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Selecting the Right Vaccine

Selecting the Right Vaccine
Vaccines are designed to offer effective, efficient immune control to prevent disease challenge. When vaccines fail, however, the disease process becomes derailed and the herd suffers. Veterinarians have many tools in addition to vaccination, so identification of the best option with the greatest likelihood of achieving the best end result matches the oath when considering the commitment to “do no harm.”

Vaccine selection begins and ends with a strong relationship with your veterinarian. Building a herd health program without communication with your veterinarian is like swimming in open water on a cloudy day with no idea which direction the shoreline is. You might swim fast for awhile, but you may be heading in the wrong direction.

So both you and your veterinarian need to hop in the boat together — check the weather map (with diagnostics), and then chart a course for successful production that includes routine checkups to ensure you are headed for pay dirt.

Veterinarians take an oath when they graduate to “do no harm.” The seriousness of disease problems today challenge the veterinarian’s conviction as herd health programs change and disease challenges enter the herd or change within a herd.

Vaccines are designed to offer effective, efficient immune control to prevent disease challenge. When vaccines fail, however, the disease process becomes derailed and the herd suffers.

Veterinarians have many tools in addition to vaccination, so identification of the best option with the greatest likelihood of achieving the best end result matches the oath when considering the commitment to “do no harm.”

Vaccine Selection

There are no standard health programs for a pig farm. Herd health programs are a continual series of calculated efforts designed specifically for that population in order to maximize production and optimize costs.

Vaccine selection decisions balance the need for effective, efficient control of disease, with the cost and expected benefit of the product. There are many vaccine products available for the swine producer and his/her veterinarian to consider. Some are widely used with predictable and consistent results. Some are rarely used, but also offer predictable and consistent results in the face of a known challenge. Some are less predictable and even less proven in their outcome.

The producer and his/her veterinarian need to identify disease challenges quickly and completely. They need to make vaccine selections based on a predictable outcome. They need to identify how success will be measured.

Finally, they need to maintain ongoing communication and diagnostics to stay on task with protocols, and to ensure that disease challenges have not changed.

Preparing Herd Health

Our goal with this article is to prepare you, the producer, with information you can discuss with your veterinarian as you prepare a herd health program. In formulating a herd health program, along with vaccination, consider the following six parameters:
1. Cost of disease vs. the cost of a prevention program;
2. Identification of disease and the internal controls within the herd;
3. Vaccination use as a tool to reduce medication costs;
4. Commercial vaccines in comparison to live inoculation or killed bacterins;
5. Ongoing communication with farm staff and monitoring programs; and
6. Future disease elimination programs.

Before accepting any estimates of disease cost and disease prevention, every producer has to honestly answer this question: “Do you read the label on the bottle of medical products?” The label is very telling to the actual history and proven data behind the bottle. If the label reads, “aids in the prevention of disease,” as opposed to “prevention of infection,” there are two very different sets of studies behind the product on the shelf.

Producers commonly evaluate a product based on production success in the barn and not on prevention of the infection.

There are many circumstances that can change in the ongoing process of swine production. Therefore, the producer needs to decide how success will be measured ahead of time. The specific cost controls and periods of measure allow a decision based on facts when trying to decide if an intervention was successful. Specific expectations and how success is measured are the first step.

Predicting Disease Costs

Disease costs are often relative to the severity of the infection and in combination with secondary infections. However, some estimate of range in the cost can be made in order to predict the outcome of some of the more common disease challenges.

We often break down diseases into groups by category, such as GDU (Gilt Developer Unit), BTW (breed-to-wean), and WTM (wean-to-market). The identification of a disease in an isolated GDU is certainly less costly than the identification of a specific disease in a negative sow herd BTW site. The cost/benefit for monitoring and control measures within the GDU directly relate to the success for monitoring and control in the sow herd. In the end, both are “paid for” with pig production. Therefore, we attempt to relate all costs back to the final production of healthy pigs available for to market. Table 1 provides some examples of common disease cost vs. control measures that are available.

Many more models exist for the prediction of disease cost and evaluation of control programs. The message remains the same: when diagnostics identify a clear, known pathogen and vaccines exist for specific control, the prevention is far better than any attempts at control and certainly better than the cost of disease. Producer records provide the best opportunity to manage the impact of disease. Without closeout records, the producers are left to make assumptions on their own system.

Many systems today work together for internal, system-driven research. Powerful information is being generated on system costs and disease control programs. These information networks provide the producer with the opportunity to learn and compare specific intervention strategies.

Disease Identification, Control

Challenges exist when trying to control diseases not known or specific to the vaccine. Diseases such as swine influenza virus (SIV) or Streptococcus suis (bacterial), change frequently. Both have their limitations when attempting control with vaccines.

SIV has been tested and evaluated the most. We now know that control programs designed for vaccination during gilt development, and for sow herd immunity, provide early piglet colostrum protection. This protection provides the best start for piglets instead of attempts at piglet vaccination for control in the face of active virus. With influenza, the vaccines must be changed quickly in order to keep up with changes in the virus.

Strep suis, in contrast, is not only a very different infectious organism (bacterial vs. viral), it is not the bacteria that causes the most severe disease. With Strep suis, it is the capsular antigens on the bacteria produced by active infection that are the real cost. They create the extensive inflammatory response we have commonly identified as “paddling pigs” or meningitis in piglets.

Bacteria such as Strep suis, Haemo­philus parasuis and Actino­bacillus suis, are more commonly controlled with gilt development and sow herd immunity in order to reduce infection and provide maternal colostrum protection. Much like influenza virus, these bacteria are not effectively controlled by piglet vaccinations. Rather, control programs designed to reduce the activity of these pathogens in the sow herd lead to a better start for piglets.

In contrast to killed bacterins, modified-live vaccines provide a greater level of immune response and have shown some greater degree of protection. Haemophilus parasuis bacteria is one disease where we have seen a greater degree of protection from either live exposure to the organism on the farm through live culture and exposure or use of a modified-live injection. In both cases, more complete protection leads to less losses in growing pigs. The difference is active, ongoing immune response from the piglet, and a presumed greater, long-standing protection.

Communication between veterinarians, producers and diagnostic labs has improved the ability of all parties involved to further the advancement of control programs. Laboratories now have electronic access. Diagnostic databases, both internally and at the labs, provide the producer with methods to evaluate herd history and group comparisons. Veterinarian communications are also improved as they can pull up multiple groups or even compare BTW sources with multiple WTM closeouts. The internal controls are now influenced by larger, more powerful data sets with real diagnostics behind them.

Diagnostics for information on influenza, porcine reproductive and respiratory syndrome (PRRS), and specific bacteria further a producer’s ability to know the source in greater detail. Information allows the veterinarian to advance protection programs more closely suited to the target organisms. Genetic sequencing provides better tools to track these rapidly changing disease organisms.

Vaccination Protocols

Producers and their veterinarians routinely review herd health diagnostic profiles in connection with vaccination protocols. Vaccine cost is a simple addition to the protocol sheet for the owner to review. Routine review of the vaccine protocol, as a poster on the barn door and the staff workbook, are recommended to ensure timely and appropriate vaccination protocols are maintained. Language barriers and education levels of the workforce sometimes complicate the process further. Our challenge, as caregivers for the livestock, is to train everyone involved in the daily administration of medication products.

Recently, a client notified us that his staff was giving 5cc of a product that only required 2 cc. Recognize that some products have the same bottle appearance, same color pattern, but very different products inside the bottle. Photos, worksheets, and follow-up communication reinforce the successful implementation of the program. If we were simply to ask the staff, “Has the XYZ product been given?” then, the answer is certainly “yes.” If we ask more completely, “Can I see the bottle and syringe you used for administration of the XYZ product?” then, we may get a very different answer.

Figure 1 (page 28) provides a sample farm vaccination program worksheet prepared by the Carthage Veterinary Service, Ltd. It covers potential vaccines to be given to the sow herd, pigs and replacement gilts.

Disease Control Options

Veterinarians and producers alike have long known the value of live exposure for disease control. Transmissible gastroenteritis (TGE) virus breaks have been the single fastest method for education in the value of live exposure.

When TGE virus breaks in a sow herd, three weeks of piglets are lost before the entire sow herd and gilt pool can be exposed and maternal colostrum protection can build. The best news is, once the virus exposure is created, the maternal protection is very solid, and piglet survival returns to the same level as before. Using feedback or live virus exposure through other methods is not as successful with diseases when the infectious agent is not as highly conserved as the TGE virus.

By comparison, the PRRS virus is much different and a more complex infection. Live virus inoculation with PRRS virus has been quite commonly practiced. We find it to be the most solid means of complete protection with the highest degree of success when attempting to remove this virus from a population. While this sounds backwards, the live exposure to all animals in the population, allows the entire group to develop immunity simultaneously.

We use PRRS inoculation and herd closure as an elimination tool. But the limitations of live virus inoculation with PRRS virus are many. Piglet quality is one of the first shortcomings as we know the virus will impact development of the piglets within the sow for several weeks. Piglet quality can suffer for as long as 12 weeks or as short as four weeks. The predictability of this outcome is difficult to quantify. But long-term, successful control with modified-live PRRS vaccine has also achieved mixed results in virus elimination in our experience.

The difference in using a live exposure method instead of a commercial vaccine product has to do with the organism present and the outcome you desire. With PRRS virus in sow herds, where we know we have a high likelihood of elimination, we will inoculate and close the herd. Where we have ongoing area spread and a high degree of risk, we will use herd stability through modified-live vaccination as the means of control.

Future Elimination Programs

Infectious organisms will always be a part of livestock production. Working to eliminate the list of disease-causing agents is a goal worthy of working together. Disease elimination is not a single herd decision, but rather a population decision. Area spread of diseases, like PRRS and Mycoplasma pneumonia, make both organisms difficult to remove, but there are many herds throughout the country that have eliminated both. Tight biosecurity through air filtration and location will further these elimination efforts.

In the meantime, there are certainly several disease elimination programs proven successful with bacterial and parasitic diseases that are less likely to travel long distances. Actinobacillus pleuropneumonia is a bacteria we can eliminate. Depopulation and herd cleanup can be cost effective. Elimination has a high degree of

Sarcoptic mange is a parasite we also can eliminate. Much to my surprise, there are herds still allowing these external parasites to steal production. Elimination programs for mange have been proven effective for two decades.

Finally, the commitment of producer and veterinarian to provide for the well-being of the animals in their care, challenges each of us to work harder to identify causes of disease, to review prevention, control and elimination programs, and to further the long-term implementation strategies that keep pigs healthy and make our industry profitable.

As you review your herd health program, please dig deeper into the diagnostics, organize a well-planned program, understand the limitations of the products you are using, and educate those responsible for executing the plan.