Sheep Medicine Q&A 04

This question was provided by Manson Publishing as part of the OVAL Project. See more Sheep questions

A farmer complains of apparent sudden-onset profound depression and blindness in 12 of 300 6-month-old lambs. When confined, the lambs are found head-pressing and there is frequent teeth-grinding. There are no cranial nerve deficits. The lambs are poorly grown (18–24 kg) with a dirty open fleece. The lambs have poor abdominal fill and there is faecal staining of the perineum and tail. The lambs are grazing permanent grassland in a National Park used extensively by the general public for walking their dogs.

Question	Answer		Article
What conditions would you consider?	The most likely conditions to consider include: severe cobalt deficiency causing white liver disease PEM sulphur toxicity subacute fasciolosis sarcocystosis hepatotoxin acute coenurosis focal symmetrical encephalomalacia. The poor growth rates of this group of lambs could be the result of poor grazing, overstocking, PGE, and trace element deficiency acting alone or in various combinations. The neurological signs are consistent with a diffuse cortical lesion – most likely a hepatic encephalopathy.		Link to Article
How would you investigate this problem?	Faecal worm egg counts average 400 epg. No fluke eggs are seen. Liver enzyme concentrations (AST, GLDH, and GGT) are raised four- to six-fold in the four lambs sampled. Serum vitamin B 12 concentration from six lambs reveal very low levels (mean <88.6 pmol/L, <120 pg/mL).		Link to Article
What treatments would you administer?	All lambs should be treated with vitamin B 12 by intramuscular injection. The worst affected lambs were given 4 L of diluted oral rehydration solution by orogastric tube to stimulate appetite. Two of 12 lambs failed to respond to vitamin B 12 and supportive therapy and were euthanased for welfare reasons. Necropsy revealed a pale and friable liver.		Link to Article
How would you prevent a similar problem next year?	The low unit cost of cobalt sulphate allows routine inclusion in anthelmintic drenches (commercial ‘SC’ preparations, or at inclusion rates of 15–30 g per 10 L of 2.25% benzimidazole or 1.5% levamisole drench).		Link to Article