Dystocia: Taking care of the cow and the calf
Calvings can provide some of the most daunting but also most exhilarating moments you’ll experience in practice. They can be a nail-biting time for a new vet trying to make a good impression as well as being the most hazardous time in the life of the newborn calf. Of the calves that die during the perinatal period, approximately 90% are alive at the start of the calving process thus a large proportion of perinatal mortality is avoidable (Mee, 2008). Therefore, when dealing with cases of dystocia it is important to consider not only the cow but also the calf.
Calving aids are just that… an aid and if not used correctly they can cause substantial damage to not only the calf by resulting in fractured legs or ribs (Photo One), but also the cow. Excessive force being applied can lead to severe vaginal damage and tears and in some cases rupture of the posterior vaginal arteries. A calving aid can apply up to 500kg of force and therefore it is essential that it is used in conjunction with the cow’s contractions rather than against. The arm of the calving aid should be levered up and down as the cow contracts to aid expulsion of the calf, and then the ratchet used to take up the slack on the calving ropes in between contractions. The amount of tension on the ropes should never be so great that the calving aid is pulled above a horizontal position.
Photo One: Excessive force can cause trauma, including fractured ribs
In addition to using the calving aid correctly, it is also important that the calf is delivered in the least traumatic position. The shoulders and the pelvis are the widest part of the calf and ensuring that these are at angles during traction aids in the calf’s delivery through the cow’s pelvis (Figure One). Rotating the calf through 90 degrees also helps with passage of the calf’s hips though the pelvis. When the calf is coming backwards it is also important to ensure its tail is tucked between its legs as occasionally it can become pulled vertically and thus cause extensive damage to the cow as the calf is delivered.
Figure one: To avoid unnecessary trauma traction must be applied correctly
Every cow will be dehydrated after calving whether she has required assistance or not. All cows should be offered a bucket of lukewarm water immediately after calving and if she does not drink she should be drenched. A rumen pump makes this job a lot easier and makes sure her lactation gets off to a good start (Photo Two). There are numerous sachets available that can be added to the water to provide extra mineral and energy supplementation e.g. ProRumen or Selekt Fresh Cow.
Photo Two: All cows should be offered fluids post-calving and drenched if they do not drink
Calving, particularly when assistance is required, can cause significant amounts of trauma and pain, which can decrease her intakes at this critical time as well as making her reluctant to lie in cubicles. Any cow that has had a difficult calving (whether assisted or not) should be given an NSAID as soon as possible. Flunixin has been shown to increase the risk of retained fetal membranes (RFM; Duffield et al., 2009) and therefore is not advised. Metacam (meloxicam; 2.5ml/100kg subcutaneously) is my preferred choice not only due its COX-2 preferential action thereby not increasing the risk of RFM (Mainau et al., 2014) but also because of its longer duration. It should be administered sooner rather than later, and if possible, prior to intervention.
Following dystocia cows are more at risk of RFM and uterine disease, therefore it is advisable to warn the farmer that the cow needs observing for signs of metritis (Photo Three) or endometritis. Preferably she should be checked at the next routine fertility visit when any vaginal trauma can also be assessed.
Photo Three - Cows are more at risk of metritis following dystocia
Taking Care of the Calf
Dystocia can impact on calf survival in a number of ways. In cattle it is well reported that dystocia compromises the health and welfare of the calf in the neonatal period as well as having potential long term effects with decreased survival rates to adulthood and reduced subsequent milk production.
The transition from the intrauterine environment to the outside world is a critical one for a calf since major physiological changes have to take place within the relatively short birthing process. The greatest change that the calf has to adapt to is the change in oxygen supply from the umbilical circulation to the pulmonary system with inhalation of air and inflation of the lungs being essential for survival.
When a cow strains the intrauterine pressure exceeds the blood pressure in the umbilical vessels, therefore the flow of oxygenated blood towards the calf is temporarily halted (Bleul and others, 2007). Calves are particularly at risk during assisted births since cervical manipulation and prolonged abdominal straining by the dam results in additional oxytocin release. Therefore intervention must only be carried out when necessary since stimulation of the cervix too soon can actually increase the risk to the calf.
The myometrium can also become over-stimulated to the extent that contractions occur so frequently that there are no longer any periods of relaxation in between. As a result there is a sustained decrease in uterine blood flow and therefore oxygen supply, which poses a real risk to the health of the calf. When manipulation is undertaken it must be done quickly and should not be continued when no progress is being made. Administering exogenous oxytocin whilst the calf is in the birth canal will have the same effect and therefore should never be considered.
When extensive or prolonged manipulation is required, administering clenbuterol (Planipart) will relax the myometrium not only making manipulation of the calf easier but also reducing the risk of hypoxia to the calf.
During ‘normal’ uncomplicated calvings, the calf’s acid-base status remains fairly stable until the final stages. Acidosis mainly develops during the last minutes prior to and then during the first few hours after birth. If the calf’s oxygen supply is compromised it alters its circulation in order to maintain placental perfusion to the vital organs including the heart, brain and adrenal glands, whilst significantly reducing flow to other organs. This results in the local accumulation of organic acids due to anaerobic metabolism. Following birth and the restoration of circulation through all vascular beds, there is a massive release of these organic acids into the circulation and acidosis will occur. The degree of acidosis becomes apparent during the first minutes following birth.
Calves born following a prolonged delivery will have an increased risk of respiratory and metabolic acidosis and a detrimental impact on the uptake of colostral immunoglobulins, resulting in reduced protection against neonatal disease. Therefore ensuring that all calves are fed 4 litres of good quality colostrum following an assisted delivery will increase their chances of adequate passive transfer. If they are severely acidotic then this should be addressed prior to feeding colostrum.
A recent study by Barrier and others (2013) found that calves experiencing an assisted delivery had lower immunoglobulin uptake than calves born without assistance. More than 43% of dystocial calves had absolute failure of passive transfer compared to 26.8% of those born normally. As a result there was more neonatal disease in dystocial calves, with more non-routine treatments required and a higher mortality rate to weaning. Interestingly calves that not only required assistance but also some degree of manipulation due to malpresentation had the highest levels of disease and mortality. This is potentially a consequence of prolonged periods of hypoxia due to cervical stimulation during transvaginal manual assistance.
The risk of mortality increases with the difficulty of the calving and also the length of time it takes the calf to rise into sternal recumbency (>9mins is associated with a rise in mortality risk). Calves that fail to start to breathe after calving can be stimulated in a number of ways including:
Hanging calves upside down to allow fluid to drain out of their lungs is a common practice, especially after a backwards calving, however, this actually makes breathing harder since all the internal organs put pressure on the diaphragm. The calf will absorb excess fluid given time and therefore the priority should be to clear any mucus/fluids from the nostrils and mouth and ensure the calf starts breathing as soon as possible.
We often consider the pain a cow may experience following dystocia, but rarely is the calf considered. A prolonged calving will undoubtedly result in some degree of pain to the calf since a large amount of force will not only be applied through the calving aid but also as it passes through the pelvic canal. Although off licence, treatment with an NSAID at birth has been shown to be beneficial. A large study carried out by the University of Guelph found that calves treated with Metacam (meloxicam) following an assisted delivery had improved vigour as well as suckling strength. This resulted in improved pre-weaning milk intake, weight gain and reduced disease (Murray, 2014). Calves born to an unassisted delivery did not show the same improvements and therefore it is proposed that calves do experience pain following dystocia and this can be alleviated with administration of pain relief.
An easy calving is critical for both calf and cow due to the long lasting negative effects that dystocia has in terms of future productivity and survival. Although careful planning can ensure that common causes of dystocia are avoidable (such as feto-maternal disproportion), cases of dystocia will never be eliminated. There are a number of actions that can be taken to help counter-act some of the detrimental effects dystocia ultimately leading to an improved outcome for the cow, her calf, the farmer…. and you!
This article was kindly sponsored by Boehringer Ingelheim
Duffield, T.F., Putnam-Dingwell, H., Weary, D., Skidmore, A., Neuder, L., Raphael, W., Millman, S., Newby, N. & Leslie, K.E. (2009) Effect of flunixin meglumine treatment following parturition on cow health and milk production. Journal of Dairy Science 92 (1): 118
Barrier, A.C., Haskell, M.J., Birch, S., Bagnall, A., Bell, D.J., Dickinson, J., Macrae, A.I. &
Dwyer, C.M. (2013) The impact of dystocia on dairy calf health, welfare, performance and survival. The Veterinary Journal 195: 86-90
Bleul, U., Lejeune, B., Schwantag, S. & Kahn, W. (2007) Ultrasonic transit-time measurement of blood flow in the umbilical arteries and veins in the bovine fetus during stage II of labor. Theriogenology 67: 1123-1133
Mainau, E., Cuevas, A., Ruiz-de-la-Torre, J. L., Abbeloos, E. & Manteca, X. (2014) Effect of meloxicam administration after calving on milk production, acute phase proteins and behaviour in dairy cows. Journal of Veterinary Behaviour; Clinical Applications and Research. 9(6); 357-363
Mee, J.F. (2008) Newborn dairy calf management. Vet. Clin. North Am. Food Anim. Pract. 24: 1-17
Murray, C. (2014) Characteristics, Risk Factors and Management Programs for Vitality of Newborn Dairy Calves. PhD Thesis, University of Guelph.
This article was written for VetGrad.co.uk and previously published in February 2015.
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