L. Kipjen Singha*, K. Merina Devib and M.K Patrac
a -Animal Reproduction Gynaecology and Obstetrics Division, ICAR-National Dairy Research Institute, Karnal-13200,
b -Department of Livestock Farm Complex, COVSc & A.H.,CAU, Jalukie, Nagaland-797110,
c -Animal Reproduction Division, ICAR-Indian Veterinary Research Institute, Izatnagar, U.P-243 122
*Corresponding author:laishramkipjen04@gmail.com
Introduction
Prostaglandins are local hormones that are derived from arachidonic acid. Prostaglandins have different classes viz., A, B, C, D, E, F, I according to their structures and functions. Among these, Fα and E2 groups i.e. PGE2 and PGF2α are the major abundant in reproductive tissues and organs. Prostaglandins (PGF2α) are used in the bitch for luteolysis and smooth muscle effect that results in cervical dilation and uterine contraction. PGF2α and its analogues are commercially available for veterinary use. Commercially available prostaglandin analogues in the country are cloprostenol (a synthetic analogue) and dinoprost (a natural analogue). Synthetic analogues are widely used due to their longer in action, more potent with lesser side effects than natural analogues.
Role of prostaglandins in termination of pregnancy:
Prostaglandin causes luteolysis of corpus luteum resulting in decreased progesterone concentration followed by termination of pregnancy. Most of the prostaglandins have been used for termination of pregnancy after 30-35 days of gestation. The dose of dinoprost is given @ 0.1mg/kg twice a day subcutaneously every 8 hours until abortion. Administration of cloprostenol@1- 2.5μg/kg, o.d s/c for 4-5 days has been reported with an efficacy of 100%.
Role of prostaglandins in pyometra:
Pyometra is a hormone-mediated diestrus disease and characterized by uterine pus accumulation. Prostaglandins are mostly used in pyometra for the uterine evacuation of pus. Pyometra is classified as open and closed cervix pyometra. Open cervix pyometra is less severe as compared to closed cervix pyometra concerning the systemic illness. The use of prostaglandins is contraindicated in closed cervix pyometra as there is a chance of uterine rupture. Cloprostenol is administered @5μg/kg, s/c on alternate days along with dopamine agonist, cabergoline @ 5μg/ kg, p.o. in open cervix pyometra for 7 days.
Role of prostaglandins in semen collection :
Use of PGF2α @100μg/kg 15 minutes before semen collection in male dogs results in 270 % increase in total sperm counts as compared to saline-treated controls, with no harmful effect of cooling and freezing of semen.
Side effects of prostaglandins:
The side effect of PGF2α includes tachypnea, hypersalivation, vomiting, diarrhea, ataxia, urination, anxiety and pupil dilation. The onset of side effects occurs within 5-30 minutes and subsides within 2-3 hours. Alleviation of side effects can be done by walking the dog for 15-30 minutes or administration of atropine @ 0.025 mg/kg, s/c 15 minutes before PGF2α injection.
Precautions for using prostaglandins:
Prostaglandins should be avoided when the animal is having a fever (> 106oF) and old age dogs (>10 years). Moreover, they should also not used in animals with a history of asthma and cardiac disease.
Conclusion:
Prostaglandins should be precisely used by veterinarians with minimal deleterious side effects. To achieve effective results, mechanism of action, physiological effect, metabolism and market availability of prostaglandins is needed.
