Dystocia is defined as delayed or difficult parturition. General causes are fetal-maternal size mismatch, fetal malpresentation and maternal-related causes.
Meyers et al reported that 50% of stillbirths were a direct result of dystocia. A slight calving problem increased the odds of stillbirth by 2.91 in heifers and 4.67 in multiparous cows. More difficult calvings caused a stillborn in heifers to be 6.76 times more likely and 11.36 times more likely in multiparous cows. In 1996, Wells et al reported that a dystocia requiring forced extraction, compared with unassisted calving, was 4.22 times more likely to result in heifer-calf death within the first 21 days of life.
Frank Garry, DVM, MS, Colorado State University, says physiological effects of dystocia on the calf include postnatal metabolic and respiratory acidosis, hypoxemia, failure of passive transfer and hypothermia, all of which can be immediately fatal or reduce long-term survival.
“Severe dystocia has been associated with reduced body temperature, decreased concentrations of blood cortisol and increased blood glucose,” Garry explains. “Hypoxic calves are often weak and slow to stand and suckle, and this negatively affects absorption of colostral immunoglobulins.”
Dystocia by the numbers
Jason Lombard, DVM, MS and Garry completed a dystocia study (Journal of Dairy Science, 2007) and found over 35% of calves required assistance during birthing, accounting for 75.5% of stillborn calves. Only 10.8% of calves had severe dystocia, but they accounted for 49.1% of all stillbirths. Dystocias were scored with 1 = no assistance, 2 = slight problem and 3+ = needed assistance.
“The odds of a heifer calf having any morbidity event were significantly increased for dystocia scores 2 and 3,” Garry says. “The odds of having a respiratory event were significantly increased for dystocia scores 2 and 3.” The odds of a digestive event increased for those with mild or severe dystocia. Calves born to cows having a severe dystocia had an increased risk of death after 24 hours of age than calves born unassisted.
Calves having mild dystocia were less likely to survive to 30 days than calves born unassisted. “Severe dystocia affects calf survival even more negatively beyond the first 24 hours of life,” Garry notes.
Garry says veterinarians can play a part in helping their clients perform the three steps to minimizing the impact of dystocia. Those steps are:
-Decrease its occurrence. “This is a complex management issue and not easy to accomplish,” he says.
-Decrease the impact of dystocia by good calving management practices. “This requires employee training and can be very effective in decreasing the negative impact of dystocia on dam and new-born.”
-Increase the level and quality of newborn calf care. “This also requires employee training and can help compromised calves to survive and thrive.”
Garry says the impacts of dystocia can be minimized with:
-Appropriate delivery methods.
-Identifying compromised calves.
-Administering fluids and oxygen to calves with acidosis.
-Warming chilled calves.
-Delivering high-quality colostrum immediately after birth.
-Treating every calf that was exposed to dystocia as a compromised calf.
Appropriate delivery methods
The first part of “intervention” is always examination of the cow and calf. “This evaluation is what determines whether the next step is performing some manipulation of the calf, assisting the delivery, or calling for more help,” Garry explains. “The cow should be examined with care and attention should be paid to cleanliness and lubrication.”
The employee should intervene with close examination if the cow has been in stage 1 of labor for over six hours. Some abnormal deliveries, like uterine torsion, do not allow the cow to progress into a normal stage 2 of labor. In other cases, the cow may be in a state of uterine inertia and will not go into stage 2 of labor.
Once the cow enters stage 2 of delivery – meaning the water bag appears and she begins to strain – intervention is indicated if any of the following conditions exist:
-If the water sac is visible for two hours and the cow is not trying.
-If the cow has been trying for over 30 minutes and making no progress.
-If the cow has quit trying for over a 15-20 minute period of time after a period of progress.
-If the cow or calf is showing signs of fatigue and stress such as a swollen tongue of the calf or severe bleeding from the rectum of the cow.
-If it appears that the delivery is abnormal, for example, a backwards calf, only one leg, etc.
“The most difficult thing to teach is judgment about the best approach and timing of intervention,” Garry says. “It is common for workers who have been asked to watch the calving and assist deliveries to act hastily and to assist too soon. The birthing process takes time, especially for heifers, and patience is needed. Progress can be slow as the calving canal stretches to accommodate a large calf.”
Identify compromised calves
Any calf from a dystocia delivery should be considered compromised. “Even if the calf looks OK right after the delivery, it is common for these calves to do more poorly if not given extra care,” Garry ex-plains. “The observable signs of a compromised calf are delayed time to stand, delayed or weak suckle, reduced vigor and strength, or low body temperature at any time after an hour post-delivery.
Scoring dystocias is simple and is one of the key pieces of information that should be kept for calf records. This information is very useful for monitoring and management purposes.
Dystocia greatly increases risk of calf stillbirth and later calf health problems, so monitoring its occurrence is very help-ful in assessing potential causes of poor calf performance. Dystocia records can help management evaluate performance and consider whether changes are necessary in protocols and procedures.
Administer fluids and oxygen to calves with acidosis
The signs of acidosis are the same signs as for a compromised calf. Calves suffering dystocia delivery should be assumed to have a higher than average level of metabolic and respiratory acidosis. Acidosis makes calves weak and depressed.
“Having employees capable of IV fluid administration is helpful for a variety of reasons, including treatment of sick newborns,” Garry suggests.
Warm chilled calves
There are three ways for a calf to increase body heat generation necessary to maintain body temperature in a cool or cold environment. These are brown fat metabolism, shivering and physical activity. “Compromised and dystocia-affected calves are typically less active and tend to have poor cardio-respiratory function, so they don’t deliver oxygen well to body tissues,” Garry explains. “This negatively affects all three sources of heat generation.”
Chilled calves become less active and breathe poorly, exacerbating all of the problems associated with dystocia and calf compromise. “Like any preventive medical practice, avoiding chilling is better for the calf than waiting to see if it gets chilled and then trying to rescue it later.”
Deliver high-quality colostrum immediately after birth
Compromised calves have poor suckling and so don’t consume as much colostrum. If the calf is tubed, this problem can be avoided. But calves with poor respiratory function and low oxygen also tend to have poor gut function and appear to have less ability to absorb the immunoglobulins even if they are tubed to supply sufficient colostral volume.
Since compromised calves tend to have lower oxygen delivery to tissues, they tend to absorb immunoglobulins poorly, but often can absorb the immunoglobulins over a longer time period; so it is worth providing an extra colostrum feeding to assure the calf has the best chance of good colostral immunoglobulin transfer. “Besides that, colostrum is a great nutritional supplement, and providing a compromised calf with more nutritional support is a good idea,” Garry says.
Treat every calf that was exposed to dystocia as a compromised calf
Garry says in his dystocia study, “Perhaps some of the calves that were born alive, but died within 24 hours, could have been saved by implementing simple interventions.”
Help prevent dystocia by:
-Ensuring heifers are inseminated at the proper age and bodyweight.
-Selecting potential sires on the basis of known calving ease.
-Improving personnel training regarding proper timing and methods of intervention during calving, plus appropriate methods to care for compromised newborn calves.
TLC for the compromised calf
Good supportive care can go a long way for a compromised calf. Sheila McGuirk, DVM, PhD, says calves with difficult deliveries are high-risk calves and everything about their post-natal management is difficult. “Attentive, well-trained people who care make a difference,” McGuirk says.
Stimulation, clearing an airway, stopping navel bleeding and warming up that calf will make a difference, McGuirk notes. She suggests sitting the calf in sternal recumbency, changing body positions and towel drying. Giving oxygen by mask is also useful.
Give the calf some time. “Delay colostrum feeding for the compromised calf for four hours, but if the nose and mucous membranes don’t turn pink, have your clients call a veterinarian for assistance,” McGuirk suggests. “There is no magic medication to make calves breathe or quick tricks that turn these calves around. Keep them sitting, warm and stimulated to breathe. Give warm colostrum and get assistance if needed.”