MLV or Killed Vaccines?

[Lucky_P]

Dunno about cattle, but for my horses I use MLV that I get from the vet. I can get the killed virus at feed & tack stores, or order online from horsehealthusa.com, but killed virus is not as effective as live virus.

While I'm not an 'equine' practitioner, I'm unaware of any MLV equine vaccines available on this continent. Every one I'm familiar with is a 'killed' product.

While we generally expect 'better' protection with a MLV product, that's not necessarily true across the board. For instance, initial vaccination with a MLV intranasal BRSV, followed by injectible booster with inactivated BRSV provided greater antibody titers, higher oxygen levels in challenged calves, and higher survival rates overall, compared to a single or double-dose regimen of MLV vaccines.

Use of MLV vaccines in previously unvaccinated cattle can cause abortions... and in my 30 yr career in vet diagnostic labs, the only IBR abortions I ever saw were vaccine-induced. So... I do not recommend use of MLV vaccines in bred cows with unknown vaccination histories. Some of the MLV manufacturers advise that if the animals have had two previous doses of MLV vaccine, administered properly, and within recommended timeframes, that you can safely re-vaccinate those animals with the same MLV product. Despite those assurances, I'm still a little squeamish about using a MLV in a bred cow, regardless of vaccination history.
Definitely do not want to administer a MLV containing IBR to any open cow/heifer within 30 days in advance of anticipated breeding, as the MLV IBR virus can temporarily colonize the ovaries and cause diminished fertility.

In the past, we've shied away from using MLV products containing IBR & BVD viruses in calves nursing pregnant cows, but the likelihood of calves actually 'shedding' virus and infecting their dams and causing abortion is so low that I don't worry about it.
UofMO did a small pilot study some years back, where they had a group of bred cows that were seronegative for IBR/BVD; they vaccinated calves with Bovishield Gold 5 (MLV), and turned them out in the same paddoc with the cows. They were unable to detect viral shedding in nasal secretions of the calves and the cows did not develop antibodies, nor did any abort. Very low numbers of animals in that trial, so it's not absolutely conclusive, but enough to convince me that viral shedding from today's MLV vaccines is not a significant concern.

 

[GoWyo]

While I'm not an 'equine' practitioner, I'm unaware of any MLV equine vaccines available on this continent. Every one I'm familiar with is a 'killed' product.

While we generally expect 'better' protection with a MLV product, that's not necessarily true across the board. For instance, initial vaccination with a MLV intranasal BRSV, followed by injectible booster with inactivated BRSV provided greater antibody titers, higher oxygen levels in challenged calves, and higher survival rates overall, compared to a single or double-dose regimen of MLV vaccines.

Use of MLV vaccines in previously unvaccinated cattle can cause abortions... and in my 30 yr career in vet diagnostic labs, the only IBR abortions I ever saw were vaccine-induced. So... I do not recommend use of MLV vaccines in bred cows with unknown vaccination histories. Some of the MLV manufacturers advise that if the animals have had two previous doses of MLV vaccine, administered properly, and within recommended timeframes, that you can safely re-vaccinate those animals with the same MLV product. Despite those assurances, I'm still a little squeamish about using a MLV in a bred cow, regardless of vaccination history.
Definitely do not want to administer a MLV containing IBR to any open cow/heifer within 30 days in advance of anticipated breeding, as the MLV IBR virus can temporarily colonize the ovaries and cause diminished fertility.

In the past, we've shied away from using MLV products containing IBR & BVD viruses in calves nursing pregnant cows, but the likelihood of calves actually 'shedding' virus and infecting their dams and causing abortion is so low that I don't worry about it.
UofMO did a small pilot study some years back, where they had a group of bred cows that were seronegative for IBR/BVD; they vaccinated calves with Bovishield Gold 5 (MLV), and turned them out in the same paddoc with the cows. They were unable to detect viral shedding in nasal secretions of the calves and the cows did not develop antibodies, nor did any abort. Very low numbers of animals in that trial, so it's not absolutely conclusive, but enough to convince me that viral shedding from today's MLV vaccines is not a significant concern.

Thanks Lucky_P. That is the same thing my vet says on the MLV to nursing calves on bred cows that have had the killed vaccine. The cows all had MLV as calves and as yearlings then cows all get killed vaccine at preg check annually.

 

[Lucky_P]

For an outfit with a really tight calving season, such that all the cows are 'open' in a window large enough to allow use of a MLV at least 30 days before anticipated breeding, it makes sense to use a MLV if warranted. I never saw many outfits that didn't have calving spread out enough that using a MLV wouldn't work well, so a 'killed' product was safest.
We had a closed herd (purchased and brought in 2 bulls from outside, over a 15-yr period) with no fence-to-fence contact with other cattle, and very rarely ever had any respiratory issues and no viral abortions, so we never vaccinated mature cows against IBR/BVD/PI3/BRSV. Weanling heifers got 2 rounds of MLV viral vaccines along with their steer counterparts, so that any that weren't retained would qualify as 'value-added' when we sold them.

 

[Silver]

We give newborns and weaned calve MLV, after that they get killed. That's the program the vets have us on, and we have no health issues so we'll carry on. 45 day calving season here, generally expect 6-7 percent open or late.

 

[gcreekrch]

I don't worry about giving calves getting a MLV vaccine causing their mothers to abort. I am much more concerned about having protocol that is effective without putting undo stress on the calves. I don't give any vaccines before 90 days of age because they won't take because of maternal antibodies. At branding, I give a modified live respiratory vaccine and an eight way blackleg. 45 days before weaning, I repeat the MLV respiratory, add blackleg with shipping fever and give a pinkeye implant. So the immune system is ready when the stress of weaning happens.
I don't vaccinate the bulls that I leave intact because I want to put selection pressure on health.

How long have you not been vaccinating and do you bring any new animals into the herd at all?