Urolithiasis in dogs: Evaluation of trends in urolith composition and risk factors (2006-2018)

Diagnosis and treatment of urolithiasis in a Toy Poodle dog

Background

Urolithiasis in dogs is a disorder of the urinary tract caused by the development of crystals. These crystals are composed of minerals such as phosphates, oxalates, urates, cystine, carbonates, and silica. It can be fatal if the diagnosis and treatment are inaccurate. This report aims to report a case of urolithiasis in a Toy Poodle dog.

Case Description

A 2-year-old male Toy Poodle dog weighing 4.2 kg with black hair, and having trouble urinating was presented to Prof. Soeparwi Animal Hospital, Universitas Gadjah Mada, Indonesia. The dog is examined physically and, in the laboratory, diagnosed and continued with operative therapy. The history and physical examination revealed that the dog had been experiencing hematuria, stranguria, and oliguria for 2 months, with the last few days accompanied by decreased appetite. The dog exhibited decreased skin turgor, a capillary refill time (CRT) of less than 2 seconds, signs of pain and distress during urination, and palpation of distended urinary vesicles. Ultrasound scans revealed uroliths in the urinary vesica, which were identified by an acoustic shadow. Blood tests indicated a decrease in hematocrit and erythrocytes along with an increase in leukocytes. Urolithiasis was diagnosed in the case dog based on anamnesis, physical examination, hematological examination, and ultrasonography. Subsequently, a cystotomy was performed, and uroliths located in urinary vesicles were removed. The dog received ceftriaxone injections at 15 mg/kg body weight and vitamin B-complex injections at a concentration of 10 mg/kg body weight for 5 days. Four days post-surgery, the case dog was able to successfully urinate and pass clean urine.

Conclusion

The Toy Poodle dog was diagnosed with silica urolithiasis in the urinary vesicles and the urolith is quite large. Cystotomy was performed to remove the urolith. Postoperative care were included the administration of antibiotics and vitamins to facilitate the healing process. The condition of the Poodle toy dog improved.

Clinical Differences in Dogs with Enterococcal Bacteriuria Compared with Other Bacteriuria: A Retrospective, Case-Control Study

A retrospective case-control study was performed to determine the clinical differences between dogs with enterococcal bacteriuria (n = 96 cases) and control dogs with any other bacteriuria (n = 288). More dogs with nonenterococcal bacteriuria demonstrated lower urinary tract clinical signs such as hematuria, pollakiuria, and stranguria (40% versus 27%, P = .02). Recessed vulva (odds ratio [OR] 2.5, 95% confidence interval [CI] 1.4-4.2, P < .001), hyperadrenocorticism (OR 0.149, 95% CI 0.004-0.066, P = .03), chronic kidney disease (OR 2.29, 95% CI 1.14-4.51, P = .01), and myelopathy (OR 5.77, 95% CI 3.07-10.82, P < .001) were more common in dogs with enterococcal bacteriuria. Enterococcus spp. cases were more likely to have polymicrobial growth than controls (OR 28.52; 95% CI 12.63-69.62, P ≤ .001). Pugs (OR 7.4, 95% CI 2.6-19.9, P < .001), bearded collies (OR 24.3, 95% CI 2.9-205.5, P = .003), and Saint Bernards (OR 17.3, CI 1.9-154.4, P = .01) had increased odds of enterococcal growth compared with mixed-breed dogs. In the control (but not the case) population, there was an association between resolution of clinical signs and administration of antimicrobials (P = .01). The signalment, clinical signs, comorbidities, and response to therapy in dogs with enterococcal bacteriuria are different from dogs with other bacteriuria.

A retrospective study on epidemiology and management of canine cystine uroliths in one part of Norway from 2015 to 2020

BACKGROUND

Urinary tract problems are a common complaint in small animal medicine and urolithiasis is considered to be an important cause of urinary tract disease in dogs. In this study the main aim was to investigate whether the occurrence of cystine urolithiasis increased during a five-year period. A second aim was to evaluate possible risk-factors as breed, age and gender. This study also evaluated how urine specific gravity, pH and level of cystine in urine responded to preventive strategies. Medical records of dogs with urolithiasis presented at nine Norwegian animal clinics and one animal hospital between 2015 and 2020 were retrospectively reviewed.

RESULTS

The incidence of cystine uroliths increased significantly during the five study years (R2 = 0.72, P = 0.0199). Dogs with cystine uroliths were significantly younger (5.0 years (n = 84, 95% CI [4.4-5.6])) when they were diagnosed with cystine uroliths compared to dogs with other types of uroliths (8.1 years (n = 255, 95% CI[7.8-8.5]) P < < 0.0001). Cystine levels in urine were increased in 93% of the dogs with cystine urolithiasis. Cystinuria decreased significantly after neutering (P < 0.0001). Breeds most commonly affected with cystine urolithiasis in this study were Staffordshire bull terrier, Danish Swedish farmdog and Chihuahua.

CONCLUSIONS

The results from this study supports a suggested genetic basis for cystine urolithiasis as described in previous studies. Neutering is considered an important part of preventing reoccurrence since cystine values decreased significantly after neutering.

[Urinalysis in dogs and cats, part 2: Urine sediment analysis]

Examination of the urine sediment is part of a routine urinalysis and is undertaken in order to identify insoluble particles in the urine. This procedure is mainly used in the context of diagnostic evaluation of urinary tract diseases, but may also be useful for the diagnosis of systemic diseases and intoxications. Analysis of fresh urine is recommended as changes in cell morphology, cell lysis and in vitro crystal formation may occur in the course of its storage. Manual urine sediment analysis is still performed in many veterinary practices. Native wet-mount preparations are suitable for the identification and quantification of urine sediment particles. The examination of stained wet-mount preparations or air-dried smears may be necessary to further differentiate cells and to identify bacteria. For several years, automatic urine sediment analyzers have been available in veterinary medicine. These save considerable time and staff resources, however verification of the automatically generated results by an experienced observer remains necessary. Urine sediment particles that are frequently identified and clinically relevant include red blood cells, white blood cells, different types of epithelial cells, crystals, and casts as well as bacteria. Furthermore, parasite eggs, fungal hyphae, lipid droplets, spermatozoa, fibres, hair, mucus, plant parts or environmental contaminations may be found in the urine sediment and result in a complication of the result interpretation.

Prevalence and Predictors of Radiographically Apparent Upper Urinary Tract Urolithiasis in Eight Dog Breeds Predisposed to Calcium Oxalate Urolithiasis and Mixed Breed Dogs

Data on upper urinary tract (UUT) uroliths in dogs are important to understanding their etiology. The aim of this retrospective case-control study was to determine the prevalence and identify predictors of radiographically apparent UUT uroliths in dog breeds at increased risk for calcium oxalate uroliths (CaOx risk breeds) and mixed breed dogs. Radiologist reports of three-view abdominal radiographs were reviewed from 251 purebred dogs of 8 CaOx risk breeds and 68 mixed breed dogs. UUT uroliths were more common in CaOx risk breeds than mixed breed dogs (23% versus 6%, respectively; OR = 4.8, 95% confidence interval [CI] 1.7−18.9, p < 0.001). UUT uroliths were more common in dogs with lower urinary tract (LUT) uroliths (predominantly calcium-containing) than those without (41% versus 5%, respectively; OR = 13.6, 95% CI 6.3−33.1, p < 0.001), and LUT uroliths predicted the presence of UUT uroliths in the multivariable regression (OR = 6.5, 95% CI 2.8−16.7, p < 0.001). Increasing age (p < 0.001) and lower body weight (p = 0.0016) were also predictors of UUT urolith presence in the multivariable regression. The high prevalence of UUT uroliths in dogs with LUT uroliths supports a shared mechanism for their formation.

Obstructive struvite ureterolithiasis in 4-month-old intact male Bernese mountain dog

A 4-month-old, 7 kg, intact male, Bernese mountain dog was presented for obstructive struvite ureterolithiasis. Multiple urethroliths, ureteroliths, and urocystoliths were present. Based on an abdominal ultrasound, there was severe left hydronephrosis and hydroureter from distal ureterolith obstruction, just proximal to the vesicoureteral junction. The dog was not azotemic. Successful treatment was accomplished via ventral cystotomy. Bladder wall culture revealed a methicillin-resistant Staphylococcus spp. No predisposing cause was identified. There are no known genetic predispositions in Bernese mountain dogs for struvite urolithiasis. The urinary tract infection resolved with surgical retrieval of the uroliths and antibiotic treatment. The dog remained clinically normal after the cystotomy but developed a subclinical urinary tract infection 4 mo post-operatively. Key clinical message: Urolithiasis is rare in pediatric veterinary patients. To the authors' knowledge, this is the first report of obstructive ureterolithiasis in a puppy. There is no known genetic predisposition for urolithiasis in Bernese mountain dogs.

Computed tomographic assessment of retrograde urohydropropulsion in male dogs and prediction of stone composition using Hounsfield unit in dogs and cats

Background

Persistent uroliths after a cystotomy in dogs are a common cause of surgical failure.

Objectives

This study examined the following: the success rate of retrograde urohydropropulsion in male dogs using non-enhanced computed tomography (CT), whether the CT mean beam attenuation values in Hounsfield Units (mHU) measured in vivo could predict the urolithiasis composition and whether the selected reconstruction kernel may influence the measured mHU.

Methods

All dogs and cats that presented with lower urinary tract uroliths and had a non-enhanced CT preceding surgery were included. In male dogs, CT was performed after retrograde urohydropropulsion to detect the remaining urethral calculi. The percentage and location of persistent calculi were recorded. The images were reconstructed using three kernels, from smooth to ultrasharp, and the calculi mHU were measured.

Results

Sixty-five patients were included in the study. The success rate of retrograde urohydropropulsion in the 45 male dogs was 55.6% and 86.7% at the first and second attempts, respectively. The predominant components of the calculi were cystine (20), struvite (15), calcium oxalate (8), and urate (7). The convolution kernel influenced the mHU values (p < 0.05). The difference in mHU regarding the calculus composition was better assessed using the smoother kernel. A mHU greater than 1,000 HU was predictive of calcium oxalate calculi.

Conclusions

Non-enhanced CT is useful for controlling the success of retrograde urohydropropulsion. The mHU could allow a prediction of the calculus composition, particularly for calcium oxalate, which may help determine the therapeutic strategy.

Cystinuria in Dogs and Cats: What Do We Know after Almost 200 Years?

The purpose of this review is to summarize current knowledge on canine and feline cystinuria from available scientific reports. Cystinuria is an inherited metabolic defect characterized by abnormal intestinal and renal amino acid transport in which cystine and the dibasic amino acids ornithine, lysine, and arginine are involved (COLA). At a normal urine pH, ornithine, lysine, and arginine are soluble, but cysteine forms a dimer, cystine, which is relatively insoluble, resulting in crystal precipitation. Mutations in genes coding COLA transporter and the mode of inheritance were identified only in some canine breeds. Cystinuric dogs may form uroliths (mostly in lower urinary tract) which are associated with typical clinical symptoms. The prevalence of cystine urolithiasis is much higher in European countries (up to 14% according to the recent reports) when compared to North America (United States and Canada) where it is approximately 1-3%. Cystinuria may be diagnosed by the detection of cystine urolithiasis, cystine crystalluria, assessment of amino aciduria, or using genetic tests. The management of cystinuria is aimed at urolith removal or dissolution which may be reached by dietary changes or medical treatment. In dogs with androgen-dependent cystinuria, castration will help. In cats, cystinuria occurs less frequently in comparison with dogs.

Urolithiasis in dogs: Evaluation of trends in urolith composition and risk factors (2006-2018)

BACKGROUND

Urolithiasis is a common and often recurrent problem in dogs.

OBJECTIVE

To evaluate trends in urolith composition in dogs and to assess risk factors for urolithiasis, including age, breed, sex, neuter status, urolith location, and bacterial urolith cultures.

SAMPLE POPULATION

A total of 10 444 uroliths and the dogs from which they were obtained.

METHODS

The laboratory database at the UC Davis Gerald V. Ling Urinary Stone Analysis Laboratory was searched for all urolith submissions from dogs between January 2006 and December 2018. Mineral type, age, breed, sex, neuter status, urolith location, and urolith culture were recorded. Trends were evaluated and variables compared to evaluate risk factors.

RESULTS

Calcium oxalate (CaOx) and struvite-containing uroliths comprised the majority of all submissions from dogs, representing 47.0% and 43.6%, respectively. The proportion of CaOx-containing uroliths significantly decreased from 49.5% in 2006 to 41.8% in 2018 (P = .006), with no change in the proportion of struvite-containing urolith submissions. Cystine-containing uroliths comprised 2.7% of all submissions between 2006 and 2018 and a significant nonlinear increase in this mineral type occurred over time (1.4% of all submissions in 2006 to 8.7% in 2018; P < .001). Of all cystine-containing uroliths, 70.3% were from intact male dogs. Age, breed, and sex predispositions for uroliths were similar to those previously identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although calcium oxalate- and struvite-containing uroliths continue to be the most common uroliths submitted from dogs, a decrease in the proportion of CaOx-containing uroliths and an increase in the proportion of cystine-containing uroliths occurred during the time period evaluated.