A female miniature schnauzer who was eight years old and spayed was brought in for pollakiuria and gross hematuria. A bacterial urinary tract infection and infection-induced struvite urolithiasis were diagnosed. Following a brief discussion of struvite stones and their medical management, the course of treatment is described.
Summary — Use a noncalculolytic diet and antibiotic therapy to make struvite calculations caused by vesicular infections. An 8-year-old sterilized Schnauzer dog was examined due to pollakiuria and macroscopically abnormal bleeding. An infection-related diagnosis of struvite urolithiasis with concurrent bacterial urinary tract infection was made. Following a brief discussion on the struvite calculations and their medical oversight, the treatment is described.
The referring veterinarian received a presentation from an 8-year-old, 7-kg female miniature schnauzer for pollakiuria and hematuria. The dog had a history of seasonal allergies-related pruritus. There were no reported modifications to eating or drinking routines, and there was no prior history of nausea or diarrhea. An industrial dry formula diet (Purina Lamb and Rice; Purina, St. Louis, Missouri, USA), the dog’s shots were up to date, and no medication was being given to it.
Physical examination revealed a thin hair coat, good overall health, and moderate periodontal disease. Urinalysis, urine culture and sensitivity testing, and abdominal radiographs were all performed as part of the evaluation.
Free-flow urine collection and storage in a refrigerator for several hours before testing The urine was cloudy and had a specific gravity of 1 upon initial inspection. 050. A urine dipstick test revealed that the urine had a pH of 8, 3 g/L of protein, and significant amounts of red blood cells. Numerous red and white blood cells, a small amount of coccoid bacteria, struvite crystals, and clumps of epithelial cells could all be seen under a microscope. Multiple round to ovoid radiodense uroliths, the largest measuring 1 cm in diameter, were visible on a single lateral abdominal radiograph () No other radiographic abnormalities were identified. The culture of urine obtained through cystocentesis revealed a significant growth of Staphylococcus intermedius, which is susceptible to a variety of antibiotics, including cephalexin.
These results supported the diagnosis of concurrent urinary tract infection and infection-induced struvite urolithiasis. Due to financial limitations, cephalexin (Novo-Lexin; Novopharm, Toronto, Ontario) 250 mg, PO, q12h for 30 d was started as medical therapy rather than surgical treatment. The dog was switched to a commercial canned food called Medi-Cal Weight/Control Mature Formula from Veterinary Medical Diets in Guelph, Ontario, which is low in fat, mildly protein-restricted, and moderately acidifying. The amount fed was based on the manufacturer’s feeding guidelines. Abdominal radiographs, urine cultures, sensitivity tests, and follow-up appointments were scheduled every 30 days.
The dog had a period of hematuria, dysuria, lethargy, and dribbling urine after being clinically normal for about 14 days. These signs resolved within 24 h. The dog was rechecked at around 40 days, at which point its clinical condition appeared to be normal and its body weight remained constant at 7 kg. Less stone was seen on abdominal radiographs, and the stones that were seen were less radiodense (), with the largest stones measuring 0). 5 cm in diameter. Urine obtained by cystocentesis revealed a urine pH of 6. 5; although generally recommended, specific gravity was not evaluated. A urine dipstick test revealed minimal red blood cell counts and trace protein. A few red and white blood cells, a modest amount of amorphous crystals, sporadic struvite crystals, and a modest amount of coccoid bacteria were all found upon microscopic examination. Since urine culture produced no growth, it was assumed that the stain was contaminated with bacteria. It was advised to continue using an antibiotic until the next scheduled checkup (30 days). Dietary recommendations remained unchanged.
Due to owner restrictions, the subsequent recheck was carried out 45 days later. The owner had stopped his or her antibiotic regimen 15 days before the evaluation. Clinically, the dog appeared to be in good health, and his weight remained constant. Urine obtained by free-flow was evaluated microscopically only. Occasional red and white blood cells and bacteria were observed. No crystals were visualized. Abdominal radiographs revealed no anomalies, and there was no indication of urinary calculi. The owner was advised to culture the urine, keep up the current diet, and keep an eye out for reoccurring UTIs.
The most frequent cause of struvite urolithiasis in dogs is a urinary tract infection with urease-producing bacteria (1,2). The bacteria (often Staphylococcus spp. , Proteus spp. ,) convert the urea in urine to ammonia and carbon dioxide The ammonia is converted to ammonium, which raises the pH of the urine and makes it possible for magnesium ammonium phosphate crystals (struvite) to form. Phosphorus becomes more available to contribute to the formation of struvite crystals and struvite becomes less soluble as the pH of the urine rises. Supersaturation of the urine happens as the concentrations of phosphate, magnesium, and ammonium in the urine increase, which helps crystal and urolith formation (1,2).
In a recent analysis of 16 000 submissions to the Canadian Veterinary Urolith Center, it was discovered that struvite urolithiasis was equally prevalent in female miniature schnauzers as calcium oxalate urolithiasis (3). The diagnosis of infection-induced struvite urolithiasis was most likely made in the case at hand because of the alkaline urine pH, the presence of struvite crystals, the infection with Staphylococcus intermedius, and the size of the radiographically observed uroliths (1 cm diameter) (4). Since calcium oxalate uroliths typically form in more acidic urine and are smaller in size, they were less common. The presence of struvite crystals was deemed significant in this case despite the fact that they can form in vitro if urine is allowed to sit or is chilled before analysis (5) due to the high urine pH and signs of a urinary tract infection.
Surgery to remove the uroliths is one method of treating infection-related or sterile struvite urolithiasis; alternatively, medication is used. A calculolytic diet, such as Hill’s Prescription Diet s/d from Hill’s Pet Nutrition in Topeka, Kansas, USA, is typically used in the medical treatment of infection-induced struvite for 4 weeks after the apparent urolith dissolution (1,2). A typical calculolytic diet reduces the substrate for urease-producing bacteria (low protein), acidifies the urine (increasing struvite solubility), and lowers magnesium and phosphorus levels. Increasing sodium chloride intake and reducing protein intake both promote diuresis. Low serum urea nitrogen levels result from consuming this much protein-restricted diets, and low renal medulla urea concentrations follow. This results in the production of dilute urine. Additionally, lowering the concentration of urine also lowers the concentration of substances that cause calculi. Studies in both experimental and clinical settings have shown the effectiveness of these diets. A calculolytic diet (Hill’s Prescription Diet s/d) was demonstrated in a study of female beagles to be efficient in removing infection-induced struvite stones in an average of 14 days. 4 wk (range 2 to 5 mo) (6). In an average of three days, the same diet completely eliminated sterile struvite stones. 3 wk (range 2 to 4 wk) (6).
Calculolytic diets tend to be high in fat because they are low in protein (7). Such diets may be contraindicated in dog breeds predisposed to pancreatitis or other fat-intolerant conditions (1,2,7,8). Hypertensive conditions such as those linked to renal or adrenal disease as well as heart disease are other conditions that should not be used in conjunction with a calculolytic diet that is high in sodium chloride. Increased sodium levels can exacerbate abnormal blood pressure or cardiogenic pulmonary edema and cause volume expansion in patients with hypertension or cardiac disease. Finally, because the diets severely restrict protein, it is advised that they only be used for a brief period of time and in conjunction with close monitoring of the body condition and serum biochemical profile in both young and old animals (1,2,7,8). Due to the tendency of miniature schnauzers to develop pancreatitis and hyperlipidemia in this situation, a high-fat diet was not advised (8, 9).
The spontaneous dissolution of struvite nephroliths has been documented in numerous reports in the veterinary literature (10,11). Dissolution happened in one instance two weeks after ureteral patency was established (10) In a different instance, sodium chloride and a urinary acidifier were administered, and dissolution happened within 4 weeks (11). Both times, antibiotics were used, but neither time was diet therapy mentioned. Dissolution happened in 2 out of 6 dogs fed a maintenance diet while receiving concurrent antibiotic therapy in a study of dogs with struvite urolithiasis (1). Finally, in dogs on a maintenance diet, sterile struvite uroliths disintegrated over a mean of 14 weeks (range, 2 to 5 months) (6). These cases show that struvite urolith dissolution can happen quickly even without a calculolytic diet and may even happen when a maintenance-type diet is used.
For one month after the stones appear to have dissolved on radiographs, appropriate antibiotic therapy is continued in cases of infection-induced struvite urolithiasis for a number of reasons. The bacteria under the surface of the urolith may be protected from antimicrobial medications and may be released during stone dissolution, even though the surface of the stone and the urine may be sterile during dissolution (1,2). Even when a urine culture appears sterile, bacteria may occasionally be adherent to the bladder epithelium (12). Additionally, antibiotics that eliminate urea-producing bacteria reduce urine pH without the use of additional acidifying agents by stopping the production of ammonium. Last but not least, small uroliths (3 mm) may not be seen on routine radiographs or ultrasounds and may contain bacteria (1,2). In this instance, the owner stopped her own antibiotic therapy despite advice to do otherwise.
Since no stones were found at the 45-day (6 week) mark in the case described here, the dog may have passed one or more of the stones. 5 wk) recheck. The number and diameter of the remaining stones were reduced on radiographs at 30 days, which may have been due to ongoing urolith dissolution.
Antibiotic use may have caused dissolution by lowering urine pH and increasing struvite solubility. The decreased urea concentration in the urine brought on by feeding a mildly protein-restricted diet is another potential factor that may have aided in the dissolution of the stones. This case has limitations due to incomplete urinalyses performed during medical treatment and a lack of follow-up. Monitoring urine pH, specific gravity, and microscopic examination of urine sediment are advised throughout the course of treatment. To ensure that any urinary tract infection has been eradicated, urine should be cultured at the conclusion of the treatment period. In this instance, the owner decided against pursuing additional diagnostic procedures.
By describing this case, we provide a different course of action for dogs who might be predisposed to conditions like fat intolerance, cardiac disease, or hypertension, or in cases where surgical urolith removal is not an option. To ensure success if medical dissolution of stones is attempted, strict adherence to the follow-up guidelines should be established. CVJ.
My dog has struvite bladder stones. What does that mean?
Urinary bladder stones, also known as uroliths or cystic calculi, are mineral-based rocks that develop more frequently than kidney stones in dogs. Magnesium Ammonium Phosphate Hexahydrate is the main component of one of the more prevalent uroliths in dogs. This type of bladder stone is also known as a struvite bladder stone.
Silica or silicate bladder stones
Little is known about the development of silicate stones.7 Veterinarians believe they have to do with the ingestion of silica and silicates.
Are bladder stones in dogs contagious for humans or other pets?
Several tests may be needed to determine whether bladder stones are present. For instance, a urinalysis can cost between $65 and $175; x-rays can cost up to $50; ultrasounds can cost up to $250; and bloodwork can cost at least $100. Given that these are merely diagnostic procedures, the overall cost of a bladder stone case may be quite high.
Depending on the veterinarian or specialist and where you live, surgery can cost up to $1700 and start at around $700. Some offices charge separately for the anesthesia/sedation.
Follow-up appointments, medication, and possibly a prescription diet that your dog may need to use for the rest of his or her life are post-surgery costs to take into account.
FAQ
How long does it take to dissolve bladder stones in dogs?
Some dogs’ struvite stones may dissolve in two weeks, while others may need up to 12 weeks. Throughout this entire time, your dog will require antibiotics.
What can I give my dog to dissolve bladder stones?
It may seem obvious, but make sure your dog drinks plenty of water. However, don’t undervalue the ability of water to help, regardless of the type of stones your dog has. It’s a crucial component of bladder stone management that veterinarians frequently ignore. Most dogs develop bladder stones when they are on kibble.
How do you treat bladder stones in dogs naturally?
To prevent substances from accumulating in the urinary tract, a diet that includes some vegetables and raw or cooked food, such as raw bones, may be advised. High potency probiotics are known to reduce the formation of mineral stones, so adding them to your dog’s diet will be beneficial.
Do bladder stones in dogs need to be removed?
If bladder stones are causing obstruction, swelling, lower urinary tract symptoms (dysuria, pollakiuria, hematuria), or recurring infections, they should be removed. A management protocol should be put in place after the stones are removed to try to prevent recurrence.