Evaluation of clinical status, renal function, and hematopoietic variables after unilateral nephrectomy in canine kidney donors

Levopositioned caudal vena cava and circumcaval left ureter with subsequent hydronephrosis and hydroureter in a dog

The presentation and investigation of a levopositioned caudal vena cava, a rare congenital vascular abnormality seen mainly in Bernese Mountain Dogs, which resulted in ureteral compression, hydronephrosis and hydroureter. Surgical transection, transposition and anastomosis were performed to reposition the circumcaval ureter. A 19-month-old male neutered Bernese Mountain Dog was presented with a 13-month history of vague signs including intermittent abdominal pain, inappetence and diarrhoea, which were poorly responsive to medical management. Abdominal ultrasound revealed left-sided hydronephrosis and hydroureter. Further investigation included abdominal computed tomography and pre- and post-intravenous iodinated contrast, which revealed a levopositioned caudal vena cava with associated ureteral displacement to a circumcaval position, resulting in ureteral compression and proximal dilation affecting both the proximal ureter and the left kidney. The patient was also found to have concomitant gall bladder agenesis. Surgery was performed to transect, transpose and anastomose the ureter in a normal anatomical position, and the patient made an excellent clinical recovery. All gastrointestinal signs resolved within 2 weeks of surgery and remained resolved 12 months later. Follow-up ultrasound and pyelography were performed at 4-month post-surgery, revealing a mild improvement in the hydronephrosis and hydroureter. Although rare, circumcaval ureter should be considered a differential in dogs presenting with hydroureter and hydronephrosis, especially Bernese Mountain Dogs.

Strategies for Improving Vascularization in Kidney Organoids: A Review of Current Trends

Kidney organoids possess the potential to revolutionize the treatment of renal diseases. However, their growth and maturation are impeded by insufficient growth of blood vessels. Through a PubMed search, we have identified 34 studies that attempted to address this challenge. Researchers are exploring various approaches including animal transplantation, organ-on-chips, and extracellular matrices (ECMs). The most prevalent method to promote the maturation and vascularization of organoids involves transplanting them into animals for in vivo culture, creating an optimal environment for organoid growth and the development of a chimeric vessel network between the host and organoids. Organ-on-chip technology permits the in vitro culture of organoids, enabling researchers to manipulate the microenvironment and investigate the key factors that influence organoid development. Lastly, ECMs have been discovered to aid the formation of blood vessels during organoid differentiation. ECMs from animal tissue have been particularly successful, although the underlying mechanisms require further research. Future research building upon these recent studies may enable the generation of functional kidney tissues for replacement therapies.

A longitudinal study of the persistence of increased creatinine and concordance between kidney biomarkers in cats and dogs

Kidney disease causes morbidity and mortality in dogs and cats. Serum creatinine concentration is an important surrogate marker for glomerular filtration rate (GFR). However, it is not always sensitive to small decreases in kidney function. Efforts to identify additional, more sensitive surrogate markers of GFR to improve detection of early kidney disease has led to the use of symmetrical dimethylarginine (SDMA) in veterinary medicine. There is insufficient information about the behavior of creatinine after an increase and the expected behavior of creatinine and SDMA in these cats and dogs. This study assesses the probability of persistence of increases in creatinine and the subsequent behavior of creatinine and SDMA in animals with persistently increased creatinine. For enrollment, three paired SDMA and creatinine concentrations were required: baseline (T0) with creatinine and SDMA at or below the upper reference limit (URL), T1, and T2 0.5-18 months after T1. The study included 4517 cats and 4576 dogs with increased T1 creatinine concentrations and 54,295 cats and 125,403 dogs with T1 creatinine at or below the URL. The probability of a persistently increased creatinine at T2 was approximately 58% for cats and 49% for dogs after a T1 increase. For animals without a T1 increase the probability of increased creatinine at T2 was only 7% for cats and 3% for dogs. For cats and dogs with persistently increased Cr, the probability of an increased SDMA concentration at T1 was 70-75%. By 24 months, that probability rose to 94% for cats and 88% for dogs.

Longitudinal evaluation of symmetric dimethylarginine and concordance of kidney biomarkers in cats and dogs

Symmetric dimethylarginine (SDMA) is a sensitive surrogate marker for glomerular filtration rate; however, there are uncertainties as to how to interpret mild increases (SDMA 15-19 μg/dL). This descriptive study used retrospective data to evaluate whether cats or dogs that had initial SDMA values (at T0) within the reference interval followed by an increased SDMA (at T1) had persistently increased SDMA (at T2; measured from 14 days to 18 months following T1; Persistence Cohort), and if and when cats or dogs with persistently increased SDMA had increased creatinine up to 24 months (Concordance Cohort). The Persistence Cohort included 16,670 cats and 16,712 dogs. If SDMA at T1 was 15-19 μg/dL, the probability of persistence was 53% for cats and 42% for dogs, while creatinine was concurrently increased in 20% of cats and 18% of dogs. For comparison, if SDMA was not increased at T1 the probability of increased SDMA at recheck was only 20% for cats and 9% for dogs. For cats and dogs with a T1 SDMA of 15-19 μg/dL and with persistent increases at T2, the probability of increased creatinine at T1 was 20% for cats and 18% for dogs, rising to 61% and 55%, respectively, by 24 months. When SDMA at T1 was >25 μg/dL, creatinine was increased in 93% of cats and 92% of dogs by 24 months. Mildly increased SDMA results may provide an opportunity to identify some cats and dogs earlier in their kidney disease.

induction and engraftment of kidney organoids derived from human pluripotent stem cells

The shortage of transplantable organs impedes the development of tissue-engineered alternatives. Producing tissues similar to immature kidneys from pluripotent stem cells is possible in vitro, but the size of the organoids is limited. Furthermore, in vivo implantation is necessary for organoid development and functional maturation. In the present study, the induction procedure was optimized and kidney organoids derived from induced pluripotent stem cells in vitro were produced. The kidney organoids were examined by immunofluorescence and quantitative PCR. Then, a unilateral nephrectomy model was established that was beneficial to the compensatory proliferation of the other kidney. Finally, these organoids were implanted below the kidney capsules of immunodeficient mouse hosts that had been nephrectomized unilaterally. This implantation resulted in the enlargement of the organoids and the production of vascular cells. Although signs of organoid maturation were lacking in short-term culture in vivo, the present study provided a method for studying kidney organoid development in vivo.

Double pigtail ureteral stenting and renal pelvic lavage for renal-sparing treatment of obstructive pyonephrosis in dogs: 13 cases (2008-2012)

OBJECTIVE

To describe the technical aspects and clinical outcome of endoscopic- and fluoroscopic-guided ureteropelvic lavage and ureteral stent placement for treatment of obstructive pyonephrosis in dogs.

DESIGN

Retrospective case series.

ANIMALS

13 client-owned dogs (14 obstructed ureters).

PROCEDURES

All patients with obstructive pyonephrosis were treated with a ureteral stent. Medical records were reviewed for history, clinical signs, pre- and postprocedural clinical and imaging data, and short- and long-term outcomes.

RESULTS

13 dogs (14 ureters) had unilateral or bilateral ureteral obstructions and pyonephrosis due to ureterolithiasis (n = 13) or a suspected ureteral stricture (1). Eleven dogs had positive results of bacteriologic culture of urine obtained from the bladder, renal pelvis, or both. Ten were thrombocytopenic, and 8 were azotemic. Stents were placed fluoroscopically with endoscopic (n = 11) or surgical (3) assistance. Median hospitalization time was 48 hours (range, 6 to 260 hours). Median follow-up time was 480 days (range, 2 to 1,460 days). Intraoperative complications occurred in 2 patients (stent occlusion from shearing of a guide wire, and wire penetration of the ureter at the location of a stone). Short-term complications included a bladder hematoma (n = 1) and transient dysuria (1). Long-term complications included stent encrustation (n = 1), stent migration (1), and tissue proliferation at the ureterovesicular junction (5), which had no clinical implications. Recurrent urinary tract infections were documented in 7 dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Ureteral stenting was a successful renal-sparing treatment for obstructive pyonephrosis in dogs and could often be performed in a minimally invasive manner. There were few major complications. This technique may be considered as an effective treatment option for this condition in dogs.

Unilateral nephrectomy in 10 cattle

OBJECTIVE

To describe clinical and imaging findings, treatment, and long-term outcome of cattle undergoing unilateral nephrectomy.

STUDY DESIGN

Case series.

ANIMALS

Cattle (n=10).

METHODS

Medical records (January 1991-August 2008) of cattle that had unilateral nephrectomy were reviewed. Follow-up data were obtained by owner telephone interview.

RESULTS

Nephrectomy was performed without surgical complications. Transient increases in blood urea nitrogen and creatinine concentrations occurred after surgery and then returned to, or below, presurgical values in 9 cattle. Nine cows were discharged and 7 rejoined their respective herd as productive animals without long-term complications.

CONCLUSIONS

Ultrasonography was the most useful imaging tool for presurgical diagnosis. Based on our follow-up data, unilateral nephrectomy resulted in few serious short-term or long-term complications, and cattle undergoing this procedure are capable of satisfactory growth, reproduction, and milk production after surgery.

Compensatory changes in the function of the remaining kidney immediately after unilateral nephrectomy in sheep

Live kidney donation is an established form of organ donation but carries the risk of an unnecessary surgery in a normal individual for the benefit of the recipient. Despite a number of recent studies on the renal function of long-term kidney donors, little attention has been paid to the damaging effects of compensatory hyper-filtration on renal tubular cells immediately after donor nephrectomy. The present study therefore aimed to examine the immediate changes in renal function of the remaining kidney using a sheep model of unilateral nephrectomy. We used the gamma camera-based method to measure the glomerular filtration rate and the tubular excretion values after simultaneous injection of (99m)Tc-diethylene triamine pentaacetic acid and (131)I-ortho-iodohippurate tracers. Compared were the differences in the functions between the remaining left kidney immediately after clamping the right renal pedicle and the baseline values that were measured one week before unilateral nephrectomy. After radionuclide data acquisition was completed, the right kidney was removed. The mean glomerular filtration rate (GFR) increased by 52.3% from the baseline values (29.5 +/- 2.7 to 45.0 +/- 6.7 ml/min; n = 40, p < 0.001), while the mean effective renal plasma flow (ERPF) increased by 40% (225.5 +/- 27.8 to 357.8 +/- 38.94 ml/min; p < 0.001), respectively. Mean filtration fraction was increased from 0.117 to 0.127 immediately after nephrectomy (p < 0.001). We conclude that after unilateral nephrectomy the remaining kidney immediately compensates for the loss of a donated kidney by increasing glomerular filtration rate and effective renal plasma flow.