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Coccidiosis is a parasitic disease usually affecting young stock aged 3-8 months although young calves may be infected as early as 4 weeks of age. The incidence of coccidiosis seems to be increasing notably in weaned dairy calves. The disease causes calves to become sick, some may die and surviving animals will have long term production effects to overcome.

It is only when animals are exposed to large amounts of the parasite (dirty calf pens) or when their resistance is lowered due to poor nutrition, stress or other disease that clinical disease is seen.

The infective stages of Coccidia are very hardy in the environment and may survive up to 2 years. Dry conditions and high temperatures however will shorten survival to a few weeks.

In calves that are infected the end result of the coccidian lifecycle is damage to the intestine leading to severe bleeeding and reduced water absorption causing diarrhoea, dehydration and death. Less severe infections result in malabsortion from the intestine causing ill thrift and poor growth.

Stressors are a common precipitating factor in a coccidia outbreak. There are 2 main situations that can lead to a coccidiosis outbreak. 

The first is associated with management of calves. Large numbers of coccidia may build up on pastures that are used year after year for calf rearing. If climate conditions remain mild and moist, the parasite can survive for long periods of time, thus large numbers of oocysts may be ingested by young stock on these paddocks.

The other time that coccidiosis outbreaks may occur is at the time of removal of meal feeding to the calves. Most good quality calf meals have a coccidostat in them preventing establishment of infection. However, when meal is removed, the calves may still have minimal immunity to coccidia leading to outbreaks.

Another situation occurs in young calves that are not yet eating enough meal yet or calves that are being weaned, therefore eating more grass, may not be consuming protective levels of coccidiostat. Outbreaks will usually present as sudden development of diarrhoea in many animals.

Clinical signs that may be seen in calves include:

  1. Diarrhoea. These faeces are typically mucoid and contain blood. Undisturbed poo may show a metallic sheen on its surface.

  2. Severe straining is usually seen and rectal prolapse may occur.

  3. The tail, hind quarters and hocks are often stained with faecal material.

  4. Calves appear unhappy and uncomfortable.

  5. Rapid loss of body condition. Recovering animals take a long to time gain condition. Some may be chronically ill-thrifty.

  6. Mild cases can cause calves to be weak and listless with drooping ears and a rough coat. These animals show weight loss but may not develop diarrhoea.

Diagnosis is made by testing faecal samples along with clinical signs.

In the case of an outbreak, sick calves must be isolated from healthy animals. Sick calves will need supportive therapy such as stomach tubing or IV fluids. Baycox®C is our treamtent of choice. One dose is effective because it attacks all stages of the parasite in the animal.

The prognosis can be grave for severe cases, however, provided prompt treatment most animals should survive. Preferential feeding may be needed to achieve target growth rates, although some animals may still not achieve these due to damage to the gut.

To prevent outbreks:

  1. Use of meal containing a coccidiostat, this should still be available up until weaning and for a further 28 days on farms that have had previous problems.

  2. Rotational grazing at appropriate stocking rates to prevent pasture build up of oocysts.

  3. Isolation of infected calves.

  4. Treating all animals in groups including those not yet showing signs.

  5. Avoiding faecal contamination of feed troughs.

  6. Minimising stressors.

Please contact the clinic if you have any questions regarding coccidiosis or your calf rearing.

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