Neurodegenerative disease characterised by spongiform degeneration of the white matter of the central nervous system, with progressive motor signs of juvenile onset. It is caused by variants in NAPEPLD and has been described in the Leonberger and the Rottweiler; the same Rottweiler variant has also been found in the Great Dane. It is inherited in an autosomal recessive manner, with reduced penetrance.

The Leonberger is the best-characterised breed. The Rottweiler/Great Dane variant has been found in diverse haplotypes, suggesting an ancient origin; no reliable population frequencies are available for the Rottweiler and the Great Dane.

- Progressive spastic tetraparesis\n- Ataxia\n- Decreased proprioceptive reflexes\n- Relative preservation of cranial nerve functions\n- Age of onset in the young adult to middle age

Leukoencephalopathy/leukoencephalomyelopathy (LEMP) is a neurodegenerative disorder of the white matter described in the Rottweiler and the Leonberger. Oevermann and colleagues (2008) described a novel leukoencephalomyelopathy in the Leonberger, and Hirschvogel and colleagues (2013) documented by magnetic resonance imaging a case in a Rottweiler, ruling out DARS2 as a candidate. In 2018, Minor and colleagues mapped the Leonberger disease to chromosome 18 and identified a missense variant in NAPEPLD; in the Rottweiler and the Great Dane they found a different frameshift variant in the same gene.

- Genotype Leonberger breeding animals for NAPEPLD before mating\n- Do not mate two carriers: 25 % risk of homozygotes, although penetrance is reduced and not all homozygotes develop the disease\n- For the Great Dane and the Rottweiler, maximise vigilance of family history\n- Progressively replace carrier lines while preserving genetic diversity\n- Exclude affected animals from breeding

Differential diagnosis with other canine leukoencephalopathies (Schnauzer leukodystrophy, Border Terrier SLEM) and with distal axonal degeneration. Magnetic resonance imaging shows white matter lesions; in the Rottweiler, white matter involvement with T2 hyperintensity has been described (Hirschvogel 2013).

1. Oevermann A et al. (2008) A novel leukoencephalomyelopathy of Leonberger dogs. J Vet Intern Med 22(2):467-471. PMID: 18371035
2. Hirschvogel K et al. (2013) Magnetic resonance imaging and genetic investigation of a case of Rottweiler leukoencephalomyelopathy. BMC Vet Res 9:57. PMID: 23531239
3. Minor KM et al. (2018) Canine NAPEPLD-associated models of human myelin disorders. Sci Rep 8:5818. PMID: 29643404