Too much water: The effects on livestock

Farm Forum

The past couple weeks have reminded us of the swings in weather here in the Dakotas. Less than two years ago, most of us were in the grips of severe drought. Now we are dealing with deluges that have filled up creeks, rivers and basements, not to mention pastures and cattle yards.

Even when there’s too much rain, it usually goes along with good pastures, good crops, and full stock dams. All of these benefit animal health and outweigh many of the negatives. However, nine inches of rain in one night – as some areas in southeastern South Dakota saw – is way too much of a good thing! As I write this, people are still struggling with high water and its aftermath.

When most people think about flooding and livestock, it’s a picture of carcasses washed down a swollen river, or cows clinging to a patch of high ground. Fortunately, those instances are rare compared to what’s experienced by most livestock during times of high water.

Just like for people, a major effect of flooding on cattle, horses, and sheep on pastures or in feedlots is that of disruption. Water over a road or a knocked-out bridge disrupts our ability to travel and take care of what needs taking care of. Water in pastures does the same for livestock. Standing water or high creek levels limit their access to grazing or the mineral feeder. Calves could get separated from their mothers for a while. One potential result of this separation could be enterotoxemia, or “overeating disease” after the reunion finally takes place and the hungry calf engorges himself on a load of milk.

Foot problems are another common result of excess moisture. Cattle standing in water or mud left behind by the rains can be particularly prone to foot rot. Moisture breaks down the normal resistance of the skin surface, so environmental germs can penetrate and cause infection. Standing water can hide debris that can cause cuts and scrapes. This is especially important for horses, since they’re highly prone to tetanus. These are reasons to consider fencing livestock away from muddy or flooded land. At the very least, animals should be watched closely for lameness during and after wet weather. Foot rot in cattle and sheep should be promptly treated, and injured horses should get tetanus boosters and appropriate care.

Another aspect of flooded lots and pastures has more to do with what the water does to the soil rather than what it does to the animals. When water floods a pasture, it can disrupt the soil and vegetation. In many areas around our region, microorganisms in the soil include some that are potentially hazardous, even fatal, to livestock – anthrax and blackleg, in particular.

Once in the soil, these germs go into a spore form that enables their survival for many years. But they’re only problems for cattle if the cattle find them. If they stay buried underneath the soil surface, they can’t harm the animal. However, when water comes onto a pasture, it can stir these spores up from the soil underneath. When the water recedes, these spores are left behind on growing grass, where they’re eaten by the unsuspecting animal. Once they enter the animal’s system, they activate and release toxins that can rapidly kill the animal.

Signs of both anthrax and blackleg occur during such a narrow window that we rarely find anything except a dead animal. Treatment, then, is usually not an option. Vaccinations ahead of time are effective at preventing both of these conditions, however. Knowing what an animal died from on pasture, therefore, can be very useful in applying preventive measures to the rest of the herd.

Seeing standing water on pasture would be a good trigger to vaccinate animals against these illnesses if they haven’t been already. It’s rarely handy to do so once animals are already on pasture, but if the opportunity exists, it should be discussed with your veterinarian. At the very least, being aware of the conditions that come with flooded lots and pastures – and dealing with them promptly – can head off big problems for an animal or a herd.

Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University. He can be reached via e-mail at or at 605-688-5171.