Contrast radiography of the lower urinary tract in the management of obstructive urolithiasis in small ruminants and swine

Präpubische Urethrostomie bei einem Wiesenauer Minischwein mit Urolithiasis

Ein 10-jähriges kastriertes, männliches Minischwein wurde aufgrund eines Tenesmus vesicae mit Anurie vorgestellt. Begleitsymptom war eine Tachypnoe. Röntgenologisch waren zahlreiche Harnsteine in Blase und Urethra nachweisbar. Über die Harnröhre konnte nicht katheterisiert werden, sodass eine Notfallzystostomie mit Einlegen eines Ballonkatheters durchgeführt wurde. Trotz Blasenspülung gelang es nicht die Harnröhrensteine so auszuspülen. Deswegen wurde ein präpubisches Urethrostoma angelegt. Das Tier erholte sich vollständig und setzt seither problemlos Urin über die urethrale Fistel ab. Prophylaktische Maßnahmen der Urolithiasis beinhalten unter anderem eine ausreichende Wasseraufnahme, eine ausgewogene Fütterung und balancierte Futterzusammensetzung sowie die Gewährleistung eines physiologischen Urin-pH-Werts.

Imaging of the Urinary and Reproductive Tract in Small Ruminants

Ultrasound imaging is the mainstay of urinary and reproductive imaging in small ruminants, assisted by the relatively superficial location of the urinary and reproductive tracts in these species. Radiography can provide an excellent overview of the abdomen, but is often limited by a lack of adequate penetration. Computed tomography scans provide summation-free imaging of the urinary and reproductive tracts in addition to information about the excretion of contrast agent by the kidneys, but can be limited by availability and cost.

Use of tube cystostomy in the surgical management of obstructive urolithiasis in a Bactrian camel

CASE DESCRIPTION

A 6-year-old castrated male Bactrian camel was evaluated because of a 14hour history of oliguria and stranguria that progressed to anuria.

CLINICAL FINDINGS

Perineal urethral pulsations and intermittent tail flagging with no accompanying urination were observed. Ultrasonography of the urethra revealed multiple hyperechoic foci with shadowing artifact indicative of calculi present in the penile urethra distal to the sigmoid flexure. Rectal palpation revealed a pulsating hard urethra and intact distended urinary bladder. Further clinical examination was not possible because of challenges associated with handling the camel.

TREATMENT AND OUTCOME

Urethral catheterization through a perineal urethral incision failed to achieve urinary bladder decompression. Tube cystostomy was performed to prevent bladder rupture. Urethrocystography performed 3 days after surgery revealed a urethral rupture at the level of the prepuce. Five weeks after surgery, the camel could urinate a steady stream via the urethrotomy site. Seven weeks after surgery, the cystostomy tube was removed, and the urethrotomy site was modified to provide a permanent urethral opening via perineal urethrostomy. During 6 years of subsequent periodic follow-up by telephone, the owner reported that the camel continued to do well and urinate through the revised opening.

CLINICAL RELEVANCE

To the authors' knowledge, this is the first detailed description of a tube cystostomy in an adult camel with obstructive urolithiasis that includes information on the patient's long-term outcome. This technique was a viable option in the surgical management of obstructive urolithiasis in this camel and may be useful for other large camelids as well.

Variables of initial examination and clinical management associated with survival in small ruminants with obstructive urolithiasis

BACKGROUND

Obstructive urolithiasis is a common disease associated with a guarded prognosis in small ruminants.

HYPOTHESIS/OBJECTIVE

The results of physical examination, laboratory analyses, and clinical management of male small ruminants presented to 2 referral clinics were investigated to identify variables significantly associated with disease outcome, so as to provide better recommendations to animal owners regarding the management of these patients.

ANIMALS

Two-hundred ten small ruminants (130 sheep and 80 goats) with confirmed diagnosis of obstructive urolithiasis.

METHODS

Clinical findings (including diagnostic imaging) and laboratory results of the 210 animals were reviewed, and relevant information regarding clinical and laboratory variables recorded upon admission and clinical management was retrieved. The association of the different variables with nonsurvival was investigated by univariable and multivariable logistic regression models.

RESULTS

Only 39% of all patients considered for treatment and 52% of those undergoing tube cystostomy survived to be released from the clinic. Nonsurvival was strongly associated with a very poor clinical condition upon presentation, obesity, castration, and evidence of uroperitoneum. Among blood variables, abnormal PCV, severely increased serum creatinine concentrations, and increased activity of the creatine kinase were associated with increased risk of nonsurvival. Presence of signs of colic or macroscopic appearance of urine was not significantly associated with outcome.

CONCLUSIONS AND CLINICAL IMPORTANCE

The prognosis of obstructive urolithiasis was guarded with survival rates of 39% (overall) to 52% (after tube cystostomy). Intact young males with normal body condition presented early in the course of disease had the best chances of survival.

Clinical findings and diagnostic procedures in 270 small ruminants with obstructive urolithiasis

Background

Details of the clinical signs of obstructive urolithiasis in male small ruminants have not been documented in a large population.

Objective

To describe the clinical presentation and diagnostic procedures in a large group of small ruminants with urolithiasis.

Animals

Two hundred and seventy small ruminants (158 sheep and 112 goats).

Methods

Retrospective study of 270 cases identified based on clinical records.

Results

81.2% affected goats were castrated and 91.7% sheep were intact males; 65.5% of the animals had been sick ≤2 days before referral. Common abnormalities included dysuria (93.6%), indigestion (84.4%), reduced general state of health (79.5%), signs of pain (73%), increased heart and respiratory rates (53.6% and 39.1%), and azotemia (89.4%). Blood urea nitrogen (BUN) and creatinine concentrations were strongly correlated (r² = 0.81). Hypochloremia (52.2%), hyponatremia (43.3%), hypophosphatemia (52.4%), and abnormal potassium concentrations (26.2% hypokalemia and 24.5% hyperkalemia) were the most common serum electrolyte imbalances. Packed cell volume (PCV), plasma proteins, potassium, BUN, and creatinine concentrations were significantly increased in animals with uroperitoneum. Ultrasonography allowed for confirmation of diagnosis in 83.9% of the cases (135/161 with sufficient available information), uroliths were visible on 34 of 56 plain radiographs.

Conclusions and Clinical Importance

Our study confirmed that clinical and ultrasonographic examinations are sufficient to diagnose urolithiasis. Clinical signs can be divided into an early stage with discrete unspecific clinical signs, a painful stage with frequent straining, expression of pain and moderately reduced general condition, and an advanced stage with a markedly reduced general condition and eventually recumbency.

Studies using a porcine model: what insights into human calcium oxalate stone formation mechanisms has this model facilitated?

Animal models are useful in the study of many human diseases. Our current understanding of the biological, physiological, and biochemical aspects of hyperoxaluria and calcium oxalate urolithiasis has been greatly informed by studies using animals. Recently, limitations in the extrapolation to humans of research results derived from laboratory rodents have been identified. The use in biomedical research of a variety of organisms, including large animals, is increasingly encouraged. The purpose of this article is to review the use of pigs in biomedical and stone research, to provide a rationale for using pigs in metabolic stone research, and to describe our 8-year experience in developing a porcine platform for studying hyperoxaluria and calcium oxalate urolithiasis. In this article, we share and review some of the highlights of our findings. We also report results from a recent feeding swine study that demonstrated oxalate-induced renal nephropathy. Finally, we offer ideas for future directions in urolithiasis research using swine.

Alterações ultrassonográficas renais e vesicais de ovinos confinados e suplementados com cloreto de amônio

Resumo: A incidência da urolitíase obstrutiva em ovinos é elevada, principalmente em machos confinados, tanto para produção de carne, quanto reprodutores de alto valor genético. A acidificação urinária é um dos métodos para prevenção desta enfermidade e pode ser realizada de forma eficaz com a suplementação de cloreto de amônio (CA) na dieta. Utilizaram-se 100 ovinos, machos não castrados, mestiços (Ile de France X White Dorper), confinados, com idade aproximada de três meses. Constituíram-se três grupos experimentais: Grupo 21CA (n=40) que recebeu 400mg/kg/PV de cloreto de amônio/animal/dia, por 21 dias consecutivos; Grupo 42CA (n=40) que foi suplementado com 400mg/kg/PV de cloreto de amônio/animal/dia, por 42 dias consecutivos; Grupo controle (n=20), que não recebeu CA. A alimentação consistiu de ração total, composta por 15% de feno triturado e 85% de concentrado, água e sal mineral ad libitum. Após 14 dias de adaptação à alimentação e ao ambiente, os Momentos (M) de avaliação clínica, colheita de sangue e exame ultrassonográfico foram realizados com intervalo de sete dias, sendo M0 (imediatamente antes do início do tratamento com cloreto de amônio), M1 (sete dias após), M2 (14 dias após), M3 (21 dias após o início do tratamento e suspensão do cloreto de amônio em Grupo 21CA), M4 (28 dias após), M5 (35 dias após) e M6 (42 dias após), totalizando 56 dias de confinamento. As dosagens de ureia e creatinina não evidenciaram alteração na função renal, embora a ureia estivesse acima dos valores de referência para espécie ovina. Observaram-se imagens ultrassonográficas compatíveis com cálculos vesicais e dilatação de pelve renal. No Grupo 21CA, 15% (6/40) dos animais apresentaram cálculos vesicais; no Grupo 42CA, 5% (2/40); e no Grupo controle, 20% (4/20) dos cordeiros. Visibilizaram-se também imagens sugestivas de sedimentos e cristais em 31% (31/100) dos animais examinados. A ultrassonografia permitiu a visibilização de alterações renais e vesicais, porém não relacionados ao quadro clínico de urolitíase obstrutiva, revelando-se como um exame complementar de grande relevância para o diagnóstico precoce de alterações no sistema urinário de ovinos.

Use of plain radiography in the diagnosis, surgical management, and postoperative treatment of obstructive urolithiasis in 25 goats and 2 sheep

OBJECTIVE

To describe use of plain radiography for diagnosis, surgical management, and postoperative treatment of obstructive urolithiasis in small ruminants.

STUDY DESIGN

Retrospective case series.

ANIMALS

Small ruminants (n = 27; 25 goats, 2 sheep).

METHODS

Medical records (January 2002-November 2011) and radiographs for all small ruminants diagnosed with obstructive urolithiasis and having plain abdominal radiographs were reviewed. Signalment, surgical procedures, radiographic findings, ultrasonographic findings, position of calculi, and how plain radiography influenced surgical management and postoperative treatment were recorded.

RESULTS

Radiopaque urinary calculi were detected in 23 (85%) plain radiographic studies. Location of uroliths determined by plain radiography included: cystic only (n = 5), distal to the sigmoid flexure and cystic (5), subischial (5), distal to the sigmoid flexure only (3), sigmoid flexure (3), and subischial and cystic (2). In 8 of these animals, postoperative radiographs revealed residual calculi in the urethra and were essential for their targeted removal by urethrotomy in 7 animals.

CONCLUSIONS

In regions where radiopaque calculi (calcium carbonate, calcium oxalate, silica) are commonly encountered in small ruminants, plain radiographs are recommended to determine the appropriate surgical approach(es) and to confirm resolution of the obstruction.

Short- and long-term outcome and factors predicting survival after surgical tube cystostomy for treatment of obstructive urolithiasis in small ruminants

OBJECTIVE

To evaluate outcome of small ruminants after tube cystostomy without urethral flushing.

STUDY DESIGN

Retrospective clinical study.

ANIMALS

Small ruminants (n=63; 50 goats, 13 sheep).

METHODS

Medical records (January 1996-October 2003) for all small ruminants undergoing tube cystostomy were analyzed. Signalment, laboratory data, intraoperative findings, urolith type, and postoperative outcome were compared. Long-term follow-up was obtained at 6 and > or= 12 months postoperatively.

RESULTS

Most animals were castrated males. Pygmy goats were overrepresented. Mean time to normal urination after tube cystostomy was 11 days, and mean hospitalization was 14 days. Seventy-six percent of animals were successfully treated with tube cystostomy (90% of those discharged from hospital). Short- and long-term survival was good for those animals with follow-up data. Reobstruction occurred in <20% of animals at 6 and 12 months. Goats, castrated males, and animals with normal serum potassium, no fluid in the abdomen, or no urethral process amputation were more likely to survive. Stone type, bladder appearance, and age at castration were not associated with outcome.

CONCLUSION

Surgical tube cystostomy without urethral flushing is an effective technique for resolution of obstructive urolithiasis in small ruminants.

CLINICAL RELEVANCE

Goats, small ruminants with an intact urethral process, absence of abdominal fluid, and serum potassium concentration <5.2 mEq/L at admission were all associated with survival after tube cystostomy. Castrated males may also be more likely to survive. These factors should be considered in management of small ruminants with urolithiasis.

Caprine obstructive urolithiasis: requirement for 2nd surgical intervention and mortality after percutaneous tube cystostomy, surgical tube cystostomy, or urinary bladder marsupialization

OBJECTIVES

To determine the requirement for 2nd surgical interventions and mortality after 3 different surgical techniques (percutaneous tube cystostomy [10 goats], surgical tube cystostomy [25 goats], urinary bladder marsupialization [10 goats]) for caprine obstructive urolithiasis, and to determine whether pre- or 24-hour postoperative physical examination findings or serum chemistry results could be used as predictors of mortality.

STUDY DESIGN

Retrospective study.

ANIMALS

Male goats (45) with obstructive urolithiasis.

METHODS

Medical records for all male goats admitted and operated for obstructive urolithiasis between 1993 and 2003 were reviewed. Data retrieved included signalment, pre- and 24-hour postoperative values for temperature, pulse, respiratory rate, packed cell volume, serum K(+), serum creatinine, and blood urea nitrogen [BUN]. The type of initial surgical procedure, time to 2nd surgical intervention, time to death, and duration and cost of hospitalization were also obtained.

RESULTS

Percutaneous tube cystostomy was associated with a significantly increased requirement for (5.6-fold increased hazard) and decreased time to a 2nd intervention (P=.002). There were no differences between the 3 procedures for time to mortality. Increased BUN and respiratory rate at admission were associated with increased mortality (hazards ratio of 4.8 and 5.0, respectively). Urinary bladder marsupialization was associated with significantly decreased hospitalization time (P=.02) and cost (P=.04) compared with surgical tube cystostomy and percutaneous tube cystostomy.

CONCLUSION

Surgical tube cystostomy and bladder marsupialization are both acceptable surgical methods for treatment of caprine obstructive urolithiasis. Each procedure has inherent complications that should be discussed with the owner before choosing the surgical treatment.

CLINICAL RELEVANCE

There are acceptable options for treatment of caprine obstructive urolithiasis; however, percutaneous tube cystostomy should be avoided.