Sleepy Flies, Sore Teats and Swollen Legs

Dairy Farms

This sounds like quite a combination and certainly a case of the October blues if you are an affected cow!  We have had numerous, recent telephone reports of clusters of these cases on a range of dairy farms with some samples from these cases testing positive for Mycoplasma wenyonii. 


This is a blood borne non-culturable Mycoplasma species that can be detected in either blood smears or by a pan-Mycoplasma DGGE test.  Over the years we have had blood samples test positive from both healthy and clinically affected cattle but there is always an increase in the number of case reports at this time of year.  Clinical history and signs are clearly important, however a positive Mycoplasma DGGE result in a clinically affected case is thought to be significant. 

The facts to be aware of are:

  • The clinical signs are hind limb pitting oedema (see picture below), painful swollen udders and teats leading to problems being milked.
  • Pyrexia, milk drop and reduced feed intake are seen in the acute phase. 
  • Recovery can be gradual over 10-14 days with or without treatment.
  • Usually there will be multiple cases at any time.
  • Transmission is thought to be through contact with blood and body fluids.
  • We suspect this is why there are more cases at this time of year with biting fly numbers currently very high in sheds.

Treatment and Diagnosis

A diagnosis is confirmed from an EDTA blood sample.  Smears can be of use in acutely infected animals, however they need to be made straight away and examined by an experienced haematologist as the parasites can be easily confused with artefact material in older samples. An EDTA blood sample can be tested by the Mycoplasma DGGE test to confirm a positive result, although please be aware that this test is expensive £69.
Treatment with antibiotics (oxytetracycline and tylosin) has been tried and can help, but supportive therapy with NSAIDS or corticosteroids if appropriate may be just as effective. 
A continued focus on fly control at this time of year is important, particularly as many farmers may not be using fly control products at this time of year.   

If have you have suspect cases and wish to discuss diagnostic options, please do not hesitate to get in touch with us. 

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