Death typically occurs if a calf loses 12% of body weight. Considering a calf can lose 5-10% of bodyweight in a day, quick identification and treatment is paramount (Garthwaite et al., 1994). It is important that all farms have a protocol on how to deal with scouring/dehydration, with all employees capable of identifying and treating calves swiftly. Sick calves can be identified through sunken eyes, breathing speed, coughing, runny nose, droopy ears and delayed suckle response, but the best/simplest method to evaluate hydration is neck skin tenting (Fig.1). Here you pinch the skin, then release and count the seconds until the pinch flattens. If skin takes 2-6 seconds, a calf is 8% dehydrated and over 6 seconds, a calf is 10% dehydrated (Fig.2).
Fig 1. Skin Tenting
Calves become susceptible to infection when their passive immunity (via colostrum) decreases, but their own immune system has not fully strengthened, meaning that calves are very vulnerable to scouring. Scouring causes dehydration which can then be broken down into nutritional and pathogenic.
Nutritional scours tend to be stress related and temporary, for example milk powder changes, waste milk to powder, movement, vaccines and dehorning.
Pathogenic scours are bacterial or virus and tend to be seen from 1-3 weeks of age with the most common being rotavirus, coronavirus, E. coli, salmonella and cryptosporidia. These bugs are in the surrounding environment, including handling, older calves, feeding apparatus and worker contact. Often digestive villi are damaged, limiting future cow performance.
Results indicate (Garthwaite et al., 1994) that feeding the same level of milk and dehydration treatment is the best way to maintain weights and contend with dehydration, as oral rehydration solutions cannot provide sufficient energy.
Oral rehydration solutions should contain water, sodium, glucose, alkalizing agent, other electrolytes (Potassium and chloride) and minerals. To maximise water absorption the calf needs additional sodium and glucose at a 1:1 ratio. More work is required on the use of gelling agents; whilst they do slow digestion passage, they also reduce the ability of the calf to flush out toxins.
Fig 2. Clinical symptoms that help evaluate amount of dehydration in calves
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