Bilateral Vertebral Venous Sinus Thrombosis Causing Cervical Spinal Cord Compression in a Dog

A case of suspected canine multifocal cervical venous sinus thrombosis causing cervical myelopathy

A 10-year-old spayed female standard poodle was admitted for marked cervical pain. Magnetic resonance imaging (MRI) suggested cervical venous sinus thrombi. An excellent clinical response to clopidogrel and warfarin combination was achieved. Repeat MRI showed partial resolution of the thrombosis. The etiology of the thrombosis is suspected to be due to the previous long-term, chronic use of corticosteroids. To the authors' knowledge, this is the first case report with follow-up imaging of canine venous sinus thrombosis. This clinical case report may help practitioners recognize this condition as a possible differential diagnosis for cervical pain, and it provides important guidelines in the prognosis. This case report highlights the use of anticoagulant therapy for 14 wk leading to complete resolution of clinical signs and to partial resolution of the thrombus 5 wk into the treatment, based on comparative MRI. Key clinical message: To the authors' knowledge, this is the first report of suspected multiple cervical venous sinus thrombi that includes comparative imaging into the course of therapy. The aim of this report is to provide additional information for future guidance on the duration of venous sinus thrombosis therapy.

Morphometrical Study of the Lumbar Segment of the Internal Vertebral Venous Plexus in Dogs: A Contrast CT-Based Study

Simple Summary

The internal vertebral venous plexus (IVVP) is a valveless venous network running inside the vertebral canal. The objective of this study was to morphometrically describe the IVVP, dural sac, epidural space and vertebral canal of the lumbar segment in dogs with enhanced computerized tomography. Six clinically healthy adult dogs were used for the study. Dorsal reconstructed computed tomography (CT) images showed a continuous rhomboidal morphological pattern for the IVVP. The dural sac was observed as an isodense structure with a rounded shape throughout the vertebral canal. The average percentage area occupied by the IVVP between L1 and L7 vertebrae ranged between 6.3% and 8.9% of the area of the vertebral canal, and the dural sac ranged between 13.8% and 72.2% of the vertebral canal. The epidural space accounted between 27.08% and 86.2% of the lumbar vertebral canal. CT venography is a safe technique that allows adequate visualization and evaluation of the lumbar IVVP and adjacent structures in dogs.

Abstract

The internal vertebral venous plexus (IVVP) is a thin-walled, valveless venous network that is located inside the vertebral canal, communicating with the cerebral venous sinuses. The objective of this study was to perform a morphometric analysis of the IVVP, dural sac, epidural space and vertebral canal between the L1 and L7 vertebrae with contrast-enhanced computed tomography (CT). Six clinically healthy adult dogs weighing between 12 kg to 28 kg were used in the study. The CT venographic protocol consisted of a manual injection of 880 mgI/kg of contrast agent (587 mgI/kg in a bolus and 293 mgI/mL by continuous infusion). In all CT images, the dimensions of the IVVP, dural sac, and vertebral canal were collected. Dorsal reconstruction CT images showed a continuous rhomboidal morphological pattern for the IVVP. The dural sac was observed as a rounded isodense structure throughout the vertebral canal. The average area of the IVVP ranged from 0.61 to 0.74 mm² between L1 and L7 vertebrae (6.3–8.9% of the vertebral canal), and the area of the dural sac was between 1.22 and 7.42 mm² (13.8–72.2% of the vertebral canal). The area of the epidural space between L1 and L7 ranged from 2.85 to 7.78 mm² (27.8–86.2% of the vertebral canal). This CT venography protocol is a safe method that allows adequate visualization and morphometric evaluation of the IVVP and adjacent structures.

American College of Veterinary Emergency and Critical Care (ACVECC) Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE) guidelines: Small animal

OBJECTIVES

To systematically review available evidence and establish guidelines related to the risk of developing thrombosis and the management of small animals with antithrombotics.

DESIGN

Standardized, systematic evaluation of the literature (identified by searching Medline via PubMed and CAB abstracts) was carried out in 5 domains (Defining populations at risk; Defining rational therapeutic use; Defining evidence-based protocols; Refining and monitoring antithrombotic therapies; and Discontinuing antithrombotic therapies). Evidence evaluation was carried out using Population, Intervention, Comparison, Outcome generated within each domain questions to address specific aims. This was followed by categorization of relevant articles according to level of evidence and quality (Good, Fair, or Poor). Synthesis of these data led to the development of a series of statements. Consensus on the final guidelines was achieved via Delphi-style surveys. Draft recommendations were presented at 2 international veterinary conferences and made available for community assessment, review, and comment prior to final revisions and publication.

SETTINGS

Academic and referral veterinary medical centers.

RESULTS

Over 500 studies were reviewed in detail. Worksheets from all 5 domains generated 59 statements with 83 guideline recommendations that were refined during 3 rounds of Delphi surveys. A high degree of consensus was reached across all guideline recommendations.

CONCLUSIONS

Overall, systematic evidence evaluations yielded more than 80 recommendations for the treatment of small animals with or at risk of developing thrombosis. Numerous significant knowledge gaps were highlighted by the evidence reviews undertaken, indicating the need for substantial additional research in this field.

Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE): Domain 3-Defining antithrombotic protocols

OBJECTIVES

To systematically examine the evidence for use of a specific protocol (dose, frequency, route) of selected antithrombotic drugs, in comparisons to no therapy or to other antithrombotic therapies, to reduce the risk of complications or improve outcomes in dogs and cats at risk for thrombosis.

DESIGN

Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence (LOE) and quality (Good, Fair, or Poor), and development of consensus on conclusions via a Delphi-style survey for application of the concepts to clinical practice.

SETTINGS

Academic and referral veterinary medical centers.

RESULTS

Databases searched included Medline via PubMed and CAB abstracts. Eight different antithrombotic drugs were investigated using a standardized Patient, Intervention, Comparison, Outcome (PICO) question format both for dogs and cats, including aspirin, clopidogrel, warfarin, unfractionated heparin (UFH), dalteparin, enoxaparin, fondaparinux, and rivaroxaban, generating a total of 16 worksheets. Most studies identified were experimental controlled laboratory studies in companion animals (LOE 3) with only four randomized controlled clinical trials in companion animals (LOE 1).

CONCLUSIONS

Overall, evidence-based recommendations concerning specific protocols could not be formulated for most antithrombotic drugs evaluated, either because of the wide range of dosage reported (eg, aspirin in dogs) or the lack of evidence in the current literature. However, clopidogrel administration in dogs and cats at risk of arterial thrombosis, notably in cats at risk of cardiogenic thromboembolism, is supported by the literature, and specific protocols were recommended. Comparably, aspirin should not be used as a sole antithrombotic in cats with cardiomyopathy. Using the available safety profile information contained in the literature, the panel reached consensus on suggested dosage schemes for most antithrombotics. Significant knowledge gaps were highlighted, which will hopefully drive novel research.