Hidden or longer-term health problems are making a significant contribution to lost productivity in sheep flocks, according to sheep veterinarian Phillipa Page, who spoke at the AgriSearch Flock Focus 2026 event in Co. Tyrone.
Page, a former president of the Sheep Veterinary Society, said the effect of so-called “iceberg diseases” becomes particularly important when annual ewe mortality rises above 3%. She described these conditions as problems that can add to the consequences of more visible issues, including lameness and poor body condition scores.
Setting measurable flock targets
The veterinarian said sustainable sheep production depended on setting and monitoring specific targets rather than addressing individual problems in isolation. She identified keeping annual lameness below 1% and ewe mortality below 3% as examples of the type of measures that can be used to assess progress.
“Sustainable sheep production is all about setting targets. For example, getting lameness levels below 1% per annum is one of these: another is keeping ewe mortality below 3%.”
Conditions identified by Page as “iceberg diseases” included Maedi Visna, caseous lymphadenitis (CLA), Johne’s disease and Border disease virus. She said these were mostly bought-in diseases and could be screened for, making health checks an important part of decisions involving livestock entering a flock.
- Maedi Visna
- Caseous lymphadenitis (CLA)
- Johne’s disease
- Border disease virus
Page said that making small improvements across several areas of flock management each year could produce a substantial cumulative effect. Her comments placed disease screening alongside routine performance measures, rather than treating health issues as isolated events.
Lameness requires prompt attention
Foot rot and Contagious Ovine Digital Dermatitis (CODD) were identified as significant contributors to lameness. Page said the immediate problem needed to be addressed promptly, while the longer-term objective should be to prevent recurring cases.
“Lameness is an issue that must be tackled promptly. And if proprietary antibiotics are needed to address the problem, so be it. But the long-term plan must be to prevent the problem from arising in the first place.”
She also questioned the use of foot bathing as a treatment for foot rot, particularly in older ewes. Page said bringing animals together for the process could accelerate the spread of foot rot and other conditions, and that lame animals should be kept separate from flock mates where possible. She described the active chemicals in foot-bath solutions as disinfectants rather than a treatment in themselves.
Any flock experiencing recurring lameness, elevated ewe losses or suspected infectious disease should be assessed with the farm’s own veterinary surgeon. Page’s wider message was that screening, accurate recording and incremental management changes should be combined to improve flock health and productivity over time.
