Thursday, 2 April 2015

Controlling parasitic disease in lambs

Farmers are urged this week to take care in relation to two parasitic diseases affecting lambs, Nematodirosis and Coccidosis.

Nematodirosis is a severe disease of 6-12 week old lambs, which become infected through ingesting large numbers of infected larvae present on contaminated pasture. Infection is characterised by profuse diarrhoea and wasting and mortalities in untreated lambs can be high. Nematodirus larvae invade the intestinal mucosa and in some cases death may occur before signs of diarrhoea induced by adult worms are observed. This disease is best prevented by keeping the current year’s lambs off pasture that was grazed by lambs last year. 

Meteorological information and soil temperature data for March indicate that on the west, southwest and south coasts, as well as inland areas of counties Mayo, Galway, Clare, Limerick, Kerry and west Cork hatching occurred in late March. In the rest of the country peak hatching occurred during the first week of April. Farmers should be aware that lambs might start to show clinical signs of infection two to three weeks from these dates.

Weather conditions during December, January and February were more typical of a normal Irish winter than in previous years. Therefore synchronisation of egg hatch will be more evident this year than in 2007 and 2008. Lambs, particularly those that are grazing on pasture where lambs grazed last spring should be dosed with a suitable anthelmintic in late April or early May to decrease the likelihood of clinical problems later in the season and also to lower pasture contamination for the next year.

It is also important that farmers are aware that other parasites cause diarrhoea in young lambs and require different control measures and medication. Nematodirus can be wrongly assumed to be the cause of severe diarrhoea in lambs when in fact the cause is a coccidial infection. Rotation of pasture and frequent movement of feeding troughs and watering points help prevent coccidiosis in young lambs as localised poaching creates moist conditions suitable for the spread of this parasite. 

It is advisable to consult a private veterinary practitioner for an accurate diagnosis and advice on appropriate medication if lambs with severe diarrhoea and straining are observed. Faecal samples can be submitted to the Central and Regional Veterinary Laboratories for testing. This service is available through veterinary practitioners and can be used to assess the level of parasite infection on farms and also to assist in the development of parasite control programmes.