It is known that humans have perished through lack of water, particularly in hot weather, and that death is more certain or hastened if water provided afer abstinence is copious, fresh and cold. Mortality in cattle, notorious for high water demand normally, is not surprising when water is provided after substantial enforced abstinence; such as during lengthy vehicular transport, particularly during hot weather.
In some parts of this state such accidents are fairly common when stock, particularly cattle, are unloaded in shade temperatures over the Fahrenheit century and despite even reasonable precautions against them.
Improvement in transport conditions is not very likely, but it might be possible to do something immediately after unloading to lessen losses in cattle that unload in reasonably good order, but so often deteriorate after their first drink. There have been earlier cases in the Hay Pastures Protection District, but none is known with the severity of that reported here.
In January of 1959, 834 apparently sound enough Hereford steers unloaded rather well after a three day's trip by rail from near the Queensland border to Hillston. They were said to have been untrucked and offered food and water about half-way through the trip, but whether they avalled themselves of it or not is unknown. It was in a heat wave with shade temperatures ranging towards 100 deg. F. each day but, for all things concerned, was not regarded as very exceptional or the trip particularly arduous. All walked unaided from trucks and the illustration is said to have been typical of the herd with which all involved were satisfied at that time. They were moved away on foot from untrucking near the river, and without a drink, as soon as unloaded at about 9 a.m.; the idea being to walk them gently about six miles in eight hours and water them on the Lachlan towards the end of the day. At about 10.30 am., en route, they apparently smelled the river and broke through a market garden, with great resultant damage thereto, and many of them drank of the river before being removed. From untrucking until drinking, their food intake would be of a nature believed to be quite unlikely to cause trouble under any circumstances. Deaths commenced at about 12.30 p.m. and 55 were dead by 7 p.m. Fourteen died by next evening and nine by the next; loss ceasing at a total of 79 by the third evening, after which the herd was moved without trouble from its resting site by the river towards its destination.
Unfortunately, veterinary inspection was impossible during the mortality, but the latter apparently followed the pattern usual in such cases; unlike Transit Tetany and probably resistant to the notvery-hopeful treatment recommended for that condition. However, those in charge agreed that any carcases opened up had small haemorrhages into the small bowel. Many had five hours agonal suffering from apparent abdominal pain; and, from one indication and other, this mortality would appear very similar to others in remote and recent past where there was veterinary inspection with out there being any suspicion that the precipitating factor was anything other than the water drunk. The herd was first seen by the writer immediately after losses had ceased, and at which time baled lucerne was being consumed. Some cattle were listless, some were 'tucked up' and some were lachrymating more than usual. Up to date, the most common precaution has been to try to restrict water intake and that gradually until a herd eventually has got back to normal and has eaten some safe feed; something usually easier said than done.
That which follows herein results from study of a problem that certainly needs it if one is to be able to advise worth-while means of alleviation.
Despite breed improvement, most stock from great areas of western New South Wales and elsewhere live almost wild and, added to stress normal to all handling, cattle in particular have to withstand more than normal stress due to shock. Under such conditions, cattle tend to stop ruminating; a function difficult to start again more or less proportionate to length of cessation. Such animals are so powerful, and gear and quantities so substantial that any controlled water intake may not be easy; nor are troughs always available. The best that has seemed feasible has been to let them get their feet, proceed gently, preferably camp in shade, provide hay if feed otherwise available seems unsuitable; and water in as restricted fashion as possible towards the cool of the day. However, to withhold water seems often merely to prolong the apparently inevitable, for sometimes very small quantities seem fatal. In the case in point, the owner stated that he gave one affected beast about half a gallon from a container; the effect being apparently to kill it almost before he could rise. Such a beast, being visibly affected, had almost undoubtedly drunk from the river earlier and was affected already by water intake.
Hitherto, one has been unable to give a reasonable explanation of the actual train of events leading logically to death. To give an idea of the confusion that exists, there have been made quite responsible suggestions involving no less than six widely divergent causes; the most likely of which seeme to me to be what is known as Water Intoxication.
On study, this term seems less inapt than at first sight for, much as water is usually harmless and essential under normal circumstances, and much as its lack seems definitely to lead up to the danger associated with its ultimate supply, it does seem as if its intake can cause death; just as if it were a poison. Now, it is fairly well-known also that persons losing much sweat in a short time must replace salt lost as well as the water, otherwise there is danger of severe colic, cramps and possibly, death; unless the body can mobilise sufficient salt in time from bowel contents, while sweating eased somewhat during incapacitation by colic. This is why salt often is in water supplied in places where such sweating is likely to cause internal salt deficiency. It is believed that this leads to solution of the problem being studied and this is supported somewhat by what has been described as the very "meagre literature" available.
Officers of the Department of Agriculture of this state have extracted from "The Physiological Basis of Medical Practice" (Best and Taylor, 5th Edition) and elsewhere the following picture of changes during heat exhaustion and water deprivation. These are dehydration of tissues and tissue fluids; concentration of the mineral contents of the blood; catabolism or break-down of body storages of fats, carbohydrates and tissue proteins; depression of oxidative processes with a shift towards acid in the normal acid/base balance; reduction of urinary output with retention of the acid product of deranged metabolism; rise in the non-protein nitrogen of the blood and in temperature; thirst and depression of all secretions. Such extracts describe what happens when there is unlimited access to water following such deprivation. As might well be expected (accepted might be a better word) this is water-logging of tissues by the greater osmotic pull of the more concentrated tissue fluids on those freshly taken into the gut. If the resultant oedema embarrasses the heart, lungs or brain, rapid death is neither unlikely or illogical. Together with such oedema, there is rapid depression of what was probably abnormally high temperature, and this would be worsened on intake of cold water. This contributes to shock in the deranged body, which may try to get rid of the offending water by vomition. Finally, there may be convulsions, coma and death following rapidly from cerebral oedema. Voiding of all body products is under some very variable control, but much water is lost by even normal respiration; which is under the least control. When this is accelerated by fear, discomfort and heat of close packing in vehicles for long periods it is reasonable to expect even a body that is automatically trying to conserve its fluids to lose them by every means and become dangerously dehydrated.
The foregoing observations of such a self-worsening or vicious cycle seems acceptable enough explanation of the train of events in this problem and suggest preventive measures before and after loading. As for the latter, it is unfortunate that upset in the living body may not often be corrected simply, even if it has comparatively short space of time. It appears that such measures should still be limited intake of water, but preferably warmed and containing, say, one ounce of common salt to the gallon to bring it into line with normal tissue fluids; and still be safely below that built up in those tissues which are dehydrated, so that there will be a slow and safe passage of fluids from the gut to the tissues so much in need of them. Salt is procured easily and is cheap. It should be dissolved first in a smaller quantity than the full amount of water used, so as to get safer and more even distribution through the whole.
It would need roughly half a chain of triangular cross-sectioned trench measuring two feet across the top by nine inches deep to hold 100 gallons when full. In such a trench would go slightly more than six pounds of common salt and enough water to give 100 cattle a gallon each. A herd such as that before mentioned would need about 4 chains of trench and about 50 pounds of salt dissolved in about 800 gallons of water. Such a trench would be well chopped up by cattle movement in an around ti; the whole is a very messy business, but better than the losses. it is not known whether a herd would even drink such water or whether it would be necessary to restrict them to one or two gallons each, but it would be reasonable to believe that over-rapid water-logging of tissues would be lessened by use of such salt-containing water of about normal saline strength.
This suggestion probably is a new one; suggesting caution in its trial on very few animals first. It would be illuminating if an equal number were given unrestricted access to pure water. It is apparent that, if caution were needed, this would be manifested so quickly as to put the issue beyond doubt either way fairly quickly.