The immediate survival of a calf experiencing a dystocia birth is critical, but the effects of dystocia can put the calf at a higher risk of death or illness in the first four months of life. The USDA NAHMS Dairy 2007 report says that calves experiencing a dystocia have a higher risk of being stillborn. In dairy cattle, stillborn is usually defined as death at or within 24 to 48 hours of delivery. 2002 data from Meyer et al. showed the reported stillbirth rate for dairy calves based on 666,341 calving records was 7%, and a 2007 study by Lombard et al. of three Colorado dairies reported a stillbirth rate of 8.2%.
What dystocia does
Calves experiencing a prolonged dystocia are likely to have low levels of oxygen in their blood (hypoxia), and their blood pH is frequently acidic (acidosis) instead of neutral. These impairments lead to a cascade of events, such as decreased ability to nurse, decreased absorption of IgG, and poor temperature regulation.
Calf problems associated with dystocia are most profound in the time immediately after birth. Dystocia is the major cause of stillbirth and approximately half of the calf losses from birth to weaning occur in the first day of life.
Most deaths that are directly related to dystocia occur within hours after birth and are attributable to physical trauma and to physiological problems associated with prolonged birth asphyxia, explains Frank Garry, DVM, MS, Colorado State University. These include poor cardiac and respiratory function, poor blood oxygenation, poor blood circulation, and resultant poor metabolic function. Dystocia increases the amount of physiologic derangement of newborn calves and decreases the calf’s ability to correct these physiological problems.
“Residual physiological problems attributable to dystocia can still kill calves throughout the first two to three days after delivery,” Garry says. Problems after that time are typically associated with the common infectious conditions of newborn calves. “Higher death rates in dystocia affected calves after the first two days of life a greater susceptibility to infection because the calf got off to a poor start. I do not believe that a specific cellular mechanism for this susceptibility has been identified.”
Calves that experience prolonged hypoxia and survive are often weak and slow to stand and suckle which affects absorption of colostral immunoglobulins and also impairs temperature regulation, notes Jason Lombard, DVM, MS, USDA:APHIS:VS:CEAH, Fort Collins, Colo.
From 2 to 14 days of age calf death is usually attributable to infectious gastrointestinal problems. “Dystocia calves seem to be less capable of dealing with these infectious diseases and therefore have a higher mortality rate when they occur,” Garry says. “Most calf deaths from 1 to 4 months of age are attributable to infectious respiratory disease. While dystocia calves are more prone to these problems, this impact is less profound than the tendency to do poorly in the first hours, to days, to two weeks.”
Immediate care of dystocia calves
Dystocia calves suffer a greater than normal degree of birth asphyxia and will have both respiratory and metabolic acidosis, will be weak, and will be less responsive than normal calves. Typically the calf will not breathe as well as a normal calf, so it will not take in as much oxygen nor eliminate as much CO2. “This means the calf will have less ability to correct these physiological derangements,” Garry says. “In turn, the calf will not rise as quickly and will not use as much muscle activity and will not generate as much body heat.” The quickest and easiest thing to do is to provide oxygen through a tube to the nasal passage.
Sam Leadley, PhD, Attica Veterinary Associates, P.C., Attica, N.Y., says a common error is that the farm does not have oxygen on hand to provide supplemental oxygen to the newborn calf when needed. “Another common error is to hold a calf upside down for more than just a few seconds,” he explains. “The mistaken thought is that this position will help drain fluids out of the mouth and nasal passages. It might do that in the first few seconds, but after that time there is a good chance the liquid is coming out of the esophagus, thus the fluids can be aspirated and calf health compromised.”
Leadley says as soon as the calf’s chest is out of the dam, it is not too soon to start oxygen supplementation. Oxygen supplementation may be continued after the calf is on the ground, too. The oxygen flow rate should be about 5 to 10 liters/minute as measured by the flow meter on the oxygen tank or a gentle breeze on your face. Measure the tube from the tip of the nose to the corner of the eye. Do not insert the tube past this measured point. Leadley says the nasal tube not only provides oxygen but it also may irritate the calf enough to cause a sneeze response which will help clear any fluid from the upper airways.
Calf stimulation as soon as the calf is out of the dam is vital to survival. Use a clean bath towel to rub the calf “fluff dry.” “Concentrate efforts especially around the neck and shoulders,” Leadley recommends. “Those areas best stimulate strong breathing responses.”
The calf should be dried so it does not lose as much body heat from a wet hair coat. Even in very modest temperature environments the calf will lose heat because it has a wet hair coat. The act of drying will help stimulate the calf so that it becomes more active. Additional heat can be provided by heating lamp, and Lombard suggests administering warmed colostrum to assist in warming the calf. The simplest measurement that can be done is a rectal temperature, which can be measured at half-hour intervals until the calf is active, alert, strong, and suckling well, Garry suggests.
Leadley adds that the body temperature should be 1-2 degrees above the dam’s rectal temperature immediately after birth. It will then drop to about 102° F within 15-30 minutes and should maintain that temperature. “A typical sign of poor adaptation is a falling body temperature,” he says. “Calves that are very cold may not shiver.”
Respiratory acidosis will be resolved by improved breathing function. In severe cases the calf’s ventilation can be assisted through a tracheal tube, but this is not practical in most farm settings. Making the calf move and sit in sternal recumbency will promote better breathing.
Metabolic acidosis will usually resolve if there is good circulating blood volume. Usually this is provided by promptly giving colostrum to the calf which increases blood volume as fluid is absorbed from the colostrum. In more severe cases, IV fluids can be administered. Only the most severe cases need additional bicarbonate.
Research has shown that calves with respiratory acidosis or low blood oxygen absorb immunoglobulins less effectively. Low oxygen and high CO2 contribute to poor cellular respiratory function in all tissues that have high metabolic rates. “Plausibly, this should have an adverse effect on many cellular functions of the newborn calf,” Garry says. “It is worth noting that just like other problems in dystocia calves, decreased immunoglobulin absorption is not uniform across all affected individuals. Some calves administered normal amounts of colostrum will still show good immunoglobulin transfer, while other affected calves will perform poorly.”
Lombard adds that it appears that 10-20% of non-dystocia calves will not have adequate passive transfer even when given adequate colostrum and “we don’t have a good explanation for failures in these calves, either.”
Garry recommends that dystocia calves are given colostrum for both the first and the second day of life, amounting to four quarts in the first day and four quarts the second day.
Urge clients to be proactive
Garry says the most common mistake in handling a dystocia calf is making the assumption that it is normal until it proves otherwise. “This wait-and-see attitude usually means the calf got off to a poor start and continued to do poorly until a problem was observed. Many calves after dystocia still look pretty normal for the first 15 minutes to half an hour while they have high circulating catecholamine levels. Then they get quiet, depressed and weak rather than looking stronger and standing and moving around.” Therefore the best approach is to assume the calf needs help, dry it promptly, put it under a heat lamp, and make sure it is making vigorous attempts to stand and move and breathe.
Many of these calves are probably tubed with colostrum soon after birth and not monitored for an extended period of time, Lombard says. “So no one observes the calf crashing.”
It’s best to assume a dystocia calf needs help, even in the absence of specific measurements. Garry believes all dystocia calves should be treated and monitored more closely to see that they are dried promptly, kept warm, stimulated to move, provided supplemental oxygen, and promptly given colostrum. “The required treatments are basically supportive care, and will do no harm in the case where the calf does not need them.”
Although it makes sense that a mild dystocia calf will be mildly affected and a severe dystocia calf will be severely affected, in reality the correlation is not that close, Garry explains. “Some calves with mild dystocia will have very significant problems. Many calves that suffer severe dystocia will actually survive quite well. This explains in part why many producers are not as proactive as they should be in treating dystocia calves. When they have seen calves affected by severe dystocia perform reasonably well, it removes some of the urgency of the need to do something special.”
Lombard agrees. “Although almost half of calves with severe dystocia will die before weaning, if the death occurs a period of time from the dystocia event, the producer does not link the dystocia and the death.”
Records should be kept of all deliveries so calf performance can be later analyzed to see if dystocia calves are performing adequately. On average, dystocia calves will have higher levels of sickness and death which should prompt closer attention to the calf immediately after delivery. Leadley tries to keep track of the calves that had a hard time coming into the world. An old cow tag clipped to the top front of their hutches can flag them for special attention. “In addition to being badly stressed, a fair proportion of these calves can have broken ribs,” he says. “Some TLC is called for when handling the calves even when getting them into their hutches.”
Leadley tries to be more lenient with leaving dystocia calves on a bottle longer than other calves. “At risk of overtreating calves I probably started treatment for pneumonia symptoms for these calves a little sooner than for ‘un-assisted delivery’ calves as well.”
“If calves right after birth are being assisted and cared for most of the residual problems will be greatly diminished,” Garry says. “Anything you are going to do to improve the performance of dystocia calves needs to be done within the first minutes to hours after delivery. Just like administering colostrum, care of the newborn calf needs to be done right after delivery, otherwise it is too late.”
Calving and Calf Care on Dairy Farms, Colorado State University
University of Wisconsin, Food Animal Production Medicine
Dystocia by the numbers
The USDA NAHMS Dairy 2007 report, Heifer Calf Health and Management Practices on U.S. Dairy Operations, 2007, includes this information on dystocia on U.S. dairies:
Approximately 60% of operations had guidelines on when to intervene during calving for heifers or cows (62.3% on <100 head of cows vs. 57.4% on 500 or more cows), and over 90% of operations provided some type of training in calving intervention
Almost 9 of 10 operations reported that they would wait less than 3 hours to assist heifers or cows that are observed to be straining but are not progressing in delivery. Almost one-half of operations would assist heifers and cows within 1 hour of the water bag appearing at the vulva.
A higher percentage of small operations (14.6%) than large operations (3.6%) would generally call a veterinarian to assist with a dystocia or difficult calving that necessitated intervention.
Of those operations that seek veterinary assistance for difficult deliveries, 93.5% would seek assistance to help correct the calf’s position for delivery and 85.6% would seek veterinary assistance after applying traction for a specific amount of time with no progress.
About 30% of operations would call for veterinary assistance within 30 minutes of intervening in a calving, and about 45% would seek assistance within 30-59 minutes of intervening for both heifers and cows.
About 62% of large operations resuscitated calves via assisted breathing, compared with slightly more than one-third of small and medium operations.
Source: USDA NAHMS