Chapter 146 Portosystemic Shunt Management
• Clinical signs of portosystemic shunt (PSS) include neurologic, gastrointestinal, and urinary abnormalities, and can manifest as other signs such as prolonged recovery from anesthesia.
• Intrahepatic PSS is more common in large breed dogs and extrahepatic PSS usually occurs in small dogs and cats.
• The goal of preoperative PSS stabilization and medical treatment is to control clinical signs of hepatic encephalopathy and prevent progression of neurologic signs.
• Perioperative morbidity and mortality is higher with intrahepatic PSS repair than with surgical correction of extrahepatic PSS.
• Serious postoperative complications of PSS include hemorrhage, hypoglycemia, seizures, and portal hypertension.
MEDICAL MANAGEMENT
Table 146-1 Suggested Preoperative Anticonvulsant Therapy in Dogs and Cats With PSSs
Drug | Canine and Feline Dosage | Therapeutic Blood Levels |
---|---|---|
Phenobarbital | 1 to 2 mg/kg PO q12h | 15 to 45 μg/ml |
Potassium bromide | Loading dosage*: 100 mg/kg PO q6h × 4 doses (total dosage of 400 mg/kg in 24 hr) Maintenance dosage: 60 to 100 (canine) mg/kg once a day | 2 to 3 mg/ml when used as a sole agent 1 to 2 mg/ml when used in conjunction with phenobarbital |
*A loading dose is recommended if therapeutic levels are required quickly. This is one of several protocols for potassium bromide loading. A maintenance dose given longer than 15 days in dogs will provide adequate blood levels as an alternative to giving the loading dose.22 These drugs can be associated with neurologic and respiratory depression and patients should be monitored accordingly. Loading doses of potassium bromide can cause gastrointestinal disturbances.
PO, Per os, PSSs, portosystemic shunts.
From Plumb DC. Plumb’s veterinary drug handbook, ed 5, Stockholm, 2005. PharmaVet Inc.
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