Issue Description Polyneuropathy in dogs and cats is a
collection of peripheral nerve disorders that often are breed-related
in these animals. Polyneuropathy indicates that multiple nerves are
involved. Polyneuropathy usually involves motor nerve dysfunction. Other Names Lower Motor Neuron Disease
Breeds At Risk The following breeds have the highest incidence
of inherited polyneuropathy: Alaskan Malamutes, Boxers, Dalmatians,
English Pointers, German Shepherds, Long-Haired Dachshunds,
Rottweilers and Tibetan Mastiffs. Coonhounds have a higher rate of
acquired neuropathy, even suffering from their own condition, known as
Symptoms Symptoms include decreased or absent reflexes
and muscle tone, weakness, or paralysis. It often occurs in the rear
legs and is bilateral. Most are chronic problems with a slow onset of
symptoms, but some occur suddenly.
Diagnosis A variety of blood, nerve and muscle tests are
used to diagnose polyneuropathy in dogs. Inherited forms of the
disease are incurable, so treatment is focused on making the dog as
comfortable as possible.
Treatment Dogs with acquired neuropathy can be treated
based upon the specific cause; immune-suppressing drugs like
corticosteroids are often prescribed. When the animal is severely
disabled or unable to walk, nutrition, fluid and electrolyte therapy
also may be administered. Animals that cannot walk also must be
treated and moved regularly to prevent the development of bedsores.
Most Common Types of Polyneuropathy
Birman Cat distal polyneuropathy - This is
an inherited disorder caused by decreased numbers of myelinated axons
in the central and peripheral nervous systems. Astrogliosis (an
increase in the number of astrocytes) is also noted. The lesions are
most commonly found in the lateral pyrimidal tract of the lumbar
spinal cord, the fasciculi gracili of the dorsal column of the
cervical spinal cord, and the cerebellar vermian white matter.
Symptoms start at the age of 8 to 10 weeks, and include frequent
falling and walking on the hock. The prognosis is poor. The disease is
suspected to have a recessive mode of inheritance.
Botulism - Botulism is very rare in dogs and usually follows
feeding on carrion. Symptoms include weakness, difficulty eating,
acute facial nerve paralysis, and megaesophagus. Compared to other
species, dogs and cats are relatively resistant to botulism.
Dancing Dobermann disease - This primarily affects the
gastrocnemius muscle in Dobermanns. It usually starts between the ages
of 6 to 7 months. One rear leg will flex while standing. Over the next
few months it will begin to affect the other rear leg. Eventually, the
dog is alternatively flexing and extending each rear leg in a dancing
motion. Dancing Dobermann disease progresses over a few years to rear
leg weakness and muscle atrophy. There is no treatment, but most dogs
retain the ability to walk and it is painless.
Diabetic neuropathy - This condition is more common in cats than
dogs. It is caused in part by prolonged hyperglycemia (high blood
sugar) and results in dysfunction of one or both tibial nerves and a
plantigrade stance (down on the hocks). It may resolve with treatment
of the diabetes. The pathology of this condition in cats has been
shown to be very similar to diabetic neuropathy in humans.
Distal symmetric polyneuropathy - Symptoms include atrophy of the
distal leg muscles and the muscles of the head, and rear limb
weakness. There is no treatment and the prognosis is poor. This is
most commonly seen in Chesapeake Bay Retrievers, St. Bernards, Great
Danes, Newfoundlands, Collies and Labrador Retrievers.
Dysautonomia - This is primarily seen in cats. Symptoms include
vomiting, depression, not eating, weight loss, dilated pupils, third
eyelid protrusion, sneezing, slow heart rate, and megaesophagus. There
is a poor prognosis and supportive treatment is necessary. Cats can
recover, but it may take up to one year.
Giant axonal neuropathy - This is a rare disease in the German
Shepherd Dog. It usually becomes evident between the ages of 14 and 16
months. Symptoms include rear limb weakness, decreased reflexes,
muscle atrophy, megaesophagus, and loss of bark. There is no treatment
and a poor prognosis.
Hyperchylomicronemia or hyperlipoproteinemia - This a type of
hyperlipidemia that is inherited in cats. Polyneuropathy is caused by
stretching or compression of nerves near bone by xanthomas, which are
lipid deposits. It can cause Horner's syndrome, facial nerve
paralysis, and femoral nerve, tibial nerve, radial nerve, trigeminal
nerve, or recurrent laryngeal nerve paralysis.
Hypertrophic neuropathy - This is also known as canine inherited
demyelinative neuropathy (CIDN) and is inherited in the Tibetan
Mastiff. Symptoms usually start between the ages of 7 to 10 weeks, and
include weakness, decreased reflexes, and loss of bark. Sensory
fumction remains, but there may be a poor gait or an inability to
walk. There is no treatment and a guarded prognosis. It is inherited
as an autosomal recessive trait.
Hypoglycemia - Polyneuropathy is especially seen in conjunction
Polyradiculoneuritis - This is inflammation of the nerve roots.
The most common type is Coonhound paralysis. This is similar to
Guillain-Barré syndrome in humans. Coonhound paralysis seems to be
secondary to a raccoon bite, probably due to some factor in the
saliva. However, it can also occur without any interaction with a
raccoon. It can happen in any breed of dog. When associated with a
raccoon bite, the symptoms start 7 to 11 days after the bite, and
include rear leg weakness progressing rapidly to paresis, and
decreased reflexes. When not associated with a raccoon bite, the same
symptoms occur, with the paresis taking about 3-4 days to reach it's
maximum effect. Severe cases will have a loss of bark, trouble
breathing, and an inability to lift the head. Typically the duration
of the paralysis is 2 to 3 months. However, the paralysis can last up
to 6 months. Treatment is proper nursing care, and the prognosis is
good in mild cases. In bad cases the dog doesn't completely recover
their initial muscular capability but still are able to live and enjoy
life for years. In very bad cases it is possible for breathing to be
impaired, and unless the dog is placed on a ventilator, suffocation
will occur. Polyradiculoneuritis has also been seen one to two weeks
post-vaccine in dogs and cats. It can also be caused by toxoplasmosis.
Rottweiler distal sensorimotor polyneuropathy - This is
characterized by distal muscle denervation, but the cause is unknown.
It affects young adult Rottweilers. The symptoms include weakness of
all four legs and decreased reflexes. The disease is gradually
progressive. Treatment is possible with corticosteroids, but the
prognosis is poor.
Sensory neuropathies - These are inherited conditions in dogs and
cause an inability to feel pain and a loss of proprioception. Self
mutilation is often seen. There is no treatment, and the prognosis is
poor in severe cases. There are several affected breeds.
- Boxer - usually occurs at around two months of age as a slowly
- Dachshund (longhaired) - usually occurs between 8 and 12 weeks
of age, and causes urinary incontinence, loss of pain
sensation all over the body, and penis mutilation. It is
probably inherited as an autosomal recessive trait.
- English Pointer - usually occurs between the ages of 3 and 8
months and most commonly involves licking and biting at the
paws. There is no treatment and a poor prognosis. It is
inherited as an autosomal recessive trait.
Spinal muscular atrophy - This occurs in dogs and is caused by the
death of nerve cells in the spinal cord. This progressive disease has
no treatment and a poor prognosis. Affected breeds include the Swedish
Lapland Dog, Brittany Spaniel, English Pointer, German Shepherd Dog,
Rottweiler, and Cairn Terrier.
Tick paralysis - This is an acute, ascending motor paralysis that
occurs in dogs; cats seem to be resistant. The cause is a neurotoxin
in the saliva of certain species of adult ticks. Dermacentor species
predominate as a cause in North America, while Ixodes mainly causes
the disease in Australia. The onset of symptoms is 5 to 9 days after
tick attachment, and include incoordination progressing to paralysis,
changed voice, and difficulty eating. Death can occur secondary to
paralysis of the respiratory muscles, but in North America there is a
good prognosis once the ticks are removed. Recovery is usually in 1 to
3 days. In Australia, however, it is a more severe disease with
cranial nerve effects, and death can occur in 1 to 2 days.
Toxic neuropathies - The most common causes are vincristine,
thallium, and lead.