Urethro-venous intravasation during retrograde urethrography in a dog.

A 9-year-old 6-kg male castrated mixed-breed dog was admitted to the hospital as a second opinion for left-sided nephrectomy. Plain radiographs, ultrasound, excretory urography and retrograde urethrography revealed left-sided hydronephrosis and calculi in the bladder and urethra. The urethral calculi were hydropropulsed into the bladder and nephrectomy and cystotomy were performed. Three days after surgery, the patient showed preputial inflammation, pain and pollakiuria. Retrograde urethrography was repeated and extra-urethral leakage of contrast medium into the penile tissue was identified, followed by filling of the draining veins, reaching the caudal vena cava, with subsequent opacification of the right renal pelvis and ureter and opacification of a lymph node. The dog improved during hospitalisation and a retrograde urography performed 6 months after the initial surgery confirmed full recovery.

Time-of-flight magnetic resonance angiography (TOF-MRA) of the normal equine head.

REASONS FOR PERFORMING STUDY: Noncontrast magnetic resonance angiography (MRA) is widely used in human and small animal medicine. However, this technique has not yet been described in the horse, and compared to other angiographic techniques MRA could be more cost efficient and potentially safer. OBJECTIVES: The aim of this study was to provide a comprehensive anatomical reference of the normal equine head vasculature using a noncontrast MRA technique, on both low- and high-field MRI. METHODS: Five healthy adult horses were examined, 4 with a low-field magnet (0.23T) and the remaining one with a high-field magnet (1.5T). The magnetic resonance angiography sequence used was TOF (time-of-flight) 2D-MRA and CT images of a vascular corrosion cast were subsequently used as anatomical references. RESULTS: The MRA imaging protocol provided good visualisation of all major intra- and extracranial vessels down to a size of approximately 2 mm in diameter on both low- and high-field systems. This resulted in identification of vessels to the order of 3rd-4th branches of ramification. The visibility of the arteries was higher than of the veins, which showed lower signal intensity. Overall, MRA obtained with the high-field protocol provided better visualisation of the arteries, showing all the small arterial branches with a superior resolution. CONCLUSIONS: The use of a specific vascular sequence such as TOF 2D-MRA allows good visualisation of the equine head vasculature and eliminates the need for contrast media for MRA. POTENTIAL RELEVANCE: Magnetic resonance angiography allows for visualisation of the vasculature of the equine head. Vessel morphology, symmetry and size can be evaluated and this may possibly play a role in preoperative planning or characterisation of diseases of the head, such as neoplasia or guttural pouch mycosis.