Dr. Mila Kisyova
veterinary clinics “Dobro hrumvane!”- Sofia, Bulgaria
Normal anatomy of the kidneys:
The kidneys are paired, bean-shaped structures located in the retroperitoneal space directly beneath the sublumbar muscles. The cranial pole of the right kidney lies in the renal fossa of the caudate liver lobe and is located more cranially than the left kidney. The cranial pole of the left kidney lies lateral to the ipsilateral adrenal gland, which is closely associated with the cranial aspect of the left renal vessels. The left kidney is generally more mobile than the right kidney. Each kidney has a cranial and caudal pole and a ventral and dorsal aspect .
The concave surface of the kidney is located along the medial aspect and is called the hilus. The hilus is the location where the renal artery enters the kidney and the renal vein and ureter exit. Nerves and lymphatic vessels enter at the hilus as well. Anatomically, the renal vein is located more ventrally, and the renal artery is more dorsally. In an animal of normal body condition, the kidney is typically surrounded by a substantial amount of fat; this fat is maintained even in lean animals. In obese animals, the surrounding adipose tissue can virtually hide the kidney from view, making gross evaluation difficult.
Patophysiology of duplicated ureters:
Duplicated Ureter or Duplex Collecting System is a congenital condition in which the ureteric bud, the embryological origin of the ureter, splits (or arises twice), resulting in two ureters draining a single kidney. In the case of a duplicated ureter, the ureteric bud either splits or arises twice. In most cases, the kidney is divided into two parts, an upper and lower lobe, with some overlap due to intermingling of collecting tubules. However, in some cases the division is so complete as to give rise to two separate parts, each with its own renal pelvis and ureter. Double ureters from each kidney are very rare condition in dogs. They are drain separate renal collection systems from the same kidney and open separately into the urinary or genital tract. Given the embryological migration pattern of ureters, their termination sites are often ectopic.
Duplex systems can have a variety of phenotypes, and multiple classification systems have been proposed to categorise this pathology. In incomplete duplication, the two poles of a duplex kidney share the same ureteral orifice of the bladder. Such duplex kidneys with a bifid pelvis or ureter arise when an initially single UB bifurcates before it reaches the ampulla. This is likely caused by a premature first branching event that occurred before the ureter has reached the metanephric mesenchyme (MM). Much more frequent are complete duplications, which occur when two UBs emerge from the nephric duct (ND). In most cases, the lower pole of the kidney is normal and the upper pole is abnormal an observation explained by the fact that the ectopic ureteric bud (UB) frequently emerges anteriorly to the position of the normal UB and drives the formation of the upper pole of a duplex kidney. Inverted Y-ureteral duplication is a rare condition in which two ureteral orifices drain from a single normal kidney. Inverted Y-ureteral duplication is believed to be caused by the merging of two independent UBs just before or as they reach the kidney anlagen. A very rare H-shaped ureter has also been reported. Although the vast majority of cases involve a simple duplication, multiplex ureters with up to six independent buds have also been described. In some cases, the additional ureter or ureters are ectopic and fail to connect to the bladder or the kidney (blind ending ureter).
Report and history of the patient
We saw Jonh (11 years old, non-castrated, cryptorchid, chao- chao) for first time in our clinic for second opinion related to chronic kidney disease (CKD). He was diagnosed with chronic renal failure by colleagues about 2 years ago. Prior to our examination, he had been taking only food supplements (Irc Vet) and Renal Food. He had polyuria and polydipsia (PU/PD). The owners said that the urine was very light in colour. Sometimes Jonny had episodes with vomiting and lose of appetite. There was data for periodic blood tests with a tendency to increase the basic renal parameters (urea and creatinine). There was no ultrasound or other type of imaging examination.
When we took Johnny’s case, we initially did a complete abdominal ultrasound and new blood tests:
|1. Creatinine||456.20 mmol/L||44.30-138.40 mmol/L|
|2. Urea||26.32 mmol/L||3.00-8.00 mmol/L|
|3. ALP||272.59 U/L||10.60-109.00 U/L|
|4. Na||141.60 mmol/L||140.30-153.90 mmol/L|
|5. K||6.26 mmol/L||3.50-5.10 mmol/L|
|6. P||2.10 mmol/L||1.00-2.00 mmol/L|
|7. Albumin||31.37 g/L||25.80-39.70 g/L|
|8. Glucose||3.95 mmol/L||3.40-6.00 mmol/L|
|9. Bilirubin Total||5.07 mmol/L||0.00-5.10 mmol/L|
|10. Bilirubin Direct||3.05 mmol/L||0.00-3.60 mmol/L|
|11. ALT||31.33 U/L||8.50-109.00 U/L|
|12. AST||29.30 U/L||8.90-48.50 U/L|
- Abdominal Ultrasound:
We started a standard echo-screening and the prostatic gland was normal, the bladder too. And after that on the left abdomen near the left kidney we saw a big, elongated, strange formation with anechoic fluid with a diameter of about 3 cm. The left and right kidneys had a good ultrasound density. Three small cysts were found in the cortex of the left kidney. There was no evidence of pyeloectasis or hydronephrosis. The corticomedullary border was good. This finding may be a pathologically altered testis, cystic formation, or pathological /duplicate/ ureter. During the first ultrasound examination, the dog was fed, so we decided to repeat the examination on an empty stomach. For the next echo screening Jonny was on a 12- hour fasting diet but the ultrasound finding is the same as the previous examination – the strange formation after the left kidney was there with the same size and shape. After performing the second ultrasound examination, we had suspicion for duplicate ureter. In order to be definite in the diagnosis, it necessary to perform computed tomography (CT).
After the new blood tests we started a new supplements – Ipakitine/Rubenal 300/Renassense/IrcVet. But Jonny didn’t feel very well. After some days we made a new blood tests. Before that we had spoken with the owners about the ultrasound finding and we decided to do a CT and see what the exact cause of this strange ultrasound finding.
- Rusults of the CT:
1-A – little arrows are the bought normal ureters (left and right), big arrow „А“ – duplicate/ectopic left ureter
2-B – big arrow „А“ – duplicate left ureter
3-C – little arrows are cranial and caudal renal medula, big arrow „А“ – duplicate/ectopic left ureter draining the cranial pole of the kidney
4-D – А“ – duplicate/ectopic left ureter, about 3 cm wide along entire length
5-Е – normal right kidney
6-F – Left kidney, big arrow „А“ – duplicate/ectopic left ureter
*) the photos are provided by colleagues from the CVK (Central Vet Clinic, Sofia)
Тhe conclusion of the computed tomography is the left kidney has a slightly enlarged pelvis. Two ureters originating from the left kidney are found. The ureter, originating from the left kidney, has greatly increased dimensions – a width of about 3 cm along its entire length. Before entering the bladder, it turns ventrally and then dorsally. The other ureter of the left kidney begins in the normal anatomical position and drains into the bladder in the area of the trigone. Both kidneys have no tomographic evidence of hydro/pyelonephrosis.
This kind of pathology of the urogenital system in dogs is very rare. In this case it was an incidental finding because for 11 years the patient had never previously undergone additional ultrasound examinations. Certainly, this rare pathology is directly related to the rapidly progressing renal failure.
Due to the rapidly progressing renal failure, deteriorated general condition and the age of the patient, surgical intervention could not be performed. Jonny’s prognosis is very poor.
- „Urethral duplication in a dog: case report [Duplicação uretral em cão: relato de caso] R. Stedile, E.A. Contesini, S.T. Oliveira, C.A.C. Beck, E.C. Oliveira, M.M. Alievi, D. Driemeie, M.S. Muccillo Faculdade de Veterinária – UFRGS Av. Bento Gonçalves, 9090 91540-000 – Porto Alegre, RS „
- „Duplex_kidney_formation_Developmental_mechanisms_a.pdf– in humans“
- Atlas of Small Animal CT and MRI by Erik Wisner, Allison Zwingenberger ,
- Four-dimensional CT excretory urography is an accurate technique for diagnosis of canine ureteral ectopia (Tobias Schwarz, Nick Bommer, Maciej Parys, Florence Thierry, Jonathan Bouvard, Jorge Pérez-Accino, Jimmy Saunders, Maurizio Longo – onlinelibraly.wiley.com)