INDUCTION OF WHELPING IN CANINE HIGH RISK PREGNANCIES WITH SMALL LITTER SIZE USING PROGESTERONE RECEPTOR ANTAGONIST AND PROSTAGLANDINS
Loading...
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR
Abstract
Small litter size is considered high risk pregnancy in dogs from a probable
dystocia due to prolonged gestation, uterine inertia and foetal over size. Consequently,
induction of whelping becomes inevitable for a successful outcome. The aim of the
study was to determine the efficacy and safety of progesterone antagonist,
mifepristone; prostaglandin analogue, cloprostenol and natural prostaglandin,
dinoprost tromethamine in combination with anterior vaginal administration of PGE1,
misoprostol to induce whelping in canine high risk pregnancy with three or fewer
foetuses. The induction response and course of whelping was investigated in 18 dogs
radiographically confirmed with three or fewer foetuses under three treatment groups
and also in six spontaneous whelping dogs which formed the control group. Treatment
was initiated when no impending signs of whelping was evident, but attained a
gestational age of 61±l days on sonographic measurement of foetal head diameter.
Dogs in Group I was treated with mifepristone @ 5mg/kg body weight twice daily,
orally for two consecutive days; Group II dogs were treated with a single subcutaneous
administration of cloprostenol @ 2.5 μg/kg body weight and Group III dogs were
treated with subcutaneous administration of dinoprost tromethamine @ 0.1mg/kg body
weight. Twenty four hours following the institution of treatment, misoprostol @ 400μg
was administrated in anterior vagina of all the dogs in the three treatment groups.
Induction response was 100 per cent as whelping was successfully induced in all the
18 dogs belonging to three treatment groups. Consequently, the gestation length of the
bitches in the induced group (61.67±0.42 days in Group I, 61.17±0.54 days in Group II
and 61.83± 0.60 days in Group III) was significantly shorter than that of the
spontaneously whelping bitches (64.33±1.50 days). The mean interval from first
treatment to whelping was slightly lesser in dogs administered with mifepristone
(35.58±3.54 h) when compared to cloprostenol and dinoprost tromethamine treated
groups (36.00±2.79 h and 36.58±1.22 h respectively). The mean duration of whelping
was shorter in dogs of Group II (78.00±12.90 min) followed by Group III
(102.00±21.06 min) and Group I (152.50±49.66 min). However the expulsion phase
length in the induced group did not differ significantly from that of control group. A
decreases in serum progesterone concentration was noticed after treatment in all the
dogs of treatment groups indicating the efficiency of the drugs in initiating the
parturition. However, in mifepristone treated dogs the circulating progesterone at
whelping was still higher (2.71±0.41 ng/ml) when compared to group II and group III
(0.60±0.14 ng/ml and 0.90±0.18 ng/ml respectively). An increasing trend of serum
cortisol levels were noticed in all the dogs after the treatment. Majority of the
spontaneously whelping dogs required medical and surgical assistance to complete the
whelping as against unassisted vaginal delivery in majority of the dogs in which
whelping was induced. Moreover, no side effects were noticed for any of the treatment
provided. The number of puppies born alive in the three induced groups were 12 out of
13 (92.3%), 7 out of 10 (70%) and 9 out of 11 (81.8%) respectively, while in the
spontaneously whelping dogs, only 7 out of 13 (53.8%) were born alive. However the
neonatal survival rate upto two weeks of birth did not differ significantly between the
four groups. The study revealed the merits of medical induction of whelping in canine
high risk pregnancy with small litter size as evident from a cent per cent induction
response within a relatively short and predictable period and also from the high puppy
survival at birth. A high number of puppies born alive at birth and a decreased medical
and surgical assistance for completing the whelping process makes induction of
parturition using mifepristone with anterior vaginal administration of misoprostol a
better choice than cloprostenol and dinoprost tromethamine.