Flood mud scours (Yersiniosis)
Flood Mud Scours or Yersiniosis can cause a severe diarrhoea and death in cattle.
It is often seen in winter and early spring in cattle grazing wet, waterlogged or recently flooded pastures. Often several cases are seen over a short period on properties when conditions are favourable for the bacteria.
What causes Flood Mud Scours?
Flood Mud Scours is caused by the bacteria Yersinia pseudotuberculosis. The bacteria can be carried by a range of animals including cattle, rodents and birds. Animals shedding the bacteria in their faeces contaminate pastures and the bacteria can survive for long periods and multiply in mud and water at low temperatures.
When to watch for Flood Mud Scours?
Animals that are stressed from concurrent low nutrition or parasite burdens are more likely to be affected by yersiniosis. Adults are usually affected although it is also seen in yearlings.
Mud contamination of dry feed and muddy conditions as cattle congregate around silage and hay feeders is a common risk. Watch for signs of illness and scours in cattle grazing high risk paddocks and to be prepared to respond quickly with early treatment and moving cattle to a lower risk paddock.
Clinical Signs of Flood Mud Scours
Occasionally animals will be found dead without showing prior clinical signs. However, more frequently cattle will become depressed, off feed and develop a profuse watery, foul smelling diarrhoea. Affected cattle become dehydrated and often become recumbent. Death usually occurs within 3-5 days.
A post mortem examination reveals swelling of the intestinal lining, and watery foul smelling gut contents. The diagnosis can be confirmed by submitting faecal samples to the laboratory and culturing the bacteria.
How to prevent Flood Mud Scours
Flood mud scours often occurs in an outbreak situation involving several cattle in a herd over a short period as cattle are exposed to a common bacterial source. Thus responding well to the first case can be rewarded with a cessation of cases.
When feeding round bales, be sure to move the ring to another spot before the next bale, particularly if conditions are muddy.
There is often significant stress on affected animals (predisposing to infection) ie lactation and pregnancy, wet weather, wind, concurrent low nutrition and parasite burdens. Thus ensuring good health, nutrition and being up to date with de-worming treatments can also help prevent issues.
How to treat Flood Mud Scours?
Early treatment with an appropriate antibiotic will save many animals. However, when treatment is delayed it is much less successful. Best results are achieved if treatment is given early using broad-spectrum antibiotics. Supportive therapy such as electrolytes, antidiarrheal preparations and vitamin injections are helpful. Antibiotics are restricted substances and as such must be prescribed by a veterinarian; withholding periods for meat and milk apply.
Isolation of affected animals from the rest of the mob is recommended. Because flood mud scours often occurs as an outbreak in an area it's important to tell your neighbours to be on lookout if they have similar conditions on their property. Frequent observation of cattle grazing high risk paddocks is recommended to enable early treatment.
Adapted from content by district veterinarians Lyndell Stone and Jim Kerr.