Responding to health problems out on pasture presents some unique challenges beyond those related to therapy in feedlots or other more confined environments. Two of the biggest issues are safety for man and beast, and continuing to adhere to quality assurance guidelines in a less controlled environment.
We suggest these discussion points as you sit down with your veterinarian to plan responses to challenges cattle face while on grass.
The Usual Suspects
Which diseases are the most likely in pasture cattle? This answer depends on your specific area, but there are some diseases we should watch for almost anywhere. In this column, we'll focus on infectious diseases. Be sure you know the signs to watch for and plan your responses in advance.
- Respiratory disease
Here we're dealing with a potential combination of viral and bacterial pathogens. Work with your veterinarian to classify groups of stocker cattle as low or high risk, based on history and appearance. High-risk cattle are often described as those we expect to present a 10% or greater morbidity (illness) rate related to respiratory disease.
Such cattle often do better on grass, but are still capable of presenting significant health challenges. You may want to consider a longer confinement time to more easily deal with health issues as they arise. Smaller grass traps close to treatment facilities are one option.
Typically, most of the morbidity occurs in the first 30 days with high-risk cattle. It may be helpful for you to feed a little grain to these cattle during the first 20-30 days of ownership to more quickly find cattle that have BRD. These cattle will tend to be slow to come to the bunk just like feedlot cattle with BRD.
Another respiratory disease occurs when cattle are suddenly exposed to lush, rapidly growing pastures. Acute interstitial pneumonia, also known as fog fever, results in lungs that rapidly fill with fluid and cause severe respiratory distress in the animal. A different therapeutic approach is required as compared to infectious respiratory disease, with response to therapy often poor unless instituted early and combined with removal from the offending feed source.
- Clostridial diseases
Clostridial genus of bacteria is responsible for diseases such as blackleg, malignant edema, overeating disease and tetanus. These bacteria are capable of forming spores and waiting out unfavorable conditions only to revive when conditions are favorable.
If you've had tetanus (lock jaw) in your cattle, it will likely be a potential problem any time you castrate or dehorn, as it can survive long periods in the soil as a spore. Seven-way clostridial vaccines don't contain the tetanus antigen, so this must be added to your program when needed. Prevention of clostridial diseases is the best option because response to therapy is often poor.
This disease is often seen when wet conditions are combined with compromised skin between the claws of the feet. However, outbreaks in dry conditions may occur as well. Treatment response is usually quite good when started at the first signs of lameness.
Prevention of this disease involves fly control, pasture trimming and vaccination, although you should discuss the potential of vaccines with your veterinarian. Some literature reports mixed or minimal results for common therapies of pinkeye.
Flies or contaminated needles are commonly responsible for transmitting this blood parasite. Younger animals can spike a fever and recover.
The disease may be fatal to older cows and bulls, however. They lose the ability to carry oxygen in the blood due to the loss of red blood cells, with resulting signs of exercise intolerance and rapid breathing. Rapid treatment is key to saving the animal. Most cases appear late in the summer and in the fall.
Should drug choices for grass cattle be different than for feedlot cattle?
Most producers place a premium on single-injection drug options in pasture situations. Effective, single-injection therapies are available for respiratory disease and are also possible for early treatment of footrot and pinkeye.
This is a more difficult goal for clostridial diseases. Whatever drugs are chosen, be sure to protect drug quality. Storage on pickup dashboards or in interiors that reach extreme temperatures will degrade drug quality and affect results.
Your veterinarian can help you evaluate the safety of different drugs in situations where restraint isn't optimal. Drugs labeled only for intravenous (IV) use should not be administered intramuscularly (IM) just because proper restraint isn't possible.
Not only are slaughter withdrawal time and effectiveness potentially altered but many IV-only labeled drugs may cause significant tissue damage when injected in other sites. The same principles apply when drugs labeled only for subcutaneous use are injected IM.
What About Quality Assurance?
Paying attention to needles on pasture is especially important. Bent needles are prone to break off in the animal. Discard them immediately. Never straighten a bent needle. Discard needles with burrs on the tips.
Volume per injection site is sometimes compromised when we're in a hurry. Increasing volume per site can result in increased injection-site damage, as well as altered drug absorption and increased slaughter withdrawal times.
In addition, be sure to routinely bring non-disposable syringes and equipment in from the truck or saddlebags for cleaning. Clean injection systems result in fewer injection-site reactions and improved drug efficacy.
Discuss these points with your veterinarian and ask for additional advice on being prepared for spotting and treating diseases in pasture cattle.
Editor's Note: For more on these diseases go to www.beefcowcalf.com and enter the disease name into the “Title Search” box on the opening page.
Mike Apley, DVM, PhD, is an associate professor of beef production medicine at Iowa State University in Ames. W. Mark Hilton, DVM, is clinical assistant professor of beef production medicine at Purdue University in West Lafayette, IN.