Pet of the month: Ellie
Meet our December Pet of the Month, Ellie! Ellie is a 7-year-old female spayed Cavalier King Charles Mix who presented on emergency to Dr. Osborn for what looked like straining to defecate and restlessness at home. During her physical examination, Dr. Osborn palpated a very large and painful bladder. Abdominal radiographs were performed and showed a large distended bladder with multiple urinary calculi, or stones, in both the bladder and the urethra. Based on these results, Ellie was diagnosed with a urinary obstruction secondary to stone formation.
A urinary obstruction such as Ellie’s is a serious emergency. When our pets are unable to urinate, this causes a decrease in the rate at which the kidneys filter blood. If a urinary obstruction is suspected, it is very important to check baseline bloodwork to ensure that the potassium levels have not increased, as increased potassium can lead to life-threatening cardiac arrhythmias. In addition, we can sometimes see increases in markers of kidney function called Blood Urea Nitrogen and Creatinine. Luckily for Ellie, her kidney values and potassium level were within the normal ranges. A urine sample was submitted for urinalysis and culture.
Ellie was admitted to the hospital and the obstruction was relieved by passing a urinary catheter and pushing the urethral stone back into the bladder. However, Dr. Osborn was concerned that Ellie was likely to have a repeat obstruction, and so she was referred to the Hickory Surgery Service for surgical removal of the stones via a cystotomy, i.e. an incision into the bladder wall. Ellie underwent surgery with Dr. Dobbins, and there were too-numerous-to-count urinary calculi within her bladder. The calculi were submitted for analysis and the results revealed that these were struvite stones. Ellie also had a urinary tract infection with both an Enterococcus species and a Methicillin-Resistant Staph Species. She started treatment with broad-spectrum antibiotics.
Urinary calculi can form for several reasons depending on the type of stone found. Ellie had struvite stones in her urine. In dogs, struvite stones are caused by urease-producing bacteria and thrive in an alkaline environment. Struvite stones can be dissolved by placing affected patients on antibiotics and feeding a special urinary diet such as Hill’s C/D or Royal Canin Urinary SO to make the urine more acidic. However, in cases of urinary tract obstruction, surgery is required to remove the stones because medical dissolution can take many weeks to months. Ellie’s urine was very alkaline with a pH of 8.5, so a change to a prescription diet will
help to make her urine more acidic and less amenable to stone formation in the future. It is generally recommended to recheck the urinalysis and culture once during therapy to ensure the antibiotics are effective, then again at the end of therapy. If the culture results are negative, intermittent urine testing should then be enacted every 2-3 months for the first year.
The best way to prevent struvite stone formation is to have your pet evaluated as soon as lower urinary tract signs such as straining to urinate or blood in urine arise. However, some pets do not show clinical signs of urinary tract infections! For this reason, we recommend considering a urinalysis as part of the yearly physical exam work-up, even for our healthy patients. Prescription and wet food diets can help to prevent stone formation, but diet changes should be discussed with a veterinarian. We are glad to report that Ellie has recovered from surgery, has had her sutures removed, and continues to do well at home!