The potential disease risks associated with buying in sheep were top of the agenda at the latest Forth monitor farm meeting.
The 815 acre (330 ha) Arnprior Farm, 12 miles west of Stirling, farmed by Duncan McEwen and his son also Duncan, is one of the network of Quality Meat Scotland (QMS) monitor farms throughout Scotland.
A few weeks before the meeting the McEwens, whose sheep enterprise is based on a flock of 550 breeding ewes, had purchased 70 one-crop ewes plus a Texel cross Charollais tup. All lambs, other than replacements, are finished.
Some of the parasites, bacteria and viruses which can be brought onto a farm by incoming sheep were described by David Gibson, a Veterinary Investigation Officer with SAC Consulting – Veterinary Services, a division of SRUC (Scotland’s Rural College).
“While there are numerous diseases that purchased sheep may introduce to the home flock, it’s worth first establishing what your own sheep already have. This can be done by dung and blood sampling as well as trying to establish the cause of any unexplained deaths.
“There’s little point trying to source sheep which are free of a particular disease if your own stock already have it,” commented Mr Gibson.
“Before purchasing, ask the vendor about the health status of his sheep and seek assurance regarding any pre-sale treatments they’ve received.
“Quarantine incoming stock in a location where there is no risk of infection being passed to your resident animals, by either nose to nose contact, airborne or in drainage run-off. Also be aware that you can transfer diseases yourself, on footwear and/or clothes.”
Mr Gibson outlined some of the main health issues to be aware of.
“Looking at Sheep Scab, if any quarantined sheep are scratching or have any wool loss then this must be investigated,” said Mr Gibson. “Pluck some wool from the edge of any bald areas and collect some scratch scabs into a pot to be submitted for testing.
“With regard to fluke and worms, the main concern is the risk of bringing in drug resistant internal parasites, so a quarantine dose of two different treatments is recommended. Speak to your vet for more guidance. Successfully treated sheep will shed viable worm eggs for about 48 hours after treatment. Viable liver fluke eggs can be excreted by successfully treated animals for up to four weeks after treatment. So, avoid releasing incoming sheep from quarantine onto pasture which will be grazed by other stock.”
A disease to avoid if at all possible is Jaagsiekte, also known as OPA or “Wheelbarrow Disease”, a lung disease in adult sheep.
“This disease is untreatable and there is no good diagnostic test for live sheep,” said Mr Gibson. “Any incoming sheep are potential carriers. In your own flock look for slow, coughing, tail-enders of a gather.”
Mr Gibson then moved on tofFootrot which is caused by two different bacteria, one of which has 12 different strains.
“If you bring in sheep carrying a strain which your own sheep have not been exposed to, you can cause major problems. Effective footbathing is therefore essential and vaccination could be considered,” said Mr Gibson.
Another common foot disease is Contagious Ovine Digital Dermatitis (CODD) – a highly contagious and severely painful foot infection which can result in the loss of the whole hoof capsule.
“My advice would be to footbath sheep immediately upon arrival and watch sheep closely while in quarantine, examining any which are lame,” said Mr Gibson. “If there are raw areas at the hoof/hair junction, suggesting CODD, promptly consult your vet.”
Mr Gibson then moved on to Caseous Lymphadentitis (CLA) also known as “Cheesy Gland Disease.” “There’s a blood test for CLA which is a bacterial infection of the lymph nodes,” said Mr Gibson.
“Testing is probably most relevant for high value animals like tups. Check around the head for swollen glands and/or burst abscesses.”
Mr Gibson then touched on a well-publicised disease - Schmallenberg Virus.
“Scotland has been comparatively fortunate to date, with only a small number of confirmed cases,” said Mr Gibson.
“The threat is from animals that have the virus in their bloodstream when they arrive on the farm, so testing can be restricted to any sheep purchased from areas where the disease has been identified.”
With regard to tick-borne diseases, Mr Gibson said: “Sheep from tick areas can bring diseases like louping ill onto your farm. Check the head, ‘armpits’ and in between the hind legs. If you find any ticks, treat before they can drop off and spread disease.”
Looking at Enzootic abortion and Toxoplasmosis, Mr Gibson advised that a blood test for both of these diseases can be used to establish the risk that bought-in sheep might pose. He added that it is advisable to vaccinate for these two diseases which both result in loss of un-born lambs.
Finally he focused on Border disease – a disease similar to BVD (Bovine Viral Diarrhoea) in cattle, as it is carried by P.I. (Persistently Infective) sheep. Mr Gibson advised the group that blood testing will help to establish if purchased sheep pose a risk to the flock or not.
“The basic advice when bringing sheep onto the farm is to discuss with your vet what testing, vaccination and foot bathing protocols should be followed, as well as investigating anything that causes concern,” added Mr Gibson.
The next Forth monitor farm meeting will be held in mid-December. For further information, please contact the Facilitator: Stephen Whiteford. Email: email@example.com, telephone: 01786 450964.
For general information on monitor farms, plus detailed reports of meetings: www.qmscotland.co.uk/monitorfarms