Source: University of Minnesota Extension
Joe Armstrong, DVM, Extension educator, cattle production systems
- The goal of vaccination is to provide protection from disease through immune system memory.
- There are two main types of vaccine: modified live vaccine (MLV) and killed vaccines.
- The “core” vaccinations are determined by the impact of the diseases, the likelihood of exposure, and the risk of unprotected exposure.
Why do we give vaccines?
Vaccines are given to mitigate risk. Vaccines provide added insurance for cattle producers to protect their herds from many different diseases. The factors that warrant vaccination are:
- The likelihood of disease exposure is high, or the risk of unprotected exposure to a disease is high.
- The vaccine is effective.
- The cost of the vaccine is justified.
Goal of vaccination
The purpose of vaccinating is to protect the herd from harmful diseases for health, economic and welfare reasons. To provide protection, the immune system must develop memory. With each vaccination and booster, the goal is to provide the protection needed by triggering the immune system to recognize the disease.
Vaccines do not provide absolute protection
Most vaccines do not prevent infection; instead, they prevent or aid in the prevention of clinical disease. Important to note, vaccines are not absolute protection. The immune system can be overwhelmed even if a vaccine is in place. If cattle become immune-compromised or exposed to an extremely high number of pathogens (disease-causing organisms), the vaccine may fail to protect from clinical disease.
In general, there are three types of vaccines. Modified live, killed/inactivated or a combination of both.
Modified live vaccine (MLV)
- MLV’s are non-disease causing versions of a virus or bacteria.
- The live virus or bacteria replicate in the animal similar to how the actual disease would, but does not cause the disease itself.
- The replication of the vaccine organism allows the immune system to develop a full response and create protective immunity with only one dose of the vaccine.
- Many protocols recommend revaccination because not all animals respond to each vaccination.
- Killed vaccines do not contain a live virus or bacteria.
- Killed vaccines contain a dead organism or a specific piece of an organism that is critical to the function of the disease-causing virus or bacteria.
- The crucial difference between killed and modified live vaccines is there is no replication with a killed product.
- For most vaccines, the lack of replication means the immune system does not develop the protective memory with just one dose and requires a booster.
- Some vaccines contain both modified live and killed products.
- These vaccines can protect against the live portions with one dose.
- The killed portion requires a booster to provide protection.
Revaccination and boostering
Revaccinating and boostering are often used interchangeably but technically are different. Clearing up the definitions will help everyone be on the same page. As a general rule, give vaccines three weeks apart, whether revaccinating or boostering.
A term used almost exclusively with MLV, revaccination is giving a vaccine more than once to try to reduce the total number of non-responders in a group. Not every animal mounts an immune response to every vaccination. To create a comfortably low proportion of non-responders in a group, give a MLV more than once.
- Even in the best-managed herd, the percent responders in one round of vaccination are likely no more than 90%. This leaves 10% of the herd unprotected.
- Revaccination with the same efficacy would then leave only 1% of the herd unprotected (10% first vac x 10% 2nd vac = 1% probability in the non-responder group both times).
This term refers to giving a vaccine more than once to create protective immunity that cannot be achieved with only one dose. With killed vaccines, the first dose presents the antigen to the immune system, resulting in a small immune response, but little to no memory. The second dose presents the antigen again, resulting in a more substantial response from the immune system. The second dose provides protective immunity through memory.
What are the common diseases the cattle industry vaccinates for?
Both beef and dairy operations have the same fundamental diseases that are a concern. The diseases are usually categorized by the system they affect.
Respiratory viruses and bacteria
- IBR – Infectious Bovine Rhinotracheitis – often referred to as “red-nose,” this virus causes massive upper respiratory inflammation. The virus also causes reproductive issues.
- PI3 – Parainfluenza 3 – this common disease causes an upper respiratory infection and leads to secondary infections from other viruses and bacteria.
- BRSV – Bovine Respiratory Syncytial Virus – This virus causes disease in the lower respiratory tract and can cause viral pneumonia or secondary bacterial pneumonia.
- BVD – Bovine Viral Diarrhea – BVD causes generalized immune suppression and leads to secondary infections from other viruses and bacteria. In addition to immune suppression, BVD can cause reproductive issues.
- Mannheimia haemolytica – this bacteria is often a secondary infection caused by either a primary viral infection or immunosuppression from stress. The bacteria has a unique leukotoxin, which can kill white blood cells and lead to massive inflammation in the lungs.
- Pasteurella multocida – this bacteria is often the cause of “summer pneumonia” in our pre-weaned beef calves, but can affect all cattle. Like M. haemolytica, the initial infection is usually secondary to primary viral infection, stress, or previous lung damage.
- Histophilus somni – like the other bacteria on this list, H. somni is mostly a secondary pathogen to primary viral infection or stress. The bacteria travel through the bloodstream to affect mainly the lungs but can be a significant concern in other areas of the body, especially the brain.
Reproductive viruses and bacteria
- IBR – Infectious Bovine Rhinotracheitis – IBR can cause infertility, abortions, and birth defects.
- BVD – Bovine Viral Diarrhea – BVD virus can cause abortions and birth defects. Most importantly, the BVD virus can create persistently infected calves if the cow is exposed to BVD in a specific time of pregnancy.
- Leptospirosis – Commonly referred to as “Lepto,” this bacteria causes abortions. Both deer and rodents harbor the bacteria.
- Brucella abortus (Brucellosis) – The vaccine for this disease is commonly referred to as “bangs vaccination.” This bacteria causes abortions. The wild reservoir is bison and elk in the western portions of the US.
- Clostridium chauvoei (Blackleg) – One of the most common vaccinations given, Blackleg refers to a disease caused by this bacteria. Many other clostridium organisms are common and often included in the vaccines.
- Clostridium haemolyticum (Redwater) – This bacteria causes massive kidney and liver damage by releasing a potent toxin. A liver fluke infestation often facilitates the infection.
- Clostridium tetani (Tetanus) – Tetanus is an incredibly deadly disease. The bacteria grows in areas where oxygen is scarce. The disease is a concern with specific management procedures such as banding castration.
The core vaccinations for cattle
The “core” of any vaccination protocol is determined by the likelihood of exposure and the risk of unprotected exposure. When diseases impact productivity, health, or welfare, and exposure is frequent or unprotected exposure is potentially disastrous, the disease is included in the “core.” Generally, the core vaccines are thought of as the minimum protection needed.
Respiratory core – modified live vaccine – “5-way.”
- BVD Types I and II
- BVD Types I and II
- Add Redwater (C. haemolyticum), and/or Tetanus (C. tetani) depending on location and management system.
With clostridium vaccines, Redwater and Tetanus are not included in every available vaccine. Often the standard 7-way clostridial vaccine does not include coverage for Redwater or Tetanus. Consult your veterinarian if you have questions about what is included in each vaccine.
What should you vaccinate for and what products should you use?
Ideally, each system would include coverage for at least the core diseases. No “cookie-cutter” protocol will fit every cattle system.
To produce an effective protocol that matches your system’s risks and logistics, consult with your veterinarian.
There are many different products available, and ultimately the choice of what to use will come down to efficacy, price, and personal preference. Knowing what products will fit your system best is also a question to ask your veterinarian.