Evaluation of three peripheral arteriovenous fistulas for hemodialysis access in dogs

OBJECTIVE: To design and create 3 types of arteriovenous fistulas (AVF) in normal dogs, to monitor the dogs for secondary cardiovascular complications, and to verify adequacy of these fistulas for hemodialysis vascular access. STUDY DESIGN: Experimental study. ANIMALS: ur normal adult dogs. METHODS: Cadaveric dissections were performed, and surgical protocols were generated for carotid-jugular (CJ), brachial-cephalic (BC), and distal caudal femoral-lateral saphenous anastomosis (DCFLS) AVF. Each surgical procedure was then performed in 2 live dogs. Echocardiography was performed at days 0, 1, 3, 7, 14, 28, and 56 to evaluate the dogs for evidence of volume overload secondary to AVF formation. Estimation of luminal diameter and confirmation of fistula patency were performed using percutaneous color Doppler ultrasound. At day 56, hemodialysis was performed using each fistula as a vascular access. RESULTS: No significant changes occurred in the echocardiographic variables over time. All fistulas were patent at day 56 with mean luminal diameters of 4.5 mm (CJ), 4 mm (BC), and 1.5 mm (DCFLS). The BC fistula was superior for ease of needle placement and stabilization and provided adequate blood flow for clinical hemodialysis. CONCLUSIONS: Based on this short-term study, arteriovenous fistulas appear to be a safe and effective means for hemodialysis access in dogs. CLINICAL RELEVANCE: The arteriovenous fistulas described provide an alternative to the central venous catheters currently used for chronic hemodialysis access in dogs.     

Evaluation of Environmental, Nutritional, and Host Factors in Cats with Hyperthyroidism

The pathologic changes associated with hyperthyroidism (adenomatous hyperplasia, adenoma of the thyroid gland) have been well characterized in cats, but the pathogenesis of these changes remains unclear. In this research, we undertook a case-control study to search for potential risk factors for this disease. Owners of 379 hyperthyroid and 351 control cats were questioned about their cats' exposure to potential risk factors including breed, demographic factors, medical history, indoor environment, chemicals applied to the cat and environment, and diet. The association between these hypothesized risk factors and outcome of disease was evaluated by conditional logistic regression. Two genetically related cat breeds (ie, Siamese and Himalayan) were found to have diminished risk of developing hyperthyroidism. Cats that used litter had higher risk of developing hyperthyroidism than those that did not. Use of topical ectoparasite preparations was associated with increased risk of developing hyperthyroidism. Compared with cats that did not eat canned food, those that ate commercially prepared canned food had an approximate 2-fold increase in risk of disease. When these 4 variables (breed, use of cat litter, consumption of canned cat food, and use of topical ectoparasite preparations) from the univariate analysis were selected for further study as candidate risk factors and analyzed by multivariate conditional logistic regression, a persistent protective effect of breed (ie, Siamese or Himalayan) was found. In addition, results suggested a 2- to 3-fold increase in risk of developing hyperthyroidism among cats eating a diet composed mostly of canned cat food and a 3-fold increase in risk among those using cat litter. In contrast, the use of commercial flea products did not retain a strong association. The results of this study indicate that further research into dietary and other potentially important environmental factors (eg, cat litter) is warranted.     

Application of therapeutic plasma exchange in dogs with immune-mediated thrombocytopenia

Therapeutic plasma exchange (TPE) is an emerging treatment for dogs with immune-mediated diseases, but reports for treatment of immune-mediated thrombocytopenia (IMT) are lacking. These case reports illustrate the application of centrifugal TPE in 4 dogs with IMT. All dogs presented with severe hemorrhage requiring ≥1 blood transfusions, were unresponsive to conventional treatment or both. Dogs were treated with 3 sequential centrifugal TPE sessions, totaling 4.0 to 4.9 total plasma volumes exchanged per dog. In 3 dogs, TPE was associated with improvement in clinical manifestations of bleeding and platelet count in combination with immunosuppressive drugs. One dog was euthanized after 3 treatments because of persistent severe thrombocytopenia and hemorrhage. Preliminary observations indicate that TPE is safe and may be a useful adjunct in the management of IMT that is severe or refractory to traditional treatment.     

Diagnostic Predictors of Complications and Survival after Renal Transplantation in Cats

OBJECTIVE: To identify preoperative diagnostic results that predict postoperative complications and survival in feline renal-transplant recipients. STUDY DESIGN: Retrospective clinical study. ANIMALS: Sixty-one feline renal allograft recipients. METHODS: Medical records for 61 consecutive cats that underwent renal allograft transplantation between January 1, 1996, and December 1, 1999, were reviewed. Age, diagnosis, body weight, body condition score, preoperative medical treatment, systolic blood pressure, packed cell volume, biochemical parameters at admission and at the time of surgery, postoperative complications, and postoperative survival were recorded. Associations of preoperative data with the occurrence of postoperative complications were determined using logistic regression. Postoperative survival was graphed using a Kaplan-Meier cumulative-survival plot. Associations of covariates with postoperative survival were analyzed using Cox proportional hazards analysis. RESULTS: Two parameters were significantly associated with occurrence of postoperative central nervous system (CNS) disorders: blood urea nitrogen concentration (odds ratio = 1.083; 95% CI = 1.018 to 1.148) and serum creatinine concentration (odds ratio = 1.8; 95% CI = 1.413 to 2.187) at the time of surgery. Postoperative survival 6 months after transplantation was 59%, though 3-year survival remained at 42%. Of all covariates investigated, only recipient age (relative hazard = 1.183; 95% CI = 1.039 to 1.334) was significantly associated with survival. CONCLUSION AND CLINICAL RELEVANCE: Standard measures of preoperative renal dysfunction do not predict postoperative survival in cats after renal transplantation, although an increase in the degree of preoperative azotemia is associated with an increased risk of CNS disorders after surgery. Increased recipient age is associated with decreased survival after renal transplantation.