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Draft Policy Document on Calcium, Magnesium, Glucose and Phosphorus Solutions for the Treatment of Metabolic Diseases in Sheep and Cattle

Guideline No. 40

Introduction

Hypocalcaemic recumbency (peri-parturient paresis, milk fever complex) in sheep and cattle is a metabolic disease which occurs as a result of hypocalcaemia, often complicated by concurrent hypophosphataemia and sometimes complicated by concurrent hypomagnesaemia. The disease may be mild, moderate or severe; and is normally responsive to treatment with parenteral injections of calcium at the rate of 20-40mg/kg body weight, depending on severity and response. It is recommended that half of this dose is given to effect by slow intravenous injection and the balance administered subcutaneously. The full dose can be administered by subcutaneous injection, although the peripheral circulation is likely to be inadequate for this route of administration in severe cases. A 2-3% calcium solution is normally used for this treatment, however, addition of approximately 1.0% phosphorus and 0.5% magnesium to the calcium solution is common to treat any concurrent hypophosphataemia and/or hypomagnesaemia.

Recumbency following yarding and transport (transit paresis / transit tetany) in sheep and cattle often has a similar aetiology to peri-parturient paresis. Tetany may be more prevalent in this expression of the disease, possibly due to a more serious hypomagnesaemia. Treatment with mixed solutions of calcium, phosphorus and magnesium as described above is often effective. Treatment with extra magnesium may be beneficial in some cases.

Hypomagnesemic tetany (grass tetany, lactation tetany) is a metabolic disease which occurs as a result of hypomagnesaemia, usually complicated by concurrent hypoglycaemia and sometimes complicated by concurrent hypophosphataemia. The disease may be mild, moderate or severe; and is often responsive to treatment with an injection of magnesium at the rate of 20-40mg/kg body weight, followed by a mixed solution of calcium, phosphorus and magnesium as for peri-parturient paresis, depending on severity and response. Half of this dose can be given to effect by slow intravenous injection and the balance administered subcutaneously or the full dose can be administered by subcutaneous injection. A 10 % magnesium solution is normally used for subcutaneous use which should be diluted 1:10 for intravenous use. Sedation of these animals is sometimes required before intravenous treatment can be administered.

Data is not currently available to demonstrate that the glucose included in these products has a significant effect on the treatment of any metabolic disease.

Although intravenous administration is often the preferred route of administration for some of these injections, it is not without danger. Monitoring cardinal signs of the treated animal, particularly the cardiac rhythm, while giving the injection slowly is recommended. Perivascular injection can cause irritation and can make further intravenous injection difficult. For these reasons guidance from a registered veterinary surgeon is recommended before using this route of administration.

Recommendations

  1. Use of the phrase “four in one” or “4 in 1” in the product name for products containing calcium, magnesium, glucose and phosphorus will still be accepted on the basis of historical use provided:
    1. Only the calcium, phosphorus and magnesium content are declared as active constituents.
      eg
      Active constituents: per 500 mL
      Calcium (as the gluconate) 12.50 g
      Phosphorus (as hypophosphite) 6.00 g
      Magnesium (as the hypophosphite) 2.35 g

      Also contains:
      Glucose (as dextrose monohydrate) “x” g
    2. Only the treatment of hypoglycaemia (parturient paresis / milk fever) and related metabolic diseases (transit paresis, transit tetany) in sheep and cattle can be claimed in the indications for use. The claim may also include the treatment of hypomagnesaemia (grass tetany / lactation tetany), PROVIDED THAT directions are given for initial treatment with a magnesium salt solution as well as the product making the claim. The claim is NOT TO INCLUDE any indication for hypoglycaemia (pregnancy toxaemia/ketosis/acetonaemia).
  2. The directions for use must specify that the dosage recommendations are for subcutaneous use. These products must have the statement “Use of this product intravenously can be hazardous to the animal and advice from a registered veterinary surgeon should be sought.” or such similar statement as from time to time approved by the NRA. This statement must appear under the “DIRECTIONS FOR USE” heading.
  3. Registration will only be permitted when evidence is provided that a registered product meets NRA standards for sterility and pyrogenicity. The relevant Therapeutic Goods Order should be used as a basis for sterility requirements. For requirements on pyrogenicity please refer to the APVMA Guidelines on LAL Testing. The statement “Sterile and Non-Pyrogenic” will be allowed until further notice, however, since all injectable products are expected to be sterile and non-pyrogenic, such statements will become superfluous with time.

References:

  1. (i) BLOOD, D.C. & RADOSTITS, O.M. (1989). Veterinary Medicine 7th edition p1100-1149
  2. (ii) HOWARD, J.L. et al (1993). Current Veterinary Therapy Food Animal Practice 3 p304-326