Last update: April 4, 2012 07:59:37 AM E-mail Print



E. M. van Tonder and G. F. Bath 




Although urinary calculi is a complex problem affecting rams and wethers under widely differing circumstances in the Karoo region, only the problem as it occurs in rams and wethers on artificial diets will be discussed here. Several types of urinary stones i.e. stones of different structure and composition, are also encountered, but only the type which will be referred to as phosphate calculi (phosphatic urolithiasis) which usually only affects rams and wethers on high quality rations will be considered here.

This particular problem has become one of considerable economic importance, not so much due to the number of animals involved, but mainly on account of the individual value of the animals concerned. If it is considered that it has become common practice to feed (if not overfeed) rams intended for sales, notably official sales and shows, on high concentrate diets and that these animals are therefore exposed to this disease, so it obviously follows that the economical losses to the individual farmer could be considerable. It should be added that treatment is rarely successful, i.e. to save a ram as a breeding animal and then only in the very early cases.



It has already been mentioned that many farmers, especially those raising stud sheep, in preparation of their animals for sales and shows, feed them on high quality rations. Once these animals are adapted, and because they are fed in groups liberal quantities are offered, with the result that the individual intake is virtually unrestricted. These concentrated diets usually contain high levels of protein, carbohydrates and phosphates. The high phosphate content in turn is due to the high level of protein (the addition of fish meal and oil cake meals), the phosphate rich grains (e.g. Maize, Bran, Oats) and phosphate supplements (e.g. Monosodium phosphate). Sometimes a phosphate lick or phosphate in the water is additionally supplied.

These concentrates are either fed as a mixture with, and containing at most 20 to 40 per cent lucerne meal or as a pure mixture with lucerne hay being offered separately. Whatever the case might be, the fact remains that the animal has a limited intake of lucerne meal or hay (rich in calcium) either as part of the ration or by disinclination to consume reasonable quantities when offered separately but simultaneously with the concentrate diet.

The nett result of the above situation is that these rams consume liberal quantities of a diet simply overloaded with phosphates and deficient in calcium. The excess phosphates especially in the absence of sufficient quantities of calcium are not utilized at all but are merely excreted through the kidneys. The result is that phosphates in the urine, which are normally present in only small quantities, rise to a considerable level under the influence of these diets. Due to the normal process of urinary concentration by reabsorption of water in the kidneys, as well as other possible factors, the phosphates become less soluble in the urine and are deposited as phosphate complexes. These deposits which may take the form of small flakes or may clump together to form soft crystals or stones usually occur as a layer on the floor of the bladder and are presumably washed down the urethra with the last bit of urine during the normal process of urination. When present in reasonable quantities these deposits will block the urethra anywhere along its course while the obstruction will appear as a stopper consisting of densely packed matter resembling clay.



These are probably well-known and would he as is expected in obstruction of normal urinary flow, irrespective of the cause or type of stone involved.

Initially symptoms would involve frequent attempts to urinate, accompanied by undue straining and grunting and dripping of urine, which is sometimes bloodstained, from the sheath. The animal usually stops eating at this stage. These attempts become more frequent and severe and the animal more distressed as the disease advances. At this stage no urine is passed at all, while arching of the back and stretching and grinding of the teeth are typical symptoms. This condition runs a rapid course with the animal succumbing within a few days. Towards the terminal stages the disease is usually complicated by nephritis (inflammation of the kidneys), ureamia (accumulation of urinary-compounds in the blood) and ketosis (Domsiekte), while the urethra often ruptures, usually immediately above the scrotum, with resultant seepage of urine into the tissues and gross swelling of the scrotum and adjacent lower parts of the belly.

This condition also occurs in wethers on fattening rations. Wethers are also more susceptible to the condition on account of their relatively underdeveloped urethrae due to early castration. Ewes are seldom, if ever, affected, probably because the female urethra is short and wide.



This is usually of no avail and only successful in a small percentage of early cases. It should be mentioned that animals suffering from this condition are usually only offered for attention in the advanced stages as the initial symptoms often pass unnoticed.



Excellent results have been attained on a vast number of properties where this problem incurred heavy losses by strict adherence to the following procedures:

  1. Complete elimination of pure phosphate supplements from the diet or drinking water.

  2. The supplementation of feeding lime in high concentrate diets. In general this can be done by adding up to 3 per cent of feeding lime to the ration. Where analysis of a particular ration are available feeding lime should be added to bring the calcium to phosphorus ratio in the ration to a minimum figure of 4:1. At this stage a ratio of 9:1 should be regarded as the maximum as the long term effects of a wider ration have not been duly tested



Merino Breeders Journal 36 (1)