Multiple anthelmintic resistance in Trichostrongylus colubriformis

Following the failure of anthelmintic treatment to control an outbreak of trichostrongylosis in sheep, multiple resistance to levamisole and oxfendazole was confirmed in field strains of Trichostrongylus colubriformis at the CSIRO Pastoral Research Laboratory, Armidale. Resistance in Trichostrongylus spp to levamisole was also confirmed on an adjoining farm. From the results of an experiment where lambs were treated at the recommended dose rate with one or both anthelmintics, it was estimated that 32% of T. colubriformis were resistant to levamisole, 19% to oxfendazole, and 12% to both drugs. Simultaneous administration of levamisole and oxfendazole resulted in an additive anthelmintic effect. Naphthalophos (36.6 to 51.2 mg/kg) was 93% efficient against the multiple resistant strain. The similar histories of anthelmintic usage at the CSIRO Pastoral Research Laboratory and on the northern tablelands of New South Wales generally, suggest that multiple anthelmintic resistance in T. colubriformis may soon emerge as a problem on the northern tablelands.     

Pharmacokinetics, renal clearance and metabolism of ciprofloxacin following intravenous and oral administration to calves and pigs

The pharmacokinetics of ciprofloxacin, a quinoline derivative with marked bactericidal activity against gram-negative bacteria, was studied in calves and pigs following intravenous and oral administration. Ciprofloxacin was rapidly and well distributed in the body, exhibited a short elimination half-life of 2.5 h in both species, and was rapidly absorbed after oral administration (Tmax:2 to 3 h). The oral bioavailability in calves was 53 +/- 14% and for 1 pig 37.3%. The renal clearance of the unbound ciprofloxacin for both species was of the same order, indicated a predominantly tubular secretion pattern, and accounted for about 46% of the total drug elimination. No complete drug mass balance could be demonstrated. Small amounts of two metabolites were detected in the urine of calves, but not in pig urine.     

Bayesian zero-inflated predictive modelling of herd-level Salmonella prevalence for risk-based surveillance

The national control programme for Salmonella in Danish swine herds introduced in 1993 has led to a large decrease in pork-associated human cases of salmonellosis. The pork industry is increasingly focused on the cost-effectiveness of surveillance while maintaining consumer confidence in the pork food supply. Using national control programme data from 2003 and 2004, we developed a zero-inflated binomial model to predict which farms were most at risk of Salmonella. We preferentially sampled these high-risk farms using two sampling schemes based on model predictions resulting from a farm's covariate pattern and its random effect. Zero-inflated binomial modelling allows assessment of similarities and differences between factors that affect herd infection status (introduction), and those that affect the seroprevalence in infected herds (persistence and spread). Both large (producing greater than 5000 pigs per annum), and small herds (producing less than 2000 pigs per annum) were at significantly higher risk for infection and subsequent seroprevalence, when compared with medium sized herds (producing between 2000 and 5000 pigs per annum). When compared with herds being located elsewhere, being located in the south of Jutland significantly decreased the risk of herd infection, but increased the risk of a pig from an infected herd being seropositive. The model suggested that many of the herds where Salmonella was not detected were infected, but at a low prevalence. Using cost and sensitivity, we compared the results of our model based sampling schemes with those under the standard sampling scheme, based on herd size, and the recently introduced risk-based approach. Model-based results were less sensitive but show significant cost savings. Further model refinements, sampling schemes and the methods to evaluate their performance are important areas for future work, and these should continue to occur in direct consultation with Danish authorities.     

Bioactivation of aflatoxin B1 by turkey liver microsomes: responsible cytochrome P450 enzymes

1. A study was conducted to determine the cytochrome P450 enzymes responsible for the bioactivation of aflatoxin B1 into its epoxide form (AFBO) in turkey liver microsomes. 2. The strategies used included the measurement of prototype substrate activity for specific human P450s, use of selective inhibitors, determination of correlation between aflatoxin bioactivation and enzymatic activity of prototype substrates and the determination of immunoreactive proteins using antibodies against human P450s. 3. Enzymatic activity and immunoreactive proteins corresponding to the turkey orthologs CYP1A1, CYP1A2, CYP2A6 and CYP3A4 were detected, but not for the CYP2D6 ortholog. 4. The results of the inhibition and correlation studies strongly suggest that the turkey CYP2A6 ortholog and, to a lesser extent, the CYP1A1 ortholog, are involved in the bioactivation of aflatoxin B1 in turkey liver microsomes. 5. This is the first study reporting the role of CYP2A6 in the bioactivation of AFB1 in an avian species and the role of CYP1A1 in any species.     

Assessment of an ECG event recorder in healthy dogs in a hospital environment

Ambulatory electrocardiography techniques are superior to standard electrocardiography in evaluating rhythm disturbances in dogs with episodic weakness or collapse. Disadvantages include cumbersome equipment, short recording periods and an inherent delay in trace analysis. A small programmable cardiac event recorder with combined automatic and owner-triggered recording capability was evaluated in 13 healthy dogs in a hospital environment. The unit was well tolerated and produced diagnostic recordings directly to a personal computer, with useful information about continuous heart rate. It detects premature complexes, pauses and bradycardias according to programmed detection thresholds. These events were counted frequently but trace review revealed concerns regarding specificity. Recordings were often triggered by sinus arrhythmia, sinus tachycardia and unclassifiable rate changes rather than by clinically significant arrhythmias. Correct detection of ventricular ectopic complexes, a single supraventricular premature complex, sinus arrest and second-degree atrioventricular block occurred in individual dogs. Visual review of all automatically recorded events was essential and significantly increased the time required for event recording analysis. Manual recordings might be more useful and the overall results suggest that further studies are warranted to evaluate the system in clinical cases in the home environment.     

Obesity and diet affect glucose dynamics and insulin sensitivity in Thoroughbred geldings

Insulin resistance is considered a risk factor in obesity, laminitis, exertional rhabdomyolysis, and osteochondrosis. The objective was to use the minimal model to estimate glucose effectiveness (Sg) and insulin sensitivity (Si) in nonobese to obese horses initially adapted to forage only, then adapted to forage plus supplements rich in starch and sugar (SS) or fiber and fat (FF). Ten Thoroughbred geldings, with BCS of 5 (nonobese), 6 (moderately obese), and 7 to 8 (obese), were adapted to pasture and hay, allocated to two groups, and fed SS or FF in a switch-back design with 8 wk of adaptation. Modified frequent-sampling i.v. glucose tolerance tests were applied after adaptation to forage, SS, and FF. For the tolerance tests, horses were kept in stalls overnight and provided hay, and venous catheters were placed the next morning. Baseline samples were collected, 0.3 g of glucose/kg of BW was given i.v., and blood was sampled at 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, and 19 min. At 20 min, 30 mU of insulin/kg of BW was given, followed by sampling at 22, 23, 24, 25, 27, 30, 35, 40, 50, 60, 70, 80, 90, 100, 120, 150, and 180 min. Plasma was analyzed for glucose and insulin, and Si, Sg, acute insulin response to glucose, and the disposition index were calculated. Normality was tested using the Shapiro-Wilk statistic. Body condition effects were analyzed using a mixed model with repeated measures. Diet effects were analyzed using a Wilcoxon signed rank test. The Sg was higher in obese than nonobese (P = 0.003) and moderately obese (P = 0.007) horses; Si was lower in obese than nonobese (P = 0.008) horses, and acute insulin response to glucose was higher in obese than nonobese (P = 0.039) horses. Effects of diet were likely confounded by body condition, but horses had lower Si (P = 0.066) when fed SS compared with FF, especially when nonobese. In conclusion, the minimal model effectively estimated Sg, Si, acute insulin response to glucose, and disposition index in horses. Obese geldings were insulin-resistant and seemed to rely primarily on Sg for glucose disposal. Feeding a diet rich in sugar and starch decreased insulin sensitivity of horses. Maintenance of body condition and avoidance of grain-based meals rich in sugar and starch would be beneficial to decrease the risk of developing insulin resistance and associated metabolic syndromes in horses, especially for horses at risk for these syndromes.     

The effect of topical tripeptide-copper complex on healing of ischemic open wounds

OBJECTIVE: To evaluate the effects of topical glycyl-L-histidyl-L-lysine tripeptide-copper complex (TCC; Iamin 2% Gel; Procyte Corporation, Redmond, WA) on healing in ischemic open wounds. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Twenty-four adult male Sprague-Dawley rats. METHODS: Rats were divided into 3 groups: topical TCC, topical TCC vehicle (hydroxypropyl-methylcellulose), and no treatment (control). Six-mm-diameter, full-thickness wounds were created within an ischemic bipedicle skin flap on the dorsum of each rat. Each day, for 13 days, wound margins were traced, and the TCC and TCC vehicle groups were treated topically. Tracings were scanned, and wound perimeter and area were calculated. On days 6, 10, and 13, selected wounds were biopsied and analyzed for tumor necrosis factor alpha (TNF-alpha) and matrix metalloproteinases (MMP) 2 and 9. RESULTS: A significant decrease in wound area was seen in the TCC group, but not the vehicle group, when compared with the control group on days 3 to 5, 6 to 9, and 11 to 13 and when TCC was compared with TCC vehicle on days 3 and 9. On day 13, initial wound area had decreased by 64.5% in the TCC group, 45.6% in the vehicle group, and 28.2% in the control group. On days 6, 10, and 13, TCC-treated wounds contained significantly lower concentrations of TNF-alpha and MMP-2 and MMP-9 than control wounds. CONCLUSION: Topical TCC resulted in accelerated wound healing in ischemic open wounds. CLINICAL RELEVANCE: Topical TCC is an effective stimulant of healing of ischemic open wounds in rats and may have an application for the treatment of chronic wounds in other species. Clinical evaluation of topical TCC is warranted.     

Epidemiology of Salmonella enterica serovars enteritidis and Typhimurium in animals and people in Scotland between 1990 and 2001

Two serovars of salmonella which are currently of particular importance in both human and animal infections are Salmonella enterica serovars Enteritidis phage type 4 (PT4) and Typhimurium definitive type 104 (DT104). This paper describes the trends in the relationships between the levels of infection of people and a range of farm animal species with these two serovars and explores some of the reasons behind them. In 1996, there was a peak of 520 reports of S Typhimurium DT104 infection in people in Scotland, but the number has decreased every year since, to 96 in 2001. In cattle the incidence of S Typhimurium DT104 also peaked in 1996, with 138 incidents, and it has similarly decreased every year to 2001 when there were 10 reported incidents. Similar declines have been observed in its incidence in sheep and pigs. In people the number of reports of S Enteritidis PT4 peaked in 1997 at 1684 and then declined to 457 in 2001. In chickens, the number of reports of S Enteritidis PT4 peaked in 1998 at 34 incidents, but no incidents were reported in the following three years.     

Idiopathic granulomatous pneumonia in seven horses

The history, clinical signs and pathological findings in seven adult horses with histologically confirmed idiopathic granulomatous disease, primarily of the lungs, are reviewed. They ranged in age from eight to 21 years, five were geldings and two were females, they belonged to five breeds and there were no seasonal or geographical associations. The primary clinical signs were chronic weight loss, exercise intolerance and respiratory distress which did not respond to conventional treatment. The most consistent physical findings were depression, anorexia, tachycardia, tachypnoea and adventitious lung sounds. Thoracic radiographs revealed a diffuse, structured, nodular, interstitial pulmonary pattern in each horse. Haematological measurements suggested a chronic inflammatory process and the cytology of transtracheal washes was consistent with a mild suppurative inflammation. Idiopathic granulomatous pneumonia was confirmed histologically in each of the horses, either postmortem or by a lung biopsy. The horses responded poorly to medical treatment and only one of three treated horses is still alive.