The present study was carried out the compare the amplitude and frequency of uterine contractions in 40 cases of Primary Complete Uterine Inertia (PCUI) and in 6 cases of spontaneous whelping. The strength of uterine contraction was < 10 % in 35 cases of PCUI treated with medical therapy (10 % Dextrose @ 1g/kg body weight, Calcium @ 0.2 ml / kg body weight I/V, but not exceeding a total dose of 10 ml and Oxytocin @) 2 IU, I/M) which is considered as a failure to exhibit uterine contraction. Whereas 5 cases of PCUI responded medical therapy with uterine contraction exhibiting > 10% for the duration of 30 min. and both uterine abdominal contraction was similar to spontaneous whelping.
In recent years, advances in canine reproduction have facilitated pregnancy management to emerge as an important clinical service that has application from the beginning to the end of gestation. The advance provides new application to monitoring the animals exhibiting the spontaneous whelping and dystocic female dogs by assessment of the uterine contraction by tocodynamometer. Labor is the physiological process by which a fetus is expelled from the uterus through the vagina and is characterized as regular uterine contraction accompanied by cervical effacement and dilation (Maul et al., 2003) and it is commonly believed that uterine inertia is associated with complete absence, weak or asynchronous uterine contractions. Tocodynamometry is a new approach in canine obstetrics to diagnose delivery problems. Fetal disturbances and hypoxic conditions can be suspected earlier with the possibility of immediate intervention, as in human obstetrics.
Materials and Methods
The present study was carried out in female dogs presented to Department of Veterinary Gynaecology and Obstetrics, Veterinary Collage, Bengaluru with PCUI and spontaneous whelping in bitches, after gynecological examination the cases were grouped into two groups. Group I with 40 animals diagnosed with PCUI and six animals diagnosed as spontaneous whelping. Animals in both groups were subjected to tocodynamometric studies to record the frequency and amplitude of uterine contraction using Tocodynameter (SONICAID TEAM) designed for human patients. The lateral abdomen of the animal was clipped and the animal was placed under lateral recumbency. The uterine sensor was placed over the abdominal skin and was secured with abdominal belts. During the course of uterine, the female dogs were kept quite avoiding any movements as far as possible. The frequency, duration, amplitude and baseline shifts in uterine contraction were recorded for a minimum of 15 minutes. The medical treatment employed consisted of intravenous infusion of Dextrose 10 % (1g/kg body weight), followed by 10 % calcium gluconate (CALCIUM-SANDOZ®, Novartis India Limited) at 0.2 ml / kg body weight I/V, but not exceeding a total dose of 10 ml and oxytocin at 2 IU, I/M fifteen minutes after calcium administration. The treatment was considered successful when pup was delivered within 30 min following injection of oxytocin.
Result and Discussion
A tocodynamometric method has been developed based on recording of uterine contractions across the abdominal surface. The tocodynamometer do not require invasive probes, allowing them to be used for most pregnancies without risk to the mother or the fetus. Tocodynamometric studies in female dogs with primary complete uterine inertia revealed that complete primary uterine inertia is associated with a baseline contraction state of only 10 per cent without any spikes indicative of abdominal contractile activity in any of the animals (Fig.1). This pattern was consistently seen in every animal diagnosed with primary complete uterine inertia. Groppetti et al. (2010) have stated that after the onset of labor, the intrapartum detection of zero to three mild contractions per 30 min without parturition, constituted recommendation for medical management of uterine inertia. The use of ecbolics for the management of uterine inertia has been recommended previously in numerous reports (Johnston, 1986 and Vibha, 2012). Every animal diagnosed as cases of complete primary uterine inertia was subjected to a medical treatment. Out of 40 female dogs only five female dogs responded to medical treatment with infusion of dextrose, calcium and oxytocin.
Toco Trace 1
Fig. 1: Toco trace in cases of complete primary uterine inertia
On these animals, the uterine contractions were at base line prior to initiation of treatment and following medical treatment, augmentation of uterine contraction strength to 30 to 50 per cent followed and coupled with increase in abdominal pressure spikes up to 70 to 90 per cent during the expulsion phase were noticed. Frequency of two to five close coupled uterine contractions per 30 min, each of two to three min duration followed with increase abdominal pressure spikes of three to four was also noticed (Fig. 3).
Toco Trace 3
Fig. 3: Toco trace in animals with complete primary uterine inertia which were responded to medical management
The pattern of uterine and abdominal contractions in dogs responding to medical therapy was similar to those recorded following spontaneous whelping. The results of the present study are also in agreement with the tocodynamometric studies of Davidson (2012) who also recorded increase in strength of uterine contractions following calcium administration and increase in frequency of uterine contractions following oxytocin therapy for uterine inertia in dogs. In the remaining 35 female dogs, unresponsive to medical management, the baseline strength showed no improvement and in the contractility pattern also; no progress was noticed even after treatment. But in few dogs, close coupled titanic contractions without fetal expulsion was noticed (Fig. 4).
Toco Trace 4
Fig. 4: Toco trace in animals with complete primary uterine inertia which were not responded to medical management
Six animals exhibiting the spontaneous whelping were subjected to uterine tocodynamometric studies, escalating and regular type of active labor pattern of uterine contractions followed and coupled with abdominal pressure spikes, frequent and regular uterine contractions with duration of two to five minutes and uterine contractile tone of 30 to 40 per cent followed and coupled with abdominal pressure increase in the form of spikes of 80 to 99 per cent at expulsive phase were recorded in all six animals exhibiting the spontaneous whelping (Fig. 2).
Toco Trace 2
Fig. 2: Toco trace in animals exhibited spontaneous whelping
Thirty five dogs with primary uterine inertia did not responded to medical management and tocodynamometric studies showed no improvement in the contractility pattern or in few cases, slight variations in base line strength of uterine tone to 10 to 15 per cent, unaccompanied with abdominal pressure spikes even after treatment for a period not less than 30 min of recording was noticed (Fig. 4). This could probably be due to desensitization and down regulation of oxytocin receptors as reported by Plested and Bernal (2001). However, close coupled tetanic contractions without fetal expulsion was also noticed in few dogs following medical management. This could be attributed to the effect of ecbolics that caused tetanic, ineffective uterine contractions which can further compromise fetal oxygen supply by placental separation (Davidson, 2010). The pattern of uterine contractility, tone and abdominal contractions and failure to respond to treatment in uterine inertia strongly suggests futility of further medical approaches and that dystocia should be relieved by surgical intervention as any repeat treatment with ecbolics may compromise fetal oxygen supply by placental separation. Similar views were also expressed by Copley (2002) which is in corroboration to the findings of the present study. Similar results found in Prashantkumar (2013) and Jayakumar (2015), the strength of the uterine contractions was less than 10 per cent (optimum – 80 % and above) for the entire duration of 30 min of monitoring in all cases of primary uterine inertia. On other hand administration of dextrose followed by calcium and oxytocin successfully relieved dystocia due to primary complete uterine inertia in five out of 40 dogs. The success rate obtained in the present study is higher than 6.9 per cent obtained by Gaudet (1985) using oxytocin alone. On uterine tocodynamometric studies, the frequency and amplitude of uterine contractions of all five animals prior to treatment was at basal levels and none of these animals were hypoglycemic or hypocalcemic. Augmentation in the frequency and amplitude of uterine contractions was observed following the initiation of medical treatment. These observations suggest that some cases of uterine inertia are caused by subclinical hypocalcaemia and hypoglycemia. Hypoglycemia has also been documented to cause uterine inertia during parturition (Buckner, 1979). The successful correction of uterine inertia due to hypoglycemia by intravenous glucose administration has been reported by Bennet (1974). Nearly 88 per cent of cases of primary complete uterine inertia failed to respond to medical treatment and had to be subjected for cesarean section.
In the present study, out of 40 cases of primary complete uterine inertia only five cases were responded to medical treatment. Pattern of uterine and abdominal contraction in these cases were similar to those recorded following spontaneous whelping. But remaining 35 cases were not responded to medical treatment and no improvement in the pattern of contractility tone, abdominal contraction and no progress noticed even after medical treatment. Repeated treatment with ecobolics causes teanic, ineffective uterine contraction and compromise fetal oxygen supply. Hence it was concluded that surgical procedure is the best method of treatment for the cases of primary complete uterine inertia.