Intorduction
The diagnosis of neuromuscular disease is made by
clinical-neurological examination, electrodiagnosis and biopsy of muscle
and nerve.
The histopathologie examination is the most sensitive method although it
is an invasive procedure.
A distal symmetrie polyneuropathy (PN) which can affect
related Leonbergers between of the age of 1 and 9 was first described in
2003 by Shelton et. al. in the USA.
The key to the diagnosis in dogs with typical gait
problems (hypermetric paws) , atrophy of the distal limb muscles, activity
induced weakness and possibly respiratory stridor lies in the below
mentioned procedure.
Large breed dogs often show signs of gait problems with
age that are due orthopaedic problems (such as arthrosis) and/or
neurological problems (for example discopathy, cauda equina syndrome,
polyneuropathy) and remain indifferent.
It is very important to differenciate these problems from polyneuropathy
to be able to learn more about hereditary Leonberger polyneuropathy.
It is therefore mandatory to perform biopsies post mortem in Leonbergers
even if they only had subtle gait problems that is even if they only Iimp
slightly.
Muscles and nerves of the rear leg are suitable tissue for
biopsy. The area of the lateral knee and caudal distal thigh area are
shaved, loose hair removed and washed.
Nervus peroneus:
This nerve can easily be reached from laterally (Fig.1). Between the
head of the fibula which can easily be palpated and the lateral condylus
of the knee the prominent peroneal nerve can be located. After dissection
of the skin, subcutis and the museie fascia the nerve is visible (Fig.2).
At least 2 cm of nerve should be harvested. The non traumatized nerve is
put in a container which is completely filled with 10% formaline. A label
with tissue identification, patient name/number and date are recommended.
Cranial tibial muscle:
(musculus tibialis cranialis):
This muscle lies on the cranial aspect of the tibia and can be located
via the route discribed by the nerve biopsy or a separate route.
After dissection of the fascia several at least 2x2 cm muscle specimans
should be harvested. The excision with a scalpel avoids artefacts.
The specimen should be held with the forceps only on the very edges, again
to avoid artefacts.
Formaline should also be used in a large enough and marked container.
In general: the sooner the biopsy is taken, the better. If
the animal is cooled right away the tissue specimens can be harvested up
to 24 hours post mortem. Later it is not possible due to autolysis
(autolytic processes). Frozen tissue is not suited due to artefacts which
limit analysis
