CT-first approach may be most cost-effective for suspected IVDE in dogs

 Advanced imaging is central to confirming thoracolumbar intervertebral disc extrusion (IVDE), but modality choice can have major cost implications for owners. A new UK decision-analytic study published in the Journal of Veterinary Internal Medicine suggests that starting with noncontrast CT and escalating only when needed may offer the best balance between diagnostic accuracy and cost. 

What was studied

Researchers modelled five imaging strategies for dogs with suspected thoracolumbar IVDE: CT alone; CT followed by CT-myelography (CTM) in all cases; CT with CTM only if initial findings were inconclusive (conditional-CTM); CT with MRI if needed (conditional-MRI); and MRI alone.

Effectiveness was defined as achieving a correct diagnosis. Costs were based on UK pricing data, and the model incorporated uncertainty in both test performance and financial inputs using probabilistic simulations.

Key findings

Across simulations:

• Conditional strategies that start with noncontrast CT then escalate only if noncontrast findings are inconclusive (conditional-CTM and conditional-MRI) offered the best balance of diagnostic value and cost.
• CT-only and unconditional-CTM strategies were consistently less effective and more costly than the conditional approaches and were never optimal in simulations.
• MRI-only — despite high diagnostic sensitivity — was generally not cost-effective under typical veterinary cost thresholds due to high imaging expenses.

At lower cost thresholds – reflecting tighter client budgets – conditional-CTM was most likely to represent the best value. At higher thresholds, where maximising diagnostic certainty outweighed cost considerations, conditional-MRI became more favourable. 

Limitations

This analysis was model-based; no live animals were imaged, and cost inputs, while UK-sourced, will vary between practices and regions. Outcomes depend on assumed diagnostic sensitivities and UK pricing structures, so local practice economics should inform implementation.

Key takeaway

For UK practice teams navigating imaging decisions in canine IVDE, conditional imaging pathways beginning with noncontrast CT may optimise diagnostic value per pound spent, reserving more costly modalities for cases where initial imaging is nondiagnostic or clinical suspicion remains high.

Read the study: Daniel Low, Comparative cost-effectiveness of cross-sectional imaging strategies in the diagnosis of intervertebral disc extrusion in dogs: a United Kingdom-based decision-analytic study, Journal of Veterinary Internal Medicine, Volume 40 Issue 1, January–February 2026