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Familial episodic ataxia in lambs
I G Mayhew1, R D Jolly, D Burnham
1Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North , New Zealand.
New Zealand Veterinary Journal
|September 19, 2012
Summary
A novel dominant familial episodic cerebellovestibular ataxia was identified in lambs. This neurological disorder, characterized by ataxia and motor deficits, presents with incomplete penetrance and variable expressivity, potentially impacting breeding flocks.
Area of Science:
- Veterinary Neurology
- Genetics
- Animal Science
Background:
- An episodic neurological disorder was observed in newborn lambs on two separate properties.
- The condition affected lambs from different sheep breeds, with initial suspicion of a dominant inheritance pattern due to its occurrence in specific mating groups.
Purpose of the Study:
- To investigate the pathogenesis of a newly identified episodic neurological disorder in lambs.
- To confirm the suspected dominant mode of inheritance and characterize the clinical presentation and genetic basis of the condition.
Main Methods:
- Two rams, whose offspring exhibited the disorder, were acquired and mated with unrelated sheep under controlled experimental conditions.
- Affected lambs were observed for clinical signs, gait abnormalities, and recovery patterns from birth up to 6 months of age.
Main Results:
- Lambs born to the experimental sires displayed a similar neurological disorder, with some showing abnormalities at birth, including head and neck extension, and delayed suckling.
- Clinical signs included asymmetric gait, abnormal limb tonus, nystagmus, and episodic ataxia, with recovery typically occurring within minutes.
- Episodes of dysfunction became less frequent and severe with age, with lambs appearing normal by 6 months.
Conclusions:
- The disorder was diagnosed as dominant familial episodic cerebellovestibular ataxia, inherited as a dominant trait with incomplete penetrance and variable expressivity.
- Affected lambs may die neonatally, potentially going unrecognized.
- Due to incomplete penetrance and variable expressivity, affected lambs may survive without clinical signs, enter breeding flocks, and perpetuate the disorder, contributing to neonatal mortality.
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