- Top of page
- RISK FACTORS
- CLINICAL SIGNS
- POST CORRECTION MANAGEMENT
Bovine uterine torsion is a common form of dystocia encountered by farm animal veterinary surgeons worldwide with reports of 1–20% of all attended calvings (Frazer et al., 1996). Anecdotally there have been suggestions that the incidence has been increasing although this may be biased by veterinarians seeing relatively less of the more basic forms of dystocia due to improved obstetrical competence demonstrated by farmers (Laven & Howe, 2005; Robin, 2005). A recent UK study of Holstein Friesian cattle estimated the incidence to be 0.24%, accounting for up to 22°% of all veterinary attended dystocias (Lyons et al., 2012). This article reviews the condition within the context of the fndings of this study.
- Top of page
- RISK FACTORS
- CLINICAL SIGNS
- POST CORRECTION MANAGEMENT
1. In the panel's experience, what risk factors are associated with an individual animal developing a uterine torsion?
Before answering the questions posed to the panel, I am of the opinion that in dystocia cases a vet's approach is predominantly formed by his/her previous experiences. No doubt ‘we’ have all heard of a neighbouring practice's calving from hell, we were not there and discovered later that it was at 2 o'clock in the morning, mid December, in a ditch on a grass hill, raining and the only help was an elderly farmer who had recently had a hip replacement!I am not particularly weak and have relatively long arms, even so find it difficult to palpate a calf's leg let alone its head. I spend a limited amount of time trying to correct torsion per vaginum then resort to rolling or caesarean or both depending on the circumstances.
Our experience is not dissimilar to Lyons et al., 2012 with an estimated incidence of uterine torsion of 0.13%. At a meeting some years ago a well respected veterinary surgeon stated that he personally dealt with over 100 torsions a year. I pose the question, are torsions over diagnosed rather than under diagnosed? Are some calf malpresentations, such as lateral, mistakenly diagnosed as uterine torsion?
Casting and rolling is a health and safety issue and where I am at variance with the authors is that it would be an unusual case where I would not use a sedative (Xylazine). I would agree that torsions are found more in cows compared to heifers; dairy cows are 700+ kg and suckler cows 800+ kg, many of these suckler cows are fractious and simply applying casting ropes, without sedation, is not without danger. Once the torsion has been corrected, administration of α2-antagonists to reverse the affects of the α2-agonist does not appear to have had detrimental affects on the viability of the calf and reduces myometrial contractions produced by the α2-agonist. N.B. If a caesarean has been performed under sedation the live calf benefits from α2-antagonist administration.
In the majority of cases, the risk factors associated with developing a uterine torsion must occur in the first stage of labour, had they occurred prior to this surely more cases would be seen during pregnancy especially the final trimester. The depth of the abdomen as postulated regarding Brown Swiss cattle may be a factor however, I cannot recall any major problems with Jersey or Guernsey cows; but is this due to the fact that the relative foetal size in the Channel Island cows is likely to be less when compared to the Brown Swiss?
When ‘outbreaks’ (2 – 4 cases) occur on a farm, it is difficult to establish a cause. I have found simply casting a cow has corrected some torsions. Hormone changes around calving do encourage cows to mount each other; if cows stumble or collapse to the floor this may also be a risk factor. Similarly, introducing new cows to a close-to-calving group can produce head bunting and fighting – could this be a risk factor?
No doubt, due to the time at which uterine torsion occurs (first stage labour), excessive calf mobility may be a great factor – the larger the calf, the more likely that a torsion may not correct itself.
It is very difficult to determine consistent risk factors, however in our practice there is a suspicion that moving cows prior to calving and calving cows on sloping fields can increase the risk.
As an aside, good stockmanship is required for the early detection of a uterine torsion. Sometimes the symptoms are very subtle, such as restlessness and holding the tail up, with no abdominal contractions.
I have diagnosed two uterine torsions anterior to the cervix in 22 years of Farm Animal practice. One was a successful outcome, one wasn't. In both cases the diagnosis was made per rectum. The vaginal examination was normal. The salutary lesson from these cases was ‘always perform a rectal examination on cows with slow or delayed parturition’.
Our practice workload is predominantly with beef suckler herds and sheep, so we seldom encounter uterine torsion in dairy animals. That said, our only case in a heifer was on a dairy unit. All other cases have been in cows and always in uniparous pregnancies. With one exception, all cases have been in normal anterior presentation (the exception being in normal posterior presentation).
Virtually all cases have occurred during the housed period, with a significant majority being on total mixed ration feeding. In my experience calves delivered after uterine torsions are not usually oversized.
Interestingly, we recognise that uterine torsions often occur in runs, both at a farm level and across the practice. I now resist the temptation to advise the farmer that he won't see another one for a while!
Pre-cervical torsions are not that unusual and can catch the unwary – always carry out a rectal examination.
I believe the aetiology of this condition is not fully understood, however in my mind the main predisposing cause contributing to the development of a uterine torsion in cattle is the anatomical arrangement of the bovine uterus where the broad ligaments attached to the ventral surface of the uterus support each uterine horn in a dorsolateral direction. But the design flaw lies in that in an advancing pregnancy these broad ligaments do not elongate relative to the growing gravid uterus, resulting in the uterus becoming positioned beyond the stable area of attachment, and resting on the abdominal floor supported by the rumen, abdominal viscera and abdominal wall.
Certainly when cattle rise, hindlimbs first, I can envisage the gravid uterus becoming suspended in the abdominal cavity and at that point a slip, fall or butt from another cow could feasibly result in a uterine torsion. Perhaps this may be more so in breeds of cattle with a deep capacious abdomen such as Holstein Friesian and Charolais, especially where there may be reduced rumen volume prior to calving. In my experience uterine torsion is more common in cows rather than heifers.
Excessive foetal weight and foetal movements during 1st stage of labour in response to myometrial contractions may be significant, lack of uterine tone or indeed conditions that might affect these aforementioned conditions are likely to prove significant.
There have been discrepancies in the literature regarding whether cows are more at risk if at pasture or housed, to my mind this could be related to risk of slipping, falling, or moving between pasture to concrete surfaces, but group changes with aggressive social interactions either physically or affecting feed intake and rumen volume might be just as significant. There are thoughts that housed or confined cattle may suffer from lack of exercise leading to decreased abdominal musculature which could inadvertently lead to increased space and slackness in the abdomen. Interestingly in discussion, some of my colleagues from Pakistan suggested swimming as a significant risk factor in buffalo, however not many cattle regularly partake in this pastime here in South Eastern England! Given the severity of some torsions we encounter beyond 180 degrees, I think it likely there is more to be understood in the aetiopathogenesis of this condition.
2. After correcting a uterine torsion, incomplete cervical dilatation is commonly encountered. Are the panel members in favour of waiting to see if dilatation occurs, or to try and proceed with pulling the calf as soon as possible?
Incomplete cervical dilation is a problem for the attending veterinary surgeon. I have found that in heifers, complete dilation does not occur and a caesarean is performed.
No matter what procedure is being undertaken, especially dystocia, I prefer to provide a running commentary on the progress or lack of in order that the client is fully aware of what is happening. Once the torsion has been corrected an examination of the ‘texture’ of the cervix will aid the decision as to whether to apply traction now, later or discuss other options. Where the cervix appears moist and soft, with what appears to be an average size calf I will attempt traction; alternatively if the cervix is not of sufficient dilation I advise re-examination in two to three hours. When the os of the cervix feels ‘tough’ and fibrous (similar to a true ring womb), unless the calf is small, I am against traction. I have even cut these bands with a guarded blade and still not been able to create enough room for a calf delivery. I do not administer oxytocin unless there is a fully dilated cervix and I am of the opinion that the calf is of a size that can be delivered without excessive traction.
As the author stated, if the foetal membranes are intact then waiting is definitely an option. If the foetal membranes are broken then the process of delivery has to continue. If the decision is to wait for further dilation to occur the veterinarian must always warn the owner that this does increase the risk of foetal mortality. As a rough rule of thumb if the dilation is large enough to allow both feet and the nose to partially come through the cervix I would continue with the delivery and apply gentle traction.
After uterine torsions are corrected, it is my normal policy to attempt to deliver the calf by traction straight away. I can only recall one occasion when I revisited a couple of hours later to deliver the calf. In general, I find that cows left because of incomplete dilation of the cervix almost always need further veterinary attention.
Early attempts to deliver a calf with failure of the cervix to dilate can result in cervical laceration. In addition, in most instances where I am able to perform manual correction per vaginum and the calf is live, I will attempt to deliver the calf there and then after an assessment of how friable the cervix may be. There have been hypotheses that manipulations through the cervix to correct the torsion can help to effectively dilate the cervix. If the calf is alive and cervical dilatation is incomplete waiting a few hours to see if labour will proceed to 2nd stage is an option. However if the foetal membranes have already ruptured I would not delay undertaking a caesarean. Equally holding your nerve for two hours with a live pedigree calf waiting to be born into the world or efforts to restrain a fractious cow for a second time might have a bearing on one's decision! In my experience the cervix rarely dilates if the foetus is already dead in which case a decision as to whether to perform a caesarean, embryotomy or euthanasia should be made.
3. What factors do the panel consider in deciding whether to perform a caesarean section on cases of uterine torsion?
Value of the calf may influence the decision to perform a caesarean; however, welfare considerations are important. Many clients are influenced by previous surgical success on their premises and staff availability. Uterine torsion in heifers, provided there is no abnormal uterine discharge, is corrected surgically prior to uterine incision.
A farm's recent history of dystocia due to relative foetal oversize will often sway a client into requesting a caesarean immediately preferring surgical correction to vaginal manipulation and/or casting and rolling.
Attempting to suture a friable oedematous uterus is challenging. If foetid uterine discharge is discovered with incomplete cervical dilation a frank discussion needs to occur. These animals will not calve, thus require euthanasia or caesarean section. It may be that euthanasia may be required in the midst of the surgical intervention.
My experience with dystocias, including uterine torsion, is that, if there is any doubt at all that the calf cannot be delivered without excessive traction either due to relative maternal undersize, relative foetal oversize and/or incomplete dilation of the birth canal and it indicates a caesarean then the sooner the better.
In my opinion, traumatising the cervix and/or vagina has a more deleterious affect on future fertility compared to a caesarean.
There are numerous factors which must all be taken into account. Some of the factors which would be indicators to perform a caesarean would be, as the author stated, if it is a suckler cow or pedigree then the intervention point will be earlier, the duration of stages 1 and 2, foetal stress (kicking), inability to rectify the torsion, foetal mortality prior to autolysis. Factors which would be negative indicators would be poor facilities, hygiene conditions, manpower, and foetal autolysis.
As the only annual production from a beef cow is its offspring, our priority is the delivery of a good, viable calf. Consequently, attempts at correction are seldom prolonged, especially with the larger beef breeds. Sound surgical technique, careful hygiene and pre-operative antibiosis produce a successful long-term outcome in the vast majority of cases. Postoperative NSAIDs are essential in the short term and help improve future breeding success.
In my experience, complications arising from tissue friability can be overcome by careful handling of the uterus.
In the case of a live calf, if the torsion is irreducible or the cervix refuses to dilate, I would consider performing a caesarean section with intra-abdominal correction prior to hysterotomy. The client must however be aware of the significant risk of uterine rupture and post-operative peritonitis, metritis and perimetritis, especially if the uterine wall is found to be oedematous or with symptoms of vascular compromise. In some instances closure of the uterus may not be possible, resulting in a decision to euthanize the dam. Uterine torsion is the most common cause of uterine rupture in which case euthanasia is indicated in my opinion. If the calf is dead and it was possible, I would opt for an embryotomy over a caesarean or dependant on clinical examination of the dam, euthanasia may be the best option – e.g. dam in toxic shock with a dry emphysematous calf and uterus clamped down around it.
Ultimately prognosis will depend on the duration of the torsion, degree of severity and extent of vascular compromise within the uterus and the client should be warned about this prior to surgery. Thereafter first and foremost, a thorough clinical examination of the dam is indicated prior to lifting your surgical blade!