Determine cause to curb lamb deaths

A post-mortem can help determine if starvation, birth trauma, hypothermia or a disease may be the cause

Finding one dead lamb is unfortunate. Finding two dead lambs is a concern. Three dead lambs, and the producer had better investigate.

Dr. Lynn Tait, a University of Calgary veterinary instructor and co-owner of OC Flock Management, offered information on how that investigation can take place.

“I’m a huge proponent that, if you have dead neonates, you need to figure out why,” said Tait in a recent webinar organized by Alberta Lamb Producers.

“Why is my lamb dead and how could I have prevented this?”

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She said most lamb deaths in neonates — those she defines as less than one week old — occur in the first three days of life and there are eight primary causes:

stillborn (death in utero)
dystocia
hypothermia
failure to breathe
starvation
failure of passive transfer
trauma
infection

Determining cause of death is crucial because it might alert producers about the need to change their management or take corrective measures to prevent future losses.

And that means a post-mortem may be required. Tait said producers can do basic post-mortems themselves, which is cheaper than taking the carcass to a veterinarian.

“I think you can triage a lot of your problems if you learn the common things to look for,” she said.

First, producers should check for any obvious abnormalities in head size and body shape.

Then check the feet to see if the lamb ever rose and walked. That is an important clue in learning cause of death because if the lamb never got up, it never nursed.

Cause of death might be abandonment, hypothermia, starvation or mismothering, said Tait.

To explore further, put the lamb on its back, spread the legs and make one incision from navel to tail and another from navel to head. Ribs can be cut along the sternum using scissors.

Check the lungs and if they are pink and inflated, it indicates the lamb once drew breath. Dark pink or red lung tissue indicates the opposite.

To be sure, Tait said a small piece of the lung should be placed in water. If it sinks, the lamb never breathed, and that may indicate death during birth from dystocia or possibly suffocation by the placenta.

“Does the lung tissue look like normal, health, happy tissue,” asked Tait. If not, it may be a sign the lamb died before birth because lung tissue decomposes quickly.

Producers sometimes know the lamb died from a difficult birth, but that is not always obvious, said Tait.

Signs of internal bleeding or a ruptured liver are indications of birth trauma, as is fluid under the skin. Those signs could also indicate the lamb was stepped on or squashed.

“Often lambs that have come through a difficult birthing or a delayed birthing because of things like malpositioning, they’re stressed … even in the uterus,” said Tait.

“They release the meconium, which is that first sort of yellowy manure that they pass, and they come out yellow. They often have yellow staining to the hair… That’s a sign that that fetus has been stressed at birth.”

To prevent death from dystocia, Tait suggested using plenty of water-based lubricant when assisting an ewe, and also providing a mild anti-inflammatory like Metacam to the lamb.

Back at the post-mortem, checking the abdomen will give clues about possible starvation. Check for milk curd, said Tait.

Also check for brown fat around the heart and kidneys and under the intestines. Lambs burn brown fat to stay alive until they get milk.

If the fat is gone and the stomach is empty, starvation was the likely cause of death and may point to mismothering issues, lack of bonding, weak lambs or those too chilled at birth to rise and nurse, said Tait.

“Lambs are pretty tough in general and if you can get them dry and you can get food into them, those lambs typically survive quite well. If they start to get hungry, then they’re going to get cold… They may not get up and go nurse.”

Tait said that might indicate a need to check ewes more often or change post-lambing management.

An aborted or stillborn lamb may show signs of decomposition and the placenta may appear unhealthy.

Tait advised caution in handling aborted fetuses because many conditions that cause abortion in small ruminants are contagious and can affect people.

Producers should collect stillborn fetuses and any afterbirth they can find because the cause is often diagnosed from the placenta rather than the fetus itself.

The material can be frozen until a veterinarian can examine it. One or two stillbirths may not signal a problem but three may indicate a contagious organism is at work, she said.

As for death from other causes, Tait said navel infections are a concern but they don’t usually kill within the first week of life.

If the cause of death still isn’t obvious after a post mortem, “those are the ones that maybe then you give your veterinarian a call.”

Tait said management is often the key to lamb survival.

“A lot more neonates die from mismanagement than they do from actual disease,” she said.

“Do not assume without further investigation that you are actually correct in why it died.”