Pharmacokinetics of guaifenesin following administration of multiple doses to exercised Thoroughbred horses

Guaifenesin is an expectorant commonly used in performance horses to aid in the clearance of mucus from the airways. Guaifenesin is also a centrally acting skeletal muscle relaxant and as such is a prohibited drug with withdrawal necessary prior to competition. To the authors' knowledge, there are no reports in the literature describing single or multiple oral administrations of guaifenesin in the horse to determine a regulatory threshold and related withdrawal time. Therefore, the objective of the current study was to describe the pharmacokinetics of guaifenesin following oral administration in order to provide data upon which appropriate regulatory recommendations can be established. Nine exercised Thoroughbred horses were administered 2 g of guaifenesin orally BID for a total of five doses. Blood samples were collected immediately prior to drug administration and at various times postadministration. Serum guaifenesin concentrations were determined and pharmacokinetic parameters calculated. Guaifenesin was rapidly absorbed (T_max of 15 min) following oral administration. The C_max was 681.3 ± 323.8 ng/mL and 1080 ± 732.8 following the first and last dose, respectively. The serum elimination half‐life was 2.62 ± 1.24 h. Average serum guaifenesin concentrations remained above the LOQ of the assay (0.5 ng/mL) by 48 h postadministration of the final dose in 3 of 9 horses.     

The pharmacodynamics of thiopental, medetomidine, butorphanol and atropine in beagle dogs

This study evaluated the quality of anaesthesia and some of the haemodynamic effects induced by a combination of thiopental, medetomidine, butorphanol and atropine in healthy beagle dogs ( n  = 12). Following premedication with atropine (ATR, 0.022 mg/kg intravenously (i.v.)) and butorphanol (BUT, 0.22 mg/kg i.v.), medetomidine (MED, 22 μg/kg intramuscularly (i.m.)) was administered followed in 5 min by thiopental (THIO, 2.2 mg/kg i.v.). Heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MBP) were monitored continuously with an ECG and direct arterial blood pressure monitor. Atipamezole (ATI, 110 μg/kg i.v.) was administered to half of the dogs ( n  = 6) following surgery to evaluate the speed and quality of arousal from anaesthesia. Anaesthesia was characterized by excellent muscle relaxation, analgesia and absence of purposeful movement in response to surgical castration. Arousal following antagonism of mede­tomidine was significantly faster ( P  < 0.05) than in unantagonized dogs. Recoveries were smooth but recovery times following atipamezole administration were highly variable among dogs (sternal time range 6–38 min, standing time range 9–56 min). Medetomidine caused a significant ( P  < 0.05) increase in SBP, DBP and MBP. Atropine prevented the medetomidine induced bradycardia. In conclusion, this combination provided adequate surgical anaesthesia in healthy beagle dogs. At the dosages used in this study, it seems prudent that this combination should be reserved for dogs free of myocardial disease.     

Effects of methylprednisolone acetate and glucosamine on proteoglycan production by equine chondrocytes in vitro

OBJECTIVE: To evaluate the effects of methylprednisolone acetate (MPA) on proteoglycan production by equine chondrocytes and to investigate whether glucosamine hydrochloride modulates these effects at clinically relevant concentrations. SAMPLE POPULATION: Articular cartilage with normal gross appearance from metacarpophalangeal and metatarsophalangeal joints of 8 horses (1 to 10 years of age). PROCEDURES: In vitro chondrocyte pellets were pretreated with glucosamine (0, 1, 10, and 100 microg/mL) for 48 hours and exposed to MPA (0, 0.05, and 0.5 mg/mL) for 24 hours. Pellets and media were assayed for proteoglycan production (Alcian blue precipitation) and proteoglycan content (dimethylmethylene blue assay), and pellets were assayed for DNA content. RESULTS: Methylprednisolone decreased production of proteoglycan by equine chondrocytes at both concentrations studied. Glucosamine protected proteoglycan production at all 3 concentrations studied. CONCLUSIONS AND CLINICAL RELEVANCE: Methylprednisolone, under noninflammatory conditions present in this study, decreased production of proteoglycan by equine chondrocytes. Glucosamine had a protective effect against inhibition of proteoglycan production at all 3 concentrations studied. This suggested that glucosamine may be useful as an adjunct treatment when an intra-articular injection of a corticosteroid is indicated and that it may be efficacious at concentrations relevant to clinical use.     

Coagulation values in normal ferrets (Mustela putorius furo) using selected methods and reagents

Background: Accurate determination of commonly measured coagulation values would be useful in the diagnosis and management of coagulopathies in domestic ferrets (Mustela putorius furo). We are unaware of reports of coagulation times in this species. Objectives: The purpose of this study was to determine reference values for prothrombin time (PT), activated partial thromboplastin time (PTT), fibrinogen concentration, and antithrombin (AT) activity in ferrets using selected methods and reagents. Methods: Blood samples obtained from 18 clinically healthy ferrets were anticoagulated with 0.129 M sodium citrate in a ratio of 9 parts blood to 1 part anticoagulant. Plasma was collected and stored at -70 degrees C until analysis. PT and PTT were measured with a fibrometer and with an ACL 3000 automated system. PTT was measured with and without the addition of ellagic acid. Fibrinogen was assayed by a turbidimetric method. AT activity was determined using a chromogenic assay and pooled ferret plasma (100% activity). Differences in methods and reagents were evaluated using paired t tests. Results: PT was significantly longer using the fibrometer (12.3+/-0.3, 11.6-12.7 seconds) compared with the ACL (10.9+/-0.3, 10.6-11.6 seconds) (P<.01). PTT was not significantly different with the fibrometer (18.7+/-0.9, 17.5-21.1 seconds) vs the ACL (18.1+/-1.1, 16.5-20.5 seconds), but was significantly longer on both analyzers when ellagic acid was added (fibrometer 20.4+/-0.8, 18.9-22.3 seconds; ACL 20.0+/-1.0, 18.6-22.1 seconds) (P<.01). Fibrinogen concentration was 107.4+/-19.8 mg/dL (90.0-163.5 mg/dL), and AT activity was 96%+/-12.7% (69.3-115.3%). Conclusion: These coagulation results for healthy ferrets will be useful in the evaluation of ferrets with coagulopathies, provided similar reagents and methods are used.     

STRESS FRACTURE OF THE SCAPULA IN TWO HORSES

Stress fracture of the scapula in two horses is described. Both horses had a history of acute lameness after strenuous exercise. Using elective nuclear scintigraphy focal increased radiopharmaceutical uptake in the affected scapula consistent with a fracture was identified. Standing radiography was nondiagnostic in both horses. Ultrasonographic findings in one horse were consistent with a minimally displaced incomplete fracture. Both horses were treated conservatively and returned to train and race successfully postinjury. Veterinary     

Use of successive dynamic videoendoscopic evaluations to identify progression of recurrent laryngeal neuropathy in three horses

CASE DESCRIPTION: 3 racehorses were evaluated because of poor performance or abnormal noise originating from the upper portion of the respiratory tract. CLINICAL FINDINGS: During maximal exercise, initial dynamic videoendoscopy of the upper respiratory tract revealed complete arytenoid cartilage abduction in 2 horses and incomplete but adequate abduction of the left arytenoid cartilage in 1 horse. Subsequent exercising endoscopic evaluation revealed severe dynamic collapse of the left arytenoid cartilage and vocal fold in all 3 horses. TREATMENT AND OUTCOME: 2 horses were treated with prosthetic left laryngoplasty and raced successfully. One horse was retired from racing. CLINICAL RELEVANCE: Idiopathic laryngeal hemiplegia can be a progressive disease. Successive dynamic videoendoscopic upper airway evaluations were used to confirm progression of left laryngeal hemiplegia in these 3 horses. Videoendoscopy of the upper respiratory tract during exercise should be considered as part of the clinical evaluation of horses with signs of upper respiratory tract dysfunction.     

Characterization of the renal portal system of the common green iguana (Iguana iguana) by digital subtraction imaging.

Digital subtraction angiography was used to map the venous blood flow from the pelvic limb and the tail in the common green iguana (Iguana iguana). The majority of blood returning from the pelvic limb bypassed the kidney and entered the general circulation, whereas venous blood flow from the tail entered the renal portal circulation. No evidence was found of a renal portal valve.     

Petroleum hydrocarbons: uptake and discharge by the marine mussel Mytilus edulis

The common marine mussel Mytilus edulis has been observed to rapidly take up mineral oil, [(14)C]heptadecane, 1,2,3,4-tetrahydronaphthalene, [(14)C]toluene, [(14)C]naphthalene, and [(3)C]3,4-benzopyrene from seawater solution. This species of mussel did not metabolize any of these compounds, and transfer of the mussel to fresh seawater, after exposure to the hydrocarbon in solution, resulted in the discharge of most of the hydrocarbon, although significant amounts remained (between 1 and 400 micrograms per mussel). The nontoxic paraffinic hydrocarbons mineral oil and heptadecane were taken up (10 milligrams per mussel) to a much greater extent than the aromatic hydrocarbons (2 to 20 micro-grams per mussel).     

红莲型细胞质雄性不育恢复系特青和珍汕97的恢复性遗传分析

以花粉育性和小穗育性为指标 ,对红莲型细胞质雄性不育系丛广 4 1 A、恢复系特青以及丛广 4 1 A/特青的 F1 、F2 ,丛广 4 1 A∥丛广 4 1 B/特青的三交 F1 等亲本和杂种群体的育性调查分析结果表明 :特青具有 1个主效的显性恢复基因 ,该基因暂命名为 Rf-5(t) ;对红莲型细胞质雄性不育系丛广 4 1 A、恢复系珍汕 97以及丛广 4 1 A/珍汕 97的 F1 、F2 ,丛广 4 1 A∥丛广 4 1 B/珍汕 97的三交 F1 等亲本和杂种群体的育性调查分析结果表明 :在红莲型细胞质雄性不育和恢复性上 ,这 2个亲本之间可能有两类基因 ,其中一类控制着圆败型花粉 ,另一类控制着典败型花粉 ;对丛广 4 1 A∥珍汕 97/特青三交 F1 的育性调查分析结果表明 :珍汕 97具有一个与 Rf-5(t)等位的恢复基因