What is scours, and what causes it?
Scours is a term for diarrhoea; another term that may be applied to this disease is “enteritis,” which means inflammation of the intestinal tract. While cattle of any age can develop diarrhoea, most cases of calf scours occur under one month of age, with the majority occurring between roughly 3 and 16 days of life.
There are a variety of causes of scours in baby calves. Most of these are infectious agents.
• Viruses: Examples include rotavirus and coronavirus, bovine viral diarrhoea (BVD)? • Parasites such as Cryptosporidium and coccidia
• Bacteria: Certain strains of Escherichia coli, Salmonella, and Clostridium perfringens
Scours is often caused by more than one of these infectious agents acting together. Overcrowding is a major contributing factor to calf scours. Overcrowding causes the number of these infectious agents in the environment to increase dramatically.
• Certain dietary items may result in diarrhoea. These include excess milk production by the dam (the calf ingests more than it can digest), ingestion of foreign objects such as dirt and sand, and from people feeding things that baby calves can’t digest, such as molasses or table sugar (sucrose).
How do scours harm the calf?
The primary harm from scours is loss of water and electrolytes (body salts) in the diarrhoea. This loss of water and salts creates dehydration and alteration of the acid-base balance of the bodily fluids. Inflammation of the intestinal lining impairs the calf’s ability to digest nutrients, creating weight loss and the potential for hypoglycaemia (low blood sugar). If untreated, these changes can be severe enough to result in death. In addition, certain bacteria (certain strains of Salmonella and Clostridium perfringens) can release toxins that cause harm to multiple vital organs in the calf.
What are the common signs of scours?
• Watery stools that may be brown, green, yellow, or grey in colour. Occasionally, flecks of blood and mucus may be evident in the stools. Rust colored or very bloody stools are often associated with infection with Salmonella, coccidia, or Clostridium perfringens.
• The calves are often weak and depressed, and may lose their desire to nurse.
• The calves develop a sunken-eyed appearance as a result of dehydration. The bony prominences of their hips, shoulders, and ribs may become more apparent as the calves dehydrate and burn their body fat supplies.
• The calves may stagger or sway as they walk; this often reflects weakness, low blood sugar concentrations, and/or alteration of the acid-base balance of their bodily fluids.
• The calves may become too weak to stand. Death typically occurs within a day if treatment is not initiated.
• Depending on the cause(s) and the severity of the infection, a case of scours in a calf can last 1-2 days or as long as 2 weeks.
How can calf scours be prevented?
- Because many of the infectious agents that cause calf scours are shed by healthy cows and calves, it is not considered practical to expect to prevent scours from ever occurring on a farm. Rather, a target should be to have no more than 2-3% of calves born each year develop scours.
- Maintain a clean calving area. Do not calve on pastures where cows have been kept in large numbers for long periods of time.
- Segregate calves by age to prevent passage of infectious agents from apparently healthy, older calves to new-borns.