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Sagittal T2-weighted images, thoracic vertebral column

Dorsal STIR images, thoracic vertebral column

Sagittal T2-weighted images, lumbar vertebral column

Dorsal STIR images, lumbar vertebral column

Transverse T2-weighted images, lumbar vertebral column

Transverse T1-weighted images, before and after IV contrast administration

Dorsal T1-weighted images after IV contrast administration

What's your diagnosis? Answers posted after the Imaging Interpretation Session

– No evidence of an intramedullary, intradural-extramedullary or extradural lesion

– Thoracolumbar discs are diffusely moderately to markedly desiccated with multifocal minor chronic disc herniations

– In descending aorta heterogeneously hyperintense solid appearing begins just cranial to deep circumflex vasculature and extends into the proximal aspect of the external iliac arteries; no flow artifact is seen in any imaging series through this area

– The left external iliac is more extensively affected.

– Some peripheral contrast enhancement is seen around the left half of the luminal tissue in the descending aorta and continuing right external iliac artery.

– Left iliopsoas muscle is mildly diffusely enlarged compared to the right and has subtle areas of hyperintensity in the STIR images. Left gluteal muscle is also mildly larger than right.

– Multifocal areas of abnormal muscular hyperintensity in the pelvic limb musculature, with right being more affected both in number of muscle bellies affected and degree of hyperintensity seen in the STIR images.

– Small areas of concavity are seen in the renal cortical margins

– The right adrenal gland is enlarged, measuring 1.5 cm in diameter; disruption of corticomedullary parenchymal definition is present

– Left adrenal gland is mildly enlarged at 1.0 cm in diameter, maintains normal shape, but has a hypointense nodule measuring 0.8 cm in length

1) Distal descending aortic thromboembolism with extension into the external iliac arteries – left more affected.

2) Diffuse non-compressive degenerative intervertebral disc disease of the thoracolumbar spine.

3) Multifocal paraspinal pelvic and proximal pelvic limb myopathy/myositis.

4) Left iliopsoas and gluteal swelling.

5) Mild chronic nephropathy bilaterally.

6) Right adrenomegaly and left adrenal nodule.

Aortic thromboembolism (ATE) can have an acute (45%) or chronic (48%) presentation. The patient in this case was chronically affected but the fall was judged to be an acute exacerbation of clinical signs. Chronically affected patients have longer median survival times than those acutely affected. Common identified underlying etiologies in dogs has been reported to include renal disease and/or protein-losing nephropathies, neoplasia, endocrinopathies or steroid therapy and cardiac disease. Pre-MRI blood work had been done at the rDVM in house and was judged to be normal aside from a stress leukogram. Serum biochemistry was repeated at admission for MRI and there was moderate CK and ALP elevations, mild elevation in both BUN and creatinine; all other parameters were normal. Cushing\’s disease was confirmed after the MRI examination. Weak femoral pulses were documented. The patient was treated for the ATE and discharged 3 days following the MRI with improved femoral pulse strength bilaterally. She was able to ambulate with support but left pelvic limb continued to me more affected. No ATE recurrence or associated clinical signs had occurred when rechecked 6 months post-MRI.

References

Hiebert et al. (2015) What is your neurologic diagnosis? Aortic thromboembolic disease (ATE) and hind limb ischemia. J Am Vet Med Assoc. 2015 Jun 15;246(12):1293-5. doi: 10.2460/javma.246.12.1293. No abstract available.

Gonçalves et al. (2008) Clinical and neurological characteristics of aortic thromboembolism in dogs. J Small Anim Pract. 2008 Apr;49(4):178-84. doi: 10.1111/j.1748-5827.2007.00530.x.

Lake-Bakaar et al. (2012) Aortic thrombosis in dogs: 31 cases (2000-2010). J Am Vet Med Assoc. 2012 Oct 1;241(7):910-5.