Post Mortem Investigation of Possible Mucosal Damages in Dairy Cows Following Four Oral Administrations at 12 Hour Intervals of a Calcium Chloride Paste Formulation

Abstract

It is well-known that the incidence of milk fever in dairy cows can be significantly reduced when gut absorption of approximately 50g calcium takes place 4 times with 12 hour intervals around calving.^1,2,3 There are several different oral calcium formulations available containing different calcium salts, e.g., chloride, propionate, formiate, oxide, and carbonate. The amount of absorbed calcium following oral administration, however, is dependent on water- solubility of the different salts. 4 Calcium chloride is the most readily absorbed salt. The bioavailability of calcium propionate and formiate are inferior to calcium chloride. Consequently, a higher amount of administered calcium salts like calcium propionate or formia te is needed in order to get approximately 50g calcium absorbed from the gut. Calcium oxide and calcium carbonate are not water-soluble and therefore poorly absorbed.

It is also well-known that due to its caustic effect, calcium chloride in water or watery gel causes serious mucosal damages in the pharynx, esophagus, forestomachs and abomasum.^5'6 Several of these products in Europe are withdrawn from the market due to the caustic effect of calcium chloride on the mucosa. A calcium chloride bolus with a protective layer of fat surrounding it is available in Scandinavia. However, serious consequences are reported following administration of the calcium bolus to calving cows with impaired or absent mobility of the digestive tract. In these cases the bolus or boli lie directly on the mucosa in either rumen or reticulum, and the caustic calcium chloride would be in direct contact with the mucosa. A fatal case report is published in the Danish Veterinary Journal.⁷

A water-in-oil emulsion, where the caustic calcium chloride is dissolved in water and protected by oil, has been on the market during the past 6-7 years. The mucosal damages are minimized following administration. Maladministration into the lungs, however, has been observed due to the viscosity of the product.⁸

In cooperation with the Royal Danish School of Pharmacy, a calcium chloride paste formulation (BOVIVET® Calcium Paste, Jørgen Kruuse A/S) has been developed. In this paste formulation 180g calcium chloride and 6g magnesium chloride are distributed in and protected by a special two-component oil preparation and filled on to a 255ml cartridge. During the production of the paste formulation the dry materials are sticked together with the fat part of the oil which is then covered by rape seed oil.

This publication describes an investigation of possible mucosal damages of the tongue, pharynx, larynx, oesophagus, forestomachs and abomasum following oral administration of the calcium chloride paste formulation 4 times with 12 hours interval.