Lesions in dogs following renal transplantation and immunosuppression

Renal Allograft Histopathology in Dog Leukocyte Antigen Mismatched Dogs After Renal Transplantation

OBJECTIVE

To evaluate allograft histopathology in dog leukocyte antigen (DLA)-mismatched dogs undergoing renal transplantation, with transient immunosuppression.

STUDY DESIGN

Prospective study.

ANIMALS

Ten healthy adult mongrel dogs.

METHODS

Reciprocal renal transplantation and bilateral nephrectomy were performed. Immune conditioning consisted of nonmyeloablative (200 cGy), total body irradiation (TBI), bone marrow transplantation (BMT; 7 dogs), cyclosporine (CSA; 15 mg/kg every 12 hours), mycophenolate mofetil (MMF; 10 mg/kg every 12 hours) and intermittent prednisone (1 mg/kg every 12-24 hours). Biopsies were collected at transplantation, during full immunosuppression (44-90 days), and once medications were reduced or discontinued (228-580 days). Biopsies were evaluated for interstitial, tubular, vascular, and glomerular lesions. Blood urea nitrogen, creatinine, serum CSA concentrations, and clinical score were determined at each biopsy.

RESULTS

Seven dogs survived >200 days (mean, 380 days). Transient CSA toxicity was suspected in 6 dogs. Lymphocytic, plasmacytic interstitial inflammation, and tubulitis progressed when immunosuppressive medications were decreased. All 7 dogs had histologic lesions consistent with some degree of allograft rejection at study end.

CONCLUSION

Nonmyeloablative TBI, BMT, and short-term immunosuppression with CSA, MMF, and prednisone allowed renal allograft function and dog survival for >200 days. It appears unlikely that total drug withdrawal will be possible in unrelated DLA-mismatched dogs using this protocol.

CLINICAL RELEVANCE

Transient immunosuppression with MMF, CSA, and prednisone along with BMT and nonmyeloablative TBI may make kidney transplantation a clinical reality for treatment of kidney failure in dogs. Initiating both MMF and CSA at lower dosages may potentially eliminate early renal allograft injury.

Use of Capecitabine After Renal Allograft Transplantation in Dog Erythrocyte Antigen-Matched Dogs

OBJECTIVES

To investigate the use of a capecitabine (CAP)-based regimen after renal transplantation in dogs.

STUDY DESIGN

Prospective, pilot study.

ANIMALS

Healthy, unrelated, dog erythrocyte antigen (DEA)-matched, adult beagles.

METHOD

Standard heterotopic renal transplantation with native nephrectomy was performed in 7 dogs. Dogs received oral, twice daily, CAP (250 mg/m2), cyclosporine-A (CsA) (4 mg/kg), ketoconazole (5 mg/kg), and prednisolone (0.25 mg/kg). After 90 days the surviving dogs were euthanatized and complete necropsy was performed.

RESULTS

Seven transplants were performed. All dogs survived surgery. Six dogs had acute neurotoxicity, which resulted in death or euthanasia of 2 dogs within 2 days of surgery. In the remaining dogs, toxicity resolved rapidly with cessation of drug administration. Thereafter, modification of the regimen minimized toxicity. The 5 remaining dogs survived to study end; 4 dogs had no evidence of graft rejection. Necropsy examination was mostly unremarkable in all dogs. There were no major changes in CBC or biochemical values, except for a significant increase in serum calcium.

CONCLUSIONS

CAP appeared well tolerated in most dogs. Toxicity occurred but abated with modification of the drug regimen. Efficacy for postoperative immunosuppression cannot be determined by this study, although results are promising.

CLINICAL RELEVANCE

CAP-CsA-prednisolone is an effective, oral immunosuppressive regimen for prevention of acute allograft rejection in DEA-matched beagles. Further studies on dose, toxicity, and efficacy compared with current immunosuppressive regimens are needed before use in clinical practice.

Treatment of experimental ureteral strictures by endourological ureterotomy and implantation of stents in the porcine animal model

The objective of this study is to evaluate the dilation of the ureter using endoureterotomy and an expanding-sheath double pigtail ureteral stent in the treatment of experimentally induced ureteral strictures in the porcine animal model. This is a new treatment in the ureteral strictures resolution in Veterinary Urology, although it is not a common affection, it usually appears as a consequence of ureteritis and in the iatrogenic female genital surgery. The experimental study is design in three phases: induction of experimental stricture, diagnosis and treatment of the stricture and follow-up. We have used 10 healthy Large White female pigs. The internal ureteral diameter was measured prior to laparoscopic ligature stricture induction using retrograde ureteropyelography (RUPG). Experimental stricture was diagnosed 4 weeks after intervention, using RUPG and ultrasound, and treated by endoureterotomy and subsequent placement of a double pigtail ureteral stent, which was removed 6 weeks later. The study finished 4 weeks later with measurement of ureteral diameters using RPUG and ultrasound evaluation. Except in one case, all ureters displayed permanent dilation of the strictured area for 10 weeks after treatment (6 weeks with ureteral stent and 4 more weeks without stent). Finally, this technique proved to be effective in cases of short-length and short-living ureteral strictures, and represents a viable alternative to conventional surgery in animals.

Acute vascular and interstitial rejection following renal allograft transplantation in dogs

Renal allograft transplantation was performed in four beagles. Immunosuppressive treatment using cyclosporine, mizoribin and prednisolone was continued from Day 5 pre- until Day 20 post-transplantation. Between Days 28 and 32 post-transplantation, an abrupt elevation of the serum creatinine values followed by the development of uremia was seen in all recipients. Histopathology of the allografts examined between Days 28 and 37 revealed edema, necrosis, hemorrhage and severe diffuse interstitial cellular infiltration as well as tubulitis. Glomerular changes notably included swelling of the tufts due to hypercellularity, which was consistent with transplant glomerulitis. The intrarenal arteries exhibited fibrinoid necrosis of the walls and intimal or transmural cellular infiltration. These renal lesions were consistent with those of acute vascular and interstitial rejection in humans.

Renal allograft survival in outbred mongrel dogs using rabbit anti-dog thymocyte serum in combination with immunosuppressive drug therapy with or without donor bone marrow

Therapeutic renal transplantation in dogs is currently being investigated as a treatment for endstage renal disease. This pilot study examines the effect of donor bone marrow (DBM) infusion and antithymocyte serum (ATS) in combination with immunosuppressive drug therapy in prolonging renal allograft survival in dogs. Seven normal outbred mongrel dogs received an unmatched renal allograft. All dogs received rabbit anti-dog thymocyte serum (RADTS), prednisone (Pr), cyclosporine-A (CsA) and azathioprine (Aza). In addition, three dogs (group 1 test) received DBM and four dogs (group 2 control) did not receive DBM. Serum CsA levels were measured throughout the study. Immunosuppressive therapy was gradually reduced with Pr, CsA, and Aza withdrawn at 200, 450, and 680 days, respectively. Allograft rejection was treated with prednisolone sodium succinate. One dog in group 1 and one in group 2 died as a result of infectious canine rhinotracheitis and rejection early in the study. Renal allograft torsion occurred in one group 1 dog. The remaining four dogs survived the 2 years of the study. The dogs in group 2 (three dogs) all rejected the renal allograft after total drug withdrawal, the surviving dog in group 1 did not. This study demonstrates that RADTS, Pr, CsA, and Aza in combination can prolong renal allograft survival in mongrel dogs, whereas DBM may enhance the unresponsive state.

Pulmonary microcalcifications associated with Strongyloides stercoralis infection

Diffuse alveolar deposits of calcium phosphate have been identified in the lungs of two prednisolone-treated beagles with chronic S stercoralis infection. Such lesions have not previously been described in dogs and have not been found in humans in association with either strongyloidiasis or prolonged steroid therapy. S stercoralis infections in the industrialized world are frequently found in patients on maintenance regimens of corticosteroids. We suggest that the possibility that pulmonary calcifications represent an unsuspected complication in these patients should be investigated.

Efficacy of azathioprine versus cyclosporine on kidney graft survival in transfused and nontransfused unmatched mongrel dogs

Sixteen mongrel dogs had bilateral nephrectomy and received a renal allograft from an unmatched mongrel. One group of eight dogs was treated orally with azathioprine and prednisone; another group of eight dogs was treated orally with cyclosporine and prednisone. Four dogs of each group received four blood transfusions each prior to surgery. Mean survival time was nearly the same in the azathioprine-treated and the cyclosporine-treated dogs. Transfusions prolonged survival in the azathioprine-treated group but not in the cyclosporine-treated group. Retrospective measurement of whole blood trough cyclosporine concentrations indicated marked variation between dogs and in the same dog at different times. This variation may have influenced graft survival. Only one dog survived the 9-month period of observation, indicating that refinements of the techniques used in this study will be required for long-term survival of renal allografts in unrelated mongrel dogs.