“Sudden death” or “Suddenly found dead”?
It’s an experience not unfamiliar to cattle producers this time of year. You’re out on your regular check of the cattle in the far pasture. You scan the grassland as you dismount the four-wheeler and open the barbed-wire gate. Way off toward the top of the next hill, apart from the group of cattle grazing contentedly, your eyes are drawn to an object that is not normally there. Your suspicions are confirmed as you approach it. It’s a cow. A dead cow. One of your better ones, you determine, as you get close enough to read her tag.
It’s a bummer to lose a cow like that. After all, she certainly was alive the day before yesterday when you last checked the pasture. Disappointment over the loss, however, can quickly turn to anxiety about the rest of the herd possibly meeting the same fate.
In veterinary parlance, this is termed a case of “sudden death.” While technically, all deaths occur “suddenly,” it’s a useful way to describe our perception of a mortality – that whatever killed the animal was quick to occur, in contrast to a chronic poor-doer we expect to keel over any day.
While the term “sudden death” implies there are no prior signs of illness before death, in reality, some sort of clinical sign is almost always present before an animal dies. It just depends on whether we were there to see it – how often we observe the animals. A dead cow found on a pasture only checked twice a week could have been showing signs of sickness for a few days prior to death, leading some veterinarians to deem these cases “suddenly found dead” rather than sudden death.
To be sure, some diseases do act very quickly, causing death within hours or even minutes after the first signs of illness. Many of these conditions occur in pasture situations.
The most important of these conditions is anthrax. Cattle eat the spores (dormant bacteria) from the soil, then once they activate inside the body, the bacterial toxins cause multiple organ failure within hours or minutes. If you were observing the animal at just the right time, you’d see it start to breathe quickly, become weak, collapse and expire without much of a fight. It’s important to know if a cow or bull died due to anthrax because of the need to protect the rest of the herd and take appropriate precautions for the people involved.
Blackleg is another bacterial spore disease that can result in rapid death loss on pasture. Blackleg tends to affect calves in contrast to anthrax, which typically affects adult animals. Similarly, knowing an animal died from blackleg will help you take action (vaccination) to protect others on the pasture.
One cause of sudden death is truly sudden – lightning strike. These cases can be hard for vets to diagnose because few clues tend to be left behind afterwards. Sometimes lightning can be an easy scapegoat when other reasons for death are not obvious.
This time of year rapid cattle deaths can also occur due to blue-green algae contaminated water in stock dams. In addition, dry conditions in some areas mean that nitrate poisoning is moving up on our list of sudden death possibilities this year. Water and feed testing can help sort out those possibilities.
Summertime temperatures can foil our attempts to diagnose causes of sudden death on pasture. Once death has occurred, the quality of tissue samples for lab diagnosis can deteriorate quickly – another reason to observe cattle frequently. For some of these cases, it might not be possible to definitively know the cause of death.
That doesn’t mean that we shouldn’t try, especially those in which anthrax is suspected. For that disease, a useful sample (blood) can be obtained even after the animal has been dead a while. A timely call to your veterinarian may mean that at least a presumptive idea of the cause of death can be obtained. In many situations it makes a lot of sense to consider removal of the animals from the pasture or feed source.
These conditions are another reminder that frequent observation is an important part of animal care. Detecting problems quickly can avert more serious herd issues later.
Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University. He can be reached via email at firstname.lastname@example.org or at 605-688-5171.