by Tamara Scully
The Veterinary Feed Directive, going into effect fully in Jan. 1, 2017, will change the way producers handle some common treatments for diseases. Any medically important antibiotics will have to be prescribed by a veterinarian. But before cattle get sick, vaccination is a preventative step available for many diseases.
Dr. Heidi Ward, DVM, of the University of Arkansas Department of Animal Science, recently discussed common cattle diseases, prevention and treatments. The top disease concerns, ranging in severity, are: bovine respiratory disease; diarrheal disease; reproductive disease; and muscoskeletal disease. Vector diseases, transmitted by a bite, typically from a fly or tick, are also of concern.
Most of these diseases can be caused by multiple organisms. Viruses and bacteria can all cause bovine respiratory disease, diarrheal disease, and reproductive disease, while protozoa, too, can play a role in reproductive and diarrheal disease. All categories of cattle disease also have an environmental component, so keeping cattle away from situations where causative agents thrive is important.
Also known as pneumonia or shipping fever, Bovine Respiratory Disease (BRD) can impact the upper and lower respiratory system. Symptoms of infection include nasal discharge and coughing. High fever, going off feed and depression are also common symptoms. Stress due to weaning and transport can trigger the disease. The microorganism causes the immune system to overreact, ultimately causing lung damage, and the animal will exhibit advanced symptoms of breathing difficulty. As soon as BRD disease is suspected, a veterinarian needs to become immediately involved.
“It’s more than just an infection,” Dr. Ward said. “You’re going to have to fight to save those guys,” once breathing problems occur.
Four different viruses can cause the illness, as can three bacteria, including mycoplasm, which has no cell wall and is therefore not impacted by most antibiotics. Many vaccines are available in combination form, and can guard against more than one disease-causing organism. Antibiotics aren’t effective against viruses, so prevention is critical.
“Vaccines are the way to prevent this,” she said of the many causes of BRD One causative agent, Bovine Respiratory Syncytial Virus (BRSV) is “always bad. You should be vaccinating for that one.”
Sick animals need to be immediately isolated, and given supportive treatment of anti-inflammatory medication. Biosecurity protocols should be immediately activated. Work with healthy animals before sick ones. Use boot covers and throw them away before leaving the sick areas. Wash hands or use sanitizer regularly, and wash clothes daily.
Washing clothes “helps very much to reduce the spread of these viruses to your healthy calves,” Dr. Ward said.
Diarrheal disease is primarily a disease of young calves, and is the second leading cause of calf death, following BRD. It is a disease of overcrowding and unsanitary conditions. It is exacerbated by cold and wet weather. It can be caused by two viruses — rotavirus and coronavirus, three bacteria — E.coli, salmonella, and clostridia, as well as two protozoa — coccidia and cryptosporidia.
“The most important thing is to correct the dehydration,” Dr. Ward said. “Treatment is unreliable. Prevention is going to be your best practice.”
Disease risk is reduced when calves receive proper colostrum. While an oral vaccine for newborns is available, Dr. Ward expressed concern that it might conflict with maternal antibodies and cause issues. A colostrum supplement with antibodies is also available, which will fall under the Veterinary Feed Directive, requiring a prescription.
The disease can affect adults. Typically adults become susceptible due to over-nutrition. This upsets the flora of the gut, and the rumen microbes can no longer function properly.
Reproductive disorders are zoonotic, and these infections can be passed on to humans. Microorganisms, including the bacteria leptospirosis and Brucella, several common bovine viruses, and neospora and trichomonas protozoa, can cause reproductive issues and abortion. Aborted fetuses often hold clues to the causative agent, and photos should be taken and available for veterinary scrutiny, Dr. Ward said.
Vaccines exist to protect against common bacterial and viral causative agents, but not against the protozoa. When vaccinating bulls, reduced sperm counts will occur due to inflammation, so timing should be considered.
New stock should be tested for Bovine Diarrheal Virus (BVD), which causes infertility, abortion, weak or deformed calves, and persistently infected calves. Heifers and cows should be tested for neosporosis. If abortions persist despite negative tests, nutritional deficiencies need to be considered. Heat stress is another cause of reproductive issues and abortion.
Blackleg, footrot and septic joint are all musculoskeletal cattle diseases.
Blackleg is caused by clostridia bacteria, and is swiftly fatal if not detected in the very early stages. The disease causes a painful, swollen hard muscle at the wound entry point, leading to gaseous gangrene.
“Clostridia is always in the environment,” Dr. Ward said.
Footrot has two bacterial causative agents, which enter compromised skin. When the wound seals off, the anaerobic bacteria cause the area to swell. The abscesses will eventually rupture, distributing spores. Infected animals need to be isolated to stop the spread. Environments that are wet and muddy, and rough ground, favor the development of the disease.
Septic joint is a common feedlot issue, caused by several bacterial species, including mycoplasma. Animals need to be treated or culled immediately. Animals in the early stages may be culled rather than treated. If treated, but the disease progresses, the animal may need to be euthanized. Withdrawal times from antibiotics and extent of the disease are factors in determining treatment.
Vector diseases of concern include pinkeye and anaplasmosis. These bacterial diseases are carried by face flies and ticks, respectively.
Pinkeye causes pain and vision loss, which leads to weight loss and weakness. Long grass or “anything that causes irritation to the eyes” invites face flies, which feed off of secretions, and cause and spread the disease. Windy conditions can cause eye irritation, too. Treating with antibiotics, as well as flumixin, an anti-inflammatory for pain, is required.
“Fly control is very important,” Dr. Ward said.
Anaplasmosis attaches to red blood cells causing loss of oxygen, weakness, anemia, weight loss and jaundice. Ticks carry anaplasmosis, but the disease can be transmitted via needle stick or flies as well. Two-year old cows are most susceptible, and infected animals are “very susceptible to stress.” A vaccine is available.
Prevention is the best way to manage these disease concerns. Oftentimes, vaccines offer combination protection, bundling protection against many disease into one. Treatment, in the form of antibiotics, is used when prevention — both via vaccine and by environmental management — isn’t enough to keep issues at bay.
“A lot of people don’t use bacterial vaccines,” Dr. Ward said, although they are effective and can prevent many issues.
“A lot of these vaccines you can get in combinations together. And these combinations really don’t cost more.”