Pharmacokinetics and pharmacodynamics of intravenous dexmedetomidine (2 μg∙kg-1) in dogs

This study assessed the pharmacokinetics and pharmacodynamics of low-dose dexmedetomidine after IV bolus in dogs. Six healthy adult dogs (6.8 ± 3.0 kg) received dexmedetomidine (2 μg.kg-1 IV) over 2 min, using an infusion pump. Blood samples were collected totaling 5 h of monitoring. A validated UHPLC-MS/MS method was used to determine the plasma concentration of dexemedetomidine. For pharmacodynamics, HR, RR, oscillometric MBP, Grint END sedation score were evaluated at baseline (T0), every 3 min (T3 to T21), and after 30 (T30) and 60 (T60) minutes, with p < 0.05. T1/2 was 28.28 ± 6.14 min; the area under the curve was 467.44 ± 60.42 ng/mL/min. The total clearance was 5.46 ± 0.41 mL/min/kg, the Vdss was 146.19 ± 21.04 mL/kg, and the C max was 3.13 ± 1.15 ng/mL. HR (bpm) decreased significantly from T6 (79 ± 21) to T21 (78 ± 31) compared to T0 (116 ± 28). RR(mpm) decreased from T3 (43 ± 44) to T60 (41 ± 23), with T0 being 70 ± 48. The MBP (mmHg) increased at T18 (151 ± 34), T21 (152 ± 35), and T30 (140 ± 27), compared to T0 (111 ± 22). Sedation occurred at all times post-bolus, with a maximum peak at T12 (END 8 ± 6). The low dose of dexmedetomidine provided sedation in all animals, characterizing rapid metabolization and elimination. However, cardiovascular effects still may have negative repercussions in dogs with hemodynamic comorbidities, highlighting the caution and individualization of its use in certain patients.

Development of perioperative premature ventricular contractions as an indicator of splenic hemangiosarcoma and median survival times

OBJECTIVE

The objectives of this study are (1) to determine whether there is an association between dogs with splenic hemangiosarcoma (HSA) and the development of premature ventricular contractions (VPCs), (2) to determine if there is a higher likelihood for dogs with ruptured splenic masses to be diagnosed with HSA and to develop VPCs, (3) to determine if the development of VPCs affects median survival times compared to dogs with benign or non-HSA malignant splenic masses.

STUDY DESIGN

Retrospective case series.

ANIMALS

Forty-five dogs.

METHODS

Medical records of dogs undergoing splenectomy were reviewed for signalment, perioperative electrocardiogram (ECG), hematological values, histologic diagnosis, metastasis, and survival times. ECGs were performed preoperatively, intraoperatively, and continuously postoperatively. The presence of VPCs was recorded. The data were evaluated for an association between the development of VPCs and the histologic diagnosis of HSA.

RESULTS

Eighteen out of 45 (40%) dogs were diagnosed with HSA with 13/18 (72%) dogs having VPCs postoperatively (P = .02). Ruptured splenic HSA and VPCs were noted in 13 dogs (P = .73). An association between dogs with and without VPCs diagnosed with HSA and median survival times could not be established.

CONCLUSION

Postoperative VPCs were more likely with splenic HSA. Splenic masses were more likely to be HSA if ruptured but less likely to develop VPCs. Development of VPCs does not affect median survival times.

CLINICAL SIGNIFICANCE

Development of postoperative VPCs may be a potential indicator of HSA, however, this warrants further investigations. Development of VPCs does not have a deleterious effect on survival.