In a normal, unassisted birth, the calf is stimulated to start breathing as soon as his umbilical cord breaks (since that’s his lifeline from the dam) and/or his face and nose are uncovered when the amnion sac comes off his head.
There are several causes for breathing failure in a newborn calf. These include the sac not breaking, a hard birth in which the calf has become exhausted or unconscious from too much pressure for too long in the birth canal, and the placenta detaching too soon.
Some calves are born with the amnion sac intact, often with fluid still in it. If it does not break, and membrane or fluids remain over the calf’s nostrils, he won’t take a breath. This immersion reflex keeps him from drawing fluid into his lungs, but also means that some calves die soon after birth — unless the cow gets up immediately and starts licking it off and nudging the calf to get him moving and breathing. If the calf goes too long without oxygen, he will suffocate.
The sac often remains intact in a quick, easy birth. If the membranes are thin and easily broken, the calf can lift or shake his head and the sac breaks. If the membranes are thick, however, the calf can’t break them by himself. 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 labour, or a first-calf heifer, she may not get up quickly enough. Most of the birth losses due to failure of the sac to break are in first calvers — such as an easy birth in which the calf slides out quickly, still encased, and the heifer may not realize she has a new baby and does not get up immediately.
Another common cause for breathing failure is a hard birth. The calf’s nose and tongue may be swollen and his airways constricted by swelling. The calf may also be unconscious if the cord was pinched off or broken before he was fully born, and he is short on oxygen. The placenta may start to detach too soon, if the cow took a long time getting the calf into proper position for birth (or can’t get him in proper position, such as a breech calf) or the delivery takes too long.
In most normal births, the calf begins breathing within 30 to 60 seconds after he’s born. If 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. This usually makes him cough and take a breath. If he’s unconscious and won’t start breathing, give artificial respiration.
Traditionally, compromised calves (not breathing, with fluid in their airways) were held up by their hind legs to allow fluid to drain from the airways, but now many veterinarians don’t recommend this. They’ll tell you that most of the fluids that drain from an upside-down calf are stomach fluids, important to 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 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 during birth which has an adverse effect on proper functioning of heart and lungs. It may take several hours or several days for his body to correct this. One way to tell if he’s normal or compromised, according to Dr. Ron Skinner, a vet and seedstock producer near Drummond, Montana, is whether he tries to raise his head and become upright rather than continuing to lie flat. If the calf just lies there and has not tried to raise his head within two minutes, prop him up and rub him briskly to stimulate circulation. He can breathe better if he’s upright. Lung function and ribcage movement are impeded when he’s lying flat.
HOW YOU PULL A CALF MAKES A DIFFERENCE
If you have to pull a calf, it’s best if the cow/heifer is lying down. She can strain more effectively, and gravity is not working against her. When she’s down, you only need to pull about half as hard as when she’s standing, and this means less pressure on the calf. If she doesn’t lie down on her own once you’ve corrected a malpresentation problem, put her down on the ground using a rope.
Tie the rope loosely around her neck in a non-slip knot then use the long end to make a half hitch around her girth (behind her shoulders) and another around her flanks, with the remainder of the rope out behind her. Pull on that rope to tighten the half hitches, and the pressure will cause her to go down. This is much easier on her than trying to pull her hind legs out from under her. “If she goes down and jumps right back up, just take your time and pull on the rope again, and soon she’ll collapse without a big fight,” says Skinner.
When pulling a calf, always pull when the cow is straining, and rest when she rests. Do not put steady traction on the calf without this periodic let-up (one reason it’s best to pull by hand rather than with a calf puller). It takes time for the cervix to dilate and the birth canal to stretch to fullest capacity. “A cow doesn’t just squirt a calf out in two minutes when having a normal birth. She’ll get up and down, and push, and rest. The calf makes a little progress as she strains, then goes back in a little. The cow keeps stretching a little more, gets up and walks around and lies back down. So you can take your time when pulling the calf, and if you only pull as the cow pushes, you don’t have to pull as hard to get as much done. When she’s not pushing, let the calf back,” says Skinner.
If you pull constantly, there is constant pressure on the calf, impairing his blood circulation. “This is one reason some calves are unconscious and fail to start breathing when born. If he’s really tight in the birth canal (and you can feel his elbows pop when they enter the birth canal because it’s so tight), and you are constantly pulling on his legs that are tight against his head, his legs are putting pressure against his jugular veins. When I have a tight one like that, I’ll pull when the cow pushes, four or five times, and then I’ll push the calf back, to let him get some circulation to his head. After giving the cow a little time to rest, with the calf pushed back inside a bit (just like she’d be doing out in the field when she gets up and walks around a little), I’ll pull him out again. Once his head is out of the vulva to his eyebrows, then you can go ahead and finish pulling him. You can then get him out with a few more pulls because the cow is now stretched enough for him to come — and when he gets out he will usually breathe,” explains Skinner.
“What happens with most of the calves that don’t start breathing after birth (even though they still have a heartbeat) is that we’ve impaired the circulation to their heads too long. One of the things that stimulates the calf to breathe is the dropping level of oxygen in the bloodstream (when the umbilical cord breaks and he no longer has a constant supply of oxygen), and this triggers the brain to tell the calf to breathe. But if we’ve been pulling the calf with constant pressure, we’ve cut the circulation off to the brain enough that this trigger isn’t happening; we’ve made him brain dead and this is why he won’t breathe,” says Skinner.
If you consistently allow a calf some periodic relief from pressure as