Placement of an artificial urethral sphincter in 8 male dogs with urethral diverticulum.

BACKGROUND: Urethral diverticulum (UD) is a poorly defined anomaly consisting of an outpouching of the urethra. Management without surgical resection is not previously reported in dogs. HYPOTHESIS/OBJECTIVES: Report the outcome of male dogs presented for urinary incontinence with UD treated with an artificial urethral sphincter (AUS). ANIMALS: Eight client-owned dogs with UD treated with an AUS. METHODS: Multicenter retrospective study. Medical records from male dogs with urinary incontinence were reviewed. INCLUSION CRITERIA:  diagnosis of a UD by retrograde cystourethrography, cystoscopy, abdominal ultrasonography or contrast computed tomodensitometry (CT) or a combination of these modalities, AUS placement, and at least 1 follow-up. Urinary continence score (UCS) was attributed retrospectively. RESULTS: Median UCS at presentation was 1/5. A contrast cystourethrogram was diagnostic in 8/8 dogs. All diverticula were saccular, and 7/8 were within the prostatic urethra and 1/8 extended up to the membranous urethra. A congenital origin was suspected in 7 dogs and acquired in 1. Concurrent anomalies included renal dysplasia or chronic pyelonephritis (n = 4), bilateral cryptorchidism (n = 3), and pelvic urinary bladder (n = 3). All dogs were poorly/moderately responsive to phenylpropanolamine. Artificial urethral sphincter placement resulted in improvement in continence in all dogs with a median UCS of 4/5 (5/5 in 2/8 dogs, 4/5 in 5/8 dogs, 3/5 in 1/8 dogs). CONCLUSION: Urethral diverticulum should be considered in male dogs with persistent urinary incontinence not responding to medical management. Artificial urethral sphincter placement is an effective therapeutic option that improved continence scores in all dogs.

ACVIM consensus statement on diagnosis and management of urinary incontinence in dogs.

Urinary incontinence (UI) is a disorder of micturition that can occur in dogs of any age, sex, and breed depending on the underlying cause and time of onset. Diagnosis and treatment for various causes of UI in dogs have been described by multiple comprehensive single author review articles, but large prospective clinical trials comparing treatment outcomes in veterinary medicine are lacking. The objectives of this consensus statement therefore are to provide guidelines on both recommended diagnostic testing and treatment for various causes of UI in dogs. Specifically, pathophysiology directly related to the canine urinary system will be reviewed and diagnostic and therapeutic challenges will be addressed. A panel of 12 experts in the field (8 small animal internists [L. Adams, J. Bartges, A. Berent, J. Byron, J. Foster, A. Kendall, S. Vaden, J. Westropp], 2 neurologists [J. Coates, N. Olby], 1 radiologist [G. Oetelaar], and 1 surgeon [C. Adin]) was formed to assess and summarize evidence in the peer-reviewed literature and to complement it with consensus recommendations using the Delphi method. Some statements were not voted on by all panelists. This consensus statement aims to provide guidance for management of both male and female dogs with underlying storage or voiding disorders resulting in UI.

A novel two-catheter method for urethral catheterization improves success rates of urethral catheterization in female dogs and cats weighing less than ten kilograms.

OBJECTIVE: To compare the success rates for urethral catheterization in clinical patients using the traditional and 2-catheter techniques when placed by personnel of all experience levels. ANIMALS: 38 female cats and dogs weighing less than 10 kg were prospectively enrolled. METHODS: Enrolled animals were randomized to have a urethral catheter placed by the traditional technique or the 2-catheter method under sedation or general anesthesia. Any qualified hospital personnel of any experience level were allowed to place the catheter. If after 5 minutes the animal was not successfully catheterized, the alternate method was performed. The previous experience of the catheter placer, animal signalment, animal condition that necessitated catheter placement, time to successful placement, and which technique was successful was recorded. RESULTS: The 2-catheter technique was more successful than the traditional method (60.5% and 34.2%, respectively) for urethral catheterization when used by a variety of hospital personnel. The 2-catheter technique was successful in 63.3% of dogs and 66.6% of cats, while the traditional method was successful in 36.6% of dogs and 33.3% of cats. Eight of 9 (88.9%) novice catheter placers that placed their first urinary catheter in this study succeeded with the 2-catheter technique and only 1 was successful with the traditional method. CLINICAL RELEVANCE: The 2-catheter technique has a higher rate of success for placement of female urinary catheters in small patients that are unable to have concurrent digital palpation. This technique may also be helpful in the inexperienced catheter placer population to aid in guidance into the urethral papilla.

The use of Escherichia coli strain Nissle 1917 shows promise for improving gastrointestinal and urinary health in dogs.

OBJECTIVES: To investigate the probiotic Escherichia coli Nissle 1917 (EcN) in canine idiopathic diarrhea and urinary tract infections. ANIMALS/SAMPLES: The utility of EcN was explored in a 3-phase study from March 2017 to June 2020. Eighty-nine dogs with idiopathic diarrhea were included in phase 1, 3 healthy dogs were included in phase 2, and uropathogenic E coli (UPEC) isolates from 38 dogs with urinary tract infections were included in phase 3. PROCEDURES: In phase 1, dogs with diarrhea were prospectively enrolled in a randomized study to receive EcN (108 EcN bacteria/mL; < 10 kg received 5 mL/dose, 10 to 25 kg received 10 mL/dose, or > 25 kg received 15 mL/dose) or placebo for 3 days, followed by a 15-day observation phase. In phase 2, healthy dogs received EcN as described in phase 1, with feces analyzed for E coli populations and microbiome composition at days 0, 3, and 7. In phase 3, EcN efficacy was tested by in vitro plate assay against UPEC isolates. RESULTS: Median duration of abnormal stool consistency, time to response, and duration of diarrhea were shorter for dogs that received EcN (5.0, 3.0, and 2.0 days, respectively) versus the placebo (7.0, 5.0, and 4.0 days, respectively) (P = .21, P = .05, and P = .039, respectively). EcN induced shifts in E coli diversity in healthy dogs while having minimal impact on overall microbiome structure. Furthermore, 68% of the canine UPEC isolates were susceptible to EcN in vitro. CLINICAL RELEVANCE: EcN improved the treatment of idiopathic diarrhea, colonized the gastrointestinal tract during the trial, and displayed in vitro competition with UPEC.

Multicenter retrospective evaluation of transmural migration of subcutaneous ureteral bypass devices within the digestive tract in cats.

BACKGROUND: Placement of a subcutaneous ureteral bypass (SUB) device is an effective method to relieve all causes of ureteral obstruction in cats. Complications involving migration within the gastrointestinal tract have been seldomly described. OBJECTIVES: To characterize transmural migration of SUB devices within the digestive tract in cats. ANIMALS: Eleven migrated SUB catheters identified in 8 cats between 2017 and 2021. METHODS: Retrospective review of medical records of cats with a SUB device in which migration into the gastrointestinal tract was identified. RESULTS: The median time from SUB device placement to implant migration was 928 days (201-2298 days). Seven cats had obstruction of the SUB device and a positive urine culture at diagnosis. The migration was identified by ultrasound in 6/11, pre-operative contrast radiography in 2/2, and only at time of surgery in 3 SUB devices. All cats underwent surgical correction. Four nephrostomy and 7 cystotomy catheters migrated. Migration occurred into the duodenum (3/11), jejunum (7/11), and colon (1/11). SUB devices were removed in 7 cats and replaced in 2 cats, with 1 cat diagnosed with 2 migration events. Gastrointestinal resection and anastomosis were performed in 7/8 cats and an enterotomy in 2 cats. Six cats survived to discharge. The median follow-up time after migration diagnosis was 365 days (range, 0-1114 days) and 2 cats are still alive. CONCLUSIONS AND CLINICAL IMPORTANCE: Although a rare complication, migration of SUB device should be considered in cats with SUB device obstruction and a positive urine culture.

Escherichia coli probiotic exhibits in vitro growth-limiting effects on clinical feline uropathogenic E coli isolates.

OBJECTIVE: To characterize uropathogenic Escherichia coli (UPEC) in cases of clinical feline urinary tract infection (UTI) and subclinical bacteriuria and investigate the in vitro effects of E coli strain Nissle 1917 on isolate growth. ANIMALS: 40 cats with positive E coli culture results for urine collected during routine evaluation. PROCEDURES: Characterization of UPEC isolates was performed by PCR-based phylotype analysis and serotyping. Nissle 1917 effects on growth inhibition and competitive overgrowth against UPEC isolates were evaluated in vitro using a plate-based competition assay. RESULTS: Feline phylogroups were similar to previous human and feline UPEC studies, with most of the isolates belonging to phylogroup A (42.5%), B2 (37.5%), and D (15.0%). Fifty-two percent of isolates were found to be resistant to antimicrobials, with 19% of these being multidrug resistant (MDR). Nissle 1917 adversely affected the growth of 82.5% of all isolates and 100% of MDR isolates in vitro. The median zone of inhibition was 3.33 mm (range, 1.67 to 10.67 mm). Thirteen isolates were affected via competitive overgrowth and 20 via growth inhibition. CLINICAL RELEVANCE: UPEC isolates from cats were similar in phylogroup analysis to human and dog isolates. The in vitro effects of Nissle 1917 on UPEC warrant additional studies to determine if similar results can be duplicated in vivo.

Short-term efficacy of epidural pain management in dogs undergoing cystoscopy.

BACKGROUND: The effects of epidural anesthesia in dogs undergoing cystoscopy are unknown. OBJECTIVE: To investigate the effect of epidural analgesia on postcystoscopy pain in dogs. ANIMALS: Twenty-six dogs undergoing routine cystoscopy for lower urinary tract disease. METHODS: Prospective, randomized, blinded observational study. Dogs were assigned either to a treatment group that received epidural anesthesia (preservative free morphine sulfate, 0.09 mg/kg; 1% ropivacaine, 0.2 mg/kg; total volume delivered, 1 mL/4.5 kg of body weight to a maximum of 10 mL; n = 9) or to a nonepidural control group (n = 13). Vital signs were monitored for 24 hours, and sedation and pain scores, behavioral assessments, and presence or absence of complications was evaluated for 5 days postprocedure. RESULTS: All dogs tolerated the epidural without complications. Four dogs were removed from the study because of status unblinding, lack of patient cooperation, or incomplete follow-up. No significant differences were noted in postprocedural pain scores in dogs that received epidural analgesia. Significant differences in postprocedural pain scores were noted in the nonepidural control group. No significant differences were noted in vital signs, behavioral assessments, or the proportion of dogs with a 50% increase in pain scores between the epidural and nonepidural groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Epidural anesthesia was well-tolerated. Dogs not receiving the epidural had poor postprocedural pain control. A consistent benefit for the epidural vs nonepidural group could not be identified. Additional studies are required to better assess the impact and efficacy of epidural anesthesia for cystoscopic procedures.

Effect of a struvite dissolution diet in cats with naturally occurring struvite urolithiasis.

OBJECTIVES: The aim of the study was to determine the efficacy of the low struvite relative supersaturation diet in dissolution of feline struvite cystoliths. METHODS: This was a prospective, open-label, two-center study. Twelve client-owned cats were enrolled based on the radiographic appearance of their uroliths and urinalysis parameters. Cats were fed the test diet exclusively for up to 56 days. Cats were radiographed every other week until radiographic evidence of dissolution occurred or the end of the study period was reached. Cats with radiographically apparent uroliths at the end of the study period underwent cystotomy for stone retrieval and analysis. RESULTS: Nine of the 12 cats completed the study. Eight experienced radiographic dissolution; seven of these had complete dissolution within the first month of treatment. One cat, whose owner declined cystotomy after partial dissolution at day 56, had complete radiographic resolution at 70 days of treatment. Two calcium oxalate urolith cores were removed from a cat that had partial radiographic dissolution. CONCLUSIONS AND RELEVANCE: The test diet was successful in dissolving suspected struvite cystoliths. As this diet is suitable for maintenance feeding of adult cats, it may be a suitable choice for long-term prevention of feline struvite urolithiasis.

Persistent nonregenerative anemia in a 4-year-old cat.

A 4-year-old male neutered domestic shorthair cat was presented to The Ohio State University College of Veterinary Medicine for a 2-month history of severe weight loss, lethargy, anemia, and bilaterally hyperechoic kidneys with loss of corticomedullary distinction as reported by the referring veterinarian. Relevant initial laboratory results included severe non-regenerative normocytic hypochromic anemia, increased blood urea nitrogen, minimally concentrated urine, proteinuria, and an increased urine protein:creatinine ratio. Cytologic evaluation of a bone marrow aspirate revealed a markedly hypocellular marrow with abundant mucinous material. Gelatinous marrow transformation (GMT) was confirmed histologically by the presence of mucinous material in the bone marrow that stained positive for Alcian blue but negative for periodic acid-Schiff. The cat died despite repeated blood transfusions and supportive care. Gelatinous marrow transformation, immune complex-mediated membranoproliferative glomerulonephritis, and gastrointestinal hemorrhage were observed on autopsy and histology. It is likely that the development of GMT was secondary to chronic kidney disease (CKD) and that CKD, GMT, and gastrointestinal hemorrhage contributed to the cat's non-regenerative anemia.

Urological Sequelae to Acute Spinal Cord Injury in Pet Dogs: A Natural Disease Model of Neuropathic Bladder Dysfunction.

The authors review urologic dysfunction, including urine retention, incontinence, and recurrent and resistant urinary tract infection, in dogs as a sequela to acute spinal cord injury. Urologic sequelae to acute spinal cord injury (SCI) pose significant complications in human and canine patients impacting quality of life and long-term cost of treatment. Dogs with intervertebral disc extrusion may serve as a natural disease model of acute SCI for investigating translational interventions, both prophylactic and therapeutic, for urologic dysfunction in human SCI patients.

Urinary Tract Infection.

"Urinary tract infection (UTI) is a common diagnosis in companion animal practice and is responsible for a significant proportion of antimicrobial use in veterinary medicine. The veterinary community has begun to follow the standards of care in human medicine and shift its definition of an UTI based on culture results and toward the presence of lower urinary tract symptoms. An improved understanding of the pathophysiology of UTI, risk factors for clinical disease, and the implementation of more reliable in-house diagnostic testing can lead to improved outcomes for patients and reduce inappropriate treatment. Investigation of antibiotic-sparing therapies holds some promise as well."

Factors associated with survival in dogs with chronic kidney disease.

BACKGROUND: Chronic kidney disease (CKD) is associated with morbidity and mortality in dogs. Plasma fibroblast growth factor-23 (FGF-23) concentration is an independent predictor of CKD progression and survival in cats and people with CKD. OBJECTIVES: To investigate the relationship among FGF-23, parathyroid hormone (PTH), vitamin D metabolites, and other clinical variables with survival time in dogs with CKD. ANIMALS: Twenty-seven azotemic CKD dogs. METHODS: Dogs were recruited prospectively into the study and followed until death or study conclusion. Dogs were International Renal Interest Society (IRIS) staged into stage 2 (n = 9), stage 3 (n = 12), and stage 4 (n = 6) CKD. Survival times were calculated from the date of study inclusion. Univariable Cox regression was used to assess variables associated with survival including body condition score (BCS), muscle condition score, hematocrit, creatinine, CKD stage, serum phosphorus, urine protein:creatinine ratio (UPC), calcium phosphorus product (CaPP), PTH, 25-hydroxyvitamin D, 1,25--dihydroxyvitamin D, and FGF-23 concentrations. RESULTS: Significant hazard ratios (hazard ratio; 95% confidence interval; P value) were as follows: BCS < 4/9 (1.579; 1.003-2.282; P = .05), muscle atrophy (2.334; 1.352-4.030; P = .01), increased creatinine (1.383; 1.16-1.64; .01), hyperphosphatemia (3.20; 1.357-7.548; P = .005), increased UPC (3.191; 1.310-7.773; P = .01), increased CaPP (4.092; 1.771-9.454; P = .003), and increased FGF-23 (2.609; 1.090-6.240; P = .05). Survival times for each IRIS CKD stage were significantly different (P = .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Multiple variables, including FGF-23, were associated with duration of survival in CKD dogs. FGF-23 could be a prognostic marker in dogs with CKD.

Comparison of platelet function and viscoelastic test results between healthy dogs and dogs with naturally occurring chronic kidney disease.

OBJECTIVE To compare platelet function and viscoelastic test results between healthy dogs and dogs with chronic kidney disease (CKD) to assess whether dogs with CKD have platelet dysfunction and altered blood coagulation. ANIMALS 10 healthy control dogs and 11 dogs with naturally occurring CKD. PROCEDURES Blood and urine were collected once from each dog for a CBC, serum biochemical analysis, urinalysis, and determination of the urine protein-to-creatinine ratio, prothrombin time, activated partial thromboplastin time, plasma fibrinogen concentration, and antithrombin activity. Closure time was determined by use of a platelet function analyzer and a collagen-ADP platelet agonist. Thromboelastography (TEG) variables (reaction time, clotting time, α angle, maximum amplitude, and global clot strength [G value]) were determined by use of recalcified nonactivated TEG. Platelet expression of glycoprotein Ib (GPIb; receptor for von Willebrand factor), integrin αIIbß3 (αIIbß3; receptor for fibrinogen), and P-selectin (marker for platelet activation) was assessed by flow cytometry. RESULTS Compared with healthy control dogs, the median closure time was prolonged, the median maximum amplitude and G value were increased, and the median clotting time was decreased for dogs with CKD. Platelet expression of both αIIbß3 and P-selectin was also significantly increased for dogs with CKD, compared with that for control dogs. Platelet expression of GPIb, αIIbß3, and P-selectin was not correlated with closure time or any TEG variable. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs with CKD frequently had evidence of platelet dysfunction and hypercoagulability that were not totally attributable to alterations in platelet surface expression of GPIb, αIIbß3, and P-selectin.

Urinary Incontinence in Juvenile Female Soft-Coated Wheaten Terriers: Hospital Prevalence and Anatomic Urogenital Anomalies.

Urinary incontinence in juvenile female dogs is often associated with urogenital anatomic anomalies. Study objectives include: (1) determine hospital prevalence of urinary incontinence in juvenile female soft-coated wheaten terriers (SCWTs) compared to other affected dogs; (2) characterize anatomic anomalies affecting urinary incontinent juvenile female SCWTs utilizing uroendoscopy; and (3) compare incidence of ectopic ureters, paramesonephric remnants, and short urethras in juvenile female urinary incontinent SCWTs to other juvenile female dogs with urinary incontinence. We hypothesize juvenile SCWTs have an increased prevalence of urinary incontinence and an increased incidence of ectopic ureters, paramesonephric remnants, and short urethras compared to non-SCWTs with urinary incontinence within our hospital population. Medical records of female dogs 6 mo of age and younger with clinical signs of urinary incontinence and video uroendoscopic evaluation presenting to The Ohio State University Veterinary Medical Center from January 2000 to December 2011 were reviewed. Twelve juvenile SCWTs and 107 juvenile non-SCWTs met the inclusion criteria. Juvenile SCWTs were found to have an increased hospital prevalence of urinary incontinence compared to other affected breeds. Observed anomalies in SCWTs include: ectopic ureters, shortened urethras, paramesonephric remnants, and bifid vaginas. This information will help guide veterinarians in recognizing a breed-related disorder of the lower urogenital tract in SCWTs.

Micturition disorders.

Evaluation of dogs and cats with micturition disorders can be challenging. It is important to determine the duration, timing, and frequency of the disorder, as well as assessing for any additional medical problems, such as neurologic or orthopedic disease, that may be affecting micturition. Observation of the patient during voiding can be particularly helpful in determining the type of disorder. Treatment of micturition disorders is varied and outcome depends on an accurate diagnosis. Patient response is also highly variable, even with appropriate therapy, and owners' expectations must be set accordingly.

Suture-free technique for canine ureteral resection-anastomosis using a microvascular anastomotic system: a cadaveric study.

OBJECTIVE: To describe a suture-free technique for canine ureteral resection-anastomosis using a microvascular anastomotic system (MAS) and to compare surgical time and burst pressure of hand-sewn (HS) ureteral end-to-end anastomosis with the MAS technique. STUDY DESIGN: Experimental ex vivo study. ANIMALS: Canine cadavers (n = 8). METHODS: For each cadaver, 1 ureter was randomly assigned to undergo HS anastomosis and the contralateral ureter had MAS anastomosis. The first 3 cadavers (6 ureters) were used to refine the MAS technique. In the other 5 dogs, surgical time and ureteral burst pressure were compared between groups (n = 5 ureters/group). RESULTS: Preliminary procedures showed that selective impaling of the mucosa and submucosa (without muscularis and adventitia) is necessary to allow complete mechanical interlock of the anastomotic rings for the MAS technique. Median anastomotic time was significantly shorter for MAS (7.6 min) than HS (16.6 min; p = .029) and burst pressure higher for MAS (393 cm H2 O) than HS (180 cm H2 O; p = .012). CONCLUSION: This study demonstrated the feasibility of a suture-free technique of canine ureteral resection-anastomosis using a commercially available MAS. The MAS anastomosis was faster and had higher burst strength compared with the HS anastomosis.

Development and pilot of Case Manager: a virtual-patient experience for veterinary students.

There is an increasing demand in veterinary education to engage students, teach and reinforce clinical reasoning, and provide access anytime/anywhere to quality learning opportunities. In addition, accrediting bodies are asking for more concrete documentation of essential clinical-skills outcomes. Unfortunately, during the clinical year in a referral hospital setting, students are at the mercy of chance regarding the types of cases they will encounter and the opportunities they will have to participate. Patient- and case-simulation technology is becoming more popular as a way to achieve these objectives in human and veterinary medical education. Many of the current options available to the veterinary medical education community to develop virtual-patient cases are too time-consuming, cost prohibitive, or difficult for the instructor or learner to use. In response, we developed a learning tool, Case Manager, which is low-cost and user-friendly. Case Manager was designed to meet the demands of veterinary education by providing students with an opportunity to cultivate clinical reasoning skills and allowing for real-time student feedback. We launched a pilot test with 37 senior veterinary medical students as part of their Small Animal Internal Medicine clinical rotation. Students reported that Case Manager increased their engagement with the material, improved diagnostic and problem-solving skills, and broadened their exposure to a variety of cases. In addition, students felt that Case Manager was superior to a more traditional, less interactive case presentation format.

A retrospective study of circadian and seasonal presentations of dogs with congestive heart failure: 119 cases (1997-2009).

OBJECTIVES: To test the hypothesis that there is a daily or seasonal rhythm in the presentation of congestive heart failure (CHF) in dogs. DESIGN: Retrospective case series from 1997 to 2009. SETTING: Small animal veterinary teaching hospital. ANIMALS: One hundred and nineteen dogs with 126 acute presentations of CHF. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Medical records from a veterinary teaching hospital were searched for the occurrence of CHF. The effect of admission time, weekday, month, and season were analyzed separately using chi-square tests. CHF presentations were largely confined to Monday and Tuesday (57%) and between 9 am and 11:59 am (55%). CHF was more common during September, October, and November (37%). CONCLUSIONS: Information from this study may assist veterinarians in educating clients about the timing of clinical signs, and enable veterinary hospitals to anticipate CHF cases during certain times of the day and year.

Evaluation of effects of low-dose aspirin administration on urinary thromboxane metabolites in healthy dogs.

OBJECTIVE: To evaluate markers of in vivo platelet function (urinary 11-dehydro-thromboxane B(2) [11-dehydroTXB(2)] and 2,3-dinorTXB(2)) and assess their response to administration of 2 commonly used dosages of aspirin in healthy dogs. ANIMALS: 20 healthy dogs. PROCEDURES: Urine was collected prior to aspirin administration and on the morning following the last evening administration. Twenty dogs received aspirin (1 mg/kg, PO, q 24 h) for 7 consecutive doses. After a washout period of 5 months, 10 dogs received a single dose of aspirin (10 mg/kg, PO). Concentrations of urinary thromboxane metabolites 11-dehydroTXB(2) and 2,3-dinorTXB(2) were measured via ELISA, and values were normalized to urine creatinine concentration. RESULTS: Median baseline 11-dehydroTXB(2) concentrations were 0.38 ng/mg of creatinine (range, 0.15 to 1.13 ng/mg). Mean ± SD baseline 2 at a 3-dinorTXB(2) concentrations were 6.75 ± 2.77 ng/mg of creatinine. Administration of aspirin at a dosage of 1 mg/kg, PO, every 24 hours for 7 days did not significantly decrease urinary 11-dehydroTXB(2) concentration, but administration of the single aspirin dose of 10 mg/kg did significantly decrease 11-dehydroTXB(2) concentration by a median of 45.5% (range, 28.2% to 671%). Administration of the 1 mg/kg aspirin dosage significantly decreased urinary 2,3-dinorTXB(2) concentration by a mean ± SD of 33.0 ± 23.7%. Administration of the single aspirin dose of 10 mg/kg also significantly decreased 2,3-dinorTXB(2) concentration by a mean ± SD of 46.7 ± 12.6%. CONCLUSIONS AND CLINICAL RELEVANCE: Aspirin administration (1 mg/kg/d) may be insufficient for reliable platelet inhibition in healthy dogs.