WSU College of Veterinary Medicine senior paper highlights

By Olivia Riblett (Advisor: Dr. Craig McConnel)

Summary: Secure Milk Supply Plans are enhanced biosecurity plans created to protect a dairy in the face of a Foot and Mouth Disease outbreak. In the summer of 2022 a team of Washington State University veterinary students, Northwest Dairy Association field managers, and Washington State Department of Agriculture officials created Secure Milk Supply Plans for 38 Farm Production Units and 2 calf ranches across Washington State. This project was successful due in part to the collaboration of the different members of the team, preparation in the face of an outbreak, the follow-up meeting, and the use of technical resources. Some proposed improvements of the plan included face covering and worker movement regulation, consideration of airborne spread of FMD, vehicle movement, carcass management plans, plans for growers and calf ranches, traceability, and creating the plan in Spanish.

Conclusions: The SMS plan is an invaluable resource for every level of dairy production. It gives producers the space to prepare for an outbreak before it occurs. Observationally after a summer of creating SMS plans it was found that the producer’s input was foundational to the SMS plan. It was helpful to have a team composed of co-op employees, students, and state officials in order to form a complete and applicable plan. Creating the time and space for a follow-up meeting allowed for continued conversation and understanding of how the plan could be applied. There are many grey areas in the research of FMD and the SMS plans could grow as more research is performed. These grey areas include airborne spread of FMD and the potential for humans to act as agents of spread to susceptible animals. To increase compliance with the SMS plan it is important for it to be written in both English and Spanish. Finally, giving producers the facts about carcass disposal and providing resources for them could greatly decrease the time between decontamination on a farm and return to business. It is the author’s hope that SMS plans can continue to be made for dairies across the US to help prepare farmers for the potential of an outbreak. It is also a hope that other students can have the experience and depth of learning that a summer of creating SMS plans allowed.

By Meghan Mutch (Advisor: Dr. Craig McConnel)

Summary: The disease complex known as Bovine Respiratory Disease (BRD) is perhaps the most economically important disease in the U.S. cattle industry that many bovine veterinarians encounter on a daily basis. Although BRD is often considered to be a more common disease in beef cattle, its impact on the dairy industry is equally important, with increased costs regarding treatment, labor, and productivity loss seen in dairy animals affected by respiratory disease in early calfhood. Along with other environmental modifications, vaccination is one of the most utilized disease management strategies for BRD and can include vaccinating for both the bacterial and viral pathogens that contribute to bovine respiratory disease. The success of vaccination depends on the strength of the immune system stimulation by the vaccine, either as a modified-live virus vaccine or killed/inactivated vaccine, given either intranasally or parenterally. There is variable evidence on BRD vaccination efficacy, but the consensus of the current literature is that vaccines against BRD viral pathogens tend to be more effective than those against BRD bacterial pathogens, modified-live virus vaccines provide a more robust immune response compared to inactivated vaccines, and all dairy calves should receive at least two doses of a respiratory vaccination prior to their first breeding. There is not a singular, “one size fits all” vaccination protocol that may be applied to every dairy operation; a bovine veterinarian should attempt to understand the goals of their clients with production and disease prevention and use a multimodal management approach to BRD in order to reduce its prevalence on any dairy operation. The BRD complex may always be present in the dairy industry, but an effective vaccination protocol combined with quality animal husbandry techniques may significantly reduce BRD incidence on an individual dairy.

Conclusions: There are many different ways to build a vaccination protocol for a typical dairy cattle operation. A key similarity between protocols is the importance of vaccinating for BRD, a common disease complex that has widespread prevalence in the U.S. cattle industry. It is essential for veterinarians to also be familiar with core vs. risk-based vaccinations for cattle in order to assist their clients in building an individualized vaccination protocol for their herd, especially when it comes to BRD. Although there is an overwhelming number of vaccines to choose from, veterinarians should refer back to the basics of vaccine immunology while using the AABP vaccination guidelines as a template for providing their clients with advice on building a vaccine protocol. Understanding how the immune systems of dairy calves develop and how vaccines can help boost this immune system development is essential when designing a dairy cattle vaccination protocol. Differences in goals of the operation and movement of livestock will result in differences between protocols among clients as well, so a veterinarian should ensure they modify vaccination schedules as needed between clients to fit the needs of their dairy. Veterinarians should also explain to their clients how vaccines work so they know when to use which type (such as when to use MLV vs. killed). There is much to improve on with BRD vaccine efficacy, but the ability of the current vaccines to provide some clinical disease protection is still helpful in combating the BRD complex. Vaccines are a useful tool for both veterinarians and dairy producers; although no management strategy is perfect, a multimodal approach that includes a well understood and effective vaccination protocol is likely to be more successful on any dairy operation than an operation without vaccines targeting BRD.

By Carol Grace Maxwell Majors (Advisor: Dr. Ramanathan Kasimanickam)

Summary: Scattered areas across the United States are known to have selenium deficient soils. Paired with an improper soil pH and available selenium compounds consequently forms selenium deficient forages. In these areas, syndromes associated with selenium deficiency are relatively common. The trace mineral selenium is incorporated into many selenoproteins throughout the body which play important roles such as within the active site of a group of antioxidants called glutathione peroxidases. Through its incorporation into so many proteins it is utilized within the immune system, during conversion of thyroid hormones, in fetal development, and within reproductive systems. When selenium requirements of 0.1mg/kg for maintenance (more for pregnant and lactating cattle) are not met, clinical manifestations arise, which present differently in different age groups. These have been described as white muscle disease (WMD) in neonates, nutritional (enzootic) muscular dystrophy (NMD) in calves and yearling cattle, and reproductive deficiencies in adult cattle. Diagnosis of selenium deficiency may be done by soil and pasture analysis, serum and whole blood selenium levels, erythrocyte glutathione peroxidase activity, liver biopsies, and necropsies of deceased animals. Treatment is rarely successful in neonates but effective in older cattle. Injectable selenium along with continued preventative selenium is important. Prevention is the mainstay in deficient areas and implementing selenium supplementation year-round is recommended.

Conclusion:  As a micronutrient that is essential for the cellular functioning of all cattle, selenium is something that cannot be overlooked. With the northwestern United States having low to variable soil and forage selenium levels, it is an important topic to be discussed regarding its role in beef herd health.  Reproductive efficiency, herd immunity, and calf crop productivity all rely on selenium’s role in the bovine’s daily functions. It is important to understand how individual herds are being impacted by the selenium state of their area and their animals to create a plan for better supplementation.

By Frederick Johnson (Advisor: Dr. Patricia Talcott)

Summary:  Malignant catarrhal fever (MCF), caused by a subfamily of gammaherpesviruses, can have devastating consequences when introduced to susceptible species. Many outbreaks are sporadic with only a single or few animals that develop disease as is the common presentation in cattle; however, there is an increased morbidity and mortality experienced in bison making it common to have more cases occur due to their increased susceptibility. With its plethora of clinical signs, ability to survive in the air over long distances, and long incubation period, the disease can be a challenge for veterinarians to diagnose in cases of isolated outbreaks. It is unfortunately a disease with no cure and no vaccine, so management is the best way to prevent future outbreaks in vulnerable populations. 

Conclusion:  Malignant catarrhal fever is a disease of major concern worldwide. Even though outbreaks are uncommon, when they occur, the mental and financial toll can be immense. The clinical signs can be very sudden, severe, and overwhelming for producers to witness. While testing is available to determine if an outbreak is occurring or has occurred, there are no real resources available to treat the disease. After susceptible animals start showing signs, high levels of mortality can be expected to occur, and slaughter may be the only option available to mitigate further suffering of these animals. With no vaccine currently available, simple methods of prevention such as separation of animals from each other during periods where reservoir hosts are more likely to be shedding the virus remain the best option to prevent outbreaks.