Symmetric Dimethylarginine Assay Validation, Stability, and Evaluation as a Marker for the Early Detection of Chronic Kidney Disease in Dogs.

BACKGROUND: Symmetric dimethylarginine (SDMA) is a small molecule formed by methylation of arginine, and released into blood during protein degradation. SDMA is primarily eliminated by renal excretion and is a promising endogenous marker of glomerular filtration rate (GFR). OBJECTIVES: To validate an assay for SDMA measurement, determine stability of SDMA in blood, and compare SDMA with serum creatinine concentration (sCr) and GFR for early detection of decreasing kidney function in dogs with chronic kidney disease (CKD). ANIMALS: Eight male dogs affected with X-linked hereditary nephropathy and 4 unaffected male littermates. METHODS: Prospective study validating SDMA measurement using liquid chromatography-mass spectrometry, assessing stability of SDMA in serum and plasma, and serially determining sCr, SDMA, and GFR (using iohexol clearance) in dogs during progression from preclinical disease to end-stage renal failure. Correlations were determined using linear regression. Timepoints at which sCr, SDMA, and GFR identified decreased renal function were compared using defined cutoffs, trending in an individual dog, and comparison with unaffected littermates. RESULTS: Symmetric dimethylarginine was highly stable in serum and plasma, and the assay demonstrated excellent analytical performance. In unaffected dogs, SDMA remained unchanged whereas in affected dogs, SDMA increased during disease progression, correlating strongly with an increase in sCr (r = 0.95) and decrease in GFR (r = -0.95). Although trending improved sCr's sensitivity, SDMA identified, on average, <20% decrease in GFR, which was earlier than sCr using any comparison method. CONCLUSIONS AND CLINICAL IMPORTANCE: Symmetric dimethylarginine is useful for both early identification and monitoring of decreased renal function in dogs with CKD.

Eosinophilic pleural or peritoneal effusions in dogs and cats: 14 cases (1986-1992).

Case records of 9 dogs and 5 cats with eosinophilic effusions were reviewed. The animals ranged from 11 months to 13 years old. Seven animals had pleural effusions, 5 had peritoneal effusions, and 2 had pleural and peritoneal effusions. Neoplasia was confirmed in 6 animals and suspected in 1. Eosinophilic pleural effusion was diagnosed 2 days after pneumothorax developed as a consequence of thoracic tube placement in a cat, and pneumothorax was diagnosed in another cat with eosinophilic peritoneal effusion. Other abnormalities seen in 1 or 2 animals associated with eosinophilic effusion were radiographic signs of interstitial or peribronchial pulmonary infiltrates, a history of allergic respiratory tract and skin disease, intestinal lymphangiectasia and lung lobe torsion, chylothorax, bite wounds causing intestinal perforation, and feline leukemia virus infection. Based only on the protein concentration of the effusion, 7 effusions were classified as transudates and 7 were classified as exudates. Five of the 14 animals had eosinophilia (> 1,200 eosinophils/microliters); 3 of these animals had neoplastic disease. Mean eosinophil count in blood samples was not significantly different between animals with neoplasia and those without. Eosinophil counts in blood samples were not linearly related to counts in effusions; however, in some animals the number of eosinophils in the effusion was much higher than the eosinophil count in blood, suggesting concentration of eosinophils in the effusion.

Cholangiohepatitis in a dog.

Cholangiohepatitis was diagnosed in a dog with a 4-day history of anorexia, vomiting, fever, and icterus. Additional findings included signs of depression, dehydration, hepatosplenomegaly, and abdominal discomfort. Exploratory laparotomy was performed, and specimens of liver, spleen, and bile were obtained. Histologic evaluation of liver and spleen revealed acute, suppurative cholangio-hepatitis and splenitis, respectively. Cultures of liver and bile yielded Klebsiella sp. The dog responded to rehydration and intravenous administration of chloramphenicol. Although uncommon, cholangiohepatitis should be suspected in dogs with anorexia, fever, vomiting, icterus, and signs of abdominal discomfort. Definitive diagnosis requires bacterial cultures of liver and bile. Administration of an appropriate antibiotic should resolve clinical signs.

Serum hyperviscosity syndrome associated with multiple myeloma in two cats.

Serum hyperviscosity syndrome was diagnosed in 2 cats with multiple myeloma. Clinical signs included pale mucous membranes, dehydration, retinal hemorrhages, dilated and tortuous retinal vessels, seizures, head-tilt, nystagmus, systolic murmur, and gallop rhythm. Laboratory abnormalities included hyperglobulinemia, azotemia, hyperphosphatemia, nonregenerative anemia, and thrombocytopenia. Both cats had IgG monoclonal gammopathy, Bence Jones proteinuria, increased numbers of bone marrow plasma cells, and high values for relative serum viscosity. Renal disease was suspected in both cats. Cardiac hypertrophy was documented in 1 cat and was suspected in the other cat. Chemotherapy, using melphalan, prednisone, and vincristine, caused short-term remission in both cats, and plasmapheresis was used to lower serum protein concentration in 1 cat. Serum hyperviscosity syndrome rarely develops in cats, but should be suspected when monoclonal gammopathy exists with signs of neurologic, cardiac, or retinal disease.

Effects of a commercial malathion dip preparation on the cellular and humoral immune response of BALB/c mice.

Because of the widespread use of malathion as a treatment for ectoparasitism, a study was undertaken to determine the effects of a malathion dip preparation on the BALB/c mouse immune system. Mice were treated with either 2% (recommended dosage) or 8% solutions of malathion or a water control. The cellular immune response was evaluated by in vitro exposure of lymphocytes to mitogens, and the humoral immune response was assessed by using an enzyme-linked immunosorbent assay (ELISA) to quantify antibody production against sheep red blood cells (SRBC). Responses to the mitogens and to the SRBC were not significantly different between 2% and 8% malathion treated and water treated mice. Results indicated that malathion did not affect these two aspects of the mouse immune system when used as a 2% or 8% dipping solution.