Leonberger Club of America Health, Research, and Education Committee

Inherited Leonberger Polyneuropathy (ILP)

What is it?	A polyneuropathy is a disease which affects more than one nerve. There are many different forms of polyneuropathies and many differnt causes including toxic, metabolic and/or endocrine (diabetes, hypoglycemia, hypothyriodism, chronic liver disease, etc.), immune- mediated, carcinomatous, idiopathic and inherited. The leonberger can suffer from any of these forms of polyneuropathy. Inherited Leonberger Polyneuropathy (ILP) refers to the heritable form. This polyneuropathy affects the longest (peripheral) nerves of the body. This causes weakness and dyfunction in the muscles that are innervated by these nerves. ILP is progressive, often debilitating and can be fatal.
Symptoms:	Include an abnormal gait, exercise intolerance, tremor, muscle atrophy, and in time, an inability to walk, with symptoms occuring primarily in the rear limbs. If the laryngeal nerve is affected, there may also be a change in bark, wheezing, and coughing or choking while eating or drinking. Over the past few years we have diagnosed dogs with symptoms ranging from very mild to very severe and in which clinical signs became apparant as early as a few months to as late as over 8 years of age.
Diagnosis:	A veterinary neurologist should be consulted in the event ILP is suspected. They will collect muscle and nerve biopsy samples, either pre or post mortem from which they will make the diagnosis. We would strongly encourage you to seek an expert opinion after consultation with your regular veterinarian as, sadly, this disease is as yet not well known and has been often misdiagnosed. Though treatment options are limited at best at this time, it may well be that the earlier there is intervention, the more likely we may be able to slow progression of the disease.
Treatment:	Various treatments have been tried with limited success for the nerve and muscular symptoms. There is ongoing research including a drug trial and for dogs with laryngeal paralysis, there is "tie back" surgery, which can relieve respiratory symptoms. We continue to find cases of related dogs with these diseases. There are a number of people who are working very hard on this issue, including breeders, veterinarians, and researchers at a couple of different universities, with a strong focus on determining the mode of inheritance and trying to find genetic markers which will lead to the ability to run a blood test for carriers. We are also trying to coordinate our efforts with research being done in European countries. If you suspect you have an affected dog, please contact the HREC LP/PN representative who can give you further information on how to contact a veterinary neurologist or put you in touch with Dr. Ned Patterson - the lead researcher for this disease. Pre or Post-Mortem Biopsies: Dr. Ned Patterson at the University of Minnesota is conducting an on-going research study in the hopes of coming up with a DNA test that will definitively identify LP/PN carriers and affected dogs. Needless to say, this will be of utmost significance to the Leonberger breed in general, and specifically for all Leonberger breeders internationally. To further efforts, it is critical that post-mortem biopsies be performed on all affected dogs. Dr. Diane Shelton requires the following from your veterinarian: cranial tibial muscle and peroneal nerve, preserved in 10% buffered formalin Please send this to: Dr. Diane Shelton Department of Pathology University of California, San Diego La Jolla, CA 92093-0612
Links:	Listing of Leonbergers affected with Inherited Leonberger Polyneuropathy Article on Inherited Leonberger Polyneuropathy by our HREC PN representative, Dr. Cindy Atwood. Inherited Leonberger Polyneuropathy Muscle/Nerve Biopsy Form (downloadable) International Leonberger Database