NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare.

Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

Jaagsiekte

About 30 ill thrifty ewes were identified in an upland flock of 700 Scottish Blackface and Greyface ewes when the animals were handled for routine fluke treatment. In some animals, poor body condition was associated with tooth problems such as broken mouth or molar tooth abnormalities, but at least 20 of the ill thrifty ewes (3% of the flock) were 2 - 4 year-old animals with sound mouths. These animals showed signs of laboured breathing and dribbling of clear fluid from the nostrils when their heads were lowered. Postmortem examination following humane slaughter of four of the worst-affected animals confirmed the diagnosis of jaagsiekte.

JAAGSIEKTE IN A 6 MONTH-OLD TEXEL LAMB -

NOTE FLUID FLOWING FROM THE LEFT NOSTRIL

Jaagsiekte (sheep pulmonary adenomatosis) is an important cause of chronic respiratory disease, leading to ill thrift and death. The disease is particularly prevalent in Borders flocks of Greyface, Halfbred and Mule ewes, but has been reported throughout Britain in most breeds. In some flocks, the disease may be responsible for 50% of adult sheep losses, although the main economic significance results from the culling of ill thrifty sheep.

Jaagsiekte is a contagious lung tumour, associated with slow virus infection by both retro- and herpes viruses. The early signs of jaagsiekte are loss of body condition and exercise intolerance when gathered. These signs are usually noted in 3 - 4 year old sheep, although the disease is occasionally seen in younger or older animals. As the disease progresses, animals become increasingly breathless and breathing is exaggerated by contraction of the abdominal muscles. Fluid gathers in the airways, which may flow freely from the nostrils when the head is lowered. Affected lung tissue usually becomes secondarily infected with Mannheimia (Pasteurella) haemolytica, which is sometimes misdiagnosed as the cause of death.

The history and clinical signs of weight loss, respiratory distress and fluid flowing from the nostrils when the head is lowered, which characterise advanced cases are indicative of jaagsiekte. Raising of the sheep’s hindquarters whilst lowering the head (wheelbarrow test) often exaggerates the flow of clear fluid from the nostrils and can be a useful ancillary diagnostic test. However, the clinical signs in the earlier stages of the disease are not specific and there are currently no laboratory tests to support a diagnosis in the live animal. The diagnosis of jaagsiekte is supported by postmortem examination. Tumours are confined to the lungs and associated lymph nodes, which are enlarged and heavy. Large tumours have a characteristic solid and grey appearance and are well demarcated from less affected lung tissue. The airways contain copious frothy fluid. There is often evidence of secondary bacterial infection, such as abscesses or pleurisy, which may confuse the diagnosis. The presence of tumour cells can be confirmed by microscopic examination of stained sections of affected lung tissue.

JAAGSIEKTE IN A 6 MONTH-OLD LAMB

NOTE CLEARLY DEMARKATED AREAS

OF SWOLLEN SOLID LUNG TISSUE

Jaagsiekte is introduced into flocks with purchased sheep, which probably shed lentiviruses before tumours develop. The main route of infection is likely to be respiratory, so the close confinement of housing or trough feeding probably increase the rate of spread of infection. There is no recognised effective control method, but regular inspection and prompt culling of lean or breathless sheep may slow the spread of infection. Keeping mostly naïve younger sheep separate from older infected animals can also help to reduce the prevalence of the disease. Your vet can confirm the diagnosis of jaagsiekte and advise on its management in your flock.

Neil Sargison BA VetMB DSHP FRCVS