A producer makes an initial call to their veterinarian, concerned about a sudden and severe case of neonatal calf scours in their herd of calving beef cows. This is a call that veterinarians dread receiving and cow-calf producers throughout the country make far too often. Neonatal calf scours (diarrhea) is a multifactorial issue and can be very aggravating, time-consuming and costly for producers, particularly at this time of year. The risk and occurrence can change year to year based on many different factors, which often makes it difficult to mitigate. While much is frequently written on causative pathogens, symptoms and treatment, it is often helpful to review real-life examples to better understand all aspects of this disease and how to prevent it, which is the intent of this discussion.
The aforementioned producer states that they have been observing lethargic calves for several weeks with loose, watery stools that are mostly yellow and grey in color. Many of these calves are said to have wet manure coated on their tails and rear legs, and some have sunken eyes and appear to be dehydrated. These are all very common clinical symptoms of scours, which are often easily identified by producers and veterinarians alike.
Upon in-person inspection by the veterinarian, several critical factors regarding the herd are noted. The producer has recently purchased these pregnant first-calf females privately from another operation, but it is verified they have received appropriate pre-calving scours vaccinations. Females are in a body condition score (BCS) greater than or equal to 6, so they have received adequate energy prior to calving. This group of females is being managed in a single common calving area due to feed and water availability but are not being commingled with nor do they share a common water source or fenceline with other mature cows. Although not experiencing severe cold weather stress, the herd is subjected to cool, damp and muddy weather conditions typical for the season. Most calves affected are between 1 and 3 weeks of age. An absence of blood in the manure from affected calves eliminates coccidiosis as a potential causative agent, and it is further confirmed that calves are not experiencing “milk scours,” or nutritional scours as is often seen with white, loose manure. This initial information supports that the causative agent is not likely bacterial. However, a post-mortem necropsy was conducted by the veterinarian of fresh calves that succumbed to the illness, and proper samples were submitted to the veterinary diagnostic lab for analysis.
Providing treatment
With the specific cause yet to be determined, the attention is now turned toward providing effective treatment to calves and giving them the best chance for survival. It is clear that calves have become weak and dehydrated due to diarrhea and a lack of nursing, and treatment of scours must be directed toward rehydration and correcting the main issues of acid/base imbalance and electrolyte imbalance. Both the veterinarian and the producer understand the importance of keeping calves hydrated, and oral electrolyte and fluid therapy is initiated on affected calves using a recommended product. Likewise, a limited number of extremely dehydrated and lethargic calves received IV treatment administered by the veterinarian in addition to thermal support to help increase calf vigor and the desire to suckle. While calves do respond to treatments, the overall impact of the disease is substantial. Within a month, this herd experienced a 50% and 20% morbidity and mortality rate of newborn calves, respectively.
Diagnostic laboratory results received later on indicate the presence of both rotavirus and cryptosporidium as causative pathogens in this herd. But where did these agents originate from? The fact that this group of females was purchased and transported in from an outside herd points to a potential source of infection. Again, females were fully vaccinated and nutritionally well managed, but that doesn’t preclude them from carrying infectious pathogens. Further discussion between the producer and the veterinarian weeks after the initial call reveals a key contributing cause of disease in this herd. A sale barn calf had been brought into the herd to graft onto a female that lost her calf during the initial days of the calving period. This calf and the cow it was grafted to were not quarantined from the rest of the herd for any length of time but rather introduced to the group and calving area immediately.
An ounce of prevention …
No one’s goal is to inadvertently introduce disease into an operation, but it is something that happens often and can be easily overlooked. In this situation, both the females themselves and the orphaned calf were brought in from other herds. However, the calf acted as a disease amplifier, shedding pathogens to susceptible calves born later in the calving period. Had a quarantine been implemented as part of a basic biosecurity plan, the results may have been more positive. During these situations, it is also important to understand that the tools we use and even our clothes can be the conduit of spreading disease to newborns. Using separate feeding tubes and bottles for sick calves is a must, as well as changing clothes or handling sick calves after addressing the needs of healthy ones. The shedding of pathogens from older calves and subsequent exposure to those born later is a primary reason that calf age segregation is effective at reducing contamination and risk of the disease, much the same way the Sandhills Calving System is designed. If we can provide some degree of age segregation and limit the accumulation of pathogens on the calving ground, then we ultimately help reduce the risk of exposure due to environmental contamination. Typical of many farms and ranches, segregating cows and calves by calf age is not practical in the described case due to facility constraints. In the situation when a single calving area is utilized on the operation, strict management may be necessary to mitigate risk.
Rotating feeding and resting areas throughout the pasture can also dilute the amount of contamination that newborn calves are exposed to. This may include utilizing portable windbreaks or shelters, unrolling hay in different locations or moving hay feeders as the season progresses. Ultimately, cows and newborn calves should be turned out into a “clean” pasture as soon as possible after birth. Cleaning barns and maternity pens and removing soiled bedding is always critically important to reduce pathogen load, as these areas also become contaminated throughout the season. After assisting births, cleaning teat ends of the cow will reduce the exposure of environmental pathogens during the calf’s first suckling opportunity.
Calving is a stressful time for all involved, and an outbreak of neonatal scours only makes things more challenging. Management details that may seem minor can have significant impacts on the operation. Again, it is never anyone’s intent to make a management error. It happens, and it happens to all of us from time to time. However, having regular conversations with our local veterinarian can help us think about our management plan and reconsider those areas we need to change or improve on, hopefully before undesirable outcomes develop. Work with your local veterinarian to develop a plan for preventing and managing calf scours that fits for your operation. We wish all cattle producers and their animals a healthy and safe spring-calving season.
