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polyneuropathy is a disease which affects more than one nerve. There are many
different forms of polyneuropathy and many different causes including toxic, metabolic
(chronic liver disease) and endocrine (diabetes, hypoglycemia, hypothyroidism,
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. ILP affects the longest (peripheral) nerves
of the body. This causes weakness and dysfunction in the muscles which are innervated
by these nerves. ILP is progressive and often debilitating; if the larynx is involved
it can be fatal. The
most common early symptoms of ILP are gait abnormalities and/or a weakness in
the rear limbs. As these are non-specific symptoms, it is frequently confused
with other problems. Often subtle, it may show simply as a shortened stride on
one side or a slight dragging/wearing of the toenails. Progression, when it occurs,
may be slow and gradual or rapid. Lack of feeling and weakness is secondary to
nerve degeneration and may present as misplacement of the feet and stumbling,
wobbling, crossing of the limbs exaggerated and lengthened stride or sometimes
a high stepping "marrionette-like" walk.. Though these signs usually
involve the rear limbs they may also occur in the forelimbs. If the recurrant
laryngeal nerve is affected there may also be a change in bark, wheezing, heavy
loud panting and difficulty breathing especially with excersise, and coughing
or choking with eating or drinking. Over the past few years we have diagnosed
dogs with symptoms ranging from very mild to very severe. The signs became apparent
as early as a few months of age to as late as over 8 years of age. A
veterinary neurologist should be consulted in the event ILP is suspected. Careful
physical, orthopedic and neurological examinations are the place to start. Routine
bloodwork and radiographs should help rule out other causes of lameness and polyneuropathy.
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 often been misdiagnosed as something else. More advanced tests, including
nerve conduction velocity and muscle and nerve biopsies are needed to make a definitive
diagnosis. As
of this time there is no curative treatment for this disease though there are
several nutritional supplements that have been recommended which may help delay
the progression of symptoms and appeared to have offered some improovement in
others. We
continue to find an increasing number of affected dogs now on a world wide basis.
There are a number of people working very hard on this issue including breeders,
veterinarians, and researchers at several different facilities. The main focus
is on determining the mode of inheritance by pedigree analysis (extremely difficult
when there are many dogs we don't know were/are affected) and by looking for the
genetic markers or actual causative gene(s) in order to develop a blood test for
carriers. We are also trying to collaborate with researchers in Europe. If
you suspect you have a dog affected by this disease please contact your HREC ILP
representative who can give you further information or help you to find a veterinary
neurologist in your area. Pre
or Post-Mortem Biopsies: Dr
Ned Patterson and Dr. Mickleson at the University of Minnesota are conducting
an on-going research study in the hopes of finding the causative gene(s) and a
developing a DNA test that will identify ILP carriers and affected dogs. Needless
to say, this is of utmost importance to the Leonberger breed in general and specifically
for all leonberger breeders internationally. To further their efforts, it is critical
that biopsies be performed on all affected dogs, as well as immediate relatives
of affected dogs. Dr.
Diane Shelton is neuropathologist who reads these biopsies. She requires the following
from your veterinarian: a biopsy of the cranial tibial muscle and of the the peroneal
nerve. Ideally samples both in 10% formalin and fresh chilled samples. Please
send these to: Dr. Diane Shelton
Department of Pathology
University of California,
San Diego
La Jolia, CA 92093-0612
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