Monday, March 18, 2013

Heather Smith Thomas — Notes from Sky Range Ranch: Giving CPR to a Newborn Calf, Part One: Why Some Calves Fail to Breathe

After more than 55 years of raising cattle — which equates to nearly 8,500 new baby calves, starting as a kid on my dad’s ranch — I’ve seen a lot of births, especially during the 35 years that my husband and I calved our herd in January. At that time of year in our climate, we put every cow into the barn as soon as she went into labor, to calve in a sheltered place, protected from the wind and snow. We were present for every birth, able to intervene if anything went wrong, and most years we didn’t lose any babies. Consequently, we witnessed thousands of births and got a pretty good feel for what’s normal or not.

In a normal, easy birth, the calf is stimulated to start breathing as soon as his umbilical cord breaks or his face and nose are uncovered when the amnion sac comes off his head. The umbilical cord from the placenta supplies oxygen and nutrients to the calf. Once it breaks or the placenta starts to detach, he’s on his own.

Usually, the membrane around the calf starts to come apart as the calf’s body moves through the birth canal and is pulling away from the calf’s head as he slides on out. Occasionally, the sac is thick and tough, however, and the head is still encased in membrane and fluids after he’s born — and he can’t start breathing.

As the calf comes through the birth canal, it is usually still
encased in the fluid-filled membrane (the amnion sac).

With a few more pushes, the cow moves the calf on through,
 and the membrane starts to break and come off the calf's head.
This is my old pet cow (named P. S.) in 1971.

In other instances he may not be able to breathe if he is unconscious by the time he is born. Sometimes after a hard birth (whether assisted or unassisted), the calf has been without oxygen too long, and he won’t start breathing. If the cord broke early (as often happens with a calf coming backward) or the placenta starts to detach during a long, hard birth, his lifeline is cut off, and he will die unless he can start breathing quickly. Often these calves that were difficult to pull are limp and unconscious at birth, with blue gums. At first glance you think they are dead, until you put a hand against the rib cage and feel the heart still beating.

Calves that are born swiftly and easily may also fail to start breathing if the amnion sac does not break. If the membrane and fluids remain over the calf’s nostrils, he won’t take a breath. This immersion reflex keeps the calf from drawing fluid into his lungs, but it also means some calves die soon after birth — unless the cow gets up immediately and starts licking it off and nudging the calf around to get him moving and breathing. If the calf goes too long without oxygen, he will suffocate.

If the membranes are thin and easily broken, the calf can lift or shake his head, and the amnion sac breaks. If the membranes are thick, however, the calf can’t break them by himself. If the cow doesn’t start licking them off, or you are not there to part the membranes and pull them off in time, the calf will die.

The cow’s instinct is to get up and lick her calf as soon as he’s born, which generally resolves the problem. But if she’s tired from labor, or a first-calf heifer, she may not get up quickly. Many of the birth losses due to failure of the sac to break are in first-calf heifers, especially if it’s such an easy birth that the calf slides out quickly, still encased. The heifer may not realize she has a new baby and does not get up immediately to start licking him. Even if the cow does get up quickly and start licking, if she starts on the wrong end, the calf’s head may still be encased in membrane for too long.

As this calf slides on out, the amnion sac is completely ruptured
and is no longer holding fluid around the calf's head.

The cow's instinct is to get up as soon as the calf is born and
licking him. If the sac is still covering him, she will lick it off.

In most normal births the calf begins breathing within the first minute after he’s born. If you’ve pulled a calf and he’s not breathing, clear the fluid away from his nose with your fingers and tickle the inside of one nostril with a clean piece of hay or straw. If he is conscious, this usually makes him cough and take a breath. If he’s unconscious and won’t start breathing, you need to give artificial respiration.

If the calf doesn't start breathing immediately,
tickle the inside of one nostril with a piece of
clean straw or hay, to stimulate him to cough and sneeze.

Traditionally, compromised calves (not breathing, with fluid in their airways) were held up by their hind legs. Stockmen and veterinarians thought this would allow fluid to drain from the airways. Today veterinarians don’t recommend this strategy. They’ll tell you that most of the fluids that drain from an upside-down calf are stomach fluids, which are important to the calf’s health. Holding him up by the hind legs also puts pressure on his diaphragm from abdominal organs, interfering with normal breathing movements. It’s better to just use a suction bulb to clear the airways.

If a calf was stressed during birth and doesn’t begin breathing immediately, it may be because he is suffering from acidosis — a pH imbalance in his body caused by stress and shortage of oxygen — which has an adverse effect on proper functioning of heart and lungs. Even if he starts breathing, it may take several hours or even several days for his body to correct this. If the calf is not breathing, some veterinarians give the calf a little bicarbonate intravenously (to neutralize and reverse acidosis) and perhaps some epinephrine (adrenaline) to help stimulate the calf.

One way to tell whether a calf is normal or compromised after he’s born is to note whether the calf tries to raise his head and become upright rather than continuing to lie flat. Even if he is breathing, if the calf just lies there, prop him up and rub him briskly to stimulate circulation. He can breathe better if he is upright; lung function and rib cage movement are impeded when he’s lying flat.

If the calf is lying flat, prop him up, even if he is starting to breathe. 
 His lungs can fill more readily if he is upright and not flat on his side.

If the calf is limp and unconscious, not breathing, but his heart is still beating, there’s a chance you can get him breathing. The heart may be hammering so loudly you can hear it, as the body struggles desperately to survive without oxygen. If he doesn’t start breathing soon, however, heartbeat becomes weaker, slower, and very faint. Heart rate is one way to tell if the calf is in respiratory distress. Normal heart rate in a newborn calf is 100 to 120 beats per minute. Place your hand over the lower left side of the rib cage, just behind and above the elbow of his front leg. If heart rate has dropped below 50, the calf’s condition is critical; he needs to start breathing immediately. If his gums are grey, blue, or colorless instead of pink, he is in serious trouble.

[to be continued]

Heather Smith Thomas raises horses and cattle on her family ranch in Salmon, Idaho. She writes for numerous horse magazines and is the author of several books on horses and cattle farming, including Storey’s Guide to Raising HorsesStorey's Guide to Training HorsesStable SmartsThe Horse Conformation HandbookYour CalfGetting Started with Beef and Dairy CattleStorey's Guide to Raising Beef CattleEssential Guide to Calving, and The Cattle Health Handbook.

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