When to treat can be a matter of knowing the farm’s history and when challenges are expected. In general, lambs are most at risk from 4-8 weeks of age, and while rising faecal oocyst counts can be indicative of an emerging problem, these are not diagnostic on a single sample unless speciation is carried out. If you are unsure, talk to your vet who will be able to provide a diagnosis.
Older lambs can also be at risk, and coccidiosis is most often seen in older lambs from hill or upland flocks at weaning time. These lambs may not have had sufficient exposure earlier in life for immunity to develop, and when weaned into a higher challenge environment, often coupled with weaning and weather stress, disease outbreaks can cause significant problems.
Calves are at most risk from 3 weeks – 6 months of age, and with indoor rearing systems, treatment can be given one week before the expected disease outbreak, or two weeks after a significant stress. In calves Vecoxan has been shown to reduce oocyst shedding by 98%1, meaning cleaner pasture and bedding and a reduced risk of further infection – and in a farm challenge situation, on average 20% better weight gain over a 3 week period compared to untreated calves.1
What are the treatment options?
In many circumstances, hygiene measures alone will not adequately control the level of oocysts in the environment. And, as noted previously, with oocyst excretion from adults at a very low level, it is infections in lambs and calves that are the source of the high levels of oocysts that can lead to clinical disease and production losses.
In this case, appropriate medication can be targeted at young stock that have been exposed to a significant challenge, thus preventing disease while allowing natural immunity to develop. Treatment options for young stock include sulphonamides (antibiotics, by injection), decoquinate (in feed) or the triazinone derivatives diclazuril (e.g. Vecoxan™) and toltrazuril (oral drenches). Individuals with clinical signs of disease may also need other supportive treatments until the gut damage has had time to heal.
Whilst in-feed preparations rely on all animals eating enough to get an effective dose, oral drenches are generally the most convenient way of ensuring that each animal receives the correct dose at the correct time, allowing enough exposure to stimulate immunity before removing the parasites.