The work was completed at the Large Animal Veterinary Medical Teaching Hospital, Texas A&M University, College Station, TX.
Neurological Disease in Lambs Associated with Exposure to High Environmental Temperature and Humidity
Article first published online: 19 AUG 2013
Copyright © 2013 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 27, Issue 5, pages 1242–1247, September/October 2013
How to Cite
Sprake, P.M., Hubertus, C., Bissett, W.T., Porter, B.F., Russell, K.E., Garland, T., Young, B.D. and Washburn, K.E. (2013), Neurological Disease in Lambs Associated with Exposure to High Environmental Temperature and Humidity. Journal of Veterinary Internal Medicine, 27: 1242–1247. doi: 10.1111/jvim.12157
- Issue published online: 13 SEP 2013
- Article first published online: 19 AUG 2013
- Manuscript Accepted: 10 JUL 2013
- Manuscript Revised: 22 APR 2013
- Manuscript Received: 7 JAN 2013
- Heat stress;
- Spinal cord;
We detected a pattern of lambs presenting with hyperthermia and neurological signs during the summer.
The main objectives of this study were to compare clinical findings and results of diagnostic testing and to identify a potential etiology.
Fifteen clinical cases of lambs less than 12 months of age presenting with neurological signs, tachypnea, and hyperthermia over 4 summers.
Retrospective case series. Medical records were searched for lambs less than 12 months of age that presented with neurological signs including the following: kyphosis, pelvic limb hyperextension, treading of feet, muscle tremors and recumbency, and hyperthermia of greater than 104°F. A grading system was established to describe severity of presenting neurological signs. Weather data were collected from weather stations near the farm of origin for 3 days prior to presentation.
The lambs were from 7 flocks in central Texas. All cases occurred between July and September, with a median heat index of 90.5 for the 3 days before presentation. Complete blood count, serum chemistry, necropsy examination, rumen content, virology, brain MRI, liver copper, selenium, and vitamin E failed to identify a consistent etiology for the signs presented. The only common factor was high heat and humidity. Histopathological examination identified axonal degeneration and skeletal muscle necrosis in some lambs.
Conclusions and Clinical Importance
These clinical cases appeared similar to the Australian disease humpyback and indicate that lambs exposed to high environmental temperatures and humidity might be at risk of developing the described clinical presentation.