Nephroliths in Dogs and Cats PDF

2/26/24 Nephroliths and ureteroliths in dogs and cats Larry G. Adams, DVM, Ph.D., DACVIM (SAIM) Professor, Small Animal Internal Medicine Founding Member & Urology Advisor, ACVNU 1 Nephroliths and ureteroliths 2 1 2/26/24 Composition of nephroliths/ureteroliths The vast majority( >95%) of upper trac...

2/26/24 Nephroliths and ureteroliths in dogs and cats Larry G. Adams, DVM, Ph.D., DACVIM (SAIM) Professor, Small Animal Internal Medicine Founding Member & Urology Advisor, ACVNU 1 Nephroliths and ureteroliths 2 1 2/26/24 Composition of nephroliths/ureteroliths The vast majority( >95%) of upper tract uroliths in cats are calcium oxalate. Most nephroliths in dogs are calcium oxalate. Infection induced struvite nephroliths form in dogs with pyelonephritis with urease+ bacteria (Staph & Proteus) Less common stone types (~ radiolucent) – Urates in specific breeds Dalmatian, Bulldogs, PSS related breeds (Yorkie, etc.) – Cystine in Newfoundlands – Dried solidified blood uroliths in cats 1-2% lower tract uroliths, 10% of cats w/ DSB uroliths have nephroliths 3 Urate uroliths 2nd to PSS Nephroliths Ureteroliths 4 2 2/26/24 Dried Solidified Blood Uroliths Multiple small DSB uroliths in ureter Multiple feline DSB uroliths from bladder 5 Dried-solidified blood uroliths Large DSB Nephroliths from a dog (< 1 % mineral, 99% matrix) Ca Ox uroliths from a dog ( 99% mineral) 6 3 2/26/24 Incidental Nephroliths (dog/cat) Incidental nephroliths do NOT require treatment Nephroliths in R kidney Not complicated by UTI Not causing obstruction – Location relative to UPJ? Not growing No clinical signs Serial radiographs, ultrasound, urinalysis, and urine culture 7 Obstructive ureteroliths (dog) Nephrolith Ureteroliths Linear arrangement of uroliths in retroperitoneal space → ureteroliths? 8 4 2/26/24 Diagnosis andureteroliths ureteroliths Diagnosisofofnephroliths nephroliths and Ureteroliths Abdominalradiography radiography Abdominal Ultrasonography Ultrasonography –– Renal dilation Renalpelvic pelvic dilation – Ureterolith visualized in – Ureterolith visualized in 77% of cats by US 77% of cats by US Radiographs + US = 90% Radiographs + US = 90% Excretory urography Excretory urography Antegrade pyelography Antegrade pyelography – During intervention – During CT scan intervention Kyles et al. J Am Vet Med Assoc 2005;226:932–936 CT scan 9 Kyles et al. J Am Vet Med Assoc 2005;226:932–936 Dogs: Indications for Treatment of Nephroliths Obstruction to urine flow (UPJ or ureter) Nephroliths complicated by UTI (relapse) Nonfunctional contralateral kidney with small nephrolith at ureteropelvic junction (UPJ) Ø Could the nephrolith pass into ureter? Symptomatic patients 10 5 2/26/24 Treatment Options for Nephroliths in Dogs Medical dissolution protocols – Ureteral stent placement required for concurrent ureteral obstruction Surgery – Nephrotomy, nephrectomy, pyelolithotomy – Percutaneous nephrolithotomy (PCNL, SENL) Ureterorenoscopy Extracorporeal shock-wave lithotripsy 11 Open surgical options - dogs Nephrotomy Pyelolithotomy 12 6 2/26/24 Dodie – 7 Y F/S Dalmatian R Urate nephrolith Recurrent UTI Poor owner compliance with dissolution protocol Unilateral nephrotomy 13 Treatment Options for Nephroliths in Dogs Medical dissolution protocols – Ureteral stent placement required for concurrent ureteral obstruction Surgery – Nephrotomy, nephrectomy, pyelolithotomy – Percutaneous nephrolithotomy (PCNL, SENL) AMC in NY (Berent and Weisse) Ureterorenoscopy Extracorporeal shock-wave lithotripsy 14 7 2/26/24 Treatment Options for Ureteroliths Medical expulsive therapy – ⍺-adrenergic antagonist (tamsulosin or prazosin) Extracorporeal shock-wave lithotripsy (dogs) Surgery or minimally invasive surgery – Open ureterotomy (surgeon dependent) – Ureteral stents (dogs) – Subcutaneous ureteral bypass (cats) 15 Treatment Options for Nephroliths in Dogs Medical dissolution protocols – when? – Ureteral stent placement required for concurrent ureteral obstruction Surgery – Nephrotomy, nephrectomy, pyelolithotomy – Percutaneous nephrolithotomy (PCNL, SENL) Ureterorenoscopy Extracorporeal shock-wave lithotripsy 16 8 2/26/24 Penny Signalment: 5 yr. F/S Shih tzu History: Vomiting, anorexia, no urinary signs Physical Exam: Fever (104.1oF), painful on abdominal palpation over kidneys 17 Penny – Abdominal rads Ureterolith 18 9 2/26/24 Penny CBC: Neutrophilia with left shift, 2+ toxic neutrophils, thrombocytopenia (47K) Serum biochemistry: Hypochloremic metabolic alkalosis, hyperglobulinemia Urinalysis: pH 8.0, > 50 WBCs/hpf, 4+ cocci Urine culture: > 105 Staph pseudintermedius cfu/ml 19 Penny Problem List 1. R obstructive ureterolith 2. Staph UTI – bilateral pyelonephritis 3. Inflammatory leukogram 4. Thrombocytopenia Referred to surgeon for right nephrectomy Referred to PUVTH 20 10 2/26/24 Penny – ultrasound 21 Penny – ultrasound 22 11 2/26/24 Predicting urolith composition Signalment? pH? Radiographic density? Urine culture? 23 Urolith composition? Signalment: 5 yr. F/S Shih tzu Urine pH: 8.0 Radiographic density: Moderately radiopaque Urine culture: Staph pseudintermedius 24 12 2/26/24 Penny – Abdominal rads 25 Ureteral stenting for pyonephrosis Obstructive struvite ureteroliths Stent + medical dissolution of struvite ureteroliths 10/13 dogs were thrombocytopenic J Am Vet Med Assoc 2015;246:216–225 26 13 2/26/24 Standard care for dogs and cats with struvite bladder uroliths Clinical Situation/Recommendation Struvite uroliths should be medically dissolved unless medication cannot be administered or tolerated, the urolith cannot be adequately bathed in medicated urine (e.g. nephrolith with poor kidney function, very large solitary bladder urolith, urinary obstruction), or uncontrollable infection. Rationale Vote Medical dissolution for both 6/6 sterile and infection induced agree struvite is highly effective therapy avoiding the risks and complications of anesthesia and surgery. In many cases it is less expensive than surgery and sterile struvite uroliths usually dissolve in less than 4 weeks in both dogs and cats. Antibiotic therapy should be for entire duration of urolith dissolution. 27 Diets Marketed for Struvite dissolution Royal Canin Veterinary Diet – – – – – Canine/Feline Urinary SO Canine Urinary SO Small Dog Feline Urinary SO Olfactory Attraction Canine/Feline Urinary SO Modified Calorie Multifunction diets Hill’s Prescription Diet – – – – Canine/feline s/d Canine/feline c/d Multicare Feline c/d Multicare Stress Feline Metabolic+Urinary Purina Veterinary Diets.. – Feline UR Urinary St/Ox – Canine UR Urinary Ox/St 28 14 2/26/24 Ureteral Stents 29 Ureteral stents Placed retrograde using guidewire via cystoscopy or placed during surgery Dogs – 3.7 to 5 Fr stents Cats – 2.2 Fr feline stent 30 15 2/26/24 Penny – cystoscopy 31 Penny – stent placement 32 16 2/26/24 Penny – stent placement 33 Penny – stent placement 34 17 2/26/24 Penny – stent placement 35 Penny – ureteral stent 36 18 2/26/24 Penny – 6 week recheck 37 Ureteral stent removal 38 19 2/26/24 Penny – case outcome Ureterolith completely dissolved in 6 weeks – Royal Canin SO – Clavamox Continued antibiotic therapy until stent removal Prevention plans – Monitor urine cultures and treat any UTIs 39 Preventing Struvite Uroliths Clinical Situation/Recommendation Sterile struvite uroliths are best prevented by therapeutic maintenance foods with low magnesium and phosphorus that acidify the urine Infection-induced struvite uroliths are best prevented by controlling urinary tract infection. Therapeutic diets are not recommended to prevent recurrence of infection-induced struvite uroliths. Rationale Vote Struvite solubility is greatly increased by reducing urolith precursors and acidifying the urine (i.e. below 6.5) 6/6 agree Early eradication of recurrent bacterial infections prevents recurrence. Therefore, diagnose and eliminate structural and functional risk factors for UTI, and monitor urine for recurrent infection. 6/6 agree 40 20 2/26/24 Ureteral stent complications Stent migration UTI Pollakiuria (cats > dogs) Tissue growth in/around stent (cats > dogs) Encrustation with urolith mineral deposits? – Consider stent exchange for “long-term” stents 41 Lithotripsy Crushing or fragmenting uroliths Extracorporeal shock wave lithotripsy (dogs) – Nephroliths and ureteroliths Laser lithotripsy – Holmium: YAG laser Laser fiber passed through scope to directly urolith – Cystoliths and urethroliths – (Ureteroscopy and ureterorenoscopy in humans) 42 21 2/26/24 SWL Fragmentation of Uroliths 43 Extracorporeal Shock Wave Lithotripsy 44 22 2/26/24 45 SWL - Coupling Dornier HM3 Storz SLZT 46 23 2/26/24 220 dogs treated with SWL Most dogs had bilateral nephroliths 57 dogs with concurrent ureteroliths 51 dogs with urocystoliths – 7 male dogs too small for cystoscopy/laser lithotripsy Body weight: 1.5 to 30 kg (mean = 6.5 kg) Age: 4 to 16 years of age (mean = 9.8 yrs) 47 Follow-Up Evaluation Abdominal radiographs Ultrasound Defining success: – Stone-free – CIRF = clinically insignificant renal fragments – Recurrent UTI – resolve UTI post SWL – Urolith recurrence – fragments may facilitate recurrence 48 24 2/26/24 Results of SWL ~85% successful for nephroliths/ureteroliths – 30% with nephroliths received > 1 Treatment – Initially (1992-2005) ~50% of dogs with ureteroliths required > 1 Treatment with 76% success rate Ureteroliths treated using much higher SWL dose since 2005 – improved results – Decreased to 20-33% requiring second treatment – Ureteral stent placement before SWL if possible 49 Ureteroliths Nephrolith 50 25 2/26/24 Post SWL Post SWL Post VUH 51 Complications of SWL Perirenal hematoma (n=1) Ureteroliths (10%) – Most are transient ureteral colic rare (n=1) – “Lead fragment” requires 2nd SWL treatment Perirenal hematoma 52 26 2/26/24 Lead fragment Before SWL After 1st SWL 53 Post 2nd SWL 54 27 2/26/24 Complications of SWL Ureteroliths – transient during passage (10%) – Ureteral obstruction (~1%) Transient AKI with dry lithotripter (22%) – Creatinine returned to baseline in 48 hrs Perirenal hematoma (n=1) Pancreatitis (~2%) Contrast nephropathy/AKI (n=1) 2 SWL related deaths (