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

Oral cyclosporine treatment in dogs: a review of the literature

Cyclosporine is an immunomodulatory drug used to treat an increasing spectrum of diseases in dogs. Cyclosporine is a calcineurin inhibitor, ultimately exerting its inhibitory effects on T-lymphocytes by decreasing production of cytokines, such as interleukin-2. Although, in the United States, oral cyclosporine is approved in dogs only for treatment of atopic dermatitis, there are many other indications for its use. Cyclosporine is available in 2 oral formulations: the original oil-based formulation and the more commonly used ultramicronized emulsion that facilitates oral absorption. Ultramicronized cyclosporine is available as an approved animal product, and human proprietary and generic preparations are also available. Bioavailability of the different formulations in dogs is likely to vary among the preparations. Cyclosporine is associated with a large number of drug interactions that can also influence blood cyclosporine concentrations. Therapeutic drug monitoring (TDM) can be used to assist in attaining consistent plasma cyclosporine concentrations despite the effects of varying bioavailability and drug interactions. TDM can facilitate therapeutic success by guiding dose adjustments on an individualized basis, and is recommended in cases that do not respond to initial oral dosing, or during treatment of severe, life-threatening diseases for which a trial-and-error approach to dose adjustment is too risky. Pharmacodynamic assays that evaluate individual patient immune responses to cyclosporine can be used to augment information provided by TDM.

Use of end-to-side arterial and venous anastomosis techniques for renal transplantation in two dogs

CASE DESCRIPTION

A sexually intact male Old English Sheepdog and a sexually intact female Bull Terrier were evaluated for renal dysplasia and chronic renal failure, respectively.

CLINICAL FINDINGS

Both dogs were anemic and had high serum concentrations of urea nitrogen and creatinine. Electrolyte abnormalities (calcium and phosphorus) were also evident. The decision was made to pursue renal transplantation, and donor dogs were identified.

TREATMENT AND OUTCOME

End-to-side anastomosis of the renal artery and vein of each donor's left kidney to the recipient's ipsilateral external iliac artery and vein, respectively, was performed. The left caudal abdominal musculature was scarified by making an incision, and nephropexy to that musculature was performed with a simple interrupted pattern of polypropylene sutures. No intraoperative or postoperative complications associated with the vascular anastomoses were encountered. Azotemia, anemia, and electrolyte imbalances resolved after transplantation.

CLINICAL RELEVANCE

The end-to-side anastomosis technique described here, which is a preferred method in human medicine, was successful, providing an alternative to other renal transplantation techniques in dogs. Additional studies are needed to determine whether any vascular anastomosis technique is preferable for use in dogs requiring renal transplantation.

Hematopoietic chimerism induces renal and skin allograft tolerance in DLA-identical dogs

OBJECTIVE

Hematopoietic chimerism, a state where donor and recipient bone marrow cells coexist, is associated with donor-specific tolerance. Nonmyeloablative bone marrow transplantation (BMT) has been shown to induce stable mixed hematopoietic chimerism in dog leukocyte antigen (DLA)-matched dogs. The potential for inducing renal and skin allograft tolerance with nonmyeloablative BMT was investigated in DLA-identical and DLA-haploidentical dogs in this study.

MATERIALS AND METHODS

Renal allografts were performed in 8 DLA-identical and 4 DLA-haploidentical dogs with nonmyeloablative conditioning (200 cGy TBI) and transient immunosuppression with cyclosporine (CSP) and mycophenolate mofetil (MMF) with (n = 8) and without (n = 4) simultaneous BMT. Skin allografts were performed in 2 DLA-identical and 4 DLA-haploidentical dogs after stopping CSP and MMF. Two DLA-identical control dogs received renal allografts without TBI, BMT, or immunosuppression with CSP and MMF. Molecular chimerism was determined with a PCR-based DNA microsatellite assay. Serum creatinine (Cr) concentration, urine specific gravity, and sequential renal biopsies were monitored to assess renal allograft function.

RESULTS

Donor-type blood cells were first detected 4 weeks posttransplantation in both the myeloid and lymphoid lineages. Donor chimerism was present for at least 76 weeks in the DLA-identical dogs. Mixed chimerism was not observed in the DLA-haploidentical dogs or DLA-identical dogs that did not undergo BMT. The renal allografts were acutely rejected within 14 days in the 2 DLA-identical control dogs. There was long-term (> 5 yrs) renal allograft survival as evidenced by a normal (< 2.0 mg/dL) serum Cr concentration in both the DLA-identical and DLA-haploidentical dogs that underwent 200 cGy TBI and transient immunosuppression with CSP and MMF either with or without simultaneous BMT. Renal allograft inflammation was severe in the control dogs, mild to moderate in the DLA-haploidentical dogs, and minimal in the DLA-identical dogs. Donor-specific skin grafts were accepted in the DLA-identical dogs but rejected in the DLA-haploidentical dogs. Nonmyeloablative conditioning (200 cGy TBI) and transient immunosuppression with CSP and MMF induce renal and skin allograft tolerance in DLA-identical and permit long-term renal allograft survival in DLA-haploidentical dogs. These findings suggest it may possible to obtain long-term allograft survival in DLA-identical and -haploidentical dogs without the need for chronic immunosuppressive therapy.

Use of Capecitabine to Prevent Acute Renal Allograft Rejection in Dog Erythrocyte Antigen-Mismatched Mongrel Dogs

OBJECTIVE

To assess efficacy and toxicity of a capecitabine (CAP)-based regimen for preventing rejection of renal allografts in dog erythrocyte antigen (DEA)-mismatched mongrel dogs.

STUDY DESIGN

Prospective, pilot study.

ANIMALS

Eight healthy, unrelated, DEA mismatched, adult mongrel dogs.

METHODS

All dogs received CAP, starting at 50 mg/m2 PO b.i.d. 4 days preoperatively, increasing to 200 mg/m2 PO b.i.d. by the day of surgery. All dogs received cyclosporine-A (CsA) and prednisolone starting 2 days preoperatively. Standard heterotopic renal transplantation with native nephrectomy was performed. After 90 days, surviving dogs were euthanatized and histopathologic examination was performed.

RESULTS

Two of 8 dogs developed acute neurotoxicity leading to death or euthanasia within 5 days of surgery. For the 6 remaining dogs, there were no statistically significant changes in complete blood count or serum biochemical values. No opportunistic infections developed during the study period. Five of 6 dogs had no to minimal evidence of graft rejection. Two of 6 dogs developed superficial and pigmentary keratitis. Significant histopathologic findings in all dogs included mild lymphoplasmacytic gastroenteritis, steroid hepatopathy, and corneal epithelial thinning. One dog had moderate interstitial nephritis and pyelitis.

CONCLUSIONS

In this experimental model, a CAP-CsA-prednisolone immunosuppressive regimen was effective in preventing rejection of allografts in DEA-mismatched dogs. Severe, unpredictable neurotoxicity and variable ocular toxicity significantly limit clinical applications at this time.

CLINICAL RELEVANCE

A CAP-CsA-prednisolone protocol is an effective, oral immunosuppressive regimen for prevention of allograft rejection in DEA-mismatched mongrel dogs. For clinical application, identification of patients susceptible to toxic side effects would be necessary.

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.

Creatinine in the Dog: A Review

Creatinine is the analyte most frequently measured in human and veterinary clinical chemistry laboratories as an indirect measure of glomerular filtration rate (GFR). Although creatinine metabolism and the difficulties of creatinine measurement have been reviewed in human medicine, similar reviews are lacking in veterinary medicine. The aim of this review is to summarize information and data about creatinine metabolism, measurement, and diagnostic significance in the dog. Plasma creatinine originates from the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Creatinine is cleared by glomerular filtration with negligible renal secretion and extrarenal metabolism, and its clearance is a good estimate of GFR. Plasma and urine creatinine measurements are based on the nonspecific Jaffé reaction or specific enzymatic reactions; lack of assay accuracy precludes proper interlaboratory comparison of results. Preanalytical factors such as age and breed can have an impact on plasma creatinine (P-creatinine) concentration, while many intraindividual factors of variation have little effect. Dehydration and drugs mainly affect P-creatinine concentration in dogs by decreasing GFR. P-creatinine is increased in renal failure, whatever its cause, and correlates with a decrease in GFR according to a curvilinear relationship, such that P-creatinine is insensitive for detecting moderate decreases of GFR or for monitoring progression of GFR in dogs with severely reduced kidney function. Low sensitivity can be obviated by determining endogenous or exogenous clearance rates of creatinine. A technique for determining plasma clearance following IV bolus injection of exogenous creatinine and subsequent serial measurement of P-creatinine does not require urine collection and with additional studies may become an established technique for creatinine clearance in dogs.

An evaluation of combined immunosuppression with MNA 715 and microemulsified cyclosporine on renal allograft rejection in mismatched mongrel dogs

OBJECTIVE

To evaluate a combination of MNA 715 and microemulsifed cyclosporine for the prevention of renal allograft rejection in mismatched mongrel dogs.

STUDY DESIGN

Randomized, experimental study.

ANIMALS

Fourteen female mismatched mongrel dogs.

METHODS

Heterotopic renal transplantation and bilateral nephrectomy were performed in each dog. Dogs were randomly assigned to receive either MNA 715 and cyclosporine (n = 8) or cyclosporine alone (n = 6). Dogs were killed at 100 days after transplantation or when plasma creatinine exceeded 7 mg/dL.

RESULTS

In the cyclosporine and MNA 715 group: 4 dogs survived to 100 days with normal plasma creatinine concentrations; 2 dogs with intestinal intussusceptions were killed at 5 and 8 days, 1 dog with a wound infection and sepsis was killed at 14 days, and 1 dog with a serum creatinine concentration >7 mg/dL was killed at 51 days postoperatively. In the cyclosporine-alone group: 3 dogs with acute rejection were killed at 6 to 9 days and 3 dogs survived to 100 days. In dogs treated with cyclosporine and MNA 715, survival to histologically confirmed acute rejection was significantly longer (P =.044) and the degree of mononuclear cell infiltration was significantly reduced (P =.040), compared with dogs treated with cyclosporine alone.

CONCLUSIONS

MNA 715 combined with cyclosporine prolonged allograft survival and reduced the severity of histologic rejection in a clinically relevant renal transplant model.

CLINICAL RELEVANCE

An immunosuppressive regimen consisting of MNA715 and microemulsified cyclosporine may be effective in preventing allograft rejection in canine renal transplant patients.

Evaluation of the clinical and histologic features of renal allograft rejection in cats

OBJECTIVES

To describe the clinical signs and histopathologic features of renal allograft rejection in cats, and to provide a historical, untreated control group for use in future studies of feline renal allograft rejection.

ANIMALS

Fourteen adult research cats.

METHODS

Renal transplantation and bilateral nephrectomy were performed in pairs of immunogenically mismatched cats. A physical examination was performed, and packed cell volume, total protein, and plasma creatinine concentrations were measured each day after surgery. The cats were euthanatized when plasma creatinine concentration exceeded 7 mg/dL or when weight loss exceeded 20%. Renal histopathology was scored according to the Banff 97 criteria by 3 pathologists.

RESULTS

Nine cats completed the study. Plasma creatinine exceeded 7 mg/dL in 5 cats, weight loss exceeded 20% in 3 cats, and 1 cat was found dead. Clinical signs in cats with rejection were nonspecific or absent. Rectal temperature decreased by 0.8 +/- 0.5 degrees C in the 24 hours before euthanasia. The pathologists agreed on the allograft histopathologic category in 6 of 9 cats. The histologic consensus was acute/active rejection in 8 cats and normal in 1 cat. Median survival time of the 8 cats with histologically confirmed allograft rejection was 23 days (range, 8-34 days).

CONCLUSIONS AND CLINICAL RELEVANCE

Renal allograft rejection is associated with minimal clinical signs. Therefore, plasma creatinine concentration should be measured routinely in patients with a functioning allograft. An increase in plasma creatinine concentration is highly suspicious for allograft rejection, although a biopsy of the renal allograft is needed for definitive diagnosis.

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.

Clinical, biochemical, and hematologic evaluation of normal dogs after administration of rabbit anti-dog thymocyte serum

Renal allografting is the only long-term alternative to euthanasia in dogs with end-stage kidney disease. The purpose of this study was to determine the clinical, biochemical, and hematologic effects of rabbit anti-dog thymocyte serum (RADTS) in normal dogs and to develop a safe and practical route of administration before its use in an allograft immunosuppressive protocol. Thirteen mongrel dogs were divided into three groups; each received RADTS subcutaneously, intramuscularly, or intravenously. The inflammation and pain associated with subcutaneous administration was unacceptable. A significant (p < or = .05) leukopenia and lymphopenia developed in all dogs, regardless of the route of administration of RADTS. Thrombocytopenia was a consistent finding after intravenous administration and with high doses given intramuscularly. Both the intravenous and intramuscular routes were well tolerated by all dogs with minimal or no discomfort. Serum creatinine was unchanged, whereas serum alanine aminotransferase activity increased in one dog. There were no histologic changes in any of the kidneys examined.

Surgery of the geriatric patient

The geriatric patient commonly requires surgical intervention. Although precaution is warranted, age alone is not a contraindication to surgery. A problem-oriented approach is needed, along with proper surgical planning that incorporates preoperative, intraoperative, and postoperative needs of the patient. This article discusses both perioperative management theory and practical surgical techniques that can be applied to the aged animal. Many of the principles discussed are not limited to the practice of geriatric surgery but reflect reactions of aging patients to specific disease pathologies.