Coccidiosis is caused by a parasite that multiplies in the intestinal wall. As it progresses through its life cycle this parasite reproduces in the cells that line the intestine, leading to widespread intestinal wall damage. This damage can severely affect the health of young animals such as lambs and calves, causing poor growth rates and leaving them susceptible to other diseases. Coccidiosis is a serious disease – one that can result in significant economic losses.

Lambs take in coccidia oocysts (eggs) by mouth.  Inside the gut, the oocysts hatch, invade the gut cells and multiply dramatically with two results: damage to the inside lining of the lamb’s gut as the coccidia emerge by bursting the cells and a dramatic increase in the number of oocysts shed in the lamb’s faeces.   It takes two to three weeks from infection to the passing oocysts in the faeces.  In this time, the number of oocysts shed in the faeces can be many million-fold higher than the number that were ingested.

Significant damage to the cells lining the ileum, caecum and colon results in diarrhoea which may contain mucus or blood, and be accompanied by straining, pain, weight loss and possibly the death of the lamb.  Even in animals that show no obvious clinical signs, sub-clinical disease can lead to poor weight gain as the gut has a reduced ability to absorb nutrients from food.

Traditionally decoquinate was used in the ewe ration to suppress the number of oocysts shed by the ewes.  However, such blanket approach is not ideal for a number of reasons:

  1. The ewes are medicated despite the fact they are unaffected by coccidia.
  2. Some of the original source of coccidia for the lambs comes from those which overwintered on the pasture so medicating the ewes does not remove the need to consider control in the lambs.
  3. There are benefits of very young lambs having access to low levels of coccidia to build immunity.

Decoquinate can be mixed into the lamb creep over the period of risk at a rate of 1mg decoquinate per kilogram body weight per day for at least 28 days.  Each 10kg lamb must ingest 100g of creep a day to maintain adequate decoquinate levels.  This may be an issue for a sick lamb, possibly suffering from Nematodirus, which would not have the appetite to eat medicated creep and thus be at risk of also developing clinical coccidiosis.  Decoquinate is active only in the small intestine.  This means that lambs may still shed oocysts despite eating medicated feed and showing no clinical signs of coccidiosis.

On any one farm, clinical disease will appear to affect lambs at progressively younger ages as the season progresses.  Thus, at the beginning of the season, clinical disease may not be seen until the lambs are eight weeks old but by the end of the season clinical disease might be seen in four week old animals due to the increase in pasture contamination.  This does not mean that very young lambs should be automatically treated at the start of the following season but treatment timings should follow careful risk assessment.

The correct treatment and dosage is essential.

LAMBS: Therapeutic use 1 mg diclazuril per kg bodyweight equates to 1ml of Vecoxan per 2.5 kg bodyweight, as a single oral administration.
LAMBS: Preventative use 1 mg diclazuril per kg body weight equates to 1ml Vecoxan per 2.5 kg body weight at about 4-6 weeks of age at the time that coccidiosis can normally be expected on the farm.
Under conditions of high infection pressure, a second treatment may be indicated about 3 weeks after the first dosing. On rare occasions, in highly susceptible lambs, e.g. where they have been housed for long periods of time before being turned out onto heavily contaminated pasture, a severe scour has been seen shortly after dosing. In such cases, fluid therapy is essential and the use of a sulphonamide should be considered. It is also important to consider other potential pathogens that may be playing a role, e.g. Cryptosporidia, Nematodirus, rotavirus, Giardia and E. coli.

CALVES: As an aid in the control of coccidiosis 1 mg diclazuril per kg body weight equates to 1ml Vecoxan per 2.5 kg bodyweight, administered as a single oral dose, 14 days after moving into a potentially high-risk environment. If a satisfactory response is not observed, then further advice should be sought from your veterinary surgeon and the cause of the condition should be reviewed.
It is good practice to ensure the cleanliness of calf housing. Clinical coccidiosis generally occurs late in the parasite’s life cycle after most of the damage to the calf’s intestine has already been done. This severely damaged intestine can easily be infected by secondary bacteria and/or other agents. In cases of acute clinical coccidiosis treated with Vecoxan, fluid therapy is essential and the use of an antibiotic should be considered.
Symptoms of clinical disease may remain obvious in some calves treated with Vecoxan, even though oocyst excretion is reduced to a very low level, and overall prevalence of diarrhoea is decreased.

Withdrawal period lambs and calves: Meat and offal – zero days. Dependent on the coccidia species, diclazuril has a coccidiocidal effect on the asexual or sexual stages of the development cycle of the parasite. Treatment with diclazuril causes interruption of the coccidial cycle and eliminates excretion of oocysts for up to 14 days.

Sally Cornforth R-SQP

Ring for more advice on 01765 680215 or 07590 767655

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