Failing to scratch for orf can prove costly

Lambs are born with no antibodies to give them protection to ubiquitous disease threats and therefore rely on early life on passive transfer of immunity from the ewe in her colostrum. This however, must take place within the first few hours of life with passive immunity then starting to wear off after three weeks, leaving many lambs vulnerable to infections.

According to MSD Animal Health veterinary adviser, Dr Kat Baxter-Smith, unnecessary losses from clostridial diseases, such as pulpy kidney or from pastereurellosis, are a particular cause for concern during the spring and early summer.

Data from Farm Post Mortems Limited, shows there is often a large peak of pulpy kidney in the spring when lambs aged between two and eight weeks of age are affected. On further investigation, in almost all the cases, neither the dams nor their offspring have been protected by vaccination.

Dr Baxter-Smith says that it is impossible to control the multiple and varied stress-related ‘trigger’ factors (e.g. sudden change in the weather, alteration in diet or parasite infection) for clostridial diseases and pasteurellosis, so vaccination from three weeks of age is advised.

Coccidiosis is another disease that is often triggered by stress.. This is because any maternally derived immunity (gained from ewe colostrum) to this infection is known to wane at four to six weeks of age.

“After this, young lambs become particularly susceptible to the Eimeria parasite oocysts, which, once consumed from the environment, hatch and invade the intestinal wall, leading to diarrhoea, weight loss and slow growth rates,” she said.

Commenting on orf, Dr Baxter-Smith said: “Orf-affected lambs have been shown to be 2.2kg lighter on average at finishing, than disease-free animals. There’s also an 82% chance that the mother of a lamb with orf will have the disease on her teats, so failing to vaccinate lambs at the earliest opportunity could be costly.”