Progressive myoclonic epilepsy with accumulation of polyglucosan bodies (Lafora bodies) in the brain and other tissues. It produces myoclonus, especially triggered by sensory stimuli, which progresses to ataxia, cognitive decline and blindness. It is inherited in an autosomal recessive manner and in the dog is associated with a dodecameric repeat expansion in the EPM2B (NHLRC1) gene. It is one of the best-characterised progressive epilepsies in veterinary medicine.

Breeds with confirmed cases or carriers (OMIA000690-9615): Basset Hound, Beagle, Brussels Griffon, Chihuahua, Dachshund (Miniature Wire-Haired variety and others), French Bulldog, Newfoundland, Pembroke Welsh Corgi, Pointer and Poodle (miniature and standard). The Miniature Wire-Haired Dachshund and the Beagle are the historically most affected breeds. There are no consolidated current population frequencies for most breeds.

- Sudden myoclonus, often in bursts, frequently triggered by light, sound or touch
- Generalised tonic-clonic seizures
- Progressive ataxia
- Behavioural changes and cognitive decline
- Blindness and neurological deficits in advanced stages
- Onset in young animals or young adults

Canine Lafora disease was recognised in the Miniature Wire-Haired Dachshund and the Beagle. In 2005, Lohi and colleagues identified the molecular cause: an expansion of a dodecameric repeat in the 5' region of the EPM2B (NHLRC1) gene, which encodes laforin. Subsequent screening detected carriers in several additional breeds, which led to the offering of genetic tests for breeding animals. The dog is considered a useful model of human Lafora disease.

- Test breeding animals with the EPM2B test in the affected breeds
- Do not mate two carriers: 25% risk of affected homozygotes
- A carrier may be mated to a clear animal; offspring intended for breeding must be tested
- Exclude affected animals from breeding
- Avoid spreading the allele to lines where it is not yet present, especially in breeds with low genetic diversity

Differential diagnosis with other progressive myoclonic epilepsies and with idiopathic epilepsy. Myoclonus triggered by sensory stimuli (light, sound) is very characteristic. EEG and MRI guide the diagnosis, but confirmation is genetic. There is no curative treatment: management is palliative with antiepileptic drugs (phenobarbital, levetiracetam, valproic acid) and control of the triggers.

1. Lohi H, Young EJ, Fitzmaurice SN, Rusbridge C, et al. Expanded repeat in canine epilepsy. Science 2005. PMID:15637270.
2. Swain L, Key G, Tauro A, Ahonen S, et al. Lafora disease in miniature Wirehaired Dachshunds. PLoS One 2017. PMID:28767715.
3. Chambers JK, Thongtharb A, Shiga T, Azakami D, et al. Accumulation of Laforin and Other Related Proteins in Canine Lafora Disease With EPM2B Repeat Expansion. Vet Pathol 2018. PMID:29444631.
4. von Klopmann T, Ahonen S, Espadas-Santiuste I, Matiasek K, et al. Canine Lafora Disease: An Unstable Repeat Expansion Disorder. Life (Basel) 2021. PMID:34357061.
5. Barrientos L, Maiolini A, Häni A, Jagannathan V, et al. NHLRC1 dodecamer repeat expansion demonstrated by whole genome sequencing in a Chihuahua with Lafora disease. Anim Genet 2019. PMID:30525203.
6. OMIA:000690-9615 Myoclonus epilepsy of Lafora (Canis lupus familiaris).