Risk factors for epidemic respiratory disease in Norwegian cattle herds

An epidemic of acute respiratory disease associated with bovine respiratory syncytial virus (BRSV) occurred during the winter and spring of 1995 in two neighbouring veterinary districts in the south-eastern part of Norway.The objective of this study was to describe the time course of the outbreak associated with BRSV in the cattle herds, and to determine the association between selected herd factors and the risk of experiencing a herd outbreak of acute respiratory disease.Data from 431 cattle herds on the dates of disease occurrence, location of the farms, herd size, age profile and production type were collected retrospectively for 1995. The risk of acute respiratory disease occurring in a cattle herd was related to the herd size as well as the type of production, with an expressed interaction between these two variables. From the Cox proportional-hazards model, the risk of a herd outbreak in a mixed herd of 20 animals was estimated to be 1.7-times greater than in a dairy herd and 3.3-times greater than a beef herd (reference category) of a comparable size. On increasing the herd size to 50 animals, the risk increased 1.3-fold for a mixed herd, 3.3-fold for a dairy herd, and 2.1-fold for a beef herd, compared to the risk for a corresponding type of herd of 20 animals.     

Efficacy of doramectin against naturally acquired nematode infection in Iberian swine

Studies were carried out to determine the therapeutic efficacy of doramectin, administered intramuscularly at a dose of 300 microg/kg live weight, against naturally acquired helminths of extensively farmed Iberian pigs. The first study (slaughter study) evaluated, through necropsy of the study animals, the product's efficacy against gastrointestinal and pulmonary nematodes (Ascaris suum, Oesophagostomum dentatum and Metastrongylus sp.) whilst the second, faecal egg count reduction study, (FECR study) evaluated the drug's efficacy only against gastrointestinal helminths (A. suum, Trichuris suis and Oesophagostomum sp.).The first study used 20 animals divided into two equal groups of 10 on the basis of body weight and faecal egg count. One group constituted saline treated controls and the other was doramectin treated. On Day 14 post treatment half of the animals in each group were necropsied and the number of parasites present counted. On Day 15 the remaining half of each group underwent the same procedure. The second study was carried out with 40 animals divided equally into two groups of 20. This study determined the effect of doramectin treatment on faecal egg counts as an indicator of parasite burden.The first study demonstrated an efficacy of 100% against adult Metastrongylus sp. and A. suum, whilst the efficacy against O.dentatum was 96.3%. The second study indicated that at Day 21 post treatment there was a 100% reduction in egg counts in faeces in comparison to untreated controls.     

Spontaneous production of nitric oxide (NO), prostaglandin (PGE2) and neutral metalloproteinases (NMPs) in media of explant cultures of equine synovial membrane and articular cartilage from normal and osteoarthritic joints

Nitric oxide (NO), prostaglandin E2 (PGE2), and the activity of neutral metalloproteinases (NMPs) were measured in conditioned media of equine synovial membrane and articular cartilage explant cultures from horses with normal joints (n = 7) and from horses affected with moderate (n = 7) or severe osteoarthritis (n = 14) as judged by macroscopic appearance. Normal articular cartilage appeared glossy and bluish-white, was of normal thickness and showed no evidence of discolouration, fibrillation or other cartilage discontinuity. Slight discolouration and fibrillation or minor clefts of the cartilage were considered as moderate OA, whereas erosions of articular cartilage down to the subchondral bone were considered as cases of severe OA. Explant cultures of equine synovial membrane and articular cartilage released the local mediators, NO and PGE2, as well as detectable levels of NMP activity into culture media. Concentrations of NO were higher in articular cartilage explants compared to synovial membrane explants, whereas concentrations of PGE2 were higher in synovial membrane explants. The NMPs with collagenolytic activities were similar in both explant cultures, whereas gelatinolytic activities were higher in synovial membrane explant cultures and caseinolytic activities were generally higher in articular cartilage explant cultures. Furthermore it was shown that concentrations or enzyme activities increased according to the severity of disease of the joints. Concentrations for NO, collagenolytic and gelatinolytic NMPs were relatively stable, whereas PGE2 and caseinolytic NMP concentrations increased over time in culture.     

Cytotoxicity in pig hepatocytes induced by 8-quinolinol, chloramine-T and natamycin

The potential cytotoxic effects of the compounds 8-quinolinol, chloramine-T and natamycin have been studied in isolated pig hepatocytes. The relative cytotoxicity of these compounds was evaluated on the basis of the leakage of cytosolic lactate dehydrogenase (LDH), 3-(4,5 dimethyl)thiazol-2-yl,-2,5-diphenyl tetrazolium bromide (MTT) reduction by mitochondrial dehydrogenases, uptake of neutral red (NR) by cytosolic lysosomes, glutathion (GSH) depletion and oxidized glutathion (GSSG) efflux after 24 h exposure. Evaluation of the 20%, 50% and 80% reduced absorbance data obtained from the parameters NR20, NR50, and NR80, and MTT20, MTT50 and MTT80 enabled us to rank these compounds in decreasing order of cytotoxicity: 8-quinolinol > natamycin > chloramine-T. Also for the parameters LDH and GSH, chloramine-T appears to be less cytotoxic than natamycin and 8-quinolinol. Our study demonstrated that pig hepatocytes may be a useful model for examining cytotoxic events of drugs to be used in pigs, therefore avoiding possible extrapolation problems due to species differences.     

Effects of repeat fenbendazole treatment in dairy calves with giardiosis on cyst excretion, clinical signs and production

In this 90-day study, 60 male Holstein dairy calves were experimentally infected with Giardia duodenalis. Calves were randomly blocked by weight into treatment (N=30) and placebo (N=30) groups. Beginning on study Day 0, calves in the treatment group were administered an oral dose of 5mg/kg of fenbendazole once daily for three consecutive days. Calves in the placebo group received a daily oral treatment of 5 ml of saline for 3 days. These treatments were repeated on Days 30 and 60 of the study. Fecal samples were collected from calves once per week and examined for the presence of Giardia cysts. Calves were monitored daily for clinical signs of intestinal disease and all episodes of diarrhea recorded. Calves were weighed once per week and total feed intake, on a dry matter basis, was calculated daily. Following each treatment, the number of calves shedding Giardia cysts in the fenbendazole group was reduced (p<0.001) compared to the saline group. Also, calves in the fenbendazole group had fewer cysts (p<0.05) detected in their feces following treatment compared with calves that received saline. Within 2 weeks post treatment, the number of infected animals and fecal Giardia cysts returned to placebo levels. This pattern of reinfection was consistent after every treatment period. Calves receiving fenbendazole had fewer total days with diarrhea (p<0.01) and the average number of days each calf had diarrhea was reduced (p<0.05), compared to the placebo group. There were no differences in mean body weight, average daily gain, or feed intake between the treatment or placebo groups. This study demonstrates that fenbendazole is an effective treatment for giardiosis, resulting in a clinical benefit and reducing the number of infective cysts shed by calves. However, this treatment regime had no impact on production parameters and reinfection occurred rapidly in these calves.     

Effect of three programmes for the treatment of endometritis on the reproductive performance of a dairy herd

Three management programmes to improve the reproductive performance of a dairy herd were compared in a prospective controlled field study on one commercial farm. A total of 542 cows were examined for endometritis 22 to 28 days postpartum and assigned to one of three treatment groups: in group 1 the cows with signs of endometritis were treated with an intrauterine infusion of 100 ml of a 2 per cent polycondensated m-cresolsulphuric acid formaldehyde solution; in group 2 the cows with signs of endometritis were treated with an intrauterine infusion of 125 ml of a 20 per cent eucalyptus compositum solution; and in group 3 all the cows were injected intramuscularly with 0.75 mg of tiaprost, an analogue of prostaglandin F2alpha (PGF2alpha) at two-week intervals, starting on day 43, until they were inseminated. Thirty-four per cent of the cows showed signs of endometritis. In group 3, oestrus detection efficiency was significantly higher than in groups 1 and 2 (P<0.05), the interval to first service was shorter, and the cows had fewer days open than the cows in groups 1 and 2 (P<0.05). The results indicate that management programmes based on the strategic use of PGF2alpha are an effective alternative to traditional programmes based on rectal palpations and intrauterine infusions to control endometritis at a herd level.     

Time-space clustering of reported blowfly strike in Queensland sheep flocks

The reported occurrence of blowfly strike in 57 sheep flocks in Queensland, Australia, was investigated for time-space clustering in an exploratory study using Knox's method. Flystrike occurrence peaked in late spring and early summer, with an additional late-autumn peak in southern-Queensland flocks. A total of 1596 case-pairs was examined. Significant clustering (P = 0.07) was only detected for case-pairs occurring within 3 months and 150 km of each other; 164 case-pairs were declared close compared to an expectation of 151. We suggest that factors common to a district (such as rainfall and temperature) are responsible for clustering of flystrike in Queensland.     

Outcome following treatment of vertebral tumors in 20 dogs (1986-1995)

Twenty dogs with histopathologically confirmed primary (n=15) or metastatic (n=5) osteosarcoma (n=14) or fibrosarcoma (n=6) of the vertebral column were treated with surgery (n=4), radiation therapy and chemotherapy (n=6), surgery and chemotherapy (n=2), or surgery, radiation, and chemotherapy (n=8). All dogs died due to their disease; 15 died due to local failure, and five died due to nonvertebral metastasis. Overall median survival time was 135 days, with a range of 15 to 600 days. Of the factors evaluated, only postoperative neurological status had a significant influence on outcome by multivariate analysis. This study supports the overall guarded prognosis for dogs with vertebral neoplasia. Better combinations of surgery, chemotherapy, and radiation therapy remain to be defined for this difficult subset of animal cancer.     

Somatotropin and adipose tissue metabolism: substrate and temporal effects

The purpose of these studies was to determine the time course for changes in feed intake, blood metabolites, and lipogenic activity in adipose tissue in response to the initiation of porcine somatotropin (pST) treatment and following withdrawal from treatment in barrows. An initial study was conducted to determine the impact of chronic pST treatment (4 wk of daily injection; 0 vs 4 mg/d) on adipose tissue lipid metabolism in barrows (initial weight 67 kg). Feed efficiency was improved 27%, backfat thickness was decreased 43%, and glucose and lactate oxidation and incorporation into lipid in adipose tissue was reduced 70 to 86% in pST-treated pigs. Palmitate esterification was decreased 44%, whereas palmitate oxidation was unaffected. In vitro metabolism of lactate, glucose, and palmitate in liver slices was not affected by pST treatment. The time-course for changes in intake and adipose tissue metabolism in response to 7 d of pST (0 vs 4 mg/d) treatment and 7 d of withdrawal was examined in subsequent studies in barrows (initial weight 75 kg). Feed intake during pST treatment was significantly (P < .05) less than in control pigs within 24 h of the initiation of treatment and remained low through 3 d after withdrawal. Adipose tissue biopsies were obtained on d 0, 1, 2, 4, and 7 of the treatment phase and on d 2, 4, and 7 after withdrawal from 7 d of treatment. Maximal inhibition of lipogenesis by pST treatment in adipose tissue in vitro was observed on d 4 (-68%) and d 7 (-69%). Similarly, fatty acid synthase activity declined during the treatment period, with the greatest change noted on d 7 (-26%). After withdrawal from treatment, lipogenesis gradually increased, returning to control values 7 d after withdrawal. Levels of IGF-I began to increase from d 1 to d 7 of treatment, continually decreased during withdrawal, and were normalized by the end of the withdrawal period. Plasma urea nitrogen concentrations decreased during treatment, increased during the withdrawal phase, and were normalized 4 d after the last pST treatment. Overall results indicate that most of the metabolic changes in response to pST occur within 1 wk of treatment and return to pretreatment values after 7 d of withdrawal from treatment.