Previously I have highlighted the importance of rehydrating scouring calves. However, understanding what is causing the scours is equally important as the treatments selected are different for each of the causes.
The common causes of scours in young calves include: Nutritional. Escherichia coli and Salmonella (bacteria). Rotavirus and Coronavirus (viral). Cryptospoidia (parasite).
For the past few years, 'calf side' faecal tests have been available (there are several brands but they all work in much the same way) that can test calf faeces straight away for the four common calf scour pathogens: Ecoli, Rotovirus, Coronavirus and Cryptosporidia. The tests take about 20 minutes to do and run and are a bit like a human urine 'pregnancy test', with two lines indicating a positive, one line a negative and no lines indicating the test hasn't worked and needs to be done again.
All the vets in my practice carry these in their cars to use on farm and have them in the clinic for samples that are dropped off. They use them to tailor their advice and to monitor for changes in active pathogens. They are not applicable for all cases and some samples will still need to be sent away for full testing.
These test kits do not check for Salmonella, so if we have unwell scouring calves that test negative on the faecal tests, or if we suspect salmonella, the faecal sample is sent to the laboratory for culture (growing and identifying the bug present) and sensitivity (testing in the laboratory for which antibiotics the bug is sensitive to). They also do not check for concurrent Bovine Viral Diarrhoea (BVD). Coccidia is easily identified under a microscope from the faecal sample.
Often more than one bug is present and even different calves in the same calf shed can react to different strips on the test.
These tests work well for the four bugs they test for and they work best (highest sensitivity) in the early stages of the disease. So using them early before any treatment has the most chance of success.
It is important to use fresh faeces from the calf's bottom -- not from the ground. If the faeces cannot be tested straight away it can be kept in the fridge but should be tested within 24 hours.
How to collect faeces from a scouring calf It is important to collect it from their bottom and not from the ground. Put on gloves and collect faeces from the calf.
I do this by using a rectal glove and inserting one or two fingers into the rectum then when I pull my hand out I cup it just near the bottom and most calves will poo a sample into my hand after I remove my fingers. Poo can also be scooped out if it is a little less watery. Only a few grams is needed for these in house tests.
To collect a poo sample, remove the glove by turning it inside out and tieing a knot in it. Label with a sharpie with the calf identity. The sample can be put into a sample pot by cutting off the glove fingers with the most sample in them and put the entire sample -- plastic glove finger and all -- in the pot.
These quick tests may need to be followed up with more detailed (and more expensive) testing but often aid in choosing a treatment plan while awaiting the results from the laboratory. Sometimes the answers they give are all that are needed to start the right treatment early and get on top of scours quickly.
Until next time, good milking and calm calving.
*Sherri Jaques is a practising veterinarian and reproduction adviser in the West Gippsland region of Victoria. All comments and information discussed in this article are intended to be of a general nature only. Please consult a veterinarian for herd health advice, protocols and/or treatments that are tailored to a herd's particular needs.
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