Calf Scours (Neonatal Diarrhea)

Causative agent: Rotavirus
In cattle, there are many agents associated with calf scours. These include E.coli, rota virus, corona virus, breda virus, calici virus, parvo virus, astro virus, cryptosporidium, giardia, BVD, salmonella, and Clostridium perfringens (9). In bison, rotavirus is associated with neonatal diarrhea (19).

This disease is not as common in bison as it is in cattle. In cattle, stress factors to which neonatal calves are exposed, such as overcrowding, extreme weather conditions, poor nutrition of the dam, inadequate consumption of colostrum, are thought to predispose the calves to the disease (9). Calf scours may not be as prevalent in bison because calving occurs later in the spring when weather conditions are mild. During the calving season bison are usually out on spring pastures. The nutrition provided to the cows by the new pasture will usually be good and the cows will not be overcrowded. The occurrence of calf scours in neonatal bison calves has been associated with overcrowding (19).

Clinical signs:
The most consistent clinical sign is watery diarrhea(19). As the disease progresses the calves with scours may become dehydrated, weak, and depressed. They may stagger and will often become recumbent before death.(19). In some cases the calves show minimal clinical signs and may be identified as being sick only when the disease has progressed to the point where treatment is unrewarding, and death is impending (19). In some instances, the first indication of scours is the occurrence of mortalities in the herd (19).

Since bison calves have the ability to mask clinical signs of disease, it is important to constantly monitor the fecal output of neonatal calves. This involves observing the calves while they nurse, observing the perineal area of calves as they walk away from the observer, and observing the bedding areas of calves for diarrhea like feces.

Postmortem findings:
The pathological findings associated with calf scours in bison calves include: dehydration, emaciation, and fluid feces in the intestinal tract (19).

Fecal samples taken from bison calves with scours may be submitted to a diagnostic pathology laboratory for bacterial culture and virus isolation. Postmortem tissue samples should be sent to a pathology laboratory for histopathology, bacterial culture and virus isolation.

Many bison calves with scours recover spontaneously (19). Treat bison calves when they become dehydrated, depressed, start staggering, or are too weak to nurse. Treating scouring bison calves commonly involves removal of the calf from its mother. Removal of a calf from its mother for evan a few days will result rejection of the calf when it is re-introduced. These calves must then be hand reared, or they will starve to death. Making a decision to remove a bison calf from its mother for treatment most often involves a decision to hand rear the calf if it survives the disease. A provision for hand rearing should be made at the time the decision is made to treat the calf.

Hand rearing neonatal bison calves requires considerable time commitment. Success has been achieved by bottle feeding bison calves with fresh cows milk, bovine calf milk replacer, or by using nanny goats as surrogate mothers. It is important to consider the disease status of the donor cow, or goat, and the farm from which they originate. Johne’s disease is relatively common in beef and dairy herds. Inquiries should be made as to whether the herd of origin has had any cattle diagnosed with Johne’s disease, whether they do any testing for Johne’s disease, and whether they have had any cattle that develop chronic diarrhea. Malignant catarrhal fever is common in goat populations. The virus may be found in goats that are clinically normal. Before a goat is brought onto a bison ranch, it should be blood tested to determine if it is carrying malignant catarrhal fever virus.

Treatment of bovine calves with neonatal diarrhea involves oral or intravenous replacement of the fluid and electrolytes that are expelled from the calf’s body with the feces. The fluid and electrolyte imbalances that occur in neonatal bison calves with scours have not been documented. It may be incorrect to assume that the imbalances that occur in bison calves are the same as those that occur in beef and dairy calves. Cattle are, however, the closest species to bison from which to draw information for the development of bison treatment protocols.
Oral replacement of fluid and electrolytes may be attempted by administering commercially available electrolyte replacement solutions. There are many of these products available, none of them are specifically designed for use in bison calves.

Bison calves with scours will frequently be unable, or unwilling to suck a nipple. In this case, fluids will have to administered via a stomach tube or an esophageal feeder. Oral replacement electrolyte solutions may be administered to scouring bison calves at the rate of 1 to 2 liters every 4 to 6 hours. The calf’s hydration status and fecal output should be monitored and the rate of administration adjusted accordingly. If the calf fails to respond to oral electrolyte replacement, electrolyte solutions such as lactated ringers may be administered intravenously. Scour boluses may not have any affect on the outcome of the disease. Their use is not recommended. Scouring bison calves may be susceptible to other infections. It may be advisable to treat scouring calves with parenteral antibiotics.

In Canada and the United States there are many commercially available scour vaccines. None of these vaccines have been approved for use in bison. Since the agents that cause neonatal diarrhea in bison have not been determined, and since these agents may be different from those that cause neonatal diarrhea in cattle; the efficacy of these vaccines for the prevention of neonatal diarrhea in bison calves is questionable.

The occurrence of neonatal diarrhea may be associated with many determinants other than bacterial or viral agents, such as wet environmental conditions, overcrowding and poor nutrition of the dam. If a herd problem arises it would be prudent to try to identify not only a causative agent specific to the herd, but also other environmental factors that may be significant contributors to the development of the disease. Since the efficacy of commercially available cattle scour vaccines is questionable, better results may be achieved by altering environmental conditions and management programs, than by vaccinating bison.


Back to Bison Disease