Case Description—A 7-year-old spayed female Labrador Retriever was evaluated because of pericardial effusion.
Clinical Findings—The dog had a history of decreased appetite and exercise intolerance of 3 days' duration. Thoracic radiography performed by the referring veterinarian revealed a large cardiac silhouette. Heart sounds were muffled. Echocardiographic findings were indicative of severe pericardial effusion with cardiac tamponade; no pleural effusion was identified. Pericardiocentesis yielded a considerable amount of chylous fluid. A diagnosis of chylopericardium in the absence of pleural effusion was made.
Treatment and Outcome—Conservative management was not effective, and subtotal pericardectomy and thoracic duct ligation were recommended. Surgery was postponed by the owners for 25 days, at which time the dog had both chylopericardium and chylothorax. The dog underwent subtotal pericardectomy and thoracic duct ligation; to delineate the thoracic duct, intraoperative lymphangiography was performed by injection of a radiopaque contrast agent directly into a mesenteric lymph node and subsequent injection of methylene blue solution into another mesenteric lymph node. Surgical treatment resulted in complete resolution of the clinical signs and pleural effusion.
Clinical Relevance—To the authors' knowledge, this is the first report of the development of chylopericardium prior to development of chylothorax in a dog. Treatment with thoracic duct ligation and pericardectomy resulted in complete resolution of the effusion and clinical signs.
To compare pharmacokinetics of levetiracetam in serum and CSF of cats after oral administration of extended-release (ER) levetiracetam.
9 healthy cats.
Cats received 1 dose of a commercially available ER levetiracetam product (500 mg, PO). Thirteen blood and 10 CSF samples were collected over a 24-hour period for pharmacokinetic analysis. After 1 week, cats received 1 dose of a compounded ER levetiracetam formulation (500 mg, PO), and samples were obtained at the same times for analysis.
CSF concentrations of levetiracetam closely paralleled serum concentrations. There were significant differences between the commercially available product and the compounded formulation for mean ± SD serum maximum concentration (Cmax; 126 ± 33 μg/mL and 169 ± 51 μg/mL, respectively), Cmax corrected for dose (0.83 ± 0.10 μg/mL/mg and 1.10 ± 0.28 μg/mL/mg, respectively), and time to Cmax (5.1 ± 1.6 hours and 3.1 ± 1.5 hours, respectively). Half-life for the commercially available product and compounded formulation of ER levetiracetam was 4.3 ± 2.0 hours and 5.0 ± 1.6 hours, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE
The commercially available product and compounded formulation of ER levetiracetam both maintained concentrations in healthy cats 12 hours after oral administration that have been found to be therapeutic in humans (ie, 5 μg/mL). Results of this study supported dosing intervals of 12 hours, and potentially 24 hours, for oral administration of ER levetiracetam to cats. Monitoring of serum concentrations of levetiracetam can be used as an accurate representation of levetiracetam concentrations in CSF of cats.