The dog was anesthetized and positioned in dorsal recumbency. The entire procedure was performed through a 5-mm incision over
the right jugular vein and under fluoroscopic guidance.
A 12-Fr vascular sheath was percutaneously placed into the right jugular vein. A combination of angiographic catheters and
guide wires were used to select the left divisional PSS. A marker catheter and guidewire combination was then used to select
the caudal vena cava. Angiograms were performed to determine the caudal vena cava diameter and location of the shunt entrance
into the caudal vena cava (* in Figure 1A). Resting portal and caudal vena cava pressure measurements were obtained through
the respective catheters.
Figures 1A-1F: Serial fluoroscopic images demonstrating transvenous coil embolization of a left divisional intrahepatic portosystemic
shunt (PSS). In each image, the patient’s head is to the left of the image (CVC = caudal vena cava).
An appropriately sized self-expanding metallic stent (SEMS) was advanced into the caudal vena cava (Figure 1B) and deployed
across the shunt entrance (Figure 1C). A catheter and guidewire combination was used to reaccess the shunt through the stent
interstices (Figure 1D), and repeat pressure measurements were obtained. Thrombogenic coils were then consecutively passed
and deployed through the catheter and into the shunt until portal pressure were raised appropriately (Figure 1E). Upon completion,
the catheter was removed (Figure 1F), the sheath was replaced with a multilumen central line and the dog recovered.
The patient was discharged from the hospital two days later with instructions to continue medical therapy for the next month.
Discharge medications also included a two-week dose of amoxicillin-clavulanate (13.75 mg/kg b.i.d.) for the implanted devices.
Follow-up phone calls each week confirmed the dog continued to do well. On examination the following month, repeat bloodwork
demonstrated continued improvement.
Medical management was slowly discontinued (except for the omeprazole, which will be continued for life), a normal adult dog
food was slowly introduced and the clinical signs have not returned. Routine screening bloodwork should be repeated every
three to six months for the first year and then every six months thereafter, or sooner if needed. About 15 to 20 percent of
dogs will require an additional coil procedure in the future if clinical signs return.1
Patients with a congenital PSS often present as young animals with neurologic signs (hepatoencephalopathy) such as ataxia,
wall-walking, star-gazing and even seizure activity. In addition, the dogs can present with urinary tract signs (ammonia biurate
urolithiasis) or gastrointestinal signs (melena in intrahepatic PSS, pica, reduced appetite). Medical management is the mainstay
of initial therapy, with the goal of minimizing the clinical signs through a reduction of circulating toxins achieved through
a reduction in absorbed nitrogenous waste (low-protein diet, lactulose and antibiotics). In our experience, the addition of
proton-pump inhibition has reduced complications associated with gastrointestinal hemorrhage in dogs with an intrahepatic
While medical therapy palliates clinical signs associated with PSS in dogs, it is typically temporary, and some evidence suggests
medical therapy is inferior to attenuating the shunt.2,3 In addition, while surgical attenuation of extrahepatic PSS is typically safe, well-tolerated and successful in improving
portal perfusion, surgery for intrahepatic shunts has been associated with perioperative complication rates as high as 77
percent, perioperative mortality rates up to 28 percent and overall mortality rates as high as 64 percent.4-8
Interventional radiology techniques have been demonstrated to provide a safe, reliable, rapid and effective minimally invasive
alternative to open surgical treatment of canine intrahepatic PSS. In a recent abstract of 95 dogs with intrahepatic PSS treated
by using interventional radiology techniques, major complications occurred in only 2 percent of cases, with good to excellent
long-term outcome in about 75 percent of dogs and a median survival time of six years—longer than previously reported with
any other treatment modality.1 These techniques have also been used in cats and are being explored for use in animals with an extrahepatic PSS as well.
A video of the procedure can be viewed at http://www.amcny.org/node/341#Liver_Shunts. The embolization procedure is fairly short (average 90 minutes), and the patients are typically discharged from the hospital
two days later.
Dr. Berent is the director of Interventional Endoscopy Services in the Department of Diagnostic Imaging at The Animal Medical
Center in New York City. Dr. Weisse is the director of Interventional Radiology Services in the Department of Diagnostic Imaging
at The Animal Medical Center in New York City.
1. Weisse C, Berent A, Todd K, et al. Endovascular management of 100 dogs with intrahepatic portosystemic shunts: short- and
long-term outcome, in Proceedings. Am Coll Vet Surg, 2011.
2. Watson PJ, Herrtage ME. Medical management of congenital portosystemic shunts in 27 dogs—a retrospective study. J Small Anim Pract 1998;39(2):62-68.
3. Greenhalgh SN, Dunning MD, McKinley TJ, et al. Comparison of survival after surgical or medical treatment in dogs with a
congenital portosystemic shunt. J Am Vet Med Assoc 2010;236(11):1215-1220.
4. Komtebedde J, Koblik PD, Breznock EM, et al. Long-term clinical outcome after partial ligation of single extrahepatic anomalies
in 20 dogs. Vet Surg 1995;24(5):379-383.
5. Hunt GB, Kummeling A, Tisdall PLC, et al. Outcomes of cellophane banding for congenital portosystemic shunts in 106 dogs
and 5 cats. Vet Surg 2004;33(1):25-31.
6. White RN, Burton CA, McEvoy FJ. Surgical treatment of intrahepatic portosystemic shunts in 45 dogs. Vet Rec 1998;142(14):358-365.
7. Bostwick DR, Twedt DC. Intrahepatic and extrahepatic portal venous anomalies in dogs: 52 cases (1982-1992). J Am Vet Med Assoc 1995;206(8):1181-1185.
8. Smith KR, Bauer M, Monnet E. Portosystemic communications: follow-up of 32 cases. J Small Anim Pract 1995;36(10):435-440.