As cow-calf producers and veterinarians evaluate options for pre-breeding vaccinations on heifers and cows, it is critical to think about the long-term effects of the disease pathogens that you are protecting against. The immediate thought is protecting against vibriosis and leptospirosis; sometimes that occurs at the sacrifice of not effectively protecting against the reproductive forms of bovine viral diarrhea virus (BVDV) types 1 and 2 and infectious bovine rhinotracheitis (IBR), which may have larger effects on overall health of the herd and greater financial implications for the producer.

Jeff Sarchet

Beef Technical Services Veterinarian / Zoetis

In developing a vaccination plan for the cow herd, it’s important to understand the potential impact of each disease challenge.

• BVDV has the greatest long-term impact if allowed to enter the herd. If cows or heifers are exposed to BVDV during pregnancy, those pregnancies are at risk of early embryonic death, abortion, birth defects or stillbirth. Or if exposed in the first 140 days of pregnancy, the unborn calf can become infected for life with BVDV, which is called BVD persistent infection (BVD-PI). A calf born as BVD-PI will shed the virus and be a carrier as long as it is alive. BVD-PI calves nursing their dams allows for BVD exposure to other nursing calves as well as other dams and their unborn calves in next year’s calf crop.
  
  
• IBR can cause an abortion storm in naïve cows that are exposed. Overall, IBR causes fetal losses and is costly to producers.
  
  
• Leptospirosis has five main strains: Leptospira canicola, L. grippotyphosa, L. hardjo, L. icterohaemorrhagiae and L. pomona. The five most common strains of leptospira can cause abortions or pregnancy loss, or less commonly, make animals sick with kidney disease. Another less obvious, but important strain is Leptospira borgpetersenii serovar hardjo type hardjo-bovis (HB). Most commonly, HB causes early embryonic death manifested as conception issues. Leptospirosis protection from the five most common strains only lasts six months, but some HB vaccines have a duration of immunity of 12 months, which needs to be considered when developing a vaccination program.
  
  
• Vibriosis (Campylobacter fetus) is a sexually transmitted disease that can cause infertility, irregular estrus cycles, delayed conception and occasionally abortion.

When I designed vaccination programs for my clients, I asked a series of questions to help me give them a program that would be most effective in protecting the cow herd but also fit their management style. The first question I asked was if they could work the cows and calves prior to bull turnout. If this was the case, they had several options for the cows and calves because the cows were not pregnant at this time, so giving the calves a modified-live virus (MLV) vaccination was safe even though the calves were nursing, and it was also safe to give the cows a MLV vaccination because they were not pregnant. It is important to look for FP in the name of the vaccine because that means the product is indicated to protect against the reproductive consequences of BVDV and IBR.

If a producer didn’t handle the cow herd at pre-breeding, vaccination history was unknown or the client was uncomfortable with MLV vaccination, I would recommend using a killed BVD reproductive vaccine that provided protection against BVD-PI and IBR abortions. Not every killed virus vaccine has reproductive protection, so make sure to read label indications.

If HB is a potential challenge, then it is important to add a vaccine that protects against that type of leptospira, otherwise, protection against the basic five leptospira strains is adequate.

The final disease to consider is vibriosis. If vibriosis is a potential problem, then I recommend using a product that incorporates vibrio protection with BVD-PI and IBR abortion indications, or a stand-alone product for vibrio protection at pre-breeding. It is key that vibrio protection is given at pre-breeding to protect against early embryonic loss and reduced conception rates because like the common 5-way lepto vaccines, vibrio vaccines typically only have a duration of immunity of five to six months.

Again, it is important to think beyond protecting just against vibrio and leptospirosis. BVD-PI and losses due to abortion storms caused by IBR exposure have greater financial impact on the cow herd and can have lasting consequences on herd health and sustainability.

Last of all, don’t forget to vaccinate your bulls. These diseases can be transmitted by the bulls either through direct contact or during the natural breeding process. Bulls are also vulnerable to contracting these diseases from infected cows or calves, especially BVD-PI calves. BVDV has a predilection to reproduce in testicular tissue, which can then be transmitted through the semen during breeding. Some vaccines have the label indication for protection from BVD testicular infection.

Vaccination is one part of ensuring a healthy herd, but biosecurity and disease surveillance/testing are also important. Work with your veterinarian to help develop the most effective and comprehensive herd health program that will work for your management to help protect your whole herd and help set your future calf crops up for success.