Paresis and unusual electrocardiographic signs in a severely hypomagnesaemic, hypocalcaemic lactating bitch

A severely hypocalcaemic, hypomagnesaemic lactating bitch exhibited clinical signs of pulmonary oedema, paresis, dementia, gastrointestinal ileus and urinary bladder atony. The total calcium, ionised calcium and magnesium levels were extremely low. The clinical picture was very different from the one typically encountered in canine lactation tetany, and instead resembled bovine postparturient paresis. Muscle tremors, rigidity and seizures were not part of the acute clinical picture, but rather atony, weakness and paresis. General muscle dysfunction probably resulted from the extremely low ionised calcium levels in combination with very low levels of magnesium and possibly potassium. Heart failure and atony of the urinary bladder and intestines were probably a result of the severe hypocalcaemia. The alteration in calcium to magnesium ratio may have depressed neuromuscular transmission, leading to paresis and atony. The unusual electrocardiogram possibly also resulted from abnormal magnesium and calcium cation levels.