Central venous catheter associated thrombosis in dogs

Background:

Thrombosis in the jugular vein related to central venous catheters (CVC) is a complication empirically observed in canine patients of the Small Animal Clinic at the University of Veterinary Medicine, Hannover.

Objective:

To determine the incidence of catheter-induced thrombosis in canine intensive care patients and, thereby, the efficacy of a routine prophylactic heparin treatment. In addition, it should be assessed whether initial changes of different haemostasis parameters can be used to predict an increased risk for thrombosis formation.

Materials and methods:

Canine in-patients of the Small Animal Clinic receiving a central venous catheter in the jugular vein for medical reasons since March 2017 were included in the study. All animals received standard anticoagulatory treatment with UFH (150 IU [75 IU in surgical patients]/kg BW TID subcutaneously). Before the catheter was inserted (day 0) and on days 1, 3, 5, etc. the respective vein was assessed by color Doppler sonography and blood samples were collected. Haemostasis tests performed included routine coagulation tests, rotational elastometry, thrombin generation, and the heparin activity using a chromogenic anti-factor Xa test. Finally when the CVC was removed, electronmicroscopy of the tip was performed.

Results:

To date, 24 dogs entered the study including seven dogs receiving the reduced heparin dose. During the ultrasound controls 11 dogs developed prethrombotic or thrombotic CVC-related changes in the external jugular vein. Five dogs showed thrombi and six dogs detritus [presumably fibrin sheaths]) within or attached to the catheter. The five dogs with thrombi received 150 IU/kg BW TID, among the six dogs with fibrin precipitates were four dogs receiving 150 IU/kg and two dogs receiving 75 IU/kg BW TID.

In three of nine CVC's tips evaluated so far, thrombocytes were found inside the lumen and attached to the wall of the CVC, but all nine showed different amounts of fibrin sheaths. Interestingly, ultrasound did not reveal signs of thrombosis in any of the three dogs with detectable platelets within the catheter tip. Heparin activities in dogs receiving 150 IU/kg BW TID were 0.23 IU/ml (0.00–0.68 IU/ml, median, minimum-maximum) and 0.05 IU/ml (0.02–0.24 IU/ml) in dogs receiving 75 IU/kg BW TID.

Conclusions:

The results demonstrate that prethrombotic or thrombotic changes in the jugular vein detected by ultrasonography do not correlate to the results of the electronmicroscopic investigation of the catheter tip. Both methods showed frequently signs of catheter-associated prethrombotic states or thrombosis. The used anticoagulatory treatment with heparin is not completely effective to prevent catheter-induced thromboses.