recurrent episodes of urethral obstruction. This procedure can also be utilized for detrusor muscle atony of the bladder. The apex of the bladder mucosa is sutured to the skin, allowing constant drainage of urine from the bladder. Numerous complications associated with this procedure include urine scald, bladder mucosa prolapse, stoma stricture, cystitis, and ascending pyelonephritis [12, 24, 25, 39]. It is not recommended for cattle. One study reported a mortality rate of 77% within two weeks of surgery [2]. Another study performed bladder marsupialization 12 hours after experimental induction of the urethral obstruction; of the six calves included in the study, one calf died and the remaining five calves had stoma stricture within three weeks postoperatively [40]. A novel procedure involving vesiculopreputial anastomosis has been described in small ruminants with a 50% success rate at six months postoperatively [41].
Prevention
The most important aspect of urolithiasis prevention is dietary modification. Ideally, the urolith(s) should be submitted to a laboratory for urolith analysis to determine composition. In the absence of this information, gross appearance of the urolith and ration evaluation should assist in figuring out the likely calculi involved. For phosphate calculi, excessive dietary phosphorus should be avoided, and rations should be adjusted to contain a calcium to phosphorus ratio of 1.5–2 : 1 and dietary magnesium should be less than 0.2%. Grain and alfalfa feeding should be reduced. For individuals fed a total mixed ration, roughage content should be evaluated. The primary excretion of phosphorus in ruminants is saliva, not urine. Therefore, if roughage is increased in the ration, rumination increases and salivary excretion of phosphorus is increased while solute in the urine is decreased. For silica uroliths, avoidance of at‐risk pastures and feedstuffs is recommended. High‐risk pastures can be used to graze female cattle instead of bulls and steers.
Adequate water consumption is critical in the prevention of urolithiasis. Ensuring access and availability to good quality water sources should be evaluated. If quality water sources are available, addition of sodium chloride to the ration should be considered to increase water consumption, ultimately creating dilute urine. According to Hawkins, sodium chloride has an effect of displacing magnesium and phosphorus from nucleation centers and thus preventing crystal development and urolith formation [1]. Silica uroliths form predominantly in the last 60 days before weaning; therefore a heavily salted creep feed is recommended for calves in the prevention of siliceous uroliths [4, 27, 42]. Sodium chloride can be fed up to 3–5% of the daily dry matter intake; this level of salt should be gradually increased to this level [4, 27].
Alternatively, reduction in urine pH can be attempted by feeding ammonium chloride at 0.5–1% of dry matter intake in a ration, which may help prevent apatite, struvite, and carbonate uroliths [27]. Feeding a DCAD ration can also be used to lower urinary pH in cattle. Silica urolith formation is not affected by urine pH. Caution should be used with long‐term use; reduced bone mineral density has been reported in mature ewes fed anionic salts long term [43].
As previously discussed, urethral diameter is testosterone dependent. Delaying castration would result in a larger urethral diameter. According to Hawkins [1], a calf castrated at seven months of age could pass a urolith 13% greater in diameter and a bull could pass a urolith 44% greater in diameter than a calf castrated when one month old. While the evidence exists that delaying castration increases urethral diameter, the welfare consequences of delaying castration should be considered prior to implementation. Dietary modification and water consumption would be better areas of focus for prevention.
References
1 1 Hawkins, W. (1965). Experimental production and control of urolithiasis. J. Am. Vet. Med. Assoc. 147: 1321–1323.
2 2 Gasthuys, F., Steenhaut, M., De Moor, A., and Sercu, K. (1993). Surgical treatment of urethral obstruction due to urolithiasis in male cattle: a review of 85 cases. Vet. Rec. 133: 522–526.
3 3 Udall, R. and Chow, F. (1969). The etiology and control of urolithiasis. Adv. Vet. Sci. Comp. Med. 13: 29–57.
4 4 Larson, B. (1996). Identifying, treating, and preventing bovine urolithiasis. Vet. Med. 91: 366–377.
5 5 Parrah, J., Hussain, S., Moulvi, B. et al. (2010). Bovine uroliths analysis: a review of 30 cases. Isr. J. Vet. Med. 65: 103–107.
6 6 Radeleff, R. (1970). Poisonous plants. In: Veterinary Toxicology, 69–74. Philadelphia, PA: Lea & Febiger.
7 7 Frank, F., Meinershagen, W., Scrivner, L. et al. (1961). Urolithiasis. 1. Incidence of bladder calculi, urine properties, and urethral diameters of feedlot steers. Am. J. Vet. Res. 22: 899–901.
8 8 Makhdoomi, D. and Gazi, M. Obstructive urolithiasis in ruminants – a review. Vet. World 6 (4): 233–238.
9 9 Sharma, A., Mogha, I., Singh, G. et al. (2007). Incidence of urethral obstruction in animals. Indian J. Anim. Sci. 77: 455–456.
10 10 Marsh, H. and Safford, J. (1957). Effect of deferred castration on urethral development in calves. J. Am. Vet. Med. Assoc. 130: 342–344.
11 11 Sockett, D., Knight, A., Fettman, M. et al. (1986). Metabolic changes due to experimentally induced rupture of the bovine urinary bladder. Cornell Vet. 76: 198–212.
12 12 Ewoldt, J., Anderson, D., Miesner, M., and Saville, W. (2006). Short‐ and long‐term outcome and factors predicting survival after surgical tube cystostomy for treatment of obstructive urolithiasis in small ruminants. Vet. Surg. 35: 417–422.
13 13 Wilson, D. and Macwilliams, P. (1998). An evaluation of the clinical pathologic findings in experimentally induced urinary bladder rupture in pre‐ruminant calves. Can. J. Vet. Res. 62: 140–143.
14 14 Donecker, J. and Bellamy, J. (1982). Blood chemical abnormalities in cattle with ruptured bladders and ruptured urethras. Can. Vet. J. 23: 355–357.
15 15 Floeck, M. (2009). Ultrasonography of bovine urinary tract disorders. Vet. Clin. North Am. Food Anim. Pract. 25: 651–667.
16 16 Parrah, D., Moulvi, B., Malik, H. et al. (2011). Abdominocentesis and peritoneal fluid analysis in clinical cases of bovine obstructive urolithiasis. Vet. Pract. 12: 218–222.
17 17 Oehme, F. and Tillmann, H. (1965). Diagnosis and treatment of ruminant urolithiasis. J. Am. Vet. Med. Assoc. 147: 1331–1339.
18 18 Hastings, D. (1965). Retention catheters for treatment of steers with ruptured bladders. J. Am. Vet. Med. Assoc. 147: 1329–1330.
19 19 Prasad, B., Sharma, S., Singh, J., and Kohli, R. (1978). Surgical repair and management of bladder rupture in bullocks. Indian Vet. J. 55: 905–911.
20 20 Sharma, S. and Vikash, K. (2011). Urinary bladder rupture in bovine and its management: a retrospective study of 156 cases. Intas Polivet 12: 375–378.
21 21 Van Metre, D., House, J., Smith, B. et al. (1996). Obstructive urolithiasis in ruminants: medical treatment and urethral surgery. Compend. Contin. Educ. Pract. Vet. 18: 317–327.
22 22 Scheel, E. and Paton, I. (1960). Urinary calculi in feedlot cattle: report on treatment with amino promazine. J. Am. Vet. Med. Assoc. 137: 665–667.
23 23 Rakestraw, P., Fubini, S., Gilbert, R., and Ward, J. (1995). Tube cystostomy for treatment of obstructive urolithiasis in small ruminants. Vet. Surg. 24: 498–505.
24 24 Videla, R. and van Amstel, S. (2016). Urolithiasis. Vet. Clin. Food Anim. 32: 687–700.
25 25 Ewoldt, J., Jones, M., and Miesner, M. (2008). Surgery of obstructive urolithiasis in ruminants. Vet.
