Dog with an Aortic Thromboembolism

A 12-year old castrated male Miniature Schnauzer was evaluated for a week long history of hindlimb weakness and pain after short periods of activity. His signs were initially localized to the right hindlimb, but then progressed to both hindlimbs after several days.  Radiographs revealed no skeletal abnormalities, and there was no response to deracoxib.

On examination, the patient had weak femoral pulses on the right and moderate femoral pulses on the left.  His hindlimbs were palpably cool to the touch relative to his forelimbs.  His conscious proprioception was delayed in both hindlimbs.  Abdominal ultrasound revealed an aortic thrombus 2 cm distal to the left renal artery and extending into both internal and external iliac arteries.  A duodenal mass with loss of wall layering was also found and fine needle aspirates were obtained.  The patient was discharged with tramadol for analgesia pending aspirate results from the duodenal mass.

The patient’s comfort was initially improved with analgesics, but 5 days after diagnosis of an aortic thromboembolism, the patient became acutely paretic in the hindlimbs. Re-evaluation revealed hindlimbs which were cool to the touch, paraparesis, and absent femoral pulses.  Repeat abdominal ultrasound showed progression of the thrombus in the distal aorta, external iliacs, and internal iliac arteries.

What thrombolytic and/or thromboprophylactic medications should have been instituted upon diagnosis of an aortic thromboembolism? Is there any evidence supporting any of these therapies?

What treatment and/or management options exist for canine patients with aortic thromboembolic disease?

The decision was made to perform local thrombolysis with tissue plasminogen activator (TPA) and place bilateral external iliac stents.  The patient was placed under general anesthesia and access to both carotid arteries was obtained via surgical cut-down.  Bilateral 6-French vascular sheaths were placed in each carotid artery and sutured in place.  A 0.035” angled hydrophilic guidewire was advanced caudally in the aorta under fluoroscopic guidance to the level of the thrombus.  A 4-French hydrophilic catheter was advanced over the wire. Contrast was injected through the catheter to define the clot margins, as shown below.

Advancement of the guidewire across the thrombus in each external iliac artery was attempted but unsuccessful.  One milligram of TPA was infused over the cranial aspect of the clot.  Several minutes later, to allow time for the TPA to break down the clot, a wire was able to advanced across each external iliac thrombus.  A 4-French infusion catheter was advanced over the wire into the thrombus of each external iliac and an additional 1 mg of TPA into each external iliac thrombus.   Contrast was injected into each external carotid to determine the vessel diameter. Guide wires were replaced across each external iliac (one wire per carotid artery vascular sheath) and a 6 mm x 40 mm urethral stent was placed across the thrombus in each external iliac artery, as shown below.

Both stents were deployed simultaneously and post-deployment angiography performed to confirm patency of each external iliac artery.

Post-procedural radiographs were taken for sent location documentation and are shown below.

Why was bilateral carotid access used?  Could the procedure have been performed via one carotid artery?  If so, what would need to be done to ensure proper stent deployment and placement?

Why is placement of a urinary catheter beneficial during this procedure?

Is suturing of the carotids necessary or can one or both carotids be ligated in dogs?

What anticoagulation protocol should be used post-operatively?

Category: Cases, Vascular Interventions