ISSN 2398-2993      

Hypomagnesemia

obovis
Contributor(s):

Seamus O'Shea

Keith Cutler

Synonym(s): Staggers, Grass staggers, Grass tetany


Introduction

  • Cause: low blood magnesium (Mg) levels, as a result of inadequate dietary magnesium intake or poor absorption from the gut.
  • Signs: hyperesthesia, ataxia, seizures, sudden death.
  • Diagnosis: blood magnesium levels.
    • Definition: serum ionized magnesium <1.5mg/dL or <0.65mmol/L.
  • Treatment: intravenous and subcutaneous magnesium/calcium preparation.
    • This is a true emergency and treatment must be initiated ASAP.
    • Treatment goes beyond stabilising the individual cow.
      • These cases are often the tip of the iceberg and a herd approach will be necessary.
    • Less experienced clinicians would be encouraged to seek the assistance of their senior colleagues when advising farmers as to herd management of these cases.
  • Prognosis: variable. Dependent upon early intervention and treatment.
Print off the farmer factsheet on Staggers to give to your clients.

Pathogenesis

Etiology

  • Insufficient dietary Mg Magnesium: an overview - fails to meet maintenance requirements, growth requirements or lactational requirements.

Predisposing factors

General

  • Lush pasture: especially spring growth - fast growing.
  • Lactating cattle: due to Mg loss in milk. 
  • Fast growing calves: due to increased Mg demand.
  • Exposure to extreme weather (reduced food intake and increased stresses).
  • Beef cattle and dry cows predisposed if left to overwinter out at pasture with no supplementation.

Specific

  •  Most commonly seen around the time of calving.
  •  High levels of Potassium Sodium and potassium - an overview (in soil) and Nitrogen (from fertilizer)- reduces Mg available for uptake by the cow.

Pathophysiology

  • Magnesium Magnesium homeostasis is an essential cation involved in many intracellular enzymatic reactions, including regulating the calcium channel function, neurotransmission, vasomotor tone, muscular contraction and cardiac excitability. 
  • Magnesium is primarily an intracellular cation, with only 1% being found in the serum.
    • Intracellular magnesium is primarily in the bone (67%), muscle (2%) and other soft tissues (11%).
    • Extracellular magnesium exists in three forms:
      • Protein-bound.
      • Complexed with anions (such as phosphate).
      • Ionized.
        • Ionized magnesium is the physiologically active form.
  • Total serum levels therefore may not reflect either the active moiety or the total body concentration.
  • Magnesium is antagonistic to the actions of calcium Calcium and phosphorous - an overview.
  •  A significant role for intracellular magnesium is as a co-factor for the calcium-ATP pump that moves intracellular calcium into the sacroplasmic reticulum.
    • It performs a similar role with the sodium-potassium-ATP pump that moves these electrolytes across cell membranes.
    • Reduction of the activity of these ion pumps is likely to be the major cause of the clinical signs of hypomagnesemia.
  • Magnesium’s role in active transport of Ca and K ions across cell membranes plays an important role in the process of nerve impulse conduction. This in turn affects muscle contraction and cardiac muscle activity.
    • This altered skeletal and cardiac muscle function leads to the symptoms of ataxia, muscle weakness and dysrhythmias Dysrhythmias.
    • If not corrected can progress to death.

Timecourse

  •  Acute form: sudden death.
  •  Sub-acute form: may persist for days.

Diagnosis

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Allcroft R & Burns K (2011) Hypomagnesaemia in Cattle. NZ Vet J 16 (7).

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!

 
 
 
 

To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code