Nevertheless, it would be a mistake to overlook the effects of temperament and constitution. In human medicine the importance of hereditary predisposition and of the special diathesis is undeniable (uric or gouty diathesis). In veterinary medicine the same thing applies, for, apart from rich feeding, it is not uncommon to meet with cases of gravel in animals living under the most diverse conditions, although the issue of the same parents.
Certain infections of the urinary passages, though trifling at first, or at least of slow development, are also capable of causing mineral deposits in the urinary passages, a fact which Moussu considers to be proved by his success in experimentally reproducing given forms of pyelo-nephritis.
Symptoms. The symptoms are often overlooked, as long as the calculus deposits affect only the kidneys, their increase in that part not giving rise to alarming symptoms. It is certain that the eventual passage of the calculus through the ureter towards the bladder causes nephritic colic, but this form of colic is little understood, and has never been well described. Writers have simply mentioned cases of colic accompanied by great tenderness in the lumbar region, temporary suspension of the secretion of urine, and more or less marked dysuria.
Nothing resembling the extremely grave symptoms of nephritic colic in mankind has been described, though probably there is little difference in the complaint as it affects the bovine species.
When the sediment or the calculus reaches the bladder there is a tendency for it to be passed during micturition. The signs then become more strongly marked, because they point to obstruction of the urethra. If the deposit is simply of the nature of sediment, there is merely a little difficulty in urination, accompanied by some moderate amount of pain, and sediment is afterwards found within the sheath or adhering to the groups of hair at its extremity.
If, however, the deposit is in the form of small calculi, these are pushed towards the neck of the bladder and the urethra, which then appears to be obstructed.
The obstruction may occur at the origin, at the ischial curve, or at the S-shaped curve of the penis (Fig. 226). Henceforth strongly marked and unmistakable symptoms rapidly develop. Vesical colic appears, owing to retention of urine, and rapidly acquires extreme intensity, though it instantly ceases with rupture of the bladder in cases where no treatment is attempted. This form of vesical colic is accompanied by continual but unsuccessful efforts to urinate and by spasmodic contractions of the accelerator urinæ.
Appetite and rumination cease, and the animal shows extreme anxiety. Palpation along the course of the penis reveals unusual tenderness, and the calculus can sometimes be felt near the S curve, though more frequently in the ischial arch. The litter is not soiled with urine.
Cautious rectal examination proves the bladder to be extremely distended, or, in the case of rupture having occurred, entirely collapsed. In the latter case the spasmodic contraction of the accelerator urinæ completely ceases soon after rupture, and the animal appears to be recovering. This deceptive calm is due to the disappearance of the vesical colic, but the animal’s condition is still graver in consequence, and it must of necessity die. Rupture of the bladder is followed by inundation of the peritoneal cavity with urine, which is partly reabsorbed by the peritoneum, producing a kind of urinary intoxication, so that despite the elimination of certain volatile principles through the lungs (the breath has an odour suggestive of urine), the animal very soon dies.
In many cases, also, the urine is not aseptic, and after rupture of the bladder acute peritonitis supervenes and carries off the patient in from six to ten days.