– Dr. Michelle Arnold – DVM, MPH UK Ruminant Extension Veterinarian
“Neonatal” calf diarrhea is defined as scours occurring within the first 3 weeks of a calf’s life. Viruses (rotavirus, coronavirus), certain bacteria (E. coli K99; Clostridium perfringens Types A and C, Salmonella spp.) and the protozoan parasite Cryptosporidium parvum are the most common causes in beef cattle operations. Controlling rotavirus, coronavirus, Clostridium perfringens Type C, and E. coli K99 scours through vaccination can significantly reduce calf sickness and death loss when given correctly. Scours vaccines are formulated to be given to pregnant cows and heifers during the third trimester of gestation so they will make the specific antibodies against the pathogens that cause diarrhea while colostrum is being formed. It is important to remember that scours vaccines given to pregnant cattle will only work if an adequate amount of good quality colostrum is consumed by her newborn calf within the first 12 hours (preferably the first 6 hours) of life. If unable to vaccinate the pregnant females in the herd, a variety of products can be given to newborn calves to help reduce the risk of sickness and death from scours as well.
The three most popular vaccines available for use in pregnant cattle are ScourBos®9 and 4 (Elanco), ScourGuard®4KC (Zoetis) and Guardian® (Merck). The first time scours vaccines are used, a two-shot series must be given in the third trimester of pregnancy consisting of a first or “primary dose” followed by a booster dose. After the first year, just one annual revaccination in late gestation is required every year throughout the cow’s reproductive life. Vaccination timing is critical to stimulating and optimizing antibodies in colostrum. If cows are vaccinated too early in pregnancy, the antibody response may start to fall off prior to the colostrum being made. Vaccinating too late and the colostrum may already be produced before an antibody response is mounted. Which product is chosen often depends on when cattle will be worked; Scour Bos® is administered earlier during pregnancy, ScourGuard® is used latest in gestation and Guardian® is in-between these two options. Obviously not all calves will be born the first week of calving season but plan to give the scours vaccine based on when the first calves of the season are expected. Consider administering an additional dose to those females who have not calved within 2 months of receiving their scours vaccine.
Table 1: Retrieved from : https://firstdefensecalfhealth.com/dual-force-bolus-gel/
It takes some planning to vaccinate correctly; timing is critically important when selecting the correct product for your operation:
1) For pregnant heifers (or cows) receiving their first or “primary series” of scours vaccine, manufacturers give a date range for one dose and a set date for the other dose that varies depending on vaccine chosen. Note that Guardian is the only one administered subcutaneously.
• Scour Bos®9 – Administer the first dose (2 ml IM) 8-16 weeks prior to calving and booster with Scour Bos® 4 given 4 weeks prior to calving;
• Guardian®- Administer the first dose (2 ml SQ) 12 weeks before calving and the second dose 3-6 weeks later;
• ScourGuard® 4KC-Adminster first dose (2 ml IM) 6-9 weeks before calving and give the second dose 3 weeks later.
2) Cows (Annual revaccination)-
• Scour Bos®9 –Administer 8-10 weeks prior to calving season
• Guardian®-Administer 5-7 weeks before calving season
• ScourGuard® 4KC-Administer 3-6 weeks prior to calving season
Figure 1: Retrieved from https://www.merck-animal-healthusa.com/species/cattle/products/boviliscoronavirus
If the cow herd is not vaccinated and a calf scours problem develops, several products are available to administer to newborn calves. The First Defense® product line includes the Tri-Shield® gel tube, Dual-Force® gel tube, First Defense® bolus and First Defense Technology® bulk powder. These products are antibodies given by mouth as quickly as possible after birth. First Defense® makes their products by collecting antibody-rich colostrum that is purified and concentrated, then standardized to guarantee antibody levels for each dose. These antibodies bind directly to bacterial and viral antigens, ideally before they can enter and harm cells in a calf’s gut. These are not vaccines, so the calves are not required to trigger an immune response for protection. Although these antibodies will provide immediate protection in the gut, they are much more effective when given at the same time as good quality colostrum. Be aware of the label claims when using First Defense products (see Table 1 above); not all pathogens are covered by every product. First Defense® Tri-Shield® gel offers the broadest coverage, specifically aiding in the reduction of mortality (death) and morbidity (sickness) from scours caused by E. coli K99 and coronavirus while also reducing the severity and duration of scours caused by rotavirus. Interestingly, the First Defense® gels have an added blue dye that renders the calf feces green, allowing the producer to know the gel has gone through the calf’s GI tract. For an economical option, First Defense® offers a nutritional supplement powder with the same ingredients as the boluses, and it is shelf stable in a resealable bucket. One level scoop is mixed with fresh or thawed colostrum until completely dissolved and then fed to the newborn calf.
Figure 2: Retrieved from https://coloradoserumcom.3dcartstores.com/ cd-antitoxin
Commercially available vaccines have also been designed to be administered to the newborn calf for protection from certain viruses. Calf-Guard®, manufactured by Zoetis, is an older product that contains attenuated (modified live) strains of bovine rotavirus and bovine coronavirus. It can be administered either by injection to a pregnant cow within four weeks of calving or to newborn calves by mouth before nursing to help protect calves from scours caused by rotavirus or coronavirus. A brand-new product, Bovilis® Coronavirus (Merck), is an intranasal vaccine administered to healthy calves 3 days of age and up to reduce the duration and severity of diarrhea due to bovine coronavirus (Figure 1). To protect against Clostridium perfringens Type C, Colorado Serum Company produces a C. perfringens Types C & D antitoxin Figure 2) labeled for prevention lasting approximately 3 weeks after 10 ml administration SQ at birth. However, there is limited availability of this product because of stringent testing requirements in equine donor animals as this product is made from equine serum.
Scan QR code to go to UK Beef Cow Forage Supplementation Tool.
Preventing calf scours is much more about management than simply administering a vaccine. Cow nutrition during and after gestation, careful monitoring of the calving process, and environmental factors all contribute to a successful start. The cows’ diet must provide adequate energy, protein and trace minerals to meet her needs during gestation and lactation, especially during winter. Remember up to 80% of fetal growth occurs in the last 50 days of gestation and colostrum production ramps up during the final 4-6 weeks of pregnancy. Monitor body condition scores and be ready to offer supplemental feed to maintain a BCS at calving of 5 in mature cows and 6 in heifers. A nutritionally deprived dam will produce poor quality and quantity of colostrum, have less energy to deliver a calf quickly, and will be slow to rebreed. Calves born to energy deficient dams will be slow to stand and nurse.
Monitor and be ready to assist with calving early as necessary, especially with heifers. Make sure calves start nursing as soon as possible after calving, keeping in mind that calves should stand within 30 minutes of delivery and nurse within 30 minutes of standing. If in doubt, use a good quality colostrum replacer and feed the calf at least twice during the first 6 hours of life. Once the calf has received colostrum, it is still important to prevent the “bad bugs” (pathogens) in the environment from overwhelming the calf’s immune system. Over time, calves infected earlier in the calving season are “pathogen multipliers” and become the primary source to younger calves. Calf scour pathogens will build up exponentially in the environment as the calving season progresses.
Poor sanitation, cold, wet weather and overcrowding all contribute to a higher risk of disease, especially conditions in calving and maternity areas. Exposure to bacteria, viruses, and protozoa occurs through direct entry of manure to the mouth of a calf by contact with manure-contaminated teats, soiled bedding, and through self-grooming. Calving in the same area for an extended period of time greatly increases the disease risk to the youngest calves, especially in wet or muddy conditions. If possible, pregnant cows close to calving should be rotated onto clean pastures while cow-calf pairs remain on the old pasture. If calving in a barn or shed, the calving area should be kept as clean and dry as possible with frequent changes of bedding to remove the buildup of organisms. Make every effort to get the cow and newborn calf out of the barn quickly to lessen the chances of infection. Even the best calving management practices will have no effect if the first thing a calf ingests is manure from the calving area. Consult with your veterinarian on ways to address a calf scours problem and the best choice of vaccines for your operation.
The UK Veterinary Diagnostic Laboratory has an excellent test to diagnose the cause of calf diarrhea. A small sample of scours (in a leakproof container) from a calf that has not been treated for diarrhea with antibiotics is the best sample to run the test. The “Calf Diarrhea Panel” is a PCR assay that detects the nucleic acids in bovine coronavirus, rotavirus, E. coli K99, Salmonella and Cryptosporidium. Results are available within 2-3 days and costs $62.75 + $10 Accession Fee. Visit the website at https://vdl.uky.edu/ for more information or call (859) 257-8283.
*The products described are for educational purposes only and should not be considered an endorsement by the University of Kentucky.