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- Author or Editor: Elizabeth R. May x
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Abstract
Objective—To determine whether the stress of an ultrasonographic procedure would interfere with the suppressive effect of dexamethasone during a lowdose dexamethasone suppression test (LDDST) in healthy dogs.
Animals—6 clinically normal adult dogs.
Procedure—In phase 1, an LDDST was performed 5 times at weekly intervals in each dog. Serum samples were obtained 0, 2, 4, 6, and 8 hours after dexamethasone injection. A mock 20-minute abdominal ultrasonographic examination was performed on all dogs at each time point during the LDDST on weeks 2 through 5. In phase 2, serum cortisol concentrations were measured before and immediately after a 20-minute mock abdominal ultrasonographic examination, as described for phase 1.
Results—We did not detect significant differences after dexamethasone injection when comparing median cortisol concentrations for weeks 2 to 5 (mock ultrasonographic procedure) with median concentration for week 1 (no mock ultrasonographic procedure). For 5 of the 6 dogs, cortisol concentrations after dexamethasone injection decreased to < 35.9 nmol/L after each mock ultrasonographic procedure and remained low for the duration of the LDDST. In phase 2, all dogs had significant increases in cortisol concentrations immediately after the mock ultrasonographic procedure.
Conclusions and Clinical Relevance—A 20-minute mock abdominal ultrasonographic examination performed during LDDST did not alter results of the LDDST in most dogs. Cortisol concentrations measured immediately after a mock ultrasonographic examination were significantly increased. Ultrasonographic procedures should be performed a minimum of 2 hours before collection of samples that will be used to measure cortisol concentrations. ( Am J Vet Res 2004;65:267–270)
Abstract
OBJECTIVE To identify clinical or clinicopathologic variables that can be used to predict a positive PCR assay result for Anaplasma phagocytophilum infection in equids.
ANIMALS 162 equids.
PROCEDURES Medical records were reviewed to identify equids that underwent testing for evidence of A phagocytophilum infection by PCR assay between June 1, 2007, and December 31, 2015. For each equid that tested positive (case equid), 2 time-matched equids that tested negative for the organism (control equids) were identified. Data collected included age, sex, breed, geographic location (residence at the time of testing), physical examination findings, and CBC and plasma biochemical analysis results. Potential predictor variables were analyzed by stepwise logistic regression followed by classification and regression tree analysis. Generalized additive models were used to evaluate identified predictors of a positive test result for A phagocytophilum.
RESULTS Total lymphocyte count, plasma total bilirubin concentration, plasma sodium concentration, and geographic latitude were linear predictors of a positive PCR assay result for A phagocytophilum. Plasma creatine kinase activity was a nonlinear predictor of a positive result.
CONCLUSIONS AND CLINICAL RELEVANCE Assessment of predictors identified in this study may help veterinarians identify equids that could benefit from early treatment for anaplasmosis while definitive test results are pending. This information may also help to prevent unnecessary administration of oxytetracycline to equids that are unlikely to test positive for the disease.
Abstract
Objective—To evaluate effects of trimethoprim-sulfamethoxazole (T/SMX) on thyroid function in dogs.
Animals—6 healthy euthyroid dogs.
Procedure—Dogs were administered T/SMX (14.1 to 16 mg/kg, PO, q 12 h) for 3 weeks. Blood was collected weekly for 6 weeks for determination of total thyroxine (TT4), free thyroxine (fT4), and canine thyroid- stimulating hormone (cTSH) concentrations. Schirmer tear tests were performed weekly. Blood was collected for CBC prior to antimicrobial treatment and at 3 and 6 weeks.
Results—5 dogs had serum TT4 concentrations equal to or less than the lower reference limit, and 4 dogs had serum fT4 less than the lower reference limit after 3 weeks of T/SMX administration; cTSH concentrations were greater than the upper reference limit in 4 dogs. All dogs had TT4 and fT4 concentrations greater than the lower reference limit after T/SMX administration was discontinued for 1 week, and cTSH concentrations were less than reference range after T/SMX administration was discontinued for 2 weeks. Two dogs developed decreased tear production, which returned to normal after discontinuing administration.
Conclusions and Clinical Relevance—Results suggest that administration of T/SMX at a dosage of 14.1 to 16 mg/kg, PO, every 12 hours for 3 weeks caused decreased TT4 and fT4 concentrations and increased cTSH concentration, conditions that would be compatible with a diagnosis of hypothyroidism. Therefore, dogs should not have thyroid function evaluated while receiving this dosage of T/SMX for > 2 weeks. These results are in contrast to those of a previous study of trimethoprim- sulfadiazine. (Am J Vet Res 2005;66:256–259)
Abstract
Objective—To determine the frequency of isolation and susceptibility patterns of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both that had or had not received antimicrobial treatment.
Design—Prospective study.
Animals—50 dogs.
Procedure—Dogs were allocated to 1 of 4 groups: healthy dogs (n = 13), dogs without otitis but with pyoderma (10), dogs with otitis but without pyoderma (11), and dogs with otitis and pyoderma (16). Bacteriologic culture of ear swab specimens was performed in all dogs. Bacteriologic culture of skin swab specimens was also performed in dogs with concurrent pyoderma. Isolates were identified as S schleiferi subsp schleiferi or S schleiferi subsp coagulanson the basis of growth and biochemical characteristics.
Results—S schleiferi was not isolated from any dogs with pyoderma only. Staphylococcus schleiferi subsp schleiferi was isolated from the ears of 2 healthy dogs, and the skin and ears of 2 dogs and the skin of 1 dog with otitis and pyoderma. Staphylococcus schleiferi subsp coagulans was isolated from the ears of 3 dogs with otitis only, and the ears of 6 dogs and the skin of 2 dogs with otitis and pyoderma. One of the S schleiferi subsp schleiferi isolates from ears, 2 of the S schleiferi subsp coagulansisolates from ears, and 1 of the S schleiferi subsp coagulansisolates from the skin were resistant to methicillin. One methicillin-resistant isolate from the ears and 1 from the skin were also resistant to fluoroquinolones.
Conclusions and Clinical Relevance—S schleiferi subsp schleiferiwas detected in healthy dogs and dogs with otitis and pyoderma. Methicillin-resistant and -susceptible S schleiferi subsp schleiferi and S schleiferi subsp coagulans were detected as the predominant organisms in dogs with otitis. ( J Am Vet Med Assoc 2005;227:928–931)
Abstract
Objective—To compare the pharmacokinetics of penicillin G and procaine in racehorses following IM administration of penicillin G procaine (PGP) with pharmacokinetics following IM administration of penicillin G potassium and procaine hydrochloride (PH).
Animals—6 healthy adult mares.
Procedure—Horses were treated with PGP (22,000 units of penicillin G/kg of body weight, IM) and with penicillin G potassium (22,000 U/kg, IM) and PH (1.55 mg/kg, IM). A minimum of 3 weeks was allowed to elapse between drug treatments. Plasma and urine penicillin G and procaine concentrations were measured by use of high-pressure liquid chromatography.
Results—Median elimination phase half-lives of penicillin G were 24.7 and 12.9 hours, respectively, after administration of PGP and penicillin G potassium. Plasma penicillin G concentration 24 hours after administration of penicillin G potassium and PH was not significantly different from concentration 24 hours after administration of PGP. Median elimination phase halflife of procaine following administration of PGP (15.6 hours) was significantly longer than value obtained after administration of penicillin G potassium and PH (1 hour).
Conclusions and Clinical Relevance—Results suggest that IM administration of penicillin G potassium will result in plasma penicillin G concentrations for 24 hours after drug administration comparable to those obtained with administration of PGP. Clearance of procaine from plasma following administration of penicillin G potassium and PH was rapid, compared with clearance following administration of PGP. (Am J Vet Res 2000;61:811–815)
