Coccidiosis in Lambs

The following article, written by Susan Mckay of The Companion Consultancy and generously sponsored by Janssen Animal Health, will help the smallholder understand the disease, and what to do to minimise its impact on their flock.

Companion Consultancy website


lamb-gangScouring lambs are always a concern on any smallholding. With small flocks, the costs of treatment, or the loss of animals, can quite quickly tip the farmer into a financially perilous situation. One of the causes of scour is coccidiosis (sometimes referred to as “coxi”). Some farms suffer recurrent problems year on year as a result of coccidiosis, so it is important to understand the disease and develop a strategy for dealing with it.

Signs of Coccidiosis

Lambs in the 3-8 week age group are commonly infected, so depending on the flock lambing dates, coccidiosis is most likely to be seen in spring. The first signs may include failure to thrive, loss of appetite and staining around the tail and hindquarters. Progression of the disease results in watery diarrhoea, which can be grey, yellowish green, brown or bloody, sometimes containing strips of tissue from the lining of the intestine. Abdominal pain and dehydration also occur. Severely affected animals may die despite treatment, and those that recover may have significant intestinal damage resulting in long term poor weight gain and appetite. These signs may not seem obvious but can lead to an extended time to reach acceptable slaughter weights and poor carcass quality.


Click here to download a printable pdf of the diagram.

Causes of Coccidiosis

Coccidosis is caused by a microscopic parasite called Eimeria. Not all Eimeria species cause disease. The parasite is widely distributed and likely to be present on most farms. Although some Eimeria species cause disease, they only cause signs if the animal’s normal immune responses are compromised, and/or the animal is infected by a high parasite load. A low background dose of Eimeria will most usually just help a healthy animal go on to develop future immunity against the parasite.

The situations where coccidiosis may be observed are after any stressful event that adversely affects the immune system, or where there are high parasite numbers, such as in conditions of poor hygiene, overcrowding, or where older infected lambs excreting parasite oocysts (eggs) are mixing with younger unaffected lambs. Stressful events include poor weather, castration, mismothering and poor intake of colostrum, transport or turn out. In some farms there is an obviously identifiable trigger event that tends to lead to signs around 14-21 days later as the parasite completes its lifecycle. On sheep farms, however, coccidiosis is generally associated with the high number of susceptible lambs on pastures around lambing time.  It is important to remember that when the signs appear, most of the gut damage has already occurred.

Implications for Treatment

Coccidiosis can be treated with diclazuril (Vecoxan®2.5mg/ml Oral Solution). This kills the Eimeria parasites which cause the disease, while allowing the development of protective immunity1, although it is important to treat at the optimum time. Some animals that have already started scouring may need additional antibiotic therapy as well as treatment to address dehydration.

There are three ways to approach the timing of treatment with diclazuril. If there is an obvious identifiable trigger of coccidiodis on the farm, which is known as a result of previous experience, then lambs should be dosed 10-14 days after the trigger. Alternatively, if it is known that coccidiosis always occurs when groups of lambs reach a certain age, that group may be treated approximately one week before the appearance of signs.  These two approaches are known as metaphylactic treatment.  The other approach, if coccidiosis is suspected, is to treat all the animals in the batch as soon as one or two animals start scouring.

Diagnosis of coccidiosis can prove difficult, as faecal oocyst counts do not always differentiate between pathogenic (harmful) species that cause disease and non-pathogenic species of Eimeria.  It is always best to work with your vet to establish whether treatment is needed and the optimum timing of any treatment on any individual smallholding.


In many cases it is not possible to completely prevent animals from becoming ill due to coccidiosis through management alone but it helps to keep over crowding to a minimum, practice good hygiene, batch up lambs by age and avoid mixing of batches, feed from troughs and minimise ‘stress’.


1.  Taylor M.A., Marshall R.N., Marshall J.A., Catchpole J., Bartram D. 2011. Dose-response effects of diclazuril against pathogenic species of ovine coccidia and the development of protective immunity.  Veterinary Parasitology 178, 48-57

Vecoxan® 2.5 mg/ml Oral Suspension contains diclazuril 2.5mg/ml. Legal Category POM-VPS.

Contraindications and side effects

None known.

Warnings and precautions

No known contraindications or interactions with any other medicine.

For oral use in lambs and cattle only. Shake well before use.  It is advocated to treat all animals in a group.  Always consider other causes for the symptoms. In cases of acute clinical coccidiosis fluid therapy is essential and the use of an antibiotic should be considered.

Meat withdrawal period: zero days.

Wash hands after administration of the product.

Do not store above 30ºC. Protect from frost.

Any unused product or waste material derived from such a veterinary medicinal product should be disposed of in accordance with national requirements.

Always seek advice on the correct use of medicines from the prescriber – your veterinarian or suitably qualified person.

For full contraindications and warnings please refer to the SPC

Further information about Vecoxan® and coccidiosis is available from Janssen Animal Health, 50-100 Holmers Farm Way, High Wycombe, Bucks, HP12 4EG Tel 01494 567555 Fax 01494 567556 Email: This email address is being protected from spambots. You need JavaScript enabled to view it.



dvd-setFor further sheep welfare information, see 'Managing Your Flock for Peak Health', programme 2 in the DVD series 'Sheep on Your Smallholding'.