Sheep farmers were challenged by vet Patrick Grant to keep more accurate records of ewe and lamb mortalities, investigate deaths and take appropriate steps to prevent losses at an event organised by Parklands Veterinary Group in Cookstown last week.

“Think of every dead lamb as £50 lost. Don’t just put it in a bag and forget about it. Ask yourself why is it dead and are there controls I can put in place to stop it from happening next year,” Grant said.

He maintained that many potential neonatal losses can be prevented by ensuring lambs receive adequate colostrum. Grant described colostrum as a “free drug” that limits subsequent antibiotic treatments. Often linked to low colostrum intakes in lambs is watery mouth, caused by E coli bacteria. Treatment is by way of oral antibiotics.

Also at lambing time, good hygiene in lambing pens and disinfecting navels after birth are important for preventing joint ill. Grant recommended using strong iodine solution (10% concentration) and told farmers to make sure the full navel is covered by dipping or spraying. “For lambs that are weaker or harder to suck, put iodine on them two or three times,” he said.

Approach

Farmers were told to approach health issues in sheep in three steps – diagnose, treat and prevent for next year. Scour caused by the parasite cryptosporidium can occur in lambs from seven to 10 days and antibiotic treatment is ineffective. “It is a low-mortality disease but reduces growth and can have a high morbidity [rate of disease], affecting over 40% of lambs in bad outbreaks,” Grant said.

Halocur was recommended as a treatment, and to prevent the problem spreading. Maintaining good hygiene and using specified disinfectants is also important.

Coccidiosis

Grant described coccidiosis as an “iceberg disease” as the clinical symptoms of scour are only seen in around 10% of affected lambs from four to eight weeks old. Treatment is with a coccidiostat, which also provides a level of preventative cover.

Mastitis

Keeping records of live-weights and calculating growth weights can allow underlying health issues, such as subclinical mastitis, to be identified early.

Poor growth rates also indicate low milk yields, which can help highlight culling decisions to be made, while faster growing ewe lambs should ideally be kept for replacements in a closed flock (from milkier ewes).

“Question everything. Only when you have information can you make the right judgement call,” Grant told farmers.

Useful information includes conducting faecal egg counts to determine the need for worm treatments or identify anthelmintic resistance. Also blood testing to see if supplementary minerals are required. “Find out what works for you or what is needed on your farm. A drench becomes a lot more expensive if it doesn’t work or isn’t required,” he said.

Jaagsiekte prevalent on Northern Irish sheep farms

Respiratory disease jaagsiekte is more prevalent in the NI sheep sector than commonly thought, as cases are often incorrectly put down to respiratory disorders such as pneumonia, according to Patrick Grant. Jaagsiekte is a fatal disease, with sheep initially displaying symptoms of coughing followed by fluid dripping from the nose.

The disease is also known as ovine pulmonary adenocarcinoma (OPA) and is caused by a retrovirus that leads to abnormal or cancerous growth in the lungs.

“If you have an issue with pneumonia you have to consider the possibility of jaagsiekte. Up to 70% of flocks in NI will have it and we have to start thinking about it more,” he said.

Jaagsiekte can be passed on to lambs in colostrum but there is no evidence of transmission during pregnancy. The virus is spread among sheep by contact with the nasal discharge from infected ewes. “The virus doesn’t last long in the environment but it can have an incubation period in sheep between six months and three years,” Grant said.

The “wheelbarrow test” is a crude test for jaagsiekte which involves lifting a ewe by the back legs to see if fluid drips from her nose. However, this only works in latter stages of the disease when large tumours have developed and it also puts stress on the ewe.

There is no blood test for the disease and ultrasound scanning of lungs is the only current means of detecting jaagsiekte in sheep. Grant recommended that farmers who suspect they might have a jaagsiekte issue should scan a group of thin ewes initially, followed by the whole flock if needed for complete eradication.

“Scanning the section of the lungs where most growths start can pick up lesions from 1cm to 2cm in size. One ewe can be scanned every couple of minutes and results are immediate,” Grant said.

He said ewes lose condition before symptoms are seen and so scanning allows culling to take place early.

“By the time the symptoms are seen clinically, the ewe will have a few weeks left and will have already lost condition. It is better to cull early when she is worth something and also to stop others picking it up,” Grant said.

An infected ewe that is pregnant can be separated and not culled immediately with her lambs either lifted at birth or else kept on, but not retained as replacements.

Addressing mastitis in sheep

Keeping records of incidents of ewe mastitis was recommended by Parklands vet Rob Lawrence to see if there is an underlying infection issue in a flock and if changes to management reduce the number of cases.

Mastitis is inflammation of the udder, with around 94% of cases in sheep caused by bacteria infections. Lawrence said vets can culture samples of infected milk to diagnose the infection. “This could be particularly useful in outbreaks of low-grade chronic infections that keeping running on in a flock,” he said.

Acute mastitis usually leads to swollen udders with ewes becoming lethargic and showing depression. Chronic infections are longer term and can lead to hard udders, reduced milk production and lower lamb growth rates.

“If a ewe has mastitis in the first 30 days after lambing then she most likely got the infection at lambing due to poor hygiene in housing,” Lawrence said.

Infected ewes should be removed to stop cross-contamination, and good hygiene practices, particularly ensuring adequate bedding in houses, is needed at lambing time. He also said it was important to administer antibiotic treatments quickly to infected ewes.

Lawrence said inadequate nutrition can lead to mastitis in ewes and can be a common cause of infections later in lactation. In particular, underfeeding protein will lead to lower milk yields and subsequent over sucking by lambs, which will put a strain on the udder and lead to acute mastitis.

Lesions on teats can be an entry point for infections into the udder and can be caused by damage to teats or growths such as orf. Lawrence said it was important to cull ewes with poor udder conformation or deformities on teats.