Common Symptoms
Lafora Disease is an inherited neurological disease affecting Newfoundland dogs. Affected dogs typically present after 5 years of age with progressive, partial to generalized seizures due to an abnormal accumulation of large carbohydrate molecules in the brain. As the disease progresses, affected dogs may display other clinical signs including vision loss, deafness, Dementia, myoclonus (involuntary muscle jerks), aggression, tremors, “flybiting” behavior (attempting to catch nonexistent flies), jaw smacking, urinary and fecal incontinence, loss of house training, and/or abnormal gait. Excitement or nervousness, exposure to flickering lights, sudden sounds or movements may trigger seizure activity in some affected dogs. Seizures caused by this type of epilepsy have mixed response to treatment, becoming less effective as the disease progresses. Affected dogs are typically euthanized by 10-12 years of age due to decline in quality of life.
Breed-Specific Information for the Newfoundland
The Mutation of the NHLRC1 gene associated with Lafora Disease has been identified in the Newfoundland, although its overall frequency in this breed is unknown.
Testing Tips
Genetic testing of the NHLRC1 gene in the Newfoundland will reliably determine whether a dog is a genetic Carrier of Lafora Disease. Lafora Disease is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the NHLRC1 gene mutation. Reliable genetic testing is important for determining breeding practices. Because symptoms do not appear until adulthood, genetic testing should be performed before breeding. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Newfoundland dogs that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
References
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Swain L, Key G, Tauro A, Ahonen S, Wang P, Ackerley C, Minassian BA, Rusbridge C. Lafora disease in miniature Wirehaired Dachshunds. PLoS One. 2017 Aug 2;12(8):e0182024. doi: 10.1371/journal.pone.0182024.
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von Klopmann T, Ahonen S, Espadas-Santiuste I, Matiasek K, Sanchez-Masian D, Rupp S, Vandenberghe H, Rose J, Wang T, Wang P, Minassian BA, Rusbridge C. Canine Lafora Disease: An Unstable Repeat Expansion Disorder. Life (Basel). 2021 Jul 14;11(7):689.
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Webb AA, McMillan C, Cullen CL, Boston SE, Turnbull J, Minassian BA. Lafora disease as a cause of visually exacerbated myoclonic attacks in a dog. Can Vet J. 2009 Sep;50(9):963-7.
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