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

Epidemiological Evaluation of Neuter Status, Sex, and Breed in Dogs With Cystine Uroliths

BACKGROUND

The majority of cystine uroliths occur in intact male dogs. Androgen-dependent (Type III) cystinuria is considered the most common cause.

OBJECTIVES

Identify dog breeds in which castration is likely to decrease the risk of cystine uroliths, the potential effect of delaying castration on cystine urolith formation, and urolith recurrence frequency.

ANIMALS

Records of 5477 dogs with cystine uroliths and comparison groups without cystine uroliths (263 938 dogs with non-cystine uroliths and 44 491 dogs from a hospital population).

METHODS

In this case-control study, odds ratios and 95% confidence intervals (CIs) were calculated to identify breeds where the proportion of intact males with cystine uroliths was higher than that of intact males without cystine uroliths. The proportions of intact males forming cystine uroliths before 12, 24, and 36 months of age were calculated. Cystine urolith recurrence rates were assessed by breed in male dogs.

RESULTS

Dogs with cystine uroliths were 99% male. Across 60 breeds, the median proportion of male cystine urolith formers that were intact was 98% (range, 40%-100%). When compared with dogs without cystine uroliths, intact males were overrepresented in cystine urolith formers in all breeds except 8 (Akita, Belgian Malinois, Brussels Griffon, Cane Corso, Coonhound, Newfoundland, Scottish Terrier, and Silky Terrier). Diagnosis occurred before 36 months of age in 28% (n = 1328) of intact male cystine urolith formers. Cystine uroliths recurred in 5.0% (n = 255) of males; 81% (n = 207) were intact males.

CONCLUSIONS AND CLINICAL IMPORTANCE

Androgens likely play a role in the development of cystine uroliths across many dog breeds.

Retrospective analysis of the incidence and clinicopathological findings associated with ammonium urate urolithiasis in dogs with congenital portosystemic shunts: 363 cases (2010-2023)

OBJECTIVES

To assess the incidence and clinical findings associated with the presence of ammonium urate urolithiasis in dogs with congenital portosystemic shunts.

MATERIALS AND METHODS

A retrospective review of dogs diagnosed with extrahepatic portosystemic shunts or intrahepatic portosystemic shunts in 15 referral hospitals between 2010 and 2023. Data including signalment, clinical signs, physical examination findings and clinicopathologic test results at the time of the diagnosis were collected, and the presence of ammonium urate urolithiasis was recorded.

RESULTS

A total of 363 dogs were included. The overall incidence of ammonium urate urolithiasis was 19.3%. Dogs with extrahepatic portosystemic shunts were more likely to have urolithiasis compared to those with intrahepatic portosystemic shunts (32.2% vs. 8.0%). Dogs with urolithiasis were older (median 40 vs. 8 months) and more likely to be neutered males (51.4% vs. 9.8%). Ammonia was significantly lower in dogs with urolithiasis. Dogs with urolithiasis were more likely to have haematuria on dipstick analysis and sediment examination.

CLINICAL SIGNIFICANCE

Dogs with extrahepatic portosystemic shunts were more likely to have urolithiasis when compared to dogs with intrahepatic portosystemic shunts. Dogs with higher ammonia levels were less likely to have ammonium urate urolithiasis, and older dogs, neutered males, or those with evidence of haematuria had an increased incidence of urolithiasis.

Retrospective study of 353 confirmed cases of urolithiasis in dogs and cats treated at veterinary clinics in the northern region of Pará, Brazil

Urolithiasis is the third most prevalent disease of the urinary tract of dogs and cats, and is characterized by presence of crystals and / or formation of stones. The present study objective was to report the confirmation rate of suspected cases of urolithiasis in dogs and cats treated at veterinary clinics in the city of Santarém, Pará. A retrospective cohort study was carried out from the database of medical records from six veterinary clinics from the years 2012 to 2023. Dogs and cats were evaluated for clinical suspicion, species, age, breed, feeding type, diagnosis, location of the urolith and type of urolith. As the data did not present a normal distribution, they were submitted to the Chi-square test and Fisher's exact test. The analyses were performed using Statistical Analysis Software (SAS), considering a 5% significance level. Of the 532 files analyzed of suspected cases, 353 were confirmed. The percentage of cases in cats (72.23%) was higher than in dogs (55.37%). The age range between 2 and 5 years was the period when it had more confirmed cases and most of the uroliths were found in the urinary vesicle, both in dogs and cats. It was concluded that there was a high index of confirmed cases of urolithiasis in dogs and cats, being superior in this last species. In addition, in both species are more affected animals between 2 and 5 years of age, being more common the location of uroliths in the bladder.

Characterisation and evaluation of predisposing factors for the development of xanthinuria in dogs with leishmaniosis under allopurinol therapy

BACKGROUND

Allopurinol, one of the drugs routinely used to treat canine leishmaniosis (CanL), is an inhibitor of the enzyme xanthine oxidase, which plays a fundamental role in purine metabolism. Its inhibitory action on this enzyme leads to a state of hyperxanthinuria, favouring the development of xanthine crystals and/or uroliths. However, not all dogs with CanL treated with allopurinol develop xanthinuria and/or xanthine uroliths, and there is not much information on the possible risk factors that contribute to this event. This study aims to evaluate potential predisposing factors associated with the development of xanthinuria in dogs with a previous diagnosis of CanL that were treated with allopurinol.

METHODS

A multicentric, retrospective, observational study was conducted and included dogs with CanL undergoing allopurinol therapy. Dogs that developed xanthinuria (Xgroup) and those without xanthinuria (NXgroup) were selected from cases admitted to three referral hospitals between 2011 and 2022. Medical records were reviewed, and clinical and laboratorial variables were compared between groups. Descriptive statistics, contingency tables and non-parametric tests were used (P < 0.05).

RESULTS

In total, 90 dogs were selected, 45 for each group. Only age and serum alpha-1 globulin concentration were significantly different between groups at day 0. Dogs from Xgroup were younger (median 4 years; interquartile range (IQR) 2-7) than those from NXgroup (median 6 years; IQR 4-9; P = 0.002). At the time of CanL diagnosis, a higher percentage of dogs from NXgroup had decreased serum alpha-1 globulin concentrations (38.9% versus 13.3% in Xgroup, respectively; P = 0.020). In Xgroup, the median time to xanthinuria development after starting allopurinol was 150 days (IQR 31-455).

CONCLUSIONS

These results suggest that closer monitoring of young dogs (< 4 years) and those with normal alpha-1 globulin levels at diagnosis is recommended to ascertain the possible development of xanthinuria at an early stage, allowing for early application of measures to reduce the likelihood of its development.

Utilizing the Ellik bladder evacuator during cystoscopic retrieval of urocystoliths in 12 dogs

BACKGROUND

Urocystolithiasis is a common problem in dogs; many canine uroliths are resistant to medical dissolution. Novel management options would expand, and in some cases improve, current urolith retrieval strategies.

HYPOTHESIS/OBJECTIVES

To describe a previously unreported technique by the Ellik bladder evacuator (EE) to assist in minimally invasive, cystoscopic retrieval of canine cystoliths.

ANIMALS

Twelve client-owned dogs presented with urocystolithiasis.

METHODS

In this retrospective study, dog demographics, procedure type and duration, and clinical outcomes of dogs undergoing cystoscopic cystolith retrieval utilizing the EE are described.

RESULTS

Twelve dogs underwent 13 cystoscopic procedures utilizing EE for cystolith retrieval. The EE was used in accordance with previously described techniques via a custom-made adaptor. Ten dogs were spayed females; 8 different breeds were represented. In 8 of 13 procedures, transurethral cystoscopy alone by EE with or without wire basket or grasping forceps was performed with a median procedure duration of 36 minutes (range, 16-52). In the other 5 procedures, additional interventions (ie, laser lithotripsy, percutaneous perineal approach, urethral stricture ballooning, ethanol parathyroid ablation) were performed as indicated with a median procedure duration 110 minutes (range, 42-144). No complications were noted in association with the use of the EE; retrieval of cystoliths was complete in 12 of 13 procedures.

CONCLUSIONS AND CLINICAL IMPORTANCE

Use of the EE during cystoscopy might aid in minimally-invasive retrieval of cystoliths. This work provides a starting point for additional discussion regarding its benefit relative to current interventions.

Medical dissolution of presumptive upper urinary tract struvite uroliths in 6 dogs (2012-2018)

BACKGROUND

Minimally invasive approaches are the standard for treatment of upper urinary tract uroliths in humans.

OBJECTIVE

To describe the medical dissolution of upper urinary tract uroliths in a series of dogs and report clinical outcomes.

ANIMALS

6 female dogs (9 kidneys).

METHODS

Retrospective case series. A review of medical records in dogs that underwent medical dissolution of upper urinary tract uroliths utilizing diet, administration of antibiotics, and double-pigtail ureteral stent(s) placement, when indicated, was performed. Medical management was generally continued for 4 weeks beyond urolith dissolution. Information on biochemical, microbiological, imaging, and clinical outcomes before and after dissolution were recorded.

RESULTS

Six dogs (9 kidneys) were included with bilateral (3) or unilateral (3) nephrolithiasis, ureterolithiasis, or a combination. A ureteral stent(s) was placed endoscopically in 5/6 dogs (6/9 kidneys) for obstructive ureterolithiasis (n = 5) or a nonobstructive massive nephrolith (n = 1). All dogs had a positive urine culture of Staphylococcus pseudintermedius with a median urine pH of 7.25 (range, 6.5-8) and 4/5 had pyonephrosis. All dogs had initial evidence of urolith dissolution at a median of 1.1 months (range, 0.42-5.9), with complete dissolution of ureteroliths at a median of 3.9 months (range, 1.5-7.6), nephroliths at 5.3 months (range, 1.5-7.6), and lower urinary tract uroliths at 0.87 months (range, 0.42-5.9). Stents were removed in 3/6 once dissolution was documented. The median follow-up time was 519 days (range, 177-2492 days).

CONCLUSION AND CLINICAL IMPORTANCE

Medical dissolution and decompression of upper urinary tract struvite uroliths should be considered a minimally invasive treatment for dogs before more invasive options.

[First detection of the SLC2A9:p.C188F gene defect in a German Hunting Terrier with ammonium urate urolithiasis]

A 1,5-year-old intact male German Hunting Terrier was initially presented 2018 with hematuria. An abdominal ultrasound revealed multiple hyperechogenic structures in the urinary bladder. A urinalysis indicated severe crystalluria (ammonium urate or xanthine). Following cystotomy and urinary calculus analysis, ammonium urate urolithiasis was diagnosed in 2019. The patient was tested homozygous at the SLC2A9:p.C188F variant, which results in severe hyperuricemia and hyperuricosuria. This case report presents the first incidence of the SLC2A9:p.C188F gene variant being detected in a German Hunting Terrier. Veterinary practitioners are encouraged to consider the possibility of this gene defect presenting in breeds beyond the Dalmatian.

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.