Renal Arteriovenous Malformation in a Quarter Horse Foal

Abstract

A 9-day-old male Quarter Horse foal was presented for evaluation of red discoloration of its urine. Foaling had been observed to progress normally and physical examination at 24 hours of age revealed a healthy colt. Passive transfer assessed at that time was adequate (immunoglobulin [Ig] >SO0 mg/dL; reference range, >800 mg/dL).Red urine was first observed on the day prior to admission (day 8), and was characterized by discoloration throughout micturition. No straining or increased frequency of urination was observed, and the foal appeared otherwise normal.At admission, the colt was bright and a physical exanhation was unremarkable. However, shortly after presentation it voided a normal stream and volume of red urine. A sample obtained by free catch was clear red, had a specific gravity of 1.004, and reagent strip analysis revealed hematurialhemoglobinuria (+ + +). Sediment ex-

Macroscopic haematuria of horses

“…Vascular anomalies that can be congenital or acquired are a rare cause of haematuria in the horse. A congenital renal arteriovenous fistula was a cause of haematuria in a foal (Schott et al 1996). The haematuria and renal lesion in this foal resolved within weeks, but another horse with a renal vascular anomaly did not develop haematuria until it was mature (Divers 1999).…”

“…Diagnosis of vascular anomalies is aided by ultrasonography of the urinary tract. Colour-flow Doppler ultrasonography may be particularly useful in diagnosis of vascular anomalies (Schott et al 1996). If the contralateral kidney is functioning normally, the kidney responsible for the haematuria can be removed (Divers 1999), but more conservative treatment may be effective (Schott et al 1996).…”

“…Colour-flow Doppler ultrasonography may be particularly useful in diagnosis of vascular anomalies (Schott et al 1996). If the contralateral kidney is functioning normally, the kidney responsible for the haematuria can be removed (Divers 1999), but more conservative treatment may be effective (Schott et al 1996). Creating a thrombus within the vascular lesion by selective renal arterial embolisation (a procedure during which an occlusion device is placed, using fluoroscopic guidance, within the vascular lesion) may be effective in resolving haematuria.…”

Bloody urine – the list of differential diagnoses lengthens, but diagnostics remain the same

“…Colour‐flow Doppler ultrasonographic examination was particularly useful in diagnosing the vascular anomaly of some affected horses (Schott et al . ; Larsdotter et al . ; Nogradi et al .…”

“…Radiographic examination of the abdomen of a foal with haematuria, performed after administering contrast medium into the aorta at the level of the renal artery, confirmed the presence of a vascular anomaly (Schott et al . ), and angiography performed during computed tomographic imaging was helpful in identifying a vascular abnormality in a 5‐week‐old colt, indicating that contrast‐enhanced, cross‐sectional imaging of the abdomen might be valuable in facilitating an accurate diagnosis of a renal vascular anomaly (Nogradi et al . ).…”