Vets discuss viruses, symptoms and advise producers on treatments
for The Fence Post
With newborn calves on the minds of many producers already immersed in their calving season, it was startling when 80 Kansas ranchers heard about bovine coronavirus as a current concern during a presentation Feb. 19 in Washington, Kan.
During the event that focused on trends in the livestock industry, several serious cattle issues were discussed. Bovine coronavirus, which is now believed associated with bovine summer pneumonia in both pre-weaned calves on pasture and at the end of summer, and another issue was highlighted, bovine rotavirus. Speaker Gregg Hanzlicek, DVM, Ph.D., veterinarian at Kansas State Veterinary Diagnostic Laboratory at Kansas State University in Manhattan, told the crowd that he was surprised by the lab results in the K-State laboratory.
“We discovered the coronavirus in these calves, but we have to make it very clear it’s not the one in humans (it’s not the coronavirus that we’ve been hearing about in the news that’s been coming out of China). Hanzlicek said his laboratory team believes that this bovine coronavirus is a part of summer pneumonia, and that bovine coronavirus is now associated with both pre-weaning and post-weaning pneumonia.
“Ten percent of the samples we’ve received actually have this coronavirus in them. More and more people are saying we think coronavirus isn’t just a scour organism, but it might be involved with our respiratory diseases. Is this coronavirus becoming a major respiratory pathogen? We think so,” Hanzlicek said to the ranchers gathered at the producer meeting and customer appreciation dinner hosted by the Animal Health Center.
Hanzlicek provided details of two real cases. In one particular case of 180 pairs of a closed herd that had calved between March and April, by August 70 percent of the calves had nasal discharge over a seven-day period, were slightly anorexic and had rectal temperatures of of 103 — and the death loss is usually low,” Hanzlicek said.
According to Hanzlicek this coronavirus is associated with:
• Neonatal diarrhea
• Winter Dysentery
• Adult respiratory disease and
• Calf respiratory disease
• It’s worldwide.
Typically, summer pneumonia, also known as pasture pneumonia is a disease most often observed in pre-weaned calves on pasture late in the summer (same term for bovine respiratory disease or BRD).
“We believe we’re seeing an increase in summer pneumonia in calves on pasture, which is unusual, because we’ve always thought of bovine respiratory disease as a post-weaning disease. But we believe we’re seeing more of it now in calves on pasture — pre-weaning since 2015 — and we think it’s more prevalent than it was five or six years ago. We think there are two different scenarios now, one is early respiratory issues right after calves go to pasture, and another scenario toward the end of the grazing season, when those calves are 400 to 500 pounds heavy and 4 or 5 months old,” Hanzlicek said to the crowd.
K-State conducted a study to determine how cattle could be at higher risk. Summer pneumonia used to be rare, Hanzlicek said. He added that cattle in the K-State case studies were indeed vaccinated.
• Symptoms: Heavy breathing — a calf having obvious difficulty getting air into its lungs, struggling to breathe (due to lungs filled with fluid) and a high fever.
• Treatment: “We’d use an antibiotic to prevent a secondary bacterial infection and basically ride the storm, but then you plan for the next season.
• Lessons learned: “Although these calves were vaccinated twice before going out to pasture, they were exposed to a total of 200 pairs in a tight drylot situation and were exposed to BRSV (bovine respiratory syncytial virus) and the calves were breathing in huge amounts of BRSV. Our belief is exposure level was so high, it overwhelmed their immune system. So, we recommend synchronizing AI (artificial insemination) into smaller groups for prevention after a wreck like this. We did make some changes, and so in this herd now, we haven’t had a problem in three years,” Hanzlicek said.
• Risk Factors: Confinement — When whole herds are brought in and confined in small areas for AI synchronizing. Creep Feeding — Putting animals in a closed area/nose-to-nose seems to be associated as a risk factor for later season pneumonia/just another confined increased access to organisms.
Be careful when bringing in weaned steers from outside sources and in adjoining pastures.
Be more watchful with larger herds, if a herd has treated one animal for BRD, or scour outbreaks, then they’re at higher risk for pasture pneumonia.
The event focused on critical issues that have increasingly come to the attention of host veterinarian Dr. Phil Bentz, DVM., Dr. Adam Hatesohl, DVM and other vet specialists at his clinic and at Kansas State University. “There are currently two companies looking at respiratory coronavirus vaccines or an autogenous vaccine,” Hanzlicek said.
Hanzlicek advised the ranchers about another increasing issue of concern for livestock; the bovine rotavirus, and said that commercial rotavirus vaccines may possibly be less effective lately.
“Bovine rotavirus is responsible for most cases of neonatal diarrhea in calves, also known as calf scours. We had a research project done at K-State to answer the question, ‘How closely related are the vaccines that were designed many years ago to today’s rotaviruses that are seen these days on cow-calf operations?’” Hanzlicek said. “We did a study showing, that despite years ago that vaccine strains back in the day were very closely related to field strains but today they’re not. And, we know that the further the strains are apart the less cross-protection we’re going to get. So, if we’re not seeing effectiveness of our scour vaccines, it’s not that they’re a bad vaccine they may work in some places but it may be that the rotavirus on that typical operation is not closely related to the strains in the vaccines,” he said. They learned this, by a process called gene sequencing using thousands of DNA from the rotavirus and matching them up.
Symptoms are watery diarrhea and reluctance to eat or drink.
In severe cases, this can lead to severe dehydration and electrolyte imbalance, sometimes resulting in death. These symptoms generally persist for two to four days, with viral shedding continuing for five to seven days.
Reasons vaccine didn’t work:
• Administered at improper time
• Administered inappropriately
• Inappropriately handled (vaccine left out in the sun)
• Calf does not respond
• Vaccine strain does not closely match the field strain
So, what should ranchers do?
“First of all, make sure their colostrum protection and their environmental sanitation are in order, because these vaccines are just tools. But if they’re doing that and they’re still having Rotavirus issues, it may be time to move to an autogenous vaccine, and that’s where you take (feces) samples from the calves on an operation and send it into a laboratory which grows out the ‘rota’ (rotavirus) and then a company makes a vaccine that has your specific strains in it, which is called an autogenous vaccine.”
If your vaccine isn’t working, it may be outdated, and it’s recommended you contact your veterinarian, so a test can determine whether the issue is, based on the diarrhea.
Bovine rotavirus can have significant economic consequences for farmers. The monetary value for the loss of calves has been found to be anywhere between $3 million and $8 million per year. Even if no calves die, they may take longer to reach their full weight.
Rotaviruses are spread through the fecal-oral route. Therefore, it is crucial that calves be kept in a clean environment, especially for the first two to three weeks of life when most susceptible. The calving should be rotated every two weeks to prevent older calves from contaminating newborns. Calves suspected to be infected should be isolated until diarrhea ends. Any tools used to treat the sick calf must be thoroughly disinfected.
Vaccines exist for bovine rotavirus, but are typically administered to the mother before calving, to help boost the antibodies in the colostrum. A calf fed with about 1-2 quarts of antibody-rich colostrum within the first 6 hours after birth, will be much less susceptible to becoming ill from rotavirus infection.
“If you look around the room, there were very few youth. So, it’s great having veterinarians to help us stay up on cutting edge technology and stay up on life cycles and the latest information. Some of these chemicals will create a resistance. It’s good to have mentors,” said Peggy Nietfeld who traveled from Wymore, Neb., to the meeting.
Her son Robert agreed.
“The future of the livestock industry is quickly coming upon us. If we’re not willing to adapt, the livestock industry could end up dying, because we don’t evolve with society,” he said. “So we need to be open-minded to the different scientific researches available to these technologies, and not be self-reliant on some technology.” ❖
— Hadachek is a freelance writer who lives on a farm with her husband in north central Kansas and is also a meteorologist and storm chaser. She can be reached at email@example.com.
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