Urolitíase obstrutiva em ovino

Abstract

Background: Urolithiasis, which is characterized by the presence of stone(s) in the urinary tract, is found in young, male and confined small ruminants. It results from the interaction of several physiological and nutritional factors associated with animal management. The condition is linked to concentrated diets based on grains, with a high phosphorus and magnesium content. The illness becomes important when the stones cause obstruction, which normally occurs in the urethra and which may lead to a rupture of the bladder if the obstruction is not alleviated. In which case, an increase of the abdominal volume is observed, due to the presence of urine in the abdominal cavity. The animal may die from uremia within two to three days, but this period can be longer. Several surgical techniques for the treatment of urolithiasis have been described: amputation of the urethral process with penile transposition, urethrostomy and cystotomy. This study describes a case of obstructive urolithiasis in an ovine, with orchiectomy and penectomy, followed by a perineal urethrostomy. Case: The animal in question is an one-year old half-breed male pet sheep, weighing 11.5 kg and admitted to the Veterinary Medical Teaching Hospital of the Universidade Estadual do Maranhão (UEMA), Brazil. The main complaint was that the animal was not "urinating". During anamnesis, the owner reported that the condition started approximately seven days ago with anorexia, abdominal distension and difficult urination. At the physical examination, it was observed a slightly increased cardiac frequency, decreased ruminal movements, pale mucous, dehydration, lethargy, distension and intense abdominal pain, urinary bladder filled, strangury, trauma and penile protrusion with necrosis, urine infiltration in the subcutaneous tissue, preputial and testicular edema. Urinalysis revealed an alkaline urine (pH=9.0), hematuria, albumin and oxalate crystals. Increased serum profile: urea rate 184.84 mg/dL and creatinine rate 3.64 mg/dL. The surgical procedures consisted of orchiectomy, scrotal ablation, ligation of the testicular artery and vein with an absorbable suture, followed by penectomy and urethrostomy, with suture of the skin at the central portion of the perineal area. The animal remained probed until its healing. Discussion: Urolithiasis is still considered an important cause of death in small ruminants. Animals affected by post-renal obstructions have azotemia, due to a decrease of the renal function, secondary to hydroureter and hydronephrosis, to a disproportional increase of urea values in relation to creatinine and to the retrograde urea process when urine is already formed. Obstructions must be corrected as soon as possible, in order to avoid a rupture of the bladder and urethra. When such rupture happens, there is a subcutaneous accumulation of urine in the abdominal cavity in the perineal and preputial region. A surgical intervention then becomes inevitable. In this case, an orchiectomy and penectomy followed by perineal urethrostomy was performed. This amputation technique of the entire urethral process during the post-operatory may cause short and long term complications, such as bleeding and urethral stenosis. This study reports a case of obstructive urolithiasis in ovine, where a surgical procedure was performed, propitiating the well-being and possibility of weight gain for the animal.