Clinical diagnosis of pyelonephritis often presumptive

Clinical diagnosis of pyelonephritis often presumptive

Apr 01, 2002

Signalment: Canine, Papillon, 14-year-old, male castrated, 3.12 lbs.

Table 1
Clinical history: The dog presents for weight loss, acting strangely and urinary incontinence. Details of the past medical history indicate two years ago a cystotomy was performed for uroliths. At that time, the CBC was normal and serum chemistry profile showed an increase in BUN (54 mg/dl) and ALT (78 U/L) and a decrease in albumin (1.1 g/dl).

Note: There was no ascites present at the time; therefore, the serum albumin value must have been incorrect. The urinalysis showed specific gravity 1.020 and 100+ protein. The urolith analysis showed the mineral content to calcium oxalate.

Seven months later another blood evaluation was done, and it showed the CBC to be normal and serum chemistry profile showed an increase in BUN (44 mg/dl) and amylase (1,260 U/L). The serum albumin value was 3.2 g/dl.

Physical examination: The findings include rectal temperature 101.9° F, heart rate 135/min, respiratory rate 20/min, pink mucous membranes, normal capillary refill time, and normal heart and lung sounds. Abnormal physical findings are severe dental disease, slight enlarged kidneys on palpation, painful coxofemoral joint or dorsal spine and a lot of urine sediment material attached to the hair at the tip of the prepuce.

Laboratory results: A complete blood count, serum chemistry profile and urinalysis were performed and are in Table 1.

Radiographic review

Photo 1
Survey thoracic and abdominal radiographs were done. The thoracic radiographs are normal. The abdominal radiographs show an overdistended urinary bladder and multiple urethral calculi located behind the os penis.

Follow-up: At this point, the urethral calculi needed to be dislodged and good urine flow re-established. I suspect these urethral calculi are of the calcium oxalate type, as before. I cannot rule out the possibility that other calcium oxalate calculi are present in the urinary bladder, ureters and kidneys. Ultrasonography of the upper and lower urinary tract would be recommended.

Immediately, an appropriate sized urinary catheter was passed along with simultaneous hydropropulsion of the urethral calculi toward the urinary bladder (of course, some words of frustration while performing this procedure). Thirteen days after dislodgement of the urethral calculi, the BUN was 79 mg/dl, serum creatinine was 1.1 mg/dl, serum phosphorus was 4.3, and serum albumin was 1.9 g/dl. At this time, a urinary catheter is placed in the distal urethra and contrast material is infused into the lumen of the urethra via the urinary catheter until the urinary bladder is palpated as being distended.

My comments: The contrast material flowed easily up the urethra into the lumen of the urinary bladder and then the contrast flow was noted in the left ureter and on into the pelvis of the left kidney. The left ureter and renal pelvis are slightly dilated, and the renal pelvis shows blunting of the diverticula. No contrast material was noted in the right ureter and kidney.

Case management In this case, chronic renal disease is present. Because of the ongoing weight loss, the decreased serum albumin should be investigated. Is there significant proteinuria present?

Photo 2
In this case, I would do a urine protein-to-creatinine ratio. Urine protein-to-creatinine ratio of 3 or greater may be treated with daily administration of lisinopril at 0.25-0.5 mg/kg orally once daily.

To manage the existing cystic calculi, abdominal surgery was subsequently performed. At surgery, a splenic mass was identified, left kidney was slightly enlarged along with the left ureter, and multiple small cystic calculi were found. The spleen was removed and biopsies were obtained from the polar regions of the left kidney. The histopathologic report for the spleen indicated a grade 3 hemangiosarcoma and renal biopsies showed evidence of severe chronic interstitial nephritis.

Canine pyelonephritis Natural host defenses against ascending urinary tract infection include mucosal defense barriers, ureteral peristalsis, ureterovesical flap valves and an extensive renal blood supply. Pyelonephritis usually occurs by ascension of bacteria causing lower urinary tract infection. Hematogenous seeding of the kidneys does not usually cause pyelonephritis.

In addition, an upper urinary tract infection is frequently accompanied by lower urinary tract infection.

Ascending urinary tract infections probably occurs much more commonly than is recognized clinically - because many older dogs with pyelonephritis are asymptomatic or have signs limited to lower urinary tract infection.

Signs of pyelonephritis may be none or include polyuria/polydipsia, abdominal or lumbar pain, and/or signs associated with lower urinary tract infection - dysuria, pollakiuria, stranguria, hematuria and malodorous or discolored urine. The physical examination may show no abnormalities or pain on palpation of kidneys and a fever.

The ascending urinary tract infection may be caused by aerobic bacteria - most common bacterial isolates are Escherichia coli and Staphylococcus species and less common bacterial isolates may include Proteus, Streptococcus, Klebsiella, Enterobacter and Pseudomonas species, which frequently infect the lower urinary tract and may ascend into the upper urinary tract. Ectopic ureters, vesicoureteral reflux, congenital renal dysplasia and lower urinary tract infection increases the risk of an ascending urinary tract infection. Medical conditions that often predispose the dog to a urinary tract infection are diabetes mellitus, hyperadrenocorticism, exogenous steroid administration, renal failure, urethral catheterization, urine retention, uroliths and urinary tract neoplasia.