An 8-year-old MN Yorkshire Terrier dog was presented for the evaluation of lethargy, and chronic polyuria/polydipsia. The dog had been worked up two years previously for a possible portosystemic shunt (via ultrasound) due to elevated serum bile acids. The dog has been receiving a number of supplements as hepato-protectants. Physical exam was unremarkable. Blood chemistry revealed hypoalbuminemia. Urinalysis showed a clear, yellow appearance with a pH within the normal reference range and a decreased specific gravity (1.014).
An 8-year-old MN Yorkshire Terrier dog was presented for the evaluation of lethargy, and chronic polyuria/polydipsia. The dog had been worked up two years previously for a possible portosystemic shunt (via ultrasound) due to elevated serum bile acids. The dog has been receiving a number of supplements as hepato-protectants. Physical exam was unremarkable. Blood chemistry revealed hypoalbuminemia. Urinalysis showed a clear, yellow appearance with a pH within the normal reference range and a decreased specific gravity (1.014). Hematuria (3+) was also present and RBCs (30-35) were present on the sediment. An arterial blood pressure was attempted without any success due to the patient’s stress. A few days later a urinalysis and urine culture were submitted to an external laboratory. The second urinalysis was negative for hematuria and the culture was negative. Radiographs revealed two large stones in the bladder and a smaller stone in the penile urethra just rostral to the os penis. Urinary catheterization was performed in an effort to retropulse the urethral calculus back into the bladder. Radiographs were performed following the catheterization and confirmed that there was no longer a urethral stone.
Case Study
Possible portosystemic shunt (PSS) in an 8 year old MN Yorkshire Terrier dog
DX
Sonographic Differential Diagnosis
Microhepatica with concurrent portosystemic shunt. Renomegaly consistent with portosystemic shunt. Nephroliths consistent with portosystemic shunt. Urolith consistent with portosystemic shunt. Blue vertical vessel at portal hilus connecting the splenic vein with the vena cava: Splenocaval shunt.
Image Interpretation
The liver was homogenous and increased in echogenicity. The size of the liver was small and there was decreased portal vasculature. There was no evidence of any masses or nodules within the liver. The contours of the liver were normal. The portal vein was smaller than the caudal vena cava. The portal vein measured 0.57cm and the caudal vena cava measured 0.69cm. There was increased velocity in the caudal vena cava and a portosystemic shunt was identified and clearly seen measuring 0.63cm in diameter and was cranial to the right kidney. The increased velocity in the vena cava was present exactly at the entry of the shunt and was more normal distal to the shunt. The left kidney measured 5.11cm and the right kidney measured 5.16 cm, both were slightly enlarged for a dog of this size. Renal cortical echogenicity was normal but there was mild loss of corticomedullary distinction. Many nephroliths were noted in both kidneys. The urinary bladder was normal in appearance and there was no evidence of any masses in the bladder. Stipulated calculi were noted in the bladder.
Outcome
A day after the ultrasound, the patient re-presented to the hospital for stranguria and one episode of vomiting. The dog was anxious, however no abnormalities were noted on the physical exam. The surgeon could not find the shunt even though it was clearly present on ultrasound. Cystotomy and stone removal was performed. Lack of macroscopic detection of extrahepatic shunts will happen occasionally depending on the surgeon and experience, and position of the shunt regarding intimacy with the portal hilus. Splenocaval shunts are often short and potentially difficult to find surgically. Exposure can be an issue.
Comments
The patient was treated medically with L/D diet, lactulose and metronidazole for 3 weeks post surgery and was stable at post surgical follow-up.
Clinical Differential Diagnosis
Liver pathology – Hepatic insufficiency and secondary cirrhosis due to a PSS, intermittent hematuria possibly due to urolithiasis secondary to a PSS, microvascular dysplasia, chronic active hepatitis, neoplasia (hepatocellular adenoma, lymphoma, adenocarcinoma, leiomyoma, leiomyosarcoma, mast cell tumor.)
Sampling
Surgical wedge biopsy, liver. Ammonium biurate bladder calculi. The patient underwent an exploratory surgery and a cystotomy and liver biopsy were performed. No abnormal shunting blood vessel was seen, but the liver was small and pale. Two green stones were removed from the bladder, which were later determined to be urates. Liver histopathology: microvascular dysplasia consistent with that of patients with portosystemic shunting. Possible portal vein hypoplasia.
UA Specific Gravity Range
Video
Patient Information
Clinical Signs
- Lethargy
- PU-PD
Images
Blood Chemistry
- Albumin, Low
- Post-Prandial Bile Acids, High
Clinical Signs
- Lethargy
- PU-PD
Urinalysi
- Blood Present
- Culture negative
- Specific Gravity Low