Polyneuropathy

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Canine polyneuropathy is a neurological disease of dogs characterized by a dysfunction of multiple peripheral nerves.

This disease can be observed as either a primary genetic X-linked condition or as a result of underlying secondary disease such as is commonly observed with peripheral neuropathy associated with diabetes mellitus.

Somatic nerve dysfunctions are most predominant, but autonomic nerves may also be affected.

As autonomic dysfunction may lead to laryngeal or pharyngeal paralysis, megaesophagus and aspiration pneumonia is frequently misdiagnosed as a cause of death[1].

The cause of this disease is diverse, including infectious, immune-mediated, hereditary conditions or in association with neoplasia, drug reactions and endocrinopathies such as diabetes mellitus[2], hypothyroidism[3][4], insulinoma[5], multicentric lymphoma[6] or disseminated carcinoma.

Breed-associated polyneuropathy in Rottweiler, Border Collies[7], Pyrenean Mountain Dog, Leonberger[8] and Alaskan Malamutes[9] have been reported, with onset of disease occurring at 2 to 5 months of age, with variable phenotypic expression ranging from sub-clinical to severely affected forms. In the Rottweiler, laryngeal paralysis appears to occur commonly as a concurrent condition[10].

Clinical symptoms are associated with peripheral neuropathy signs such as hindlimb ataxia, reduced reflexes, forelimb hemiparesis, paddling-gait, which often progress to paralysis and sensory deficits. Regurgitation, vomiting and coughing may be observed associated with megaesophagus and aspiration pneumonia.

Blood tests, urinalysis and CSF testing are usually unrewarding. Electromyographic evidence of denervation and 52 decreased nerve conduction velocity has been observed in affected nerves[9].

Diagnosis usually requires tissue biopsy of peripheral nerves. Histopathologically, there are characteristic axonal swelling and pale myelin observed, with giant axons mimicking giant axonal neuropathy, atrophic axons and severe interstitial edema.

Variant forms include chronic inflammatory demyelinating polyneuropathy (observed in a Rottweiler[11] and Miniature Schnauzers[12]), greyhound polyneuropathy and acral mutilation syndrome (sensory neuropathy)[13].

Electromyography studies usually show reduced reduced nerve conduction velocity[14].

A differential diagnosis would include polyradiculoneuritis, neuroaxonal dystrophy, progressive axonopathy (Boxers), dancing Doberman disease and tick paralysis.

Treatment requires identifying any underlying disease process and address this initially, followed by prednisolone or pulsed dexamethasone therapy.

Dogs with less severe clinical signs often have good quality of life parameters.

References

  1. Gabriel, A et al (2006) Laryngeal paralysis-polyneuropathy complex in young related Pyrenean mountain dogs. J Small Anim Pract 47:144-149
  2. Johnson, CA et al (1983) Peripheral neuropathy and hypotension in a diabetic dog. J Am Vet Med Assoc 183:1007-1009
  3. Tsuboi M et al (2012) Pathological Features of Polyneuropathy in Three Dogs. J Vet Med Sci Nov 1
  4. Jaggy, A et al (1994) Neurological manifestations of hypothyroidism: a retrospective study of 29 dogs. J Vet Intern Med 8:328-336
  5. Bergman, PJ et al (1994) Canine clinical peripheral neuropathy associated with pancreatic-islet cell-carcinoma. Prog Vet Neurol 5:57-62
  6. Braund, KG et al (1987) Peripheral neuropathy associated with malignant neoplasms in dogs. Vet Pathol 24:16-21
  7. Vermeersch, K et al (2005) Sensory neuropathy in two Border collie puppies. J Small Anim Pract 46:295-299
  8. Hultin Jäderlund K et al (2011) Inherited polyneuropathy in Leonberger dogs. J Vet Intern Med 25(5):997-1002
  9. 9.0 9.1 Taylor, SM (2009) Disorders of peripheral nerves and the neuromuscular junction. In: Small Animal Internal Medicine, 4th ed. (Nelson, R. W. and Couto, C. G. eds.), Elsevier, Philadelphia. pp:1055-1056
  10. Mahony OM et al (1988) Laryngeal paralysis-polyneuropathy complex in young Rottweilers. J Vet Intern Med 12(5):330-337
  11. Molín J et al (2011) Acute clinical onset chronic inflammatory demyelinating polyneuropathy in a dog. Muscle Nerve 44(3):441-444
  12. Vanhaesebrouck AE et al (2008) Demyelinating polyneuropathy with focally folded myelin sheaths in a family of Miniature Schnauzer dogs. J Neurol Sci 275(1-2):100-105
  13. Bardagí M et al (2011) Acral mutilation syndrome in a miniature pinscher. J Comp Pathol 144(2-3):235-238
  14. Rentmeister K et al (2012) Hereditary polyneuropathy in the Alaskan Malamute. Tierarztl Prax Ausg K Kleintiere Heimtiere 40(1):26-34