Coccidiosis  Prevention - Vecoxan - Bovilis - MSD Animal Health
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Coccidiosis is a common disease in calves and lambs. It is a disease caused by a parasite called Eimeria. Oocysts are capable of surviving for long periods of time and eventually all calves and lambs are likely to become infected.

Calves and lambs can be infected from birth resulting in clinical disease from just three weeks old. Disease is usually seen in calves between three weeks and six months old and lambs aged four weeks to six months old.

Scour is one of the signs frequently associated with an outbreak of coccidiosis, although sub clinical disease results in far greater economic losses.

How does coccidiosis occur?

After ingestion, Eimeria oocystsenter the cells lining the guts. The oocysts multiply inside these cells before they emerge and destroy the cells resulting in massive damage to the gut lining.

Millions of oocysts pass out in faeces which contaminates the environment and become the main source of infection to other animals. Coccidiosis is common on farms although not all animals show clinical signs of disease, some are sub-clinically affected.

Cocciodisis cycle

Sub clinical disease occurs when the signs of illness are not as obvious. During the multiplication phase damage is occurring to the guts resulting in a reduced ability to absorb nutrients from food.

Animals maintain a good appetite without achieving their expected daily live weight gain. This leads to a generalised ill thrift in the group. Sub clinical coccidiosis can cause a greater economic loss than the clinical condition as many more animals are likely to be sub clinically affected.

Control of coccidiosis

Nearly all animals will become exposed to coccidial oocysts at some point in their lives. . As Eimeria oocysts are present on most farms, the likelihood of infection at an early age is high.

Exposure to coccidial oocysts is necessary for animals to develop immunity. To develop immunity, animals need exposure to low levels of infective parasites and a healthy immune system. Natural immunity helps animals resist future challenges. Most animals are immune by one year old.

Exposure to a high infectious pressure, or stress that diminishes the effectiveness of the animal’s immune system, can overwhelm natural defenses and result in a clinical outbreak.

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Stressors such as mixing groups, weaning, turn out or a sudden change of diet, castration and bad weather can reduce the immune response.

Overcrowding indoors or high stock numbers in paddocks as well as unhygienic conditions can contribute to the risk of disease occurring.


Coccidiosis is a group disease rather than an individual animal issue. An entire group is usually exposed to a similar infectious burden of Eimeria infection in the same environment and are subjected to the same external stressors.

Therefore, if one lamb or calf presents with clinical signs such as bloody diarrhoea, the whole group should be considered infected.


Developing immunity against Eimeria sp. is key to control. However, eliminating coccidia oocysts from farms is practically impossible. Therefore, ensuring immunity develops is crucial.

A control strategy may include:

  • Good hygiene
    • Keep the build-up of faecal material in the shed to a minimum to minimise oocyst ingestion
    • Assess the floor type – slats, deep litter bedding, concrete floors
    • Ensure feeding troughs and buckets are kept free of faecal contamination
  • Avoid over-stocking outdoors
    • Move feeders frequently
    • Drain wet areas in fields
  • Administration of prophylactic drugs such as diclazuril to infected animals during asexual reproductive stages of parasite development
  • Disinfect sheds, feeding equipment and handling areas
    • Amine, cresol and chlorocresol-based disinfectants are effective against Eimeria oocysts
    • Open doors to allow sunlight to enter the shed
  • Coccidiosis outbreaks are a herd level problem and precipitated by stress
    • Minimizing stressors such as mixing, re-grouping, dietary changes and over-crowding.

Preventative treatment options

The principle of coccidiosis treatment is to control the level of challenge to prevent disease but to still allow enough exposure so that young animals can develop immunity.

Vecoxan® is used for the prevention of coccidiosis in calves and lambs. Dosage: 1 ml of the oral suspension per 2.5 kg body weight in a single oral administration. 

To prevent disease and reduce the impact of sub-clinical disease, treatment using Vecoxan® should be administered close to the time when exposure to coccidiosis is known to occur.

Exposure is required for protective immunity to develop. Therefore, treatments should be administered 8-15 days after moving to a high-risk environment, or if historical data is available approximately one week before the expected outbreak.

A single administration to susceptible animals during risk periods is appropriate although a re-treatment may be necessary if the period of risk is prolonged.

Timing of treatment against coccidiosis ‘No one size fits all’

There is ‘no one size fits all‘ for treating coccidiosis on farms. It is important to speak to your vet about the best approach for your farm or see our brochure below for different protocols to use.

  • Historical treatment

Treat whole group 1 week before expected clinical signs: Requires excellent records, knowledge of previous coccidiosis outbreaks & management history in herd/flock.

  • Unknown

Treat 2 weeks after exposure or treat at time of stress factor (e.g. dehorning, castration, transport, weaning, regrouping etc.)

Bought in calves coming from a farm with a known or unknown risk of coccidiosis, treat upon arrival to the farm.

  • Clinical Outbreak

Reactive treatment: Treat all calves in a group when diarrhoea is first seen in 1 or 2 calves/lambs

It is important to always treat all the calves in the group, as coccidiosis is a group problem, not an individual problem.

One dose of Vecoxan is enough to protect the animal in the future, because the animal develops its own immunity. Under very severe challenge or prolonged periods of stress it may be necessary to repeat the dose after 3 weeks.

Why use Vecoxan?

  • Easy to administer
  • Licensed to prevent coccidiosis in both lambs and calves
  • Allows natural immunity to develop (1)
  • Higher daily live weight gain following use of diclazuril (2)
  • Environmentally friendly (3)

Want to learn more? Check out our new Vecoxan brochure

Use the arrows to scroll through the pdf document below. To zoom in, click the icon to the left of the arrows.


  1. Philippe, P., Alzieu, J.P., Taylor, M.A. and Dorchies, P., 2014. Comparative efficacy of diclazuril (Vecoxan®) and toltrazuril (Baycox bovis®) against natural infections of Eimeria bovis and Eimeria zuernii in French calves. Veterinary parasitology206(3-4), pp.129-137.
  2. Agneessens J, Goossens L, Louineau J, Daugschies A and Veys P (2006). Build up of immunity after a diclazuril (Vecoxan) treatment in calves, Poster at World Buiatrics Congress, Nice.
  3. Van Leemput L. & Louineau., (2007). Diclazuril for coccidiosis in ruminants: safe for the environment? Janseen Animal Health, Beerese, Belgium.