A survey of nematode control measures used by sheep farmers and of anthelmintic resistance on their farms Part 2: South Island excluding the Nelson region

Forty-three randomly selected farms located throughout South Island, excluding the Nelson region, were surveyed for anthelmintic usage and for sheep nematodes resistant to anthelmintics.

Most farmers had used both benzimidazole and non-benzimidazole broad-spectrum drenches on their properties in previous years.

Sheep were being drenched, on average, 5.6 times within their first year of life but much less frequently thereafter. Commercial interests played the dominant role in helping farmers formulate their drenching policies. On each farm 24 numbered ewe replacement lambs, born during the spring of 1980, were sampled for faeces at the beginning of the trial to provide material for egg counts and larval cultures. The lambs were weighed and divided into three groups of eight. One group received thiabendazole (TBZ) at 66 mg/kg, the second levamisole (LEV) at 8 mg/kg while the third remained untreated as controls. All were resampled 4 to 10 days later.

On 32 (88%) of the 40 farms where drenching trials were successfully carried out during autumn 1981, the faecal egg count depression (FECD) following treatment with either drench was 100%. On one farm TBZ was less than 100% effective as gauged by FECD. LEV proved to be less than 100% effective on 7 farms. On one farm the FECD was less than 80%, on 2 between 90% and 95% and on 4 between 95% and 99%.     

Veterinary practice and occupational health

Summary

The prevalence of allergy, lung function disorders, and bronchial hyperreactivity was studied in 102 Dutch veterinarians, subdivided into five professional groups (predominantly working with either swine, cattle, poultry, companion animals, or as a non‐practitioner). The mean age of the participants was 43 years; 6 participants were females. Twenty‐two per cent of the participants were overweight, and relatively more non‐practitioners than practitioners were overweight. Approximately 23% of the vets reported complaints of prolonged fatigue. The data suggest a relationship between complaints of prolonged fatigue and a more than average number of daily working hours. Only a small proportion of vets were sensitized against several allergens. There were no significant differences in prevalence of distinct lung function disorders or bronchial hyperreactivity between professional groups. It is hypothesized that the respiratory complaints (chronic coughing, chronic phlegm production, stuffed nose, sneezing) reported by the vets predominantly working in swine and/or poultry practice could be caused by irritation and/or inflammation of the first part of the trachea‐bronchial tree that has no measurable and permanent consequences for changes in lung function or increased bronchial hyperreactivity. The results of a skin test against allergens and determination of allergen‐specific IgE in blood indicated that the respiratory complaints were probably not related to allergy against the panel of allergens tested.     

A survey of Culicoides developmental sites on a farm in northern Spain,with a brief review of immature habitats of European species

Culicoides species (Diptera: Ceratopogonidae) belonging to the Obsoletus and Pulicaris groups are considered to be the main vectors of bluetongue virus (BTV) in non Mediterranean Europe. Selected terrestrial microhabitats (n = 17) on a farm in northern Spain were sampled repeatedly over a year-long period and characterized for use by Culicoides species for immature development. Concurrent use of CDC light traps showed the presence of 37 species and 66,575 specimens of adult Culicoides. A total of 28 species and 11,396 individuals emerged from laboratory-maintained soil samples. Culicoides obsoletus and Culicoides scoticus (pooled as Obsoletus complex) were particularly abundant (comprising 58.6% and 74.5% of the total collections in light traps and emergence traps respectively). Potential key vectors of animal viruses (such as BTV) were found in two main terrestrial types of microhabitats. In the case of C. obsoletus, different types of manure (old and composted manure, manure mixed with organic matter, and fresh manure) produced most of the specimens. In contrast, larvae of C. scoticus and Culicoides lupicaris were associated with soil substantially comprised of rotting leaf litter that included the parasitic plant Lathraea clandestina. Several species, Culicoides festivipennis, Culicoides punctatus and Culicoides brunnicans, were very common in mud at pond margins. Indeed, pond microhabitats and runoff below barn rooflines supported the greatest species richness. In the pond habitat, 49.4% of Culicoides specimens emerged from mud at the water edge, as opposed to 50 cm above (32.4%) and 1 meter above waterline (18%). Similar species richness, but statistically significant differences in abundance, were observed among the four pond microhabitats. Overall, the majority of the specimens were found in the upper layer (0–3 cm), except in manure, where they preferred deeper layers (>6 cm). Maximum peaks of abundance occurred in both light traps and soil samples in summer months, whereas increased captures in autumn were noticed only in light traps. Both trapping systems failed to collect adult Culicoides midges in the coldest months of December, January and February. The literature on immature habitats of species suspected in BTV transmission in Europe, the Pulicaris group and particularly the Obsoletus group, is briefly reviewed.     

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in steeplechase starts in the United Kingdom (2001–2009)

The objective of this study was to identify risk factors for superficial digital flexor (SDF) tendinopathy in Thoroughbred horses in steeplechase races in the United Kingdom. Potential risk factors for SDF tendinopathy were studied between 1st January 2001 and 31st December 2009 using a cohort study design with 648 injuries sustained in 102,894 starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building.In the final multivariable model, 12 statistically significant risk factors were identified. Variables that increased the odds of SDF tendinopathy included firmer going, increased horse age, and racing in the summer compared to other seasons. Variables that decreased the odds included having a higher official rating and the number of starts in the preceding days.Fewer and different risk factors were identified than in an equivalent model of SDF tendinopathy in hurdle racing, highlighting potential differences between these disciplines. Further collection of training and racecourse information would be beneficial and may help to explain further some of the associations identified in this study. The results will facilitate the development of strategies to improve overall safety of horses in UK steeplechase racing.     

Pharmacokinetics of Enrofloxacin and Its Metabolite Ciprofloxacin after Intramuscular Administration of Enrofloxacin in Goats

The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats after a single intramuscular administration of enrofloxacin at 2.5 mg/kg body weight. The plasma concentrations of enrofloxacin and ciprofloxacin were determined simultaneously by a HPLC method. The peak concentrations (C _max) of enrofloxacin (1.13 g/ml) and ciprofloxacin (0.24 g/ml) were observed at 0.8 and 1.2 h, respectively. The elimination half-life (t _1/2), volume of distribution (V _d(area)), total body clearance (Cl_B) and mean residence time (MRT) of enrofloxacin were 0.74 h, 1.42 L/kg, 1329 ml/h per kg and 1.54 h, respectively. The t _1/2, area under the plasma concentration–time curve (AUC) and the MRT of ciprofloxacin were 1.38 h, 0.74 g h/ml and 2.73 h, respectively. The metabolic conversion of enrofloxacin to ciprofloxacin was appreciable (36%) and the sum of the plasma concentrations of enrofloxacin and ciprofloxacin was maintained at or above 0.1 g/ml for up to 4 h. Enrofloxacin appears to be useful for the treatment of goat diseases associated with pathogens sensitive to this drug.     

Long-term outcome of gonadectomy performed at an early age or traditional age in dogs

OBJECTIVE: To determine long-term results and complications of gonadectomy performed at an early age (prepubertal) or at the traditional age in dogs. DESIGN: Cohort study. ANIMALS: 269 dogs from animal shelters. PROCEDURE: Dogs that underwent gonadectomy were allotted to 2 groups on the basis of estimated age at surgery (traditional age, > or =24 weeks old; prepubertal, < 24 weeks old). Adoptive owner information was obtained from shelter records, and telephone interviews were conducted with owners to determine physical or behavioral problems observed in the dogs since adoption. Follow-up information was obtained from attending veterinarians for dogs with complex problems or when owners were uncertain regarding the exact nature of their dog's problem. RESULTS: Prepubertal gonadectomy did not result in an increased incidence of behavioral problems or problems associated with any body system, compared with traditional-age gonadectomy, during a median follow-up period of 48 months after gonadectomy. Rate of retention in the original adoptive household was the same for dogs that underwent prepubertal gonadectomy as those that underwent traditional-age gonadectomy. Infectious diseases, however, were more common in dogs that underwent prepubertal gonadectomy. CONCLUSIONS AND CLINICAL IMPLICATIONS: With the exception of infectious diseases, prepubertal gonadectomy may be safely performed in dogs without concern for increased incidence of physical or behavioral problems during at least a 4-year period after gonadectomy.     

Effects of anti-inflammatory drugs on lipopolysaccharide-challenged and -unchallenged equine synovial explants

OBJECTIVE: To evaluate the effects of anti-inflammatory drugs on lipopolysaccharide (LPS)-challenged and -unchallenged equine synovial membrane in terms of production of prostaglandin E2 (PGE2) and hyaluronan, viability, and histomorphologic characteristics. SAMPLE POPULATION: Synovial membranes were collected from the carpal, tarsocrural, and femoropatellar joints of 6 adult horses. PROCEDURE: Synovial membranes from each horse were minced and pooled and explants were treated with one of the following: no drug (control), drug, LPS alone, or LPS and drug. Treatment drugs were phenylbutazone (PBZ), flunixin meglumine (FNX), ketoprofen (KET), carprofen (CRP), meloxicam (MEL), low-concentration methylprednisolone (METH), high-concentration METH, dimethyl sulfoxide (DMSO), or an experimental COX-2 inhibitor (dissolved in DMSO). Following 48 hours of culture, medium was assayed for PGE2 and hyaluronan concentration. Synovial explants were assessed for viability and histomorphologic characteristics. RESULTS: For the LPS-challenged explants, PBZ, FNX, KTP CRF MEL, and low-concentration METH suppressed PGE2 production, compared with LPS challenge alone. Only MEL suppressed PGE2 production from LPS-challenged explants, compared with unchallenged explants. Synovial explants maintained > 90% viability and there was no significant difference in viability or hyaluronan production among explants. Histomorphologic scores were significantly decreased for explants treated with low-concentration METH or DMSO. CONCLUSIONS AND CLINICAL RELEVANCE: PBZ, FNX, KTP, CRFP MEL, and low-concentration METH suppressed PGE2 production in LPS-challenged explants. Meloxicam appeared to have more selective suppression of COX-2 activity. Histomorphologic scores suggest detrimental effects of METH, DMSO, and the experimental COX-2 inhibitor. Commonly used nonsteroidal anti-inflammatory drugs suppress induced synovial membrane PGE2 production without detrimental effects on synovial membrane viability and function.     

Uptake and excretion of organochlorine compounds in neonatal calves

Intestinal absorption mechanisms of young calves change rapidly during the first 24 h postpartum and subsequently effect the absorption efficiencies of a wide range of compounds. This study was conducted to determine absorption efficiencies of (p,p'-dichlorodiphenyl)dichloroethylene (DDE), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153), and 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) when administered in colostrum to neonatal calves. Four male Holstein calves were given a single oral dose containing 100 mg each of DDE, PCB-153, and OCDD either 1 h (n = 2) or 65 h (n = 2) postpartum to determine whether time of exposure influenced the rate or extent of absorption. Another male calf received 100 mg each of DDE and OCDD 1 h postpartum. One gram of chromic oxide (Cr2O3) was administered as a digestion marker to dosed calves. Two male calves, receiving only colostrum, served as controls. Serum IgG concentrations indicated that the 1-h calves absorbed 20 to 37% of the ingested IgG and 65-h calves < 2%; therefore, the gut absorption mechanisms had changed by 65 h. Plasma DDE, PCB-153, and OCDD profiles did not differ based on time of exposure, suggesting that their mechanism of absorption was not influenced by the changing gut. Trapezoidal area under the curve to the last time point values indicated that, during the trial, relative plasma organochlorine concentrations amounted to PCB-153 > DDE > OCDD. Tissue concentrations were similar across treatment groups, with DDE and PCB-153 residues concentrating in adipose tissue and OCDD in the liver. Absorption efficiencies, calculated from fecal recoveries, were >97%, >74%, and >72% for DDE, PCB-153, and OCDD, respectively. These doses of DDE, PCB-153, and OCDD (2.5 +/- 0.1 mg/kg) did not produce signs of toxicosis based on detailed clinical observations, serum clinical chemistry, and gross and histological observations at necropsy. The results of this study indicate that DDE, PCB-153, and OCDD were absorbed and distributed similarly in calves exposed 1 or 65 h postpartum and did not induce toxicosis when administered in combination at these concentrations.     

Zinc and copper status in ewes supplemented with sulfate- and amino acid-complexed forms of zinc and copper

Thirty 6-yr-old Targhee ewes were randomly allotted to one of five supplemental treatments to evaluate supplementation effects on liver and fecal Zn and Cu concentrations and serum alkaline phosphatase activity: 1) control, 2) Zn complex, 3) Zn and Cu (ZnCu) complex, 4) Zn sulfate, and 5) ZnCu sulfates. Supplements were administered daily in gelatin capsules for 56 d. Liver biopsies and serum samples were collected every 14 d starting on d 0. Supplemental Zn and Cu levels were formulated to provide 90 mg/kg Zn and 10 mg/kg Cu, respectively, on a daily dry matter intake basis. Form (complex vs sulfate) x type (Zn vs ZnCu) interactions were not detected (P > 0.35). Therefore, contrast statements were used to make the following treatment comparisons: 1) control vs supplement, 2) Zn vs ZnCu, and 3) complex vs sulfate. Ewe BW at the end of the study (P = 0.09) and ewe BW change from beginning to end of the study (P = 0.07) were greater for supplemented than control ewes. Body weight and BW change did not differ between sulfate and complex (P > 0.39) or Zn- and ZnCu- (P > 0.40) supplemented ewes. Liver Cu concentrations did not differ (P = 0.41) between control and supplemented ewes. Liver Cu concentrations were higher (P < 0.10) for ewes supplemented with ZnCu than Zn and complex than sulfate forms of supplement. Liver Zn concentration tended (P = 0.13) to be higher in ZnCu than Zn-supplemented ewes. Liver and fecal Zn concentration were higher (P < 0.06) in ewes fed complex than sulfate supplements. However, serum alkaline phosphatase activity tended (P = 0.12) to be greater in ewes fed sulfate than complex supplements. Supplementing mature ewes with complexed minerals resulted in higher concentrations of Zn and Cu in the liver. In addition, supplemental Cu tended to increase concentrations of Zn in the livers of ewes; however, high levels of supplemental Zn did not negatively impact liver Cu concentrations.     

Effectiveness of GnRH plus prostaglandin F2alpha for estrus synchronization in cattle of Bos indicus breeding

Postpartum and lactating crossbred cows containing a percentage of Bos indicus breeding at three locations were studied to determine the efficacy of GnRH + PGF2alpha combinations for synchronization of estrus and(or) ovulation. Cows were equally distributed to each of three treatments by body condition score at the start of the experiment (d 0). All cows received 100 microg of GnRH on d 0 and 25 mg of PGF2alpha 7 d later. The three insemination protocols included 1) AI 12 h after exhibiting estrus during d 7 to 12 of the experiment (Select-Synch; n = 197); 2) timed-AI + 100 microg of GnRH on d 9 of the experiment (CO-Synch; n = 193); 3) AI 12 h after exhibiting estrus during d 7 to 10 of the experiment. Cows not exhibiting estrus by d 10 were timed-AI and injected with 100 microg of GnRH on d 10 of the experiment (Hybrid-Synch; n = 200). The percentage of cows exhibiting estrus during d 7 to 12 of the experiment was lower (P < 0.05) for CO-Synch (17.6%) cows than for Select-Synch or Hybrid-Synch (45.2 and 33.0%, respectively) cows, which did not differ (P > 0.05). For the Select-Synch and Hybrid-Synch cows that exhibited estrus during d 7 to 10 of the experiment and were artificially inseminated, conception rates were similar across treatments (50.5%). Pregnancy rates were greater (P < 0.01) for CO-Synch and Hybrid-Synch (31.0 and 35.5%, respectively) cows than for Select-Synch (20.8%) cows. A greater (P < 0.01) percentage of cycling cows became pregnant (34.5%) than noncycling cows (25.9%) across all treatments. The CO-Synch and Hybrid-Synch synchronization protocols resulted in greater pregnancy rates compared with the Select-Synch protocol in postpartum and lactating crossbred cows containing a percentage of Bos indicus breeding.