2015 ACVIM Forum Research Abstract Program

Computed tomography guided vertebral stereotaxy provides an accurate means of implant placement into the canine thoracolumbar vertebral column, reducing the risk of damage to vital structures and spinal cord disruption. Additionally, CT guided stereotactic navigation afforded excellent bone purchase. The purpose of the study was to evaluate the pharmacokinetics of zonisamide administered per rectum via commercially available encapsulated powder mixed with either sterile water or polyethylene glycol and to determine whether a dose of 20 mg/kg or 30 mg/kg would result in target serum concentrations (10-40 mcg/mL). Eight healthy mixed-breed dogs were randomly assigned to 4 groups of 2 dogs each in a crossover-design study. Zonisamide was administered rectally in a suspension with sterile water or polyethylene glycol at a dose of 20 mg/kg or 30 mg/kg, and blood samples were collected at predetermined time points. After a 7-day washout period, each group received an alternate treatment until all groups had received all treatments. Serum concentrations of zonisamide were analyzed via high-performance liquid chromatography. Serum concentrations of zonisamide were within the targeted range at > 1 time point after rectal administration in only 2 dogs. These concentrations were reached after 3 hours (n = 1 dog) or 6 hours (n = 1 dog). In the remaining 6 dogs, serum concentrations of zonisamide were below the target range at all time points. On the basis of these results, rectal administration of 20 mg/kg or 30 mg/kg of zonisamide via a sterile water or polyethylene glycol suspension used in the present study cannot be recommended. Conventional valve shunting for treatment of hydrocephalus has been associated with complications, as high as 22% in one study. Reported complications include dislodgement, occlusion, infections, ventricle collapse, and subdural hematoma. The necessity for shunt revision surgery is reported by several authors. In humans, complication frequency is related to young age and was 32% in a study of 14,000 patients.