Kenny Barrett Jr., DVM, MS

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July 23, 2010
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Cow Tales

The first cutting of hay is done for some ranchers but most continue burning diesel. Some spreads take all summer to roll up once and others, where it rains, bale the same ground multiple times in any given season. No matter the location, every rancher has been troubled by summer pneumonia. BRSV is an important viral component to summer pneumonia and the last installment of the immune system and pneumonia series of Cow Tales.

Bovine respiratory syncytial virus, or BRSV, is the viral plague of the rancher. Like most terms in medicine, BRSV has Latin roots. Syncytial, a nerd word to most, is a fancy Latin way to describe the microscopic appearance of infected cells. Under the microscope the infected cells group together to form giant cells called syncytium; hence syncytial virus. On the practical side, BRSV is a leading cause of pneumonia in calves. Humans can be infected with a similar virus, RSV; a cause of severe respiratory disease in young children. As with RSV, BRSV generally causes clinical disease in young calves with the initial infection. Subsequent infections are rarely clinical but do occur. Adult animal infections are rare and sporadic but can lead to death if left untreated.

The details of how BRSV survives and reemerges from year to year are not clear. It is believed to circulate much like RSV and is spread from animal to animal through aerosols and nose to nose contact. So, if BRSV only affects young animals, spreads essentially through direct contact, and calves are weaned off the ranch each year; how can it cause problems in subsequent years? BRSV is believed to circulate in adult animals without causing disease. Similarly, cattle can have a low parasite infestation and show no outward signs. In contrast, other types of viruses, like BVDV, cause persistent infections in specific individual animals. The persistently infected animals serve as the reservoir for subsequent infections.

If you can't detect reservoir animals and eliminate them, how does a producer provide adequate protection for their cattle to prevent or reduce clinical disease caused by BRSV? He or she reduces stress and vaccinates. That one five-word sentence is fairly complicated. Stress means biological stress and includes weather, feed, water, shelter, animal handling and many others. Many of the factors include Mother Nature and are as easy to manipulate as calling for rain in the middle of a ten-year drought. If you can't change it, don't try. Successful producers manage around the uncontrollable but focus their efforts where they have direct impact. Producers should concentrate on a clean comfortable (cozy for a cow) healthy environment. Make sure all animals have access to adequate feed and clean water. Make efforts to reduce stress while working cattle. How often does illness, most notably pneumonia, occur after working a group of calves? Arm the immune system with the ammunition it needs to ward off disease.

There are a whole host of commercial vaccines that include BRSV. The trouble with relying solely on vaccination is the type and length of protection provided. We are finding out that traditional injectable vaccines stimulate the production of the wrong type of antibodies and the protection is short lived. Vaccines could be made differently or stimulate the immune system in a different way. Some researchers believe a BRSV vaccine given intranasally, or in the nose, would stimulate a more "natural" immune response. The IBR/PI3 intranasal viral vaccines are highly effective at stimulating a beneficial immune response, so why not BRSV? Currently there is only one intranasal BRSV vaccine but it has had some safety/efficacy issues in the past. There is ongoing research to develop a good intranasal BRSV vaccine.

In a nutshell, BRSV is the less talked about big deal. It is the waspy cow cursed while working cattle but never mentioned any other time of the year. Most of the time she is no concern, sometimes she's a problem, and occasionally she causes a wreck. BRSV is manageable but takes a conscious effort on the part of the producer. It is not going away but careful management and a complete herd health program can minimize its negative effects. Talk to your veterinarian to develop your offense to BRSV.

The first cutting of hay is done for some ranchers but most continue burning diesel. Some spreads take all summer to roll up once and others, where it rains, bale the same ground multiple times in any given season. No matter the location, every rancher has been troubled by summer pneumonia. BRSV is an important viral component to summer pneumonia and the last installment of the immune system and pneumonia series of Cow Tales.

Bovine respiratory syncytial virus, or BRSV, is the viral plague of the rancher. Like most terms in medicine, BRSV has Latin roots. Syncytial, a nerd word to most, is a fancy Latin way to describe the microscopic appearance of infected cells. Under the microscope the infected cells group together to form giant cells called syncytium; hence syncytial virus. On the practical side, BRSV is a leading cause of pneumonia in calves. Humans can be infected with a similar virus, RSV; a cause of severe respiratory disease in young children. As with RSV, BRSV generally causes clinical disease in young calves with the initial infection. Subsequent infections are rarely clinical but do occur. Adult animal infections are rare and sporadic but can lead to death if left untreated.

The details of how BRSV survives and reemerges from year to year are not clear. It is believed to circulate much like RSV and is spread from animal to animal through aerosols and nose to nose contact. So, if BRSV only affects young animals, spreads essentially through direct contact, and calves are weaned off the ranch each year; how can it cause problems in subsequent years? BRSV is believed to circulate in adult animals without causing disease. Similarly, cattle can have a low parasite infestation and show no outward signs. In contrast, other types of viruses, like BVDV, cause persistent infections in specific individual animals. The persistently infected animals serve as the reservoir for subsequent infections.

If you can't detect reservoir animals and eliminate them, how does a producer provide adequate protection for their cattle to prevent or reduce clinical disease caused by BRSV? He or she reduces stress and vaccinates. That one five-word sentence is fairly complicated. Stress means biological stress and includes weather, feed, water, shelter, animal handling and many others. Many of the factors include Mother Nature and are as easy to manipulate as calling for rain in the middle of a ten-year drought. If you can't change it, don't try. Successful producers manage around the uncontrollable but focus their efforts where they have direct impact. Producers should concentrate on a clean comfortable (cozy for a cow) healthy environment. Make sure all animals have access to adequate feed and clean water. Make efforts to reduce stress while working cattle. How often does illness, most notably pneumonia, occur after working a group of calves? Arm the immune system with the ammunition it needs to ward off disease.

There are a whole host of commercial vaccines that include BRSV. The trouble with relying solely on vaccination is the type and length of protection provided. We are finding out that traditional injectable vaccines stimulate the production of the wrong type of antibodies and the protection is short lived. Vaccines could be made differently or stimulate the immune system in a different way. Some researchers believe a BRSV vaccine given intranasally, or in the nose, would stimulate a more "natural" immune response. The IBR/PI3 intranasal viral vaccines are highly effective at stimulating a beneficial immune response, so why not BRSV? Currently there is only one intranasal BRSV vaccine but it has had some safety/efficacy issues in the past. There is ongoing research to develop a good intranasal BRSV vaccine.

In a nutshell, BRSV is the less talked about big deal. It is the waspy cow cursed while working cattle but never mentioned any other time of the year. Most of the time she is no concern, sometimes she's a problem, and occasionally she causes a wreck. BRSV is manageable but takes a conscious effort on the part of the producer. It is not going away but careful management and a complete herd health program can minimize its negative effects. Talk to your veterinarian to develop your offense to BRSV.


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Tri-State Livestock News Updated Aug 14, 2012 04:17PM Published Jul 23, 2010 12:57PM Copyright 2010 Tri-State Livestock News. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.