Dry farm fields and pastures are not the only challenges agricultural producers are facing so far this summer. Warmer-than-usual weather and a lack of precipitation are also contributing to disease threats to livestock, according to Kansas State University veterinarian Larry Hollis.
Hollis, who is a beef cattle specialist with K-State Research and Extension, outlined three threats to cattle stemming in part, from recent weather conditions, including blue-green algae in ponds, leptospirosis and anaplasmosis.
Cyanobacteria, also known as blue-green algae, are present in many Kansas waters. Under certain conditions, harmful algal blooms (also called HABs) can produce toxins that pose a health risk to people and animals.
“It started early on this year,” Hollis says. “We’ve already had cattle deaths attributed to it in Kansas this spring.”
Although it’s commonly known as blue-green algae, it’s really a bacteria. It favors warm, stagnant water, especially if it’s nutrient-laden, so ponds that collect runoff from farm fields are at higher risk. Compounding the threat is the fact that many ponds started the spring with low water levels because of less than average winter and springtime precipitation, thus creating conditions that make the threat of blue-green algae higher than in years when water levels are higher and water temperatures cooler.
The Kansas Agricultural Statistics Service reported stock water supplies across the state at 11% very short, 26% short, and 63% adequate as of June 17. There were no reports of surplus supplies.
Hollis says blue-green algae looks like a pale greenish oil scum on the top of the water, except around the edges where it’s more a cobalt blue color. Because of the recent hot, dry conditions, he’s encouraging producers to check their ponds frequently to see if they see the scum developing. Algae blooms can happen within just a couple of days.
“I hate to see people get into a situation where their first clue is dead cattle,” he says. “Sometimes you might even find dead coyotes or other animal losses. If that occurs, check your pond water.”
Even if animals just come into contact with the water, but don’t drink it, it’s an irritant, he added.
Blue-green algae affects humans just like it does cattle, so there’s a human threat as well as a livestock and animal threat, and once the toxicity occurs, there’s no remedy. It’s something the animal or human must fight on their own, Hollis adds.
“If we get a good rain, it can dilute things really fast, but if we get only a small rain, it will just put the development of the bacteria off for a couple of days,” he says. “If you have blue-green algae, you have to find an alternative water source. If you stop to think what one death loss will cost you, you can haul a lot of water for that.”
Leptospirosis is a summertime disease that also thrives in warm, stagnant water. Unlike blue-green algae, however, there is a vaccine available for it, Hollis says.
“Most people vaccinate their cattle, but every year we hear about some who didn’t and have to be reminded the hard way,” he says. “Most cows even if vaccinated, are carriers of leptospirosis. The vaccine typically does not last a full year, so the recommendation in Kansas is typically to vaccinate in the spring just ahead of the primary transmission season. Cattle infected with leptospirosis will appear sick and typically will run a fever. They may be pale around the mouth. Third-trimester abortions are common with this disease.”
Anaplasmosis is also a threat this time of year, Hollis says. It’s carried by insect vectors, including ticks and biting flies. A milder-than-usual 2011-2012 winter may make the insect population greater this year which could increase the threat of anaplasmosis.
The most effective way to treat anaplasmosis in cattle is using Chlortetracycline (CTC) at a rate of 0.5 to 2 milligrams/1 lb. bodyweight/head/day in a mineral mix or supplement.
“We see outbreaks each year where people thought they were dosing adequately, but were actually under dosing, either because they were not adding the proper level of CTC or were dosing for 1,000-pound cows when their cows actually weighed 1,400 pounds,” Hollis says. “It’s also important for producers to make sure cattle are actually consuming adequate quantities.”