Veterinary MRI Protocols Explorer
Small-animal (dog & cat) MRI protocols by body region: representative sequences for common indications.
- Clinical small-animal MRI is performed under general anaesthesia with appropriate monitoring; lower field strength reduces achievable resolution, signal-to-noise and diffusion capability, so adapt slice thickness, matrix and sequence choice to your scanner.
- A general brain screen uses T2 TSE and FLAIR for oedema, masses and MUO lesions, T1 pre-contrast, T2* GRE for haemorrhage, DWI, and T1 post-gadolinium for the enhancement pattern; post-contrast FLAIR can show subtle meningeal enhancement.
- For acute paraparesis from suspected Hansen type I extrusion, survey with sagittal T2 and T1, add transverse T2 and T1 at the lesion to lateralise and grade the compression, and use T2* GRE to show haemorrhage.
- For a peracute, often lateralised, non-progressive deficit (FCE or ANNPE), sagittal and transverse T2 show focal intramedullary hyperintensity with no or minimal compression; add T2* GRE to exclude haemorrhage and optional DWI for ischaemic cytotoxic oedema.
- At low field, STIR is preferred for fat suppression because it is more homogeneous than spectral fat-sat or SPAIR.
Explain it simply
- Dogs and cats have MRI under general anaesthesia with proper monitoring. Weaker magnets give less detail, more grain and poorer diffusion scans, so adjust slice thickness, image grid and sequence choice to your scanner.
- A routine brain scan: T2 and FLAIR for swelling, masses and inflammation; T1 before contrast; a bleed-sensitive scan; diffusion; T1 after contrast for the uptake pattern. FLAIR after contrast can show subtle uptake in the brain’s coverings.
- For sudden back-leg weakness from a likely slipped disc, scan the spine lengthways first, then take cross-sections at the problem spot to see which side and how badly the cord is pressed, plus a bleed-sensitive scan.
- For sudden, often one-sided weakness that isn’t worsening, T2 scans in two directions show a bright spot in the cord with little or no pressure on it. Add a bleed-check scan and, optionally, diffusion for stroke-type damage.
- On lower-strength magnets, use STIR to cancel the fat signal, because it works more evenly than the frequency-based fat-suppression methods.
A guide only: follow your departmental protocols and regional requirements.
Brain / Head
Brain
Indication: new-onset seizures, forebrain signs, suspected meningoencephalitis of unknown origin (MUO) or intracranial tumour. General-purpose brain screen.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Dorsal, transverse, sagittal | Anatomy, oedema, mass, ventricular size |
| FLAIR | Transverse | Suppress CSF; peri-lesional oedema, MUO lesions |
| T1 pre | Transverse | Baseline signal; haemorrhage / fat |
| T2* GRE | Transverse | Blooming of haemorrhage / mineralisation |
| DWI | Transverse | Infarct, cellular tumour, empyema (field-dependent) |
| T1 post-Gd | Transverse, dorsal, sagittal | Enhancement pattern: tumour vs inflammation |
| FLAIR post (±) | Transverse | Subtle meningeal / leptomeningeal enhancement |
Parameters are representative; adapt to your scanner / field strength.
Pituitary / dynamic
Indication: pituitary-dependent hyperadrenocorticism, suspected macroadenoma, pre-radiotherapy planning. Thin-slice dynamic technique.
| Sequence | Plane | Purpose |
|---|---|---|
| T1 pre (thin) | Transverse / dorsal | Baseline pituitary size & position |
| Dynamic T1 post-Gd | Transverse (thin) | Neurohypophyseal flush, then adenoma; micro vs macro |
| Delayed T1 post-Gd | Dorsal / sagittal | Suprasellar extension, P:B ratio |
| T2 TSE (thin) | Transverse / dorsal | Cyst / haemorrhage within gland |
Parameters are representative; adapt to your scanner / field strength.
Otitis / middle ear / nasopharynx
Indication: otitis media/interna, tympanic bulla effusion, nasopharyngeal polyp (esp. cats), para-aural mass. Focused temporal-bone imaging.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Transverse & dorsal | Bulla fluid, nasopharyngeal soft tissue |
| T1 pre | Transverse / dorsal | Baseline of bullae & adjacent structures |
| T1 post-Gd | Transverse & dorsal | Wall enhancement, inner-ear / meningeal spread |
| FLAIR / STIR (±) | Transverse | Labyrinthitis, adjacent oedema |
Parameters are representative; adapt to your scanner / field strength.
Trigeminal / cranial nerve
Indication: unilateral masticatory (temporalis/masseter) atrophy, dropped jaw, cranial-nerve deficit; suspected trigeminal nerve-sheath tumour or neuritis.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Transverse & dorsal | Nerve thickening, muscle signal |
| T1 pre | Transverse / dorsal | Baseline nerve & foramina |
| T1 post-Gd (fat-sat) | Transverse & dorsal | Nerve-root enhancement, extension through foramen ovale |
| STIR | Dorsal | Denervation oedema of muscles of mastication |
Parameters are representative; adapt to your scanner / field strength.
Spine
Thoracolumbar IVDD
Indication: acute/subacute paraparesis or paraplegia, suspected Hansen type I disc extrusion (chondrodystrophic breeds). Localise & lateralise the compression.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Sagittal | Survey, disc degeneration, cord compression & signal |
| T1 | Sagittal | Anatomy, extradural material |
| T2 TSE | Transverse (at lesion) | Lateralisation & degree of compression |
| T1 | Transverse (at lesion) | Extruded disc material extent |
| T2* GRE | Transverse / sagittal | Haemorrhage (intramedullary / extradural) |
Parameters are representative; adapt to your scanner / field strength.
Cervical spine
Indication: cervical hyperaesthesia, tetraparesis, ataxia; caudal cervical spondylomyelopathy (Wobbler), disc disease, or Chiari-like malformation / syringomyelia (CM-SM, Cavalier King Charles Spaniel).
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Sagittal | Cord compression, syrinx, disc & ligamentous change |
| T2 TSE | Transverse | Dynamic / static compression, syrinx cross-section |
| T1 | Sagittal | Anatomy; craniocervical junction (CM) |
| T1 post-Gd (±) | Sagittal / transverse | If neoplasia / inflammation suspected |
Parameters are representative; adapt to your scanner / field strength.
FCE / ANNPE
Indication: peracute, often lateralised, non-progressive deficit, usually non-painful after onset (pain at onset is more common with ANNPE); fibrocartilaginous embolism (FCE) or acute non-compressive nucleus pulposus extrusion (ANNPE).
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Sagittal | Focal intramedullary hyperintensity, no/minimal compression |
| T2 TSE | Transverse | Grey-matter lesion, lateralisation; small disc over affected space |
| T2* GRE | Transverse / sagittal | Exclude haemorrhage |
| DWI (±) | Transverse | Cytotoxic oedema of ischaemia (field-dependent) |
Parameters are representative; adapt to your scanner / field strength.
Lumbosacral
Indication: lumbosacral pain, pelvic-limb lameness, urinary/faecal signs; degenerative lumbosacral stenosis (DLSS) / cauda equina syndrome.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Sagittal | Disc protrusion, foraminal & central stenosis |
| T1 | Sagittal | Anatomy, nerve-root anatomy, end-plate change |
| T2 TSE | Transverse | Foraminal nerve-root entrapment, articular process |
| T1 post-Gd (±) | Sagittal / transverse | If discospondylitis or neoplasia suspected (STIR helpful) |
Parameters are representative; adapt to your scanner / field strength.
Musculoskeletal
Stifle
Indication: stifle lameness, suspected cranial cruciate ligament (CCL) rupture and/or meniscal tear. High-resolution small-part imaging with a suitable coil.
| Sequence | Plane | Purpose |
|---|---|---|
| PD / T2 fat-sat (STIR) | Sagittal | CCL/CaCL integrity, joint effusion, bone marrow oedema |
| PD / T2 fat-sat | Transverse | Meniscal body & horns, collateral ligaments |
| PD / T2 | Dorsal | Meniscal tears (radial/longitudinal), cartilage |
| T1 | Sagittal / dorsal | Anatomy, osseous detail |
Parameters are representative; adapt to your scanner / field strength.
Shoulder
Indication: chronic thoracic-limb lameness; bicipital tenosynovitis, supraspinatus tendinopathy, medial shoulder instability.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 fat-sat (STIR) | Sagittal & transverse | Tendon oedema, effusion of bicipital sheath |
| T2 fat-sat | Dorsal | Supraspinatus tendon, mineralisation & oedema |
| T1 | Sagittal / transverse | Tendon & osseous anatomy |
| PD | Transverse | Fibre detail of tendons of origin/insertion |
Parameters are representative; adapt to your scanner / field strength.
Suspected soft-tissue sarcoma / mass
Indication: palpable or radiographically suspected soft-tissue mass; characterisation, local extent and surgical/radiotherapy staging.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 STIR | 2 planes | Lesion conspicuity, peri-tumoural oedema, tail extent |
| T1 pre | 2 planes | Fat planes, marrow & fascial invasion baseline |
| T1 post-Gd fat-sat | 2–3 planes | Enhancement, necrosis, true margins for staging |
| T2 / PD | Transverse | Compartment & neurovascular relationships |
Parameters are representative; adapt to your scanner / field strength.
Body / Abdomen
Abdomen / liver
Indication: congenital portosystemic shunt (MR angiography for vessel mapping), hepatic or adrenal mass characterisation, biliary disease. There is no voluntary breath-hold, but under general anaesthesia the anaesthetist can give a ventilator breath-hold or brief apnoea; otherwise use respiratory triggering or navigation, or fast single-shot sequences.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 HASTE (SS-FSE) | Transverse & dorsal | Fast survey, fluid, biliary, mass signal |
| T1 in / opposed phase | Transverse | Microscopic fat: adrenal adenoma, hepatic lipidosis |
| T1 pre fat-sat | Transverse / dorsal | Baseline for dynamic enhancement |
| Dynamic T1 post-Gd | Transverse / dorsal | Arterial/portal/delayed: mass & adrenal vascular invasion |
| MRA (CE / TOF) | Dorsal MIP | Shunt vessel origin, course & termination |
Parameters are representative; adapt to your scanner / field strength.
Nasal
Indication: chronic nasal discharge, epistaxis, facial deformity; differentiate destructive rhinitis / fungal disease from nasal tumour and assess cribriform-plate integrity.
| Sequence | Plane | Purpose |
|---|---|---|
| T2 TSE | Transverse & dorsal | Turbinate destruction, fluid vs soft-tissue mass |
| T1 pre | Transverse / dorsal | Baseline signal of nasal contents |
| T1 post-Gd fat-sat | Transverse & dorsal | Enhancing tumour vs non-enhancing secretions; cribriform / orbital / calvarial invasion |
| STIR / FLAIR (±) | Transverse | Peri-tumoural & adjacent brain oedema |
Parameters are representative; adapt to your scanner / field strength.
Sources
- Rusbridge C, Long S, Jovanovik J, et al. International Veterinary Epilepsy Task Force recommendations for a veterinary epilepsy-specific MRI protocol. BMC Vet Res 2015;11:194.
- da Costa RC, De Decker S, Lewis MJ, Volk H; Canine Spinal Cord Injury Consortium (CANSORT-SCI). Diagnostic imaging in intervertebral disc disease. Front Vet Sci 2020;7:588338.
- Mai W (ed). Diagnostic MRI in Dogs and Cats, 2nd ed. CRC Press, 2026.
- Fenn J, Drees R, Volk HA, De Decker S. Comparison of clinical signs and outcomes between dogs with presumptive ischemic myelopathy and dogs with acute noncompressive nucleus pulposus extrusion. J Am Vet Med Assoc 2016;249(7):767–775.
- Manley R, Matthews AR, Morandi F, et al. Magnetic resonance imaging of the canine abdomen: effect of pulse sequence on diagnostic quality. Vet Radiol Ultrasound 2013;54(3):253–262.
- Drees R, Johnson RA, Stepien RL, et al. Quantitative planar and volumetric cardiac measurements using 64 MDCT and 3T MRI vs. standard 2D and M-mode echocardiography: does anesthetic protocol matter? Vet Radiol Ultrasound 2015;56(6):638–657.
- Paul F, Alef M. Variation of rectal temperature in dogs undergoing 3T-MRI in general anesthesia. Front Vet Sci 2023;10:1156773.
- Berns GS, Brooks AM, Spivak M. Functional MRI in awake unrestrained dogs. PLoS One 2012;7(5):e38027.
Educational use only. This explorer summarises representative small-animal MRI protocols, drawing on the sources above, for teaching purposes and is not a substitute for clinical judgement, institutional protocols, or the advice of a board-certified veterinary radiologist / neurologist. Sequence selection, planes, contrast use and parameters must be tailored to the individual patient, the clinical question and the specific scanner and field strength. Clinical MRI in small-animal patients is performed under general anaesthesia with appropriate monitoring.
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Educational reference for imaging professionals. It does not replace local policy, manufacturer labelling or clinical judgement.