Felis ISSN 2398-2950

Hypokalemic myopathy (Burmese)

Synonym(s): Hypokalaemic myopathy in Burmese cats

Contributor(s): Prof Richard Malik, Severine Tasker

Introduction

  • Cause: inherited genetic mutation.
  • Signs: muscle weakness; ventroflexion of the head and neck.
  • Diagnosis: serum potassium concentration; clinical signs consistent with hypokalemia; PCR; Genetic testing.
  • Treatment: potassium supplementation.
  • Prognosis: excellent.

Pathogenesis

Etiology

  • Autosomal recessive inherited condition (complete penetrance), caused by a nonsense mutation in the WNK4 gene. This codes for the enzyme lysine-eficient 4 protein kinase, which is involved in sodium/potassium exchange mechanisms in the kidney.
  • Potassium loss in urine leads to hypokalemia Hypokalemia which in turn causes polymyopathy and leakage of creatine kinase (CK) from muscle cell cytoplasm into the blood and serum.
  • In humans a different mutation of the same gene causes familial hyperkalemic hypertension (FHHt, also known as Gordon's Syndrome); which is counterintuitive!

Predisposing factors

General

  • Stress may be a trigger.
  • Diet. Certain diets may somehow trigger periods of hypokalemia.

Specific

  • IV fluids without potassium may pose a risk.

Pathophysiology

  • Not well understood currently, but likely a functional renal tubular defect resulting in loss of excessive potassium ions into the urine, or reduced absorption of potassium ions.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Malik R, Musca F J, Gunew M N et al (2015) Periodic hypokalaemic polymyopathy in Burmese and closely related cats: A review including the latest genetic data. J Feline Med Surg 17 (5), 417-426 PubMed.
  • Gashen F, Jaggy A, Jones B (2004) Congenital diseases of feline muscle and neuromuscular junction. J Feline Med Surg (6), 355-366 PubMed.
  • Stolze M, Lund C, Kresken J G et al (2001) Periodic hypokalemic polymyopathy in the Burmese cat. Klientierpraxis 46 (5), 289-96 ResearchGate.
  • Lantinga E, Kooistra H S, van Nes J J (1998) Periodic muscle weakness and cervical ventroflexion caused by hypokalemia in a Burmese cat. Tijdschrift Diergeneeskd 123 (14-15), 435-437 PubMed.
  • Jones B R, Swinney G W, Alley M R (1988) Hypokalaemic myopathy in Burmese kittens. New Zealand Vet J 36 (3), 150-151 PubMed.
  • Mason K V (1988) Hereditary potassium depletion in Burmese cats? JAAHA 24 (5), 481 VetMedResource.
  • Eger C E, Robinson W F & Huxtable C R R (1983) Primary aldosteronism (Conn's syndrome) in a cat; a case report and review of comparative aspects. JSAP 24 (5), 293-307 VetMedResource.

Other sources of information

  • Hypokalaemia in a Burmese kitten. iCatCare: www.youtube.com/watch?v=HMCTg4RAEAY
  • Gruffydd-Jones T et al (1997) Proceedings of the 14th American College of Veterinary Internal Medicine (ACVIM), San Antonio, Texas, p 757.


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