Parturition and Obstetrics

Parturition and Obstetrics

Dystocia is without doubt the most common emergency in camelid practice and has been recognized as one of the leading causes of mortality and reproductive losses.1,2 Prompt diagnosis and management of obstetric situations is critical for the survival of the newborn as well as for the prevention of further complications that could be life threatening or end the reproductive function in the female. Although many of the examination techniques and obstetric procedures used in camelids are similar to those used in other large animal species, a few peculiarities do exist for camelids that the practitioner should be aware of. This chapter described the normal parturition process and approach to dystocia in alpacas and llamas.

Normal Parturition (Eutocia)

Pregnancy Length and Premonitory Signs of Parturition

Pregnancy length in llamas and alpacas has traditionally been reported to be 340 ± 5 days (335 to 359 days). However, data from outside South American countries show a great variability in the duration of pregnancy, ranging from 320 to 400 days (Figure 24-1).2

Factors suspected to affect pregnancy length include breed, sex of the fetus, season, nutrition, and sire and dam effects. In alpacas, pregnancy length is, on average, 12.5 days longer in spring-mated alpacas than in fall-mated alpacas. Breeders in North America reported unusually longer pregnancy lengths in years with longer and colder winters.3

Disorders that have been suspected to contribute to increased pregnancy length include fescue toxicosis and intrauterine growth retardation caused by congenital fetal hypothyroidism and placental and endocrine abnormalities, as well as severe nutritional deficiencies. However, these factors have not yet been investigated.

No single sign can precisely predict the exact time of parturition in alpacas and llamas. However, some premonitory signs of parturition, including relaxation of the sacropelvic ligaments, combined with relaxation of the vulva and development of the mammary gland may be helpful in monitoring the female. Relaxation of the sacrosciatic ligaments starts about 2 weeks before parturition, resulting in frequent bulging of the perineal area when the female is sitting, defecating, or urinating. The vulva shows a slight edema a few days before parturition, especially in primiparous females, and elongation is often observed on the day of parturition.

Mammary gland development occurs during the last month of pregnancy. Multiparous females may show obvious udder enlargement within the last 2 weeks before parturition. Primiparous females may not show significant udder development until a few days after parturition. Excessive mammary edema extending cranially to the xyphoid area may be seen in some females. Other females may show ventral edema, swelling of the teats, and waxing a week before parturition. Colostrum is detected 6 days and 4 days before parturition in pluriparous and primiparous animals, respectively.4 Electrolyte analysis in mammary gland secretions does not provide a good indication of parturition as it does in the equine. However, in cases where induction of parturition is considered, the presence of thick sticky colostrum is correlated with a very good outcome for the cria.

Stages of Parturition

Parturition in camelids is a relatively short event compared with that in ruminants.2 Preparation of the preparturient female is an important step to avoid puerperal problems for the dam or sickness in crias. It is important to maintain clean and dry stalls or paddocks that are provided with fresh water and good quality hay and to minimize any stressful or uncomfortable situation for the animal.

The tail of the female may be wrapped as soon as dilation of the vulva is noticed. The tail bandage should not be too tight and should be checked daily and changed every other day to avoid damage to the tail. In South American conditions, most of the births (93.5%) occur between 7:00 A.M. and 1:00 P.M., and none is observed at night.5,6 This is probably an adaptation feature in these animals to ensure the birth of the young (cria) in the most favorable time of the day for ambient temperatures and protection against predators. In North American rearing conditions, parturition may be observed at other times of the day.

As for all other species, stages of parturition are traditionally divided into three stages. The first stage of labor, or the preparatory stage, varies greatly in duration and may be as short as 3 hours and up to 48 hours long. This wide range in duration of the first stage of labor may be a result of environmental as well as individual factors. The female shows increased restlessness and anxiety and usually isolates itself from the rest of the herd. Appetite is often decreased; however, some multiparous females will maintain normal appetite throughout parturition. During this stage, an increased frequency of defecation and urination (increased visits to the “dung pile”) is observed. The female shows signs of mild discomfort and frequently alternates between the standing and sitting positions or walks in circles (Figure 24-2). These signs intensify with the progressive stretching and dilation of the cervix from the pressure exerted by the fetus as a result of uterine contraction. Abdominal contractions and straining becomes more frequent (one contraction every 2 minutes) toward the end of the first stage. Some females may go off feed and show signs of colic. Excessive signs of rolling, kicking at the belly, and vocalization or grunting should be taken seriously, as they may signal an abnormal situation such as in the case of uterine torsion.

The second stage of labor starts with the rupture of the chorioallantoic sac (allantochorion) and ends with the complete expulsion of the cria. It is very short in duration and is completed within 20 minutes on average (range 5 to 30 minutes), being longer in duration in primiparous females (up to 80 minutes). Nearly all crias are born in an anterior longitudinal presentation and in the dorsosacral position, with the chin resting on the carpus. The amniotic sac appears at the vulva within 2 or 5 minutes of the rupture of the allantochorion (Figure 24-3).7 At this stage, the head of the cria can be easily palpated within the pelvic canal. As uterine and abdominal contractions increase in intensity and frequency, the nose appears first at the vulva, followed by one foreleg.7 The other foreleg appears 3 to 5 minutes after the rupture of the amniotic sac. In some situations, the head may be completely exteriorized before both feet appear (Figure 24-4). The forelegs are extended either above or below the head at this stage. The head and forelegs up to the carpal joints should be out within 5 to 10 minutes of rupture of the amniotic sac.2,7 The female may stand at this stage, with the head, neck, and forelegs of the fetus exteriorized (Figure 24-5). Most (65% to 73%) of the fetuses are delivered while the dam is standing. Powerful abdominal contractions are needed to push the fetus out at the level of the shoulders and thorax. The frequency and intensity of uterine and abdominal contractions are increased with the passage of the fetus through the cervical canal (Ferguson reflex). Some females may lie down on the side during this stage and help orient the fetus to a diagonal (dorsoilial) position to take advantage of the widest diameter of the pelvis. The umbilical cord ruptures soon after birth about 3 to 10 cm from the fetal abdominal wall. A twisted portion of 10 to 20 cm is seen hanging from the vulva of the dam. The dam turns immediately to smell the newborn, but licking is not common in camelids.2,7

The third stage of parturition, expulsion of the placenta, lasts on average 20 minutes (range 10 to 40 minutes). The placenta appears at the vulva shortly after expulsion of the fetus as a bluish sac (fetal side, allantoamnion) and is expelled rapidly by a combined action of uterine contractions and the gravitational pull of the weight of the placenta. The majority (>80%) of placentae are delivered during the first 60 minutes after parturition, but some may take up to 4 hours.

Inspection of the fetal membranes is very important and should be performed, whenever possible, to detect any abnormality such as placentitis and to evaluate the presence of both uterine tips to ensure that the placenta is not retained partially. In alpacas, the placenta weighs between 0.8 to 1 kg. The chorionic surface usually has a dark red (burgundy) color and a velvety aspect because of the presence of microvilli. The placenta may show areas with reduced microvilli along the bifurcation and at the tip of the horns. Although not always present, hippomanes (one or two) may be found in the allantoic sac of the camelid.2

Induction of Parturition

Induction of parturition may be indicated when the dam’s health is in jeopardy or if the fetus is showing obvious signs of distress. Induction of parturition should not be attempted unless uterine torsion is ruled out. Induction of labor is not a management procedure and should not be used as such. Each case should be carefully studied. The best chances for a good outcome for the neonate (reduce the risk of neonatal maladjustment syndrome) is to induce only when breeding dates are known precisely, the stage of pregnancy is adequate (minimum 330 days), and colostrum secretion in the mammary gland is apparent. Development of the mammary gland and presence of thick colostrum is, in our opinion, the most important criterion for induction. Because camelids rely primarily on progesterone from the corpus luteum (CL) to maintain pregnancy, induction is easily achieved by administration of a luteolytic dose of prostaglandin F2-alpha (PGF; dinoprost tromethamine, 5 milligrams [mg], intramuscularly [IM]) or its analogue cloprostenol (250 micrograms [mcg], IM). Caution should be exercised when using dinoprost because it may cause severe respiratory distress and pulmonary edema in compromised females. Oxytocin and dexamethosone should not be used for induction of parturition in camelids, as these agents are not efficacious. Dexamethasone treatment results in intrauterine fetal death.4 In one study, the mean time from treatment with fluprostenol (40 mcg, IM) to parturition was 21 hours and 29 minutes (range 19 to 29 hours).4 In our experience, in emergency induction of parturition, the interval from cloprostenol injection to parturition is 20 hours, on average, but ranged from 8 to 30 hours. In our protocol for the management of high-risk pregnancies, the fetus is evaluated at 12 hours and at 20 hours after treatment, and if the fetus shows signs of distress (persistent tachycardia >130 beats per minute [beats/min], or bradycardia <50 beats/min) or is not delivered by 24 hours after induction, a cesarean section is performed.

Incidence and Causes of Dystocia

Dystocia is relatively uncommon in alpacas and llamas, with fewer than 5% of birthings requiring assistance.1,2 The incidence of dystocia in camelids has been estimated to be between 2% and 5% of all births.2,8 In our practice, dystocia requiring major obstetric intervention represents less than 1% of all births (A. Tibary, personal observation). Early diagnosis of dystocia is very important because it may evolve rapidly to a critical situation endangering the life of both the fetus and the dam.

Dystocia should be suspected if the first stage of labor exceeds 6 hours with increasing signs of discomfort or if the second stage of labor does not progress normally within 10 minutes of the rupture of the amniotic sac. Dams may show signs of distress, with frequent alternation between the standing and sitting positions, side to side rolling, and excessive vocalization and straining. Abnormal (bloody or purulent) discharge in a term female warrants immediate obstetric evaluation. One rule that we always observe is to attend immediately to any parturient female that the owner says is not acting normally. In our opinion, experienced alpaca and llama owners have the best appreciation of the progression of the first stage of labor.

Dystocia of maternal origin may be caused by uterine inertia, small pelvic size, failure of cervical dilation, and uterine torsion. Failure of cervical dilation and uterine torsion are the most common causes of dystocia of maternal origin.2,8,9 Failure of cervical dilation is associated with long-term progesterone supplementation during pregnancy.7

Dystocia caused by the small size of the dam is rarely seen if females are bred for the first time when they reach at least 65% of adult weight and height. Narrowing of the birth canal may be caused by space-occupying lesions or masses. Uterine inertia, arising from weak or absent uterine contractions, is occasionally seen in older animals or in animals with prolonged pregnancy. Hypocalcemia may also be involved in secondary uterine inertia.

Dystocia of fetal origin is generally caused by fetomaternal disproportion (large fetus), fetal abnormalities, or abnormal presentation, position, or posture. We have observed a significant increase in dystocia from very high birth weights of crias in recent years, particularly in alpacas. The most common fetal malpositions are carpal flexion and lateral or ventral deviation of the head and neck. This is caused by the long neck and limbs of the fetus in these species. Unilateral or bilateral hack or hip flexions (breech) occur in posterior presentation. Dystocia caused by fetal abnormalities is rare. Cases seen in our clinic include schistosoma reflexus, ankylosis, and hydrocephalus. Other anomalies causing dystocia include fetal anasarca and emphysematous fetus resulting from death and maceration. Term twins are rare but should always be considered in cases of dystocia.

Approach to Dystocia in Camelids

Three major differences between camelids and ruminants should be kept in mind when dealing with an obstetrical situation: (1) The pelvic inlet is narrower; (2) the cervix and vagina are more prone to laceration and severe inflammation often leading to adhesions; and (3) the risk for neonatal hypoxia and death are increased by forceful uterine and abdominal contractions and rapid detachment of the microcotyledonary placenta. Three main conclusions stem from these important differences: (1) Early recognition of dystocia is paramount; (2) obstetric decision and manipulation should be rapid; and (3) supportive care should be provided to the dam and the fetus (if alive) before and during manipulation.

Clinical management of dystocia may be performed on the farm or at a hospital, depending on the nature of the emergency and the availability of qualified help. The first rule in clinical management of an obstetric call in camelid practice is that it should be treated as a potential emergency. Upon receiving the call, the veterinarian should be clear in his or her communication with the client about the case. Clients should be educated to quickly report potential problems and know their limitations as to handling some situations.

Clinical Evaluation of the Dam

Behavioral assessment may be conducted while taking history unless the female is extremely depressed or in pain. A detailed history, including breeding dates, stage and methods of pregnancy diagnosis, previous illnesses, and reproductive disorders, should be taken. The interval from rupture of the chorioallantoic sac to detection of the problem should be noted, as it is critical for the clinical approach and survival of the cria. The duration of manipulation, if it has been attempted, should be noted. Physical examination should be performed, whenever possible, before manipulation, but in many cases, this examination will be relatively brief, particularly if the cria is already engaged in the birth canal. The minimum clinical evaluation should include body temperature, respiratory and heart rates, and evaluation of the mucous membrane and hydration status. The general appearance and demeanor of the animal are critical. If the dam is dull, is reluctant to stand, or displays obvious distress, blood samples should be taken immediately, and the female should be stabilized before further examination. Oxygen insufflations should be initiated in case of obvious respiratory stress. A jugular venous catheter should be placed immediately to allow for fluid therapy and emergency anesthesia, if needed.

Sedation may be needed in some cases to complete the evaluation. Choices of drugs and dosage for sedation should take into account their effects on the fetus. Butorphanol tartrate (0.05–0.1 milligram per kilogram [mg/kg]) provides good sedation and has minimal effect on the cardiovascular system.10 However, a mild decrease in systemic vascular resistance, which may be of consequence if the blood flow to the uterus is already restricted, has been observed. Epidural analgesia may be needed for evaluation per vaginum or per rectum. An 18-gauge, 1.5-inch needle is placed on the dorsal midline, with the bevel facing cranially and at a 60-degree angle to the tail head. The duration of analgesia depends on the drug used. In the case of lidocaine (0.2 mg/kg, maximum 1 mL/45–50 kg, maximum of 2 mL for the alpaca and 2.5 mL for the llama), onset of analgesia is seen 5 minutes after administration and lasts about 1 hour to 1.5 hours. Administration of xylazine (0.1 mg/kg) provides up to 3 hours of anesthesia, and the combination of xylazine and lidocaine (xylazine 0.17 mg/kg; lidocaine 0.22 mg/kg) provides up to 6 hours of analgesia.1

If no fetal membranes or fetal parts are visible at the vulva, the first step in evaluation is to determine the status of the cervix by direct vaginal examination. In term llamas and alpacas, this may be easily accomplished with the aid of a large-tube (3- to 5-cm diameter) vaginoscope. Caution should be taken not to contaminate the vaginal canal or cause damage to the vagina or the fetus. Also, a maiden female may have a very tight vestibular sphincter if the fetus is not engaged. If the cervix does not appear to be open or the fetus is not engaged in the pelvic canal, transrectal palpation should be performed to rule out uterine torsion. Direct manual vaginal examination should be performed if evidence of cervical dilation exists. Manual examination may be difficult in primiparous alpacas, and bleeding from the vestibular–vaginal sphincter is often observed if the operator’s hand is too large. Extreme care should be taken if the cervix is partially dilated, as aggressive manual dilation of the cervix may lead to cervical tears.

The quantity and quality of fecal material within the rectal cavity should be evaluated prior to transrectal palpation. Diarrhea is often seen in severely distressed animals. Absence of fecal material, presence of mucoid content, or both may be caused by intestinal transit disorders or tenesmus. Infusion of a mixture of 10 mL of 2% lidocaine in 60 to 100 mL of lubricant in the rectal cavity provides some rectal relaxation and reduces straining. It is important, however, to keep the use of lidocaine to a minimum to avoid toxicity in case a cesarean section is needed. The toxic dose of lidocaine has not been determined for alpacas and llamas, but most practitioners tread on the safe side and use 4 mg/kg as the maximum dose. The primary objective of transrectal palpation is to determine the location and direction of the broad ligaments and evaluate the caudal abdomen for any masses or abnormalities of the pelvic area, kidneys, and bladder. Transrectal palpation in the female sitting in the sternal position may offer some challenges to the inexperienced practitioner.

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Mar 27, 2017 | Posted by in GENERAL | Comments Off on Parturition and Obstetrics

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