Prostaglandins

Alfaprostol, cloprostenol, dinoprost, etiproston, luprostiol, and tiaprost are synthetic prostaglandin F or analogues. Prostaglandins, which are derivatives of arachidonic acid, are ubiquitous substances and have an important role in many physiological and pathological processes. Their primary effect on the reproductive system of the non-pregnant or early-pregnant animal is regression of the corpus luteum but they may have powerful direct effects on the myometrium especially near term. In veterinary practice, they are used to control cyclical ovarian activity in polyoestrous species, for termination of pregnancy, or for induction of parturition. In addition, prostaglandins are used to treat a number of pathological conditions including mummified fetus, pyometra, and luteal cysts in cattle, and pseudopregnancy in goats.

The corpus luteum is refractory to the action of prostaglandin F or analogues for at least 5 days post ovulation in mares, cows, ewes, and does; in sows the refractory period is up to 11 days; in bitches and queens the corpus luteum is generally unresponsive at any time after ovulation unless subject to repeated doses. When used for pregnancy termination, prostaglandins will only be effective when the corpus luteum is responsive and before other sources of progesterone synthesis become dominant, for example between day 7 and about day 150 of gestation in cattle. For induction of parturition, prostaglandins may be given within 7 days of full term in cattle and 3 days of full term in pigs, at which time changing hormone levels have greatly increased myometrial sensitivity to them. Prostaglandin F also has an ecbolic effect and is sometimes used to treat ‘open’ pyometra in bitches . It, or one of the analogues, has been used to terminate pregnancy in bitches in combination with cabergoline. Side-effects such as transient sweating and mild colic with or without diarrhoea occasionally follow the use of prostaglandins in mares. On occasion some prostaglandins may produce severe reactions at the site of intramuscular injections, severe cellulitis, and systemic reactions sometimes leading to death.

In general, treatment and administration of prostaglandins should be by the veterinarian but, for pigs, for induction of farrowing, the preparations may have to be dispensed for use by the farmer. When used for induction on farrowing in pigs, prostaglandins must not be given more than 2 days before expected parturition. The average gestation length should be calculated for each farm and prostaglandins used only where accurate service records are kept. Prostaglandin preparations are pom and should be issued by a veterinarian only to a farmer who is a bona fide client, on the basis that the named person(s) signs a receipt for the consignment and is responsible for its proper storage, use, and accountability. The veterinarian must advise the farmer that the product issued must be kept in a secure locked place except when required for administration. The veterinarian should issue only sufficient of the product for immediate foreseeable use on the farm, and periodic checks of the farmer’s stock and amounts used should be carried out by the veterinarian. The farmer should be instructed on the safe handling of the product as indicated above. Prostaglandins should not be dispensed to lay persons except under these very carefully controlled circumstances.

Prostaglandins of the F type can be absorbed through the skin and may cause bronchospasm or miscarriage. Care should be taken when handling the product to avoid self-injection or skin contact. In the event of accidental administration to a person, medical advice should be sought promptly. Women of child-bearing age, asthmatics, and persons with bronchial or other respiratory problems should avoid contact with, or wear disposable gloves when administering, the product. Accidental spillage on the skin should be washed off immediately with soap and water.

CLOPROSTENOL

Indications. See notes above and under Dose

Contra-indications. Pregnant animals unless termination required

Warnings. Women of child-bearing age, asthmatics, and persons with bronchial or other respiratory problems should avoid contact with, or wear disposable gloves when administering, the product. Accidental spillage on the skin should be washed off immediately with soap and water.

Dose: By intramuscular injection.

Horses: induction of oestrus in mares with persistent luteal function (prolonged dioestrus), type I pseudopregnancy (associated with persistent luteal function in the absence of endometrial cups), pregnancy termination before 35 days, induction of oestrus for service management, 250-500 micrograms

Ponies, donkeys: 125-250 micrograms

Cattle: induction of oestrus, pregnancy termination before 150 days, endometritis, pyometra, luteal cysts, fetal mummification, synchronisation of oestrus, induction of parturition, 500 micrograms

Goats: pseudopregnancy, 500 micrograms

Pigs: induction of parturition, 175 micrograms

Prescription-only medicine: Estrumate (Schering-Plough) UK

Injection, cloprostenol (as sodium salt) 250 micrograms/mL, for horses, ponies, donkeys, cattle

Withdrawal Periods. Should not be used in horses intended for human consumption.

Cattle: slaughter 1 day, milk withdrawal period nil

Prescription-only medicine: Planate (Schering-Plough) UK

Injection, cloprostenol (as sodium salt) 87.5 micrograms/mL, for pigs

Withdrawal Periods.

Pigs: slaughter 4 days

DINOPROST

Indications. See under Dose

Contra-indications. Pregnant animals unless termination required; patients with acute or subacute disorders of the vascular system, gastro-intestinal tract, or respiratory system

Side-effects. Transient sweating, decreased rectal temperature, increased heart rate, increased respiratory rate, and some abdominal discomfort in horses; transient increased body temperature, respiratory rate, salivation, defecation, urination, erythema, and restlessness in pigs; increased rectal temperature, transient salivation, tremor, restlessness, and mild diarrhoea in cattle

Warnings. Women of child-bearing age, asthmatics, and persons with bronchial or other respiratory problems should avoid contact with, or wear disposable gloves when administering, the product. Accidental spillage on the skin should be washed off immediately with soap and water.

Dose: By intramuscular injection.

Horses: induction of oestrus in mares with persistent luteal function (persistent dioestrus), type I pseudopregnancy (associated with persistent luteal function in the absence of endometrial cups), pregnancy termination before 35 days, synchronisation of oestrus for service management, 5 mg

Cattle: induction of oestrus, luteal cysts, chronic metritis and pyometra, pregnancy termination before 150 days, induction of parturition on or after 270 days, 25 mg. May be repeated after 10-12 days

Synchronisation of recipient cattle for embryo transplantation, 25 mg, repeat after 10-12 days

Pigs: induction of parturition within 3 days of farrowing, 10 mg

Stimulation of uterine contractions postpartum, 10 mg 1-2 days after parturition

Dogs: ‘open’ pyometra, 250 micrograms/kg daily for at least 5 days

Prescription-only medicine: Enzaprost T (Ceva) UK

Injection, dinoprost 5 mg/mL, for horses, cattle, pigs

Withdrawal Periods.

Cattle: slaughter 1 day, milk withdrawal period nil

Prescription-only medicine: Lutalyse (Pfizer) UK

Injection, dinoprost (as tromethamine) 5 mg/mL, for horses, cattle, pigs

Withdrawal Periods.

Horses: slaughter 1 day.

Cattle: slaughter 1 day, milk withdrawal period nil.

Pigs: slaughter 1 day

Prescription-only medicine: Noroprost (Norbrook) UK

Injection, dinoprost 5 mg/mL, for cattle

Withdrawal Periods.

Cattle: slaughter 1 day, milk withdrawal period nil

ETIPROSTON TROMETHAMINE

Indications. Fertility disorders; control of oestrus

Contra-indications. Pregnant animals unless termination required; concurrent treatment with oxytocin

Warnings. Women of child-bearing age, asthmatics, and persons with bronchial or other respiratory problems should take care when handling the product. Accidental spillage on the skin should be washed off immediately with soap and water

Dose: By intramuscular injection.

Cattle: induction of oestrus, induction of parturition, pregnancy termination, 5 mg

Synchronisation of oestrus, 5 mg, may be repeated after 11 days Endometritis, 5 mg, may be repeated after 10-14 days

Prescription-only medicine: Prostavet Injectable Solution (Bimeda) UK

Injection, etiproston tromethamine 2.5 mg/mL, for cattle

Withdrawal Periods. Slaughter 1 day, milk 6 hours

LUPROSTIOL

Indications. See notes above and under Dose

Contra-indications. Pregnant animals unless termination required

Side-effects. Transient sweating and diarrhoea in horses, abdominal discomfort in cattle

Warnings. Women of child-bearing age, asthmatics, and persons with bronchial or other respiratory problems should avoid contact with, or wear disposable gloves when administering, the product. Accidental spillage on the skin should be washed off immediately with soap and water.

Dose: By intramuscular injection.

Horses: induction of oestrus in mares with persistent luteal function (prolonged dioestrus), type I pseudopregnancy, pregnancy termination before 35 days, induction of parturition after day 330, induction of oestrus for service management, 7.5 mg

Cattle: induction of oestrus, synchronisation of oestrus, pregnancy termination before 150 days, induction of parturition after day 270, endometritis, pyometra, cows: 15 mg; heifers: 7.5 mg

Pigs: induction of parturition not earlier than 48 hours before expected farrowing, see preparation details

Prescription-only medicine: Prosolvin (Intervet) UK

Injection, luprostiol 7.5 mg/mL, for horses, cattle, pigs

Withdrawal Periods. Should not be used in horses intended for human consumption.

Cattle: slaughter 4 days, milk 6 hours.

Pigs: slaughter 4 days

Dose:

Pigs: by intramuscular injection, 7.5 mg

Prescription-only medicine: Prostapar (Intervet) UK

Injection, luprostiol 1.5 mg/mL, for pigs

Withdrawal Periods. Slaughter 1 day

Dose:

Pigs: by intramuscular injection, 3 mg