Lundehund Syndrome (LS)
Lundehund syndrome (LS) is an inherited gastoenteropathy affecting the Lundehund dog breed. The disorder is also known as the Lundehund intestinal syndrome and it is a combination of the stomach and intestinal diseases which cause malabsorption and protein loss and deficiency. The Norwegian Ludenhund, also known as the puffin dog has experienced a severe bottle neck, with only five remaining dogs in 1960’s. The bottle neck resulted in high widespread of the LS causative mutation in today’s Lundehund dogs. A similar condition has been recognized in the Soft Coated Wheaten Terrier, known as Protein Losing Nephropathy, which is affecting their immune system, gut, and kidney.
Characteristics and Symptoms
The Lundehund syndrome comprises several disorders together: protein-losing enteropathy (PLE), intestinal lymphangiectasia, gastrointestinal disturbance, inflammatory bowel disease and malabsorption. The first symptoms start to appear between 2.5 to 10.5 years of age. Clinical signs include diarrhea, vomiting, loss of appetite, weight loss, edema, swollen abdomen and/or swollen legs, low serum protein, especially albumin and apathy. Low levels of albumin are sometimes the only sign of the disorder. Hypoalbuminemia is sometimes accompanied with hyperglobulinaemia, reduced levels of fructosamines and vitamin B, hypo- or hypercalcemia, as well as high levels of serum folate and alanine aminotransferase. The condition can eventually lead to lymphoma or cancer of the intestines or stomach. Often, Lundehuns who appear healthy, show abnormal findings in histopathologic examinations.
The Lundehund syndrome (LS) is caused by a mutation in the neuropeptide operating gene LEPREL1. During the research, some Lundehund dogs showed no symptoms of the disorder although carrying two alleles of the causative mutation. Lundehunds without clinical signs for LS who carry the causative mutation are expected to be subclinically affected or fall ill later in their life by specific trigger mechanisms. The onset of the disease could be also influenced by external factors, which trigger the phenotypic expressions.
The Lundehund syndrome is inherited as an autosomal recessive disorder. Healthy parents of an affected dog are obligate heterozygotes, and therefore carry one mutant allele. Heterozygotes have no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Metzger, J., Pfahler, S., & Distl, O. (2016). Variant detection and runs of homozygosity in next generation sequencing data elucidate the genetic background of Lundehund syndrome. BMC Genomics, 17, 535. http://doi.org/10.1186/s12864-016-2844-6