Comparison of three techniques for the diagnosis of urinary tract infections in dogs with urolithiasis

OBJECTIVES: To identify an appropriate sampling technique(s) to accurately detect the bacteria causing urinary tract infections in dogs with urolithiasis. METHODS: Twenty-one dogs with urolithiasis were included in the study. Three types of samples were taken from each dog. Urine was collected by cystocentesis, and a urinary bladder mucosal biopsy and urolith were retrieved during cystotomy. The samples were then cultured on blood agar and MacConkey's agar to identify the bacteria associated with urinary tract infections. RESULTS: Bacterial urinary tract infection was found in 16 cases (76.19 per cent). The most prevalent bacteria found to cause urinary tract infection were Escherichia coli (n=7), followed by coagulase-positive Staphylococcus species (n=4), Klebsiella pneumoniae (n=2), Pseudomonas aeruginosa (n=2) and Proteus mirabilis (n=1). In the case of a positive urine culture, the same bacteria were also cultured from the urinary bladder mucosal biopsy alone or from both the urinary bladder mucosal biopsy and urolith. However, in the case of a negative urine culture, bacteria were found to be present in the urinary bladder mucosal biopsy or urolith cultures in 23.81 per cent of dogs. The uroliths that gave positive culture results were either infection-induced uroliths composed of struvite and calcium carbonate phosphate, ammonium acid urate only or metabolic uroliths composed of calcium oxalate and calcium phosphate, or calcium phosphate only. All the uroliths that gave negative culture results were metabolic uroliths composed of calcium oxalate and/or calcium phosphate, and uric acid and calcium phosphate. CLINICAL SIGNIFICANCE: When the culture from the urine obtained by cystocentesis is negative, cultures of urinary bladder mucosal biopsy and urolith are recommended in dogs with urolithiasis in order to accurately assess the microbiological status of the urinary tract.     

Mouse barley awn (Hordeum murinum) migration induced cystolithiasis in 2 male dogs

Two male dogs were presented with cystic uroliths composed of magnesium ammonium phosphate (struvite). Each had an atypical nidus, a mouse barley awn (Hordeum murinum). To our knowledge, this is the first report of grass awns located in the bladder lumen of dogs. The composition of uroliths and the pathophysiology of grass awn migration to the urinary bladder are discussed.     

The use of pneumatic impact lithotripsy and a retrieval pouch to create a closed system for removal of cystic calculi in standing male horses

Multiple techniques exist for removal of cystic calculi in the male horse, some of which use a perineal urethrotomy (PU) to facilitate access to the urinary bladder for removal of small uroliths in the standing, sedated horse. These techniques have limited efficacy in the removal of uroliths that have a diameter larger than the PU site, typically 4–5 cm. Pneumatic lithotripsy as reported in this article provides a novel way to fragment these larger uroliths while containing the fragments and protecting the urethra and urinary bladder. Ten geldings and one stallion underwent a lithotripsy procedure to remove one (n = 10) or several (n = 1) uroliths ranging in diameter from 4 to 9 cm. A PU was performed and a laparoscopic retrieval bag was inserted into the urinary bladder through the PU site. The urolith was manipulated into the bag using blind transrectal manipulation or endoscopic guidance and the opening of the bag was exteriorised out of the PU site. A pneumatic lithotrite was used to fragment the stone. When the urolith was adequately fragmented, the fragments were removed by the use of sponge forceps and by flushing the fragments from the bag with obstetrical lube. This was continued until the bag could smoothly be withdrawn from the urinary bladder. All uroliths were successfully removed. The PU sites healed without complication and none of the horses had recurrence of presenting clinical signs. This article also discusses the difference between two types of laparoscopic retrieval bags. Pneumatic impact lithotripsy in combination with a retrieval pouch offers a safe alternative to other methods for removal of cystic calculi in the horse.     

Canine Silica Urolithiasis

Silica "jack-stone" uroliths developed in the urinary bladder and urethra of 83 dogs living in the United States. Naturally occurring silica jack stones have not been encountered prior to 1976. German Shepherd Dogs comprised more than 1/3 of affected animals; the remainder encompassed 26 other breeds. In this series, 81 were males and 2 were females. The mean age of the dogs was 5.8 years, with a range of 1.5 to 12 years. Several observations prompt the hypothesis that development of silica uroliths may be related to diet. Although most silica uroliths had a characteristic jack-stone appearance, not all silica uroliths had a jack-stone configuration and not all jack stones were composed of silica. Some calculi were comprised of a combination of silica and struvite. Silica uroliths were radiodense, compared with adjacent tissue, but were not associated with identifiable crystals in urine. The urine pH of affected dogs varied from acid to alkaline. Silica urolithiasis recurred in 5 dogs following surgery. Urinary tract infections, when they occurred, appeared to be a sequela of silica urolithiasis. Pending further studies, management of silica uroliths should include their removal from the urinary tract and eradication of associated urinary tract infections. Prophylactic measures should include attempts to augment urine volume and change of diet.     

Prevalence of canine uroliths. Minnesota Urolith Center

Uroliths obtained from 839 dogs were evaluated by quantitative methods. Struvite was the most prevalent mineral detected; newberyite, calcium oxalate, calcium phosphate, uric acid, sodium and ammonium urate, cystine, and silica were detected much less frequently. Seven per cent of the uroliths had an identifiable nucleus and one or more surrounding layers of different mineral types. Although uroliths were found in all parts of the urinary tract, the urinary bladder was most common. Uroliths of different composition were encountered in a variety of breeds of both sexes and different ages.     

Transitional cell carcinoma of the urinary bladder in a 14-year-old dog

A 14-year-old spayed female poodle-pekinese dog with a history of hematuria was tentatively diagnosed with non-radiopaque uroliths or urinary bladder neoplasia following temporary resolution of clinical signs after several rounds of antibiotic treatments, normal abdominal radiographs and no growth on urine culture. Abdominal ultrasound revealed a mass in the trigone area of the urinary bladder which was confirmed to be an invasive transitional cell carcinoma by histopathology following euthanasia.     

Use of laser lithotripsy for fragmentation of uroliths in dogs: 73 cases (2005-2006)

OBJECTIVE: To describe use of transurethral cystoscope-guided laser lithotripsy for fragmentation of cystic and urethral uroliths and determine procedure duration and short-term and long-term outcome in dogs. DESIGN: Retrospective case series. ANIMALS: 73 dogs with naturally occurring uroliths in the urinary bladder, urethra, or both. PROCEDURES: Transurethral cystoscope-guided laser lithotripsy was performed in all dogs, and medical records were reviewed for short-term and long-term outcome and complications. RESULTS: Laser lithotripsy resulted in complete fragmentation of all uroliths in all 28 female dogs and a majority of male dogs (39/45 [86.7%]). Dogs with urethroliths had shorter median laser time than dogs with cystic uroliths. Basket extraction and voiding urohydro-propulsion were successful for removal of the urolith fragments following laser lithotripsy. Complications related to cystoscope-guided laser lithotripsy occurred in 5 of 28 (17.9%) female dogs and 6 of 45 (13.3%) male dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Transurethral cystoscope-guided laser lithotripsy was successful in female dogs and most male dogs for fragmentation of cystic and urethral uroliths. Short-term complications were most commonly related to urethral swelling and resolved with placement of an indwelling urinary catheter. There were no long-term complications.     

Qualitative and quantitative analysis of uroliths in dogs: definitive determination of chemical type

Effective treatment and prevention of urolithiasis depends on accurate determination of the chemical nature of the uroliths. A widely used qualitative chemical procedure was compared with quantitative crystallographic analysis of 272 canine uroliths. Agreement between the 2 methods was 78%. Qualitative analysis failed to detect 62% of calcium-containing uroliths and 83% of carbonate apatite uroliths. Qualitative analysis gave false-positive results for urates in 55% of cystine uroliths. Mixed uroliths comprising 6% of the total could not be classified without quantitative analysis. Silicate, cystine, and urate uroliths generally were of pure composition. Crystallographic analysis indicated the following distribution of major types: struvite, 69%; calcium oxalate, 10%; urate, 7%; silicate, 3.5%; cystine, 3.2%; calcium phosphate, 1%; and mixed, 6%. Among dogs with struvite uroliths, 66% had positive results of bacterial culturing from the urinary bladder. Six breeds (Miniature Schnauzer, Welsh Corgi, Lhasa Apso, Yorkshire Terrier, Pekingese, and Pug) had a significantly higher risk for urolithiasis, compared with other breeds. The German Shepherd Dog had a significantly lowered risk, compared with other breeds. Two breeds had significant relationship to a specific type of urolith: Miniature Schnauzer for oxalate, and Dalmatian for urate (P less than 0.001). It was concluded that quantitative analysis, using crystallography, was superior for the detection of calcium oxalate, carbonate apatite, cystine, urate, and mixed uroliths.     

Six cases of inguinal urinary bladder herniation in entire male domestic rabbits

Six entire male rabbits, between four and eight years old, were presented with a fluctuant scrotal and/or inguinal swelling resulting from inguinal herniation of the urinary bladder. Concurrent problems included urinary sediment (two rabbits), multiple uroliths (one rabbit) and testicular tumour (one rabbit). All rabbits underwent herniorrhaphy surgery. There was a successful outcome in four of the six cases.     

Cystinuria in the dog: clinical studies during 14 years of medical treatment

The purpose of this study was to summarize 14 years of clinical experience with medical treatment of 88 cystinuric dogs. Of special interest was evaluation of recurrence rate of cystine uroliths and adverse effects during long-term tiopronin treatment. Twenty-six different breeds were recognized, and the most common breeds were Dachshunds, Tibetan Spaniels, and Basset Hounds. In 76 of 88 treated dogs (86%), re-formation of cystine uroliths was prevented. Recurrence rate of cystine uroliths changed from 7 months before to 18 months during tiopronin treatment. On 28 occasions, bladder stones were found, and in about 60% of the dogs, the uroliths dissolved. Quantitative measurement of the urinary excretion of cystine showed a significantly (P < .03) higher excretion of cystine in dogs with recurrent urolith formation than in dogs with only 1 urolith episode. Another finding was a significant (P = .02) decrease in urinary cystine excretion in older (>5 years) than in younger (<5 years) dogs. Adverse effects were found in 11 dogs, and the most severe signs were aggressiveness and myopathy. All signs disappeared when tiopronin treatment was stopped. In conclusion, this study emphasizes the importance of an individual strategy for lifelong treatment of cystinuria. In addition to increasing water intake, chemical modification of the cysteine molecule into a more soluble form by means of tiopronin is useful. In dogs with re-formed cystine uroliths, dissolution may be induced by increasing the tiopronin dosage to 40 mg/kg body weight per day. In dogs with a low urolith recurrence rate and low urinary cystine excretion, the tiopronin dosage may be decreased or treatment discontinued.     

An abattoir survey of urinary bladder lesions in cattle

Postmortem examination of 21,340 cattle at an Ontario abattoir over a one-year period revealed macroscopic lesions in urinary bladders of 2,296 animals (10.8%). Chronic cystitis, the most frequent finding, was observed in 2,209 cases (10.4%); uroliths were found in 994 (4.7%) of the cattle with chronic cystitis. Other types of urinary bladder lesions included acute cystitis, developmental abnormalities, hyperplasia, neoplasia, emphysema, and a parasitic cystitis.     

Removal of cystic calculi using a transinguinal laparoscopic‐assisted technique in two stallions

A 12‐year‐old donkey and a 6‐year‐old Connemara pony, both sexually intact males, were admitted for surgical removal of urinary calculi. Both underwent a laparoscopic‐assisted cystotomy technique to exteriorise the bladder and remove uroliths via the inguinal canal after hemi‐castration. Both surgeries were successful and no complications occurred. This modified technique, which is minimally invasive, may be a safe and efficient way to remove bladder stones from adult stallions.     

Prevalence and chemical composition of uroliths in fattening pigs in Belgium

The present study investigated the prevalence of uroliths in fattening pigs and assessed the composition of these urinary tract concrements. In total, 2,432 urinary bladders were sampled in the slaughterhouse and checked for abnormal content. Urinary samples were analysed microscopically, and samples of the urinary bladder wall were tested for histological signs of inflammation. The composition of the concrements was examined by infrared spectrophotometry. Macroscopic and microscopic abnormalities were detected in 8.4% and 52.8% of the samples respectively. Magnesium ammonium phosphate (struvite), calcium oxalate dihydrate (COD), calcium carbonate (calcite), calcium oxalate monohydrate (COM) and amorphous crystals were detected. Analysis of stones showed COD in all samples in different proportions. The calcium content of examined stones was always considerable (up to 34%), in contrast to the magnesium content which represented max 1.9%. Struvite was found in one third of the samples, but was never part of stones and grit. COD crystals were the second most common microscopic crystal. These COD crystals and some COD stones had a rectangular shape, and therefore, they can be harmful to the bladder mucosa. In conclusion, uroliths are present in a large proportion of male fattening pigs, and consequently, urinary concrements pose a life‐threatening risk for urethra obstruction in male pigs. Further research is warranted to identify potential risk factors for urolithiasis and microscopic crystals.     

Feline urethral plugs and bladder uroliths: a review of 5484 submissions 1998-2003

The results of 5484 submissions from cats to the Canadian Veterinary Urolith Centre between February 1998 and February 2003 are presented. Of the submissions, 618 were urethral plugs and 4866 were bladder uroliths. The majority of the urethral plugs were from male domestic shorthair and longhair cats. Approximately 50% of the urolith submissions were oxalate, 44% were struvite. Oxalate uroliths were the most common mineral type in males and in Himalayan, Persian, and Siamese cats. Struvite uroliths were the most common mineral type in domestic shorthair and longhair cats. Females outnumbered males by 1.4:1 in struvite urolith submissions. A review of risk factors for urethral plugs and bladder uroliths is presented.     

Risk factors associated with feline urolithiasis

Urinary tract diseases are among the main reasons for consultation in veterinary clinics and hospitals. It affects animals of any age, breed and gender. Among the diseases that affect this system, urolithiasis is the second largest cause of clinical signs compatible with feline urinary tract disease. The term urolithiasis refers to the presence of uroliths in any region of the urinary tract, but it is more commonly seen in the bladder and urethra. Uroliths are classified based on the type of mineral present in their composition, therefore, quantitative and qualitative analyzes are important for a better therapeutic approach. The animals may suffer from the disease and be asymptomatic, or show nonspecific clinical signs, making the diagnosis difficult. The disease should not be seen as a single problem, but as a consequence of various disorders. As dietary, metabolic, genetic and infectious causes, as well as factors that potentiate the chance of development of uroliths such as breed, age, sex, age range, obesity, sedentary lifestyle, geographic region and climate. Thus, the knowledge of the factors that influence the formation of uroliths, as well as the understanding of the pathophysiology, are key elements for better alternatives of therapy and prevention. The recognition of these factors helps to identify susceptible populations, minimizing exposure and increasing the protection factors, which facilitates the diagnosis and treatment of patients with urolithiasis. The objective of this paper is to present the main risk factors involved in the formation of urinary lithiasis in felines.     

DIAGNOSIS OF URINARY BLADDER RUPTURE USING ULTRASOUND CONTRAST CYSTOGRAPHY: IN VITRO MODEL AND TWO CASE-HISTORY REPORTS

Because urinary bladder rupture can be life threatening, a simple, safe technique for evaluating patients is desirable. Current diagnostic protocols involve radiographic imaging, but ultrasound-based contrast techniques have not been methodically evaluated in veterinary patients with urologic trauma. Ultrasound contrast cystography (contrast cystosonography) involves infusion of microbubbled saline solution through a urinary catheter. It was performed in an in vitro model and in 2 dogs with naturally occurring urinary bladder rupture. A positive result consisted of visualizing microbubbles sonographically in fluid surrounding the bladder immediately after infusion of contrast into the urinary catheter. A positive result was obtained both in the in vitro model and in the 2 dogs, with radiographic and surgical confirmation of naturally occurring intraperitoneal urinary bladder rupture in the dogs. Based on the results of this study, ultrasound contrast cystography appears to be more sensitive than two-dimensional (2D) abdominal sonography for detecting naturally occurring urinary bladder rupture in dogs.     

SONOGRAPHIC EVALUATION OF URINARY BLADDER WALL THICKNESS IN NORMAL DOGS

Urinary bladder wall thickness was evaluated by ultrasonography in 16 normal dogs. Sterile saline solution was administered via urinary catheters to control the degree of bladder distention. Bladder wall thickness was measured on static ultrasound images in 4 locations and at 3 degrees of bladder distention (minimal, mild, and moderate). Four randomized distention sequences with 3 distentions per sequence were performed on each dog and the data were analyzed using Williams' balanced Latin square. Mean bladder wall thickness was 2.3 mm in minimally distended bladders (0.5 ml/kg saline), 1.6 mm in mildly distended bladders (2 ml/kg saline) and 1.4 mm in moderately distended bladders (4 ml/kg saline). Mean bladder wall thickness increased significantly with increasing body weight and with decreasing bladder distention. The caudoventral measurement location produced a statistically significant smaller measurement, with a difference of 0.3 mm. Sex did not affect bladder wall thickness. Distention sequence and repetition of distentions did not affect bladder wall thickness.     

Canine and feline urolithiasis: Examination of over 50 000 urolith submissions to the Canadian Veterinary Urolith Centre from 1998 to 2008

This study reports on trends in canine and feline urolithiasis in Canada during the past 10 years. Age, sex, breed of animals and mineral composition from 40 637 canine and 11 353 feline bladder uroliths submitted to the Canadian Veterinary Urolith Centre between 1998 and 2008 were recorded. Struvite and calcium oxalate uroliths comprised > 85% of all uroliths submitted. In dogs, the number of struvite submissions has declined and the number of calcium oxalate submissions has increased. Struvite uroliths were most common in female dogs and calcium oxalate uroliths in male dogs. The shih tzu, miniature schnauzer, bichon frisé, lhasa apso, and Yorkshire terrier were the breeds most commonly affected for both struvite and calcium oxalate uroliths. Urate uroliths were most common in male dalmatians. In cats, struvite submissions declined and calcium oxalate submissions remained constant. Struvite and calcium oxalate uroliths were common in domestic, Himalayan, Persian, and Siamese cats. Urate uroliths were over-represented in Egyptian maus.     

Chemical composition and microstructure of uroliths and urinary sediment crystals associated with the feeding of high-level cottonseed meal diet to water buffalo calves

The chemical composition and microstructure of seven uroliths and four urinary sediment samples associated with the feeding of high-level cottonseed meal diet to buffalo calves were examined by chemical qualitative analyses, scanning electron microscopy ( ), X-ray diffraction, and X-ray energy dispersive spectrometry ( ). Struvite was a major component of kidney stones and of some bladder stones. The kidney stone sample appeared cracked under low power under , aggregated into tiny balls under high power, and as a bladelike structure under even higher power. The bladder stone samples appeared finely granular or granular with various forms of prismatic crystals. The urinary sediments were prismatic crystals, with granules. The newly found prismatic crystals, which were rich in potassium and similar to struvite in crystal structure, were identified as potassium magnesium phosphate (KMgPO₄ · 6H₂O) in some bladder stones and urinary sediments. However, crystals which contained Mg and P only, which had been used for struvite identification, were not found by examination in urinary sediments from fresh urine samples of buffalo calves fed the high-level cottonseed meal diet.     

Holmium:YAG Laser Lithotripsy for Urolithiasis in Horses

Background: Laser lithotripsy has been used as an alternative to surgical removal of uroliths.
Objective: To describe the procedure and efficacy of laser lithotripsy for removal of lower urinary tract uroliths in horses. Additionally, the ultrastructure and the differences in mineralogy and microstructure from 1 successful and 1 unsuccessful laser lithotripsy case are described.
Animals: Six client-owned horses with 7 episodes of naturally occurring urocystoliths, urethroliths, or both.
Methods: Retrospective study of all horses treated between 2006 and 2008 by laser lithotripsy. All horses were sedated followed by laser lithotripsy. Quantitative urolith analysis was performed in all cases. Ultrastructure and microstructure analyses were performed on uroliths from 2 horses.
Results: Procedural success was achieved in 5 of 7 laser lithotripsy procedures. No complications occurred as a result of laser lithotripsy. One horse developed uroabdomen likely as a result of manual lithotrite disruption of the bladder after failure of laser lithotripsy. There were differences in microstructure between 1 urolith that was successfully fragmented by laser lithotripsy and 1 urolith that was resistant to laser fragmentation.
Conclusions and Clinical Importance: Laser lithotripsy is an effective procedure for removal of some urocystoliths, urethroliths, or both in horses.