Corona virus has long been known as a main cause of viral scours in newborn calves.
It, along with a couple strains of rotavirus, are the two main viruses used in scours vaccines.
It also causes a winter dysentery in mature cattle, especially housed dairy cattle.
But many people may not realize the same virus can be involved in the bovine respiratory disease complex.
The respiratory syndrome is often masked by the other much more prominent viruses, such as infectious bovine rhinotracheitis and bovine respiratory syncytial virus, or the main bacterial causes of pneumonia — Mannheimia hemolytica, Pasteurella multocida and Histophilus somnus.
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There is no respiratory vaccine on the market that contains the corona virus antigen, but in the future a company may put in the corona virus to bolster the immunity to respiratory pathogens again.
People in the cattle industry know that respiratory disease is the No. 1 economic disease in feedlots across Canada, so anything we can do to reduce cases is beneficial.
Cattle have less lung capacity than most other species and yet with their big rumens and digestive process, they require more oxygen, Their lungs have little reserve in them, so they can be prone to respiratory diseases.
When corona virus respiratory disease occurs in a few separate instances in a herd, the producer might notice some slight depression but overall animals will still look bright.
There may be increased nasal secretions and feed intake may significantly decline. The feed decrease might be the first thing producers notice.
Sick calves must be treated for secondary bacterial infection.
Corona virus might also occur if the immune system is suppressed because of vitamin or mineral deficiency, internal parasites or the occurrence of a concurrent disease.
Some cattle might be infected with the corona virus and have the enteric form. Producers would then expect to see diarrhea in a small percentage of the infected cattle.
If cattle seem to be sicker than in the past in spite of vaccinating for pneumonia, producers should have them checked for the corona virus.
Another bacterial cause of pneumonia presents itself a different way and may be an emerging disease in the United States.
The bacteria is Bibersteinia trehalosi and is closely related to M. hemolytica, which is the key bacteria involved in the whole bovine respiratory disease complex. It causes sudden death in animals it infects and in the United States has involved primarily Holstein cows.
It has also caused significant pneumonia and blood infection (septicemia) problems in sheep. The pneumonia veterinarians see on a post-mortem is indistinguishable from the M. hemolytica form and is indistinguishable on routine laboratory submissions.
Special testing is required. It may be another emerging component to the whole respiratory disease complex.
U.S. veterinarians first noticed this pneumonia was different because it kills cows quickly and was fairly unresponsive to antibiotics.
It’s believed that because of its acute nature, the antibiotic simply doesn’t have enough time to work.
Also because full grown cows do not generally develop respiratory diseases, it catches producers off guard.
In some cases, the organism can be resistant to many different antibiotics when cultured.
Several effective, long-lasting macrolide antibiotics exist for treating groups of high risk calves, but careful monitoring for unusual respiratory diseases must continue.
If the incidence of treatment or death is higher than expected or there have been sudden deaths, a veterinarian should carry out an autopsy.
Cow-calf, feeders and feedlot operators have decreased the animal deaths caused by pneumonia in Canada over the last decade.
This has been accomplished by combining vaccines that have a broader coverage, using metaphylactic antibiotics and because of better antimicrobial treatments and anti-inflammatory drugs.
Feed conversion is better with less chronically infected animals present.
If herd response to vaccines seems poor, or treatments or death rates are unacceptable, producers should have their cattle checked and post mortems carried out. One of these emerging pathogens, especially B. trehalosi, could be present.
