Canis ISSN: 2398-2942

Diabetes: neuropathy

Contributor(s): David Bruyette

Introduction

  • Very common complication in human diabetics but is a relatively infrequent occurrence in this species.
  • Cause: nerve damage secondary to diabetes mellitus Diabetes mellitus (DM).
  • Signalment: mature to older (with chronic DM).
  • Signs: hindlimb wasting and weakness.
  • Diagnosis: concurrent neurological signs and DM.
  • Treatment: manage DM but no specific therapy for nerve injury.
  • Prognosis: guarded for improvement in neurological signs.

Pathogenesis

Pathophysiology

  • Late diabetic complications are the result of damage to tissues such as nervous tissue which do not require insulin in order to take up glucose. These are therefore exposed to high concentrations of glucose in the long-term.
  • As glucose builds up in these tissues unmetabolized it is shifted into a sorbitol pathway → sorbitol. The sorbitol is more slowly converted to fructose.
  • As this conversion takes place NAD (nicotinamide adenine dinucleotide) is reduced → changes in lipid metabolism, increase in free radicals and increased nitric acid production.
  • Depletion of myo-inositol decreases sodium ATPase activity reducing transmembrane sodium gradient → slowing nerve conduction.
  • High levels of glucose also permits non-specific glycosylation of proteins and since proteins are involved in almost every biological process these changes can have far-reaching effects:
    • May affect myelin and promote myelin uptake by macrophages → demyelination of nerves.
    • Glycosylation of tubulin may cause cross-linking and tubulin aggregate formation leading to nerve injury.
  • Local vasoconstriction may contribute to nerve hypoxia due to reduced blood flow.

Timecourse

  • More likely to develop with poor glycemic control.
  • May develop years after onset of DM (even if this is diagnosed and treated correctly).
  • The time lag in development of neurological complications may explain the relatively low incidence in dogs.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Towell T L & Shell L C (1994) Endocrinopathies that affect the peripheral nerves of cats and dogs. Comp Cont Ed 16 (2), 157-161 VetMedResource.
  • Johnson C A, Kittleson M D & Indrieri R J (1983) Peripheral neuropathy and hypotension in the diabetic dog. JAVMA 183 (9), 1007-1009 PubMed.
  • Katherman A E & Braund K G (1983) Polyneuropathy associated with diabetes mellitus in a dog. JAVMA 182 (5), 552-554 PubMed.


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