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This article was published in 1945
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.

VARIATIONS IN MINERAL IMBALANCE SYNDROMES

Observed under Field Conditions

E. J. McBarron. B.V.Sc., Inspector of Stock, Holbrook.

Introduction: The following will serve to show that under field conditions there are several syndromes which appear to have a close resemblance to Grass Tetany and associated mineral imbalance diseases in cattle. They each vary in response to treatment, the presence of acetone bodies in the urine, course, and blood Ca. and Mg. values.

The mineral imbalance diseases are world-wide in their distribution, and various authors have described them,e.g., Sjollema (1930), Acute, sub-acute and chronic forms are described, the course extending from hours to days.

Material and Methods: Observations were carried out on thirty cases occurring in the late autumn and early winter of 1943 and 1944. In both years the incidence was heaviest in the period from May to July. In 1943, the dry summer was followed by good rains and a lush growth of feed, particularly on heavily top-dressed pastures. All cases investigated were from cattle, both dairy and beef breeds, grazing on improved pastures. Diagnosis was based on the clinical appearance of the animals, a history of having grazed exclusively on young fresh pastures and analysis of serum Ca. and Mg., together with the use of biochemical examination of the urine where possible.

The Mg. blood level appears to vary even in animals not affected with mineral imbalance, the writer having had experience of a steer affected with pyaemia and returning a blood Mg. value of 3.2 mg. per cent. Best and Taylor (1943) in considering the blood calcium, show that an ionised and non-ionised form exist, the latter being bound to the serum protein. Clark (1942) states that only the ionised form is physiologically active, so that the inorganic analysis of blood calcium would appear to have its limitations.

Dr. Hayden's modification of Rotheras' reaction as described by Udall (1939) was used for the detection of acetone bodies in the urine. According to Duncan et al. (1939) this test gave 70% positive reactions to urine whose ketone content varied between 25 and 49 mgrs per 100 ccs. urine. The same author quotes Henderson (1938); that any cow which shows a positive test for ketone bodies in the urine has ketonaemia.

Albumin determinations were carried out by the acetic acid heat coagulation method.

Syndrome associated with overheating, bloating and acute urinary retention.

These cases occurred in less than 5% of a mob grazing in a paddock. Animals noticed to be uneasy and tending to isolate themselves. Later they develop a stiff and stilted gait, going down within a few hours. The head invariably is drawn back to the flank; resp. 30-40; pulse invariably elevated. Temperature rarely exceeds 102º. Eye reflexes dulled and subject goes into a comatose condition within a few hours. Injections of a soluble Ca. salt i/v produce a brightening effect. The animal will regain its feet; but only to go down within an hour or so. Further administrations produce similar transient effects with the concomitant development of pain, tenderness over the flank and tremors of the limb muscles. Where this develops the administration of Mg. salts produces a sedative effect, possibly due to the depressant action on the C.N.S. The administration of Chloral will produce the same result. A characteristic feature is the suppression of ruminal movement and peristalsis. Bloating soon develops and unless relieved will soon result in a fatal termination. Urinary retention is another characteristic, the relief of which will relieve the subject considerably.

Case 1. Two Hereford steers were seen in a paddock and appeared to be similarly affected. The administration of antizymotics and ruminal massage resulted in recovery within two days. The other subject died before treatment could be adopted, and the pronounced tetany of the limb muscles led to a tentative diagnosis of grass tetany. Serum analysis collected at P.M. showed Ca. 9.8 mg. per cent., Mg. 2.4 mg. per cent. Urine analysis showed S.G. 1017, alkaline to litmus, slight reduction to Benedict's Solution, no acetone bodies, positive for albumin, small amount of bile present. Lesions observed on PM. were slight emphysema of lungs, extensive sub-endocardial haemorrhages, congestion of intestines with dark coloured ingesta and gas. The gall bladder was grossly distended. Portions of intestines showed enteritis and smears revealed numerous enterococci.

Case 2. In a herd of 45 dairy cows there were three deaths and one recovery within a fortnight. A heavy fall of rain a week prior to the commencement of trouble resulted in a lush growth of pastures. Symptoms noticed were uneasiness, followed by kicking at the abdomen, paddling movement of hind limbs, tremors of the thigh muscles. Animals went down within 12 hours. Clinical examination showed a normal temperature; pulse. 25-30 and strong. Two serum samples were submitted for analysis; the first, from an animal which appeared to be developing an attack, returned Ca. 10.6 mg. per cent. Mg. 2.1 per cent. The other, which had had the attack for three days, gave Ca. 7.3 mgms. per cent. and Mg. 2.1 mgms. per cent. Urine examination for ketone bodies was negative. Use of saline purgatives freely, and change to natural, unimproved pastures resulted in cessation of trouble without further losses. This syndrome did not differ from a clinical picture of grass tetany which is considered later.

The administration of drenches of Mg. and Ca. salts in solution or in the form of molasses is considered to have an effect on the blood mineral balance. Cunningham (1934) found that 680 gms. of molasses. when administered to fasting sheep per os, raised the Ca. and Mg. levels 50% within an hour. The effect persisted beyond five hours, but subsided after 24 hours. Clark (1942) quotes Matthew Hay as showing that if magnesium sulphate were given in concentrated solution to thirsting animals a large proportion of the salt was absorbed and excreted in the urine, but no purgation was produced; whereas dilute solutions of the same salt produced a rapid purgation but none was absorbed. In the above cases, no improvement was noticed in the subjects until free purgation was produced and increase in ruminal movements occurred. In one particular area of the district, where grass tetany seems to be endemic, the owner repeatedly has drenched the animals with molasses, dolomite and MgSO4 without success. The parenteral administration of Ca. and Mg. brings about temporary relief but a relapse soon occurs. It can be noted in passing that often other cattle, after a few hours grazing on the same paddock, wander up and down the fence, presumably with the desire to find roughage; even eating some of the weeds which grow on the ground.

Syndrome Associated with the presence of Acetone Bodies in the Urine.

One case of this condition was investigated fully. Two other cases were encountered, and in each instance the course was prolonged over 10 days. An aged Jersey cow, four days after calving, developed a stilted gait. She was grazing on a highly super-phosphated paddock. Went down within three hours after abnormality was noticed, and commenced struggling on the ground. When examined appeared to have milk fever except that the muscles of the limbs had more irritability than in milk fever. Rumination had ceased; pulse soft and slow; resp. 30; Temp. 101º. Given Ca. borogluconate i/v, after injection the animal brightened and attempted to rise, but within 20 minutes pronounced tetany of limbs set in. This was thought to be due to a hypercalcaemia, so MgS04 givens s/c. The tetany ceased, animal rose and staggered about 100 yards and again went down. A urine test taken after injection returned a strong Rotheras' reaction. Subsequent injection of Ca. and Mg. next day effected no improvement. On 3rd day, given 500 mls. of 4O% glucose i/v combined with drench of 1lb of treacle. Animal brightened immediately and rose within 20 minutes. A relapse occurred later and further administration of glucose resulted in the same improvement. However, heavy rain fell during the night and pneumonia developed. A serum sample taken before death (5th day) revealed that the blood Ca. and Mg. were within normal levels. Urine examined at autopsy gave a strong positive for acetone bodies. On P.M. the gall bladder was markedly distended, and lungs showed early pneumonic lesions.

The feature of the above case was the persistence of acetone bodies in the urine and the prompt response to glucose therapy. A similar case was treated at the same time. In which there was a faint Rotheras' reaction. Recovery after the prolonged administration of chloral and molasses; occupying 10 days after use of Ca. and Mg. salts had proved ineffective.

Although the number of cases investigated in this class is small, it is possible that the development of Ketosis when grazing on lush pastures may account for the failure of Ca. and Mg. therapy, and for the prolonged course of the condition. It is thought that the more refractory cases such as described by Hungerford (1940) may fall into this category.

However, Udall (1939) points out that the extent of the presence of acetone in the urine in diseases has not been determined. According to Best and Taylor (1943) ketones can be excreted after fasting, so that the anorexia associated with the condition may produce ketosis.

Syndrome associated with prompt response to Ca. and Mg. therapy.

This comprises the bulk of the cases encountered. The subject shows more motor irritation, and response to the prick of a hypodermic needle may bring on convulsions. The response to treatment is prompt and lasting, few relapses occurring. Serum samples invariably show altered Mg. and Ca. levels.

In a herd of 60 cows, two deaths occurred within a fortnight, and at the time of investigation four animals were affected. They had been grazing on young oats. All showed staggering, stilted gait and stood about with back arched. The condition developed within three days of being put on to the oats. When put into a bail they were hyper-excitable; the prick of a hypodermic producing a convulsive fit, followed by a collapse of comparatively short, duration. The respiration was increased. The administration of Mg. parenterally in advanced cases produced little benefit, but in early cases there was an immediate improvement. Serum samples submitted from two animals returned Ca. 11.2 mg, per cent., Mg. 1.1 per cent.; and Ca. 11.5 mg. per cent., Mg, 0.85 mg. per cent. Use was made of an injection of 15 gms. MgCl2 and 40 gms. CaCl2 in 10 to 12 ozs. of water. The injection brings on a violent heart action and administration should be carried on slowly over a period of 15 minutes to avoid heart block. The alternative mixture of Ca. borogluconate and MgSO4 was equally satisfactory.

Summary and Conclusions.

1. A syndrome associated with over-feeding on green succulent pastures has been described, in which the symptoms closely approximate those of mineral imbalance. Analysis of Ca. and Mg. values of the blood showed that they were in the normal range. Suppression of peristalsis and ruminal movements, and the occurrence of bloating after going down were constant features; as was acute urinary retention. Recovery occurs when cattle are changed to natural pastures with adequate roughage. The effect of drenching with materials rich in minerals is discussed.

2. Two cases are cited in which there is a prolonged course over 10 days, and the presence of ketone bodies in the urine. Response to glucose therapy is prompt. The usual therapy for mineral imbalance is ineffective. The possibility of the occurrence of ketosis under field conditions is considered.

3. Observations on the true grass tetany, where there is a state of imbalance, are presented. The presence of more motor irritation is a consistent feature.

Acknowledgements: It is desired to acknowledge the assistance of Departmental Officers, particularly the Director of Veterinary Research, in the matter of Ca. and Mg. determinations in serum samples submitted.

References:

Sjollema, B. (1930). Veterinary Record 10:425 and 450
Best, C.H. and Taylor, N.B. (1943). Physiological Basis of Medical Practice. 3rd Edit. Williams and Wilkins Co., Baltimore
Clark, M. C. (1942). "Applied Pharmacology." 7th Edit. J. and A. Churchill., London.
Udall, D. H. (1939) "The Practice of Veterinary Medicine," 3rd Edit. New York.
Duncan, C. W. et al. (1939) Journal American Veterinary Medical Association 95:690-700.
Duncan, C. W. et al. Ibid. Henderson. J. A. (1938) Cornell Vet., 28: 173-195.
Cunningham, 1. J. (1934). N.Z. Journ. of Sc. & Technology. Sept. 1934.
Hungerford, T. G. (1940). Aust. vet. J., 16: 216.