Evaluation of cell-based and tissue-based immunofluorescent assays for detection of glial fibrillary acidic protein autoantibodies in the cerebrospinal fluid of dogs with meningoencephalitis of unknown origin and other central nervous system disorders.

OBJECTIVE: To evaluate whether cell-based and tissue-based immunofluorescent assays (IFAs) run in parallel could be used to detect glial fibrillary acidic protein (GFAP) autoantibodies in the CSF of dogs with meningoencephalitis of unknown origin (MUO) and other CNS disorders. ANIMALS: 15 CSF samples obtained from dogs with presumed MUO (n = 5), CNS disease other than MUO (5), and idiopathic epilepsy (5). PROCEDURES: All CSF samples underwent parallel analysis with a cell-based IFA that targeted the α isoform of human GFAP and a tissue-based IFA that involved mouse brain cryosections. Descriptive data were generated. RESULTS: Only 1 CSF sample yielded mildly positive results on the cell-based IFA; that sample was from 1 of the dogs with presumed MUO. The remaining 14 CSF samples tested negative on the cell-based IFA. All 15 CSF samples yielded negative results on the tissue-based IFA. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that concurrent use of a cell-based IFA designed to target the human GFAP-α isoform and a tissue-based IFA that involved mouse tissue cryosections was inadequate for detection of GFAP autoantibodies in canine CSF samples. Given that GFAP autoantibodies were likely present in the CSF samples analyzed, these findings suggested that epitopes differ substantially between canine and human GFAP and that canine GFAP autoantibody does not bind to mouse GFAP. Without a positive control, absence of GFAP autoantibody in this cohort cannot be ruled out. Further research is necessary to develop a noninvasive and sensitive method for diagnosis of MUO in dogs.

Effects of clopidogrel and prednisone on platelet function in healthy dogs.

BACKGROUND: Glucocorticoids cause hypercoagulability, but it is unknown if they counteract clopidogrel's antiplatelet effects. HYPOTHESIS/OBJECTIVES: Determine the effects of clopidogrel and prednisone on platelet function. ANIMALS: Twenty-four healthy dogs. METHODS: Double-blinded, placebo-controlled randomized trial. Platelet function was evaluated using a platelet function analyzer and impedance aggregometry (days 0, 14, and 28) for dogs treated with placebo, clopidogrel (2-3 mg/kg/d), prednisone (2 mg/kg/d), or prednisone with clopidogrel PO for 28 days. Results were categorized as nonresponder versus responder (platelet function analyzer), and inadequate, ideal, or excessive response (aggregometry). Results were compared using mixed model, split-plot repeated measures analysis of variance and generalized estimating equation proportional odds models. P < .05 was considered significant. RESULTS: Closure times differed by treatment (F [3, 20] = 10.5; P < .001), time (F [2, 40] = 14.3; P < .001), and treatment-by-time (F [6, 40] = 3.4; P = .01). Area under the curve (AUC) differed by treatment (F [3, 20] = 19.6; P < .001), time (F [2, 40] = 35.4; P < .001), and treatment-by-time (F [6, 40] = 13.5; P < .001). Based on closure times, 5/6 dogs each in the clopidogrel and prednisone/clopidogrel groups were responders. All dogs in the prednisone/clopidogrel group were overcontrolled based on AUC (days 14 and 28), whereas 5/6 (day 14) and 2/6 (day 28) dogs treated with clopidogrel were overcontrolled. Compared to clopidogrel, dogs receiving prednisone/clopidogrel were 11 times (P = .03) more likely to have an excessive response. CONCLUSIONS AND CLINICAL IMPORTANCE: Administration of clopidogrel/prednisone increases platelet dysfunction in healthy dogs.

Effects of Aspirin and Prednisone on Platelet Function and Thromboxane Synthesis in Healthy Dogs.

Glucocorticoid administration is a risk factor for thromboembolism in hypercoagulable dogs, and it is unknown if aspirin counteracts glucocorticoid-induced hypercoagulability. The objective was to determine the effects of sustained aspirin and prednisone administration on platelet function and thromboxane synthesis. Our hypothesis was that aspirin would consistently inhibit platelet function and thromboxane synthesis when administered with or without prednisone. In 24 healthy dogs, platelet aggregometry and urine 11-dehydro-thromboxane-B2 (11-dTXB2)-to-creatinine ratios were measured on days 0, 14, and 28. Dogs were administered placebos, aspirin (2 mg/kg/d), prednisone (2 mg/kg/d), or prednisone/aspirin combination therapy PO for 28 days in a randomized double-blinded study. Aspirin response was based on a >25% reduction in platelet aggregation compared to pre-treatment values. Results were compared using mixed model, split-plot repeated measures ANOVAs. P < 0.05 was considered significant. AUC differed significantly by time [F (2,40) = 10.2, P < 0.001] but not treatment or treatment-by-time. On day 14, 2 dogs were aspirin responders (aspirin, 1; placebo, 1). On day 28, 3 dogs were aspirin responders (aspirin, 2; prednisone/aspirin, 1). Urine 11-dTXB2-to-creatinine ratios differed significantly by group [F (3,20) = 3.9, P = 0.024] and time [F (2,40) = 8.7, P < 0.001), but not treatment-by-time. Post-hoc analysis revealed significant differences between aspirin and placebo groups (P=0.008), aspirin and prednisone/aspirin groups (P = 0.030), and placebo and prednisone groups (P = 0.030). In healthy dogs, sustained aspirin, prednisone, and combination therapy do not inhibit platelet aggregation, and when used as individual therapies, aspirin and prednisone decreased thromboxane synthesis. Additional studies using varied platelet function methodologies in hypercoagulable dogs are necessary.

Clinical, clinicopathologic, and gastrointestinal changes from administration of clopidogrel, prednisone, or combination in healthy dogs: A double-blind randomized trial.

BACKGROUND: Dogs with immune-mediated disease often receive glucocorticoids with clopidogrel, but ulcerogenic effects of current protocols are unknown. HYPOTHESIS/OBJECTIVES: To compare gastrointestinal endoscopic findings among dogs administered clopidogrel, prednisone, and combination treatment. ANIMALS: Twenty-four healthy research dogs. METHODS: Double-blinded, placebo-controlled randomized trial. Dogs received placebo, clopidogrel (2-3 mg/kg q24h), prednisone (2 mg/kg q24h), or prednisone with clopidogrel PO for 28 days. Attitude, food intake, vomiting, and fecal score were determined daily. Clinicopathologic testing was performed at baseline and on day 28. Gastrointestinal hemorrhages, erosions, and ulcers were numerated by 2 blinded investigators for endoscopies performed on days 0, 14, and 28, and endoscopic mucosal lesion scores were calculated. Results were compared using mixed model, split-plot repeated measures ANOVAs and generalized estimating equation proportional odds models as appropriate. P < .05 was considered significant. RESULTS: Clinical signs of gastrointestinal bleeding were not noted. Endoscopic mucosal lesion scores differed significantly by group (F[3, 20] = 12.8, P < .001) and time (F[2, 40] = 8.3, P < .001). Posthoc analysis revealed higher lesion scores in the prednisone-receiving groups (P ≤ .006 for each) and on day 14 (P ≤ .007 for each). Ulcers were identified in 4 dogs administered prednisone and 3 dogs administered prednisone/clopidogrel. Odds of having endoscopic mucosal lesion scores ≥4 were 7-times higher for dogs in prednisone (95%CI 1.1, 43.0; P = .037) and prednisone-clopidogrel (95%CI 1.1, 43.4; P = .037) groups than those in the placebo group. CONCLUSIONS AND CLINICAL IMPORTANCE: Gastrointestinal bleeding and ulceration occur commonly in healthy dogs administered prednisone or prednisone/clopidogrel treatment, but not clopidogrel monotherapy. Though lesions are severe in many cases, they are not accompanied by clinical signs.

Clinical, clinicopathologic, and gastrointestinal changes from aspirin, prednisone, or combination treatment in healthy research dogs: A double-blind randomized trial.

BACKGROUND: Dogs with immune-mediated disease are often coadministered glucocorticoids and aspirin, but ulcerogenic effects of current protocols are unknown. OBJECTIVES: To compare gastrointestinal changes among dogs administered aspirin, prednisone, and combination treatment. ANIMALS: Twenty-four healthy research dogs. METHODS: Double-blinded, placebo-controlled randomized trial of dogs administered placebo, aspirin (2 mg/kg q24h), prednisone (2 mg/kg q24h), or combination treatment PO for 28 days. Clinical signs were recorded daily, with laboratory work performed at baseline and day 28. Gastrointestinal mucosal hemorrhages, erosions, and ulcers were numerated for endoscopic studies performed on days 0, 14, and 28; endoscopic mucosal lesion scores were calculated. Results were compared using mixed model repeated-measures analyses of variance and generalized estimating equation proportional odds models. P < .05 was considered significant. RESULTS: Gastric mucosal lesion scores differed by treatment-by-time (F[6, 40] = 4.4, P = .002), treatment (F[3, 20] = 7.1, P = .002), and time (F[2, 40] = 18.9, P < .001). Post hoc analysis revealed increased scores in the aspirin (day 14 only), prednisone, and prednisone/aspirin groups during treatment. Ulcers were identified on 14 studies, representing 10 dogs. Dogs receiving prednisone and prednisone/aspirin had 11.1 times (95% CI, 1.7-73.6) and 31.5 times (95% CI, 3.5-288.0) higher odds, respectively, of having endoscopic mucosal lesion scores ≥4 than dogs receiving placebo (P ≤ .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Gastrointestinal bleeding occurs commonly in dogs administered aspirin, prednisone, or prednisone/aspirin treatment, with higher lesion scores for dogs receiving combination treatment. Even severe lesions are not accompanied by clinical signs.

Effects of various factors on Doppler flow ultrasonic radial and coccygeal artery systolic blood pressure measurements in privately-owned, conscious dogs.

OBJECTIVE: The purpose of this study was to assess the effects of age, body condition score (BCS) and muscle condition score (MCS) on indirect radial and coccygeal Doppler systolic arterial blood pressure (SAP) measurements in dogs. METHODS: Sixty-two privately-owned dogs were enrolled between June and July 2016. The BCS and MCS were determined by two investigators. Blood pressure was measured per published guidelines and using headphones, and the order of measurement site was randomized. Dogs were positioned in right lateral recumbency for radial measurements and sternal recumbency or standing for coccygeal measurements. Associations between SAP and other variables were assessed by correlation coefficients and analysis of covariance. RESULTS: Radial and coccygeal SAP measurements were moderately correlated (r = 0.45, P < 0.01). Radial SAP measurements were higher than coccygeal SAP measurements (mean difference 9 mmHg, P < 0.01), but discordance occurred in both directions. No difference was observed between the first measurement taken, the average of measurements 2-6, or the average of all 6 measurements for either the radial (128, 129, and 129 mmHg; P = 0.36) or coccygeal (121, 122, and 122 mmHg; P = 0.82) site. Associations were not found between SAP measurements for either site and age, weight, BCS, MCS, anxiety score, or cuff size. Heart rate decreased significantly from the start of acclimation to the end of the first data collection series regardless of site (P < 0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Initial measurement site can be based on patient and operator preference given lack of associations with patient variables, but the same site should be used for serial SAP measurements given discordant results between sites.