distinction: FLUID/ELECTROLYTE REGULATION, rather than the glucocorticoid anti-inflammatory and parturition role emphasized for dexamethasone.