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Biomedical subjects

T Løken

Publications and source records attributed to T Løken.

At least 19 recordsLinked to original sources
PubMed2004

Indirect transmission of bovine viral diarrhoea virus at calving and during the postparturient period.

Two trials were designed to investigate whether bovine viral diarrhoea virus (BVDV) could be transmitted after the birth of persistently infected calves, even if they were removed immediately after birth. In trial 1, 11 calves were actively exposed to fetal fluids and uterine lochia collected from cows that had delivered calves persistently infected with type 1 BVDV. One calf that was exposed to a sample taken on the day of calving seroconverted. In trial 2, six calves were housed in stables where persistently infected calves were being born and then removed immediately from their dams and from the stable unit within two to three hours. One of four calves in close contact with the cows after delivery seroconverted and one of two calves housed within the same stable unit became infected.

Animals↗
PubMed2004

Evaluation of stratification factors and score-scales in clinical trials of treatment of clinical mastitis in dairy cows.

There is often a need to reduce sample size in clinical trials due to practical limitations and ethical considerations. Better comparability between treatment groups by use of stratification in the design, and use of continuous outcome variables in the evaluation of treatment results, are two methods that can be used in order to achieve this. In this paper the choice of stratification factors in trials of clinical mastitis in dairy cows is investigated, and two score-scales for evaluation of clinical mastitis are introduced. The outcome in 57 dairy cows suffering from clinical mastitis and included in a clinical trial comparing homeopathic treatment, placebo and a standard antibiotic treatment is investigated. The strata of various stratification factors are compared across treatments to determine which other factors influence outcome. The two score scales, measuring acute and chronic mastitis symptoms, respectively, are evaluated on their ability to differentiate between patients classified from clinical criteria as responders or non-responders to treatment. Differences were found between the strata of the factors severity of mastitis, lactation number, previous mastitis this lactation and bacteriological findings. These factors influence outcome of treatment and appear relevant as stratification factors in mastitis trials. Both score scales differentiated between responders and non-responders to treatment and were found useful for evaluation of mastitis and mastitis treatment.

Animals↗
PubMed2004

Comparison of homeopathy, placebo and antibiotic treatment of clinical mastitis in dairy cows - methodological issues and results from a randomized-clinical trial.

Based on the widespread use of homeopathy in treatment of animal disease and the poor documentation of its possible effects and consequences, a clinical trial was carried out in order to evaluate the efficacy of homeopathy in treatment of clinical mastitis in dairy cows and a design for clinical studies on homeopathic treatment, taking into account the guidelines for randomized-clinical trials (RCT) as well as the basic principles of homeopathy. A three-armed, stratified, semi-crossover design comparing homeopathy, placebo and a standardized antibiotic treatment was used. Fifty-seven dairy cows were included. Evaluation was made by two score scales, with score I measuring acute symptoms and score II measuring chronic symptoms, and by recording the frequencies of responders to treatment based on four different responder definitions. Significant reductions in mastitis signs were observed in all treatment groups. Homeopathic treatment was not statistically different from either placebo or antibiotic treatment at day 7 (P = 0.56, P = 0.09) or at day 28 (P = 0.07, P = 0.35). The antibiotic treatment was significantly better than placebo measured by the reduction in score I (P < 0.01). Two-thirds of the cases both in the homeopathy and placebo groups responded clinically within 7 days. The outcome measured by frequencies of responders at day 28 was poor in all treatment groups. Evidence of efficacy of homeopathic treatment beyond placebo was not found in this study, but the design can be useful in subsequent larger trials on individualized homeopathic treatment.

Animals↗
PubMed2003

The role of the defective interfering particle DI9c in mucosal disease in cattle.

Mucosal disease occurs in cattle persistently infected with a noncytopathogenic strain of bovine viral diarrhoea virus (BVDVnc) following in utero infection. The disease can be initiated by superinfection with a cytopathogenic biotype (BVDVc) of the virus with antigenic "homology" to the persisting virus. A BVDVc isolated from a clinical case of mucosal disease has been discovered to consist of a defective interfering particle, DI9, and an associated BVDVnc helper virus. A defective virus corresponding to DI9 was recently recovered from an infectious cDNA clone and was named DI9c. To evaluate the role of DI9 in the pathogenesis of mucosal disease a two-part experimental study was carried out which included clinical, haematological, pathological and virological investigations. Eight of nine calves persistently infected with BVDVnc were experimentally inoculated with DI9c. The defective virus was propagated in cells preinfected with the same strain of virus used to persistently infect the calves in utero. The calves were euthanased on days 4, 7, 14, 21, 28, 40, 40 or 87 post inoculation. None of the inoculated animals developed classical mucosal disease, neither clinically nor pathologically. DI9c was not found in serum, nasal swab or tissue samples from the calves by observing cytopathogenic effect and/or using a polymerase chain reaction after reverse transcription (RT-PCR) of viral RNA. DI9c did not replicate to a detectable extent in these assays, and its participation in the pathogenesis of mucosal disease could not be proven.

Animals↗
PubMed2003

Experimental infection of cows with bovine viral diarrhoea virus in early pregnancy - findings in serum and foetal fluids.

Nineteen pregnant cows were experimentally infected with bovine viral diarrhoea virus (BVDV) between day 74 and 81 of pregnancy. All cows became infected and developed serum antibodies. Sixteen of the cows delivered persistently infected (PI) offspring, whereas the remaining three gave birth to calves with detectable serum antibodies and free from BVDV. The 16 cows with PI foetuses developed higher levels of antibodies in serum during pregnancy than did their three peers carrying non-PI calves. Multivariate analysis showed that the antibody levels in these two groups of cows were significantly different from day 135 of pregnancy. Foetal fluid was successfully collected from 18 of the 19 infected cows and from five uninfected control cows between 10 and 24 days before delivery by use of a percutaneous, blind puncture technique. No negative effects were observed in the cows or their offspring. BVDV was isolated and detected with an immunoperoxidase test in foetal fluid from 13 of the 16 cows carrying PI foetuses, and from 15 of the cows when a quantitative fluorescent polymerase chain reaction (PCR) technique was used. The negative sample in the PCR assay was positive for BVDV antibodies. The number of viral copies per microlitre in foetal fluids varied between 103 and 1080 in the positive samples. All samples taken from the cows carrying non-PI foetuses were negative for BVDV in both assays. In this experiment, examination of either serum or foetal fluids could identify the cows carrying a PI foetus. Examination of serum for BVDV antibodies was a reliable indicator of a PI foetus if the serum was collected during the last 2 months of pregnancy. For examination of foetal fluids, both viral and serological analyses should be performed. For viral analysis, PCR should be the test of choice. High levels of BVDV antibodies in conjunction with a negative result in the PCR may be indicative of a false-negative virus result. Further experience with the method of collection of foetal fluids is necessary for evaluation of its safety. Investigation of pregnant cows in order to discover a PI offspring before it is born could be a useful tool in control and eradication of BVDV.

Animals↗
PubMed2002

Pestivirus in cattle: experimentally induced persistent infection in calves.

Twenty-two heifers were infected intranasally with non-cytopathic bovine viral diarrhoea virus (BVDV) between days 74 and 82 of pregnancy. All animals had developed serum antibodies against BVDV 5 weeks later. No clinical effects were seen in the heifers, and they all delivered a live calf. The newborn calves were generally small, appeared unthrifty as typical 'poor doers', and some developed secondary infections with diarrhoea and signs of respiratory disease. Eighteen of the 22 calves were born without antibodies against BVDV and were persistently infected (PI) with the virus. One was weak at birth and died the following day. Four calves were born with serum antibodies against BVDV and with no detectable virus. Three of these showed signs and/or pathological changes indicating disease in the central nervous system. Otherwise, there were no obvious clinical differences between these calves and the PI calves, nor were there any apparent significant differences in blood parameters between these groups. In general, the calves showed low gamma-globulin values and thrombocytopaenia, but moderately increased fibrinogen values and relatively normal lymphocyte numbers.

Animals↗
PubMed2001

Alternative therapy of animals--homeopathy and other alternative methods of therapy.

Alternative therapy of animals is described, in the meaning of alternatives to veterinary therapy traditionally accepted by veterinary faculties and schools and included in their curricula. Alternative therapy composes of different disciplines, of which homeopathy is emphasised in this presentation. Information is given on the use and interest of such therapy among veterinarians and animal owners. Homeopathy as other alternative therapies, may offer great advances, if they induce any effect. Some of the disciplines are based on a scientifically accepted documentation. Others, and homeopathy in particular, are missing such a documentation of effect. The justification of including alternative therapy in treating animals is discussed. Research in alternative therapy of animals is greatly needed, in particular to evaluate therapeutic methods which are in extensive use without any documented effect. An ongoing research project in Norway on the effect of homeopathic treatment of mastitis in cows is shortly presented.

Animals↗
PubMed1999

Level and duration of serum antibodies in cattle infected experimentally and naturally with bovine virus diarrhoea virus.

Neutralising serum antibodies against bovine virus diarrhoea virus (BVDV) were monitored for three years in 35 cattle that were infected with the virus as calves; 24 of the calves were inoculated intramuscularly or intranasally, and 11 contracted the infection naturally. All the experimentally infected calves seroconverted within 14 to 28 days after inoculation, and all the animals still had high serum levels of antibodies to BVDV three years after infection. Determinations of antibody levels in milk and blood samples excluded the possibility that the calves had been reinfected with BVDV during the study.

Animals↗
PubMed1999

Distribution of viral antigen in uterus, placenta and foetus of cattle persistently infected with bovine virus diarrhoea virus.

The tissue distribution and cellular localisation of bovine virus diarrhoea virus (BVDV) was investigated in the uterus, placentomes, intercotyledonary foetal membranes and foetal organs of three persistently infected (PI) pregnant heifers. The uterus and ovaries of a non-pregnant PI heifer were also included in the study. Cryostat sections were examined using immunohistochemical techniques and monoclonal antibodies against BVDV. A double immunofluorescence technique was used to identify BVDV positive cells that also showed staining for either the leukocyte common antigen CD45 or the cytoskeletal filament vimentin. BVDV antigen was detected in all the organs examined, and was present in both epithelial and non-epithelial cells. In all organs many of the virus-positive cells also showed reactivity for vimentin. In the foetal liver and spleen a small, scattered population of virus-positive cells showed reactivity for CD45. A few cells showed reactivity both for BVDV antigen and for CD45 in the placentomes and intercotyledonary foetal membranes. In contrast to earlier reports, only scattered cells in the foetal part of the placentomes, the cotyledons, showed reactivity for BVDV antigen. However, in the chorion of the intercotyledonary foetal membranes, a larger proportion of the trophoblast cells showed reactivity for BVDV, especially the binuclear trophoblast cells. In the uterus, pregnancy appeared to favour virus replication, as the section from the pregnant heifers showed much stronger staining and a higher proportion of viral antigen-positive cells than sections from the non-pregnant PI heifer.

Animals↗
PubMed1999

Detection of viral antigen in placenta and fetus of cattle acutely infected with bovine viral diarrhea virus.

The reproductive organs and fetuses of seven Norwegian Red heifers were investigated for the presence of bovine viral diarrhea virus (BVDV) antigen during the time of initial transplacental transmission of the virus. The heifers were inoculated with a noncytopathogenic BVDV at day 85/86 of gestation and were slaughtered at day 7, 10, 14, 18, or 22 postinoculation (pi). Cryostat sections of uterus, ovaries, placentomes, intercotyledonary fetal membranes, and fetal organs were examined using immunohistochemical techniques. A double immunofluorescence technique was used to identify cells that showed staining with antibodies against the leukocyte common antigen CD45 or the intermediate filament vimentin and BVDV antigens. The earliest stage of infection at which BVDV antigen could be detected in the fetuses was 14 days pi. At this stage, BVDV antigen was detected in cells of mesenchymal origin in the lungs and in large cells that morphologically resembled immature megakaryocytes in the liver. In the intercotyledonary fetal membranes and in the placentomes, BVDV antigen was not detected until 18 and 22 days pi, respectively. BVDV antigen was not detected in maternal tissue from any of the heifers. The present results indicate that fetal infection with BVDV can take place without preceding or simultaneous high concentrations of BVDV in uterus or placenta of acutely infected heifers.

Animals↗
PubMed1998

Malignant catarrhal fever caused by ovine herpesvirus-2 in pigs in Norway.

This paper describes the first cases of malignant catarrhal fever (MCF) in pigs in which the diagnosis was verified aetiologically by polymerase chain reaction (PCR) and DNA analysis and by the demonstration of antibodies. Three pigs on two separate premises showed clinical signs, gross pathological and histopathological lesions which were in many respects similar to those of MCF in ruminants. The pigs were housed adjacent to sheep and DNA of ovine herpesvirus-2 (OHV-2) was detected by PCR in tissues of all the pigs. In addition, antibody to alcelaphine herpesvirus-1 was detected in the serum of the pigs and in five in-contact sheep. It is concluded that the disease described is MCF of pigs caused by OHV-2.

Animals↗
PubMed1998

The duration of antibodies against bovine virus diarrhoea virus in bulk milk.

Fifty-eight dairy herds, suspected to be recently infected with bovine virus diarrhoea virus (BVDV) due to a rise in BVDV antibodies in bulk milk, were followed over a two-year period. In 34 (59%) of these 58 herds (Group 1), pooled milk samples from heifers or pooled blood samples from calves were negative for BVDV antibodies. In this group as many as 53 and 76% of the herds again had antibody-negative bulk milk one and two years after the positive sample, respectively. Of the remaining herds, 5 and 17% had negative samples after one and 2 years respectively. Possible explanations for the limited duration of antibodies against BVDV in bulk milk are discussed. In 65% of the herds in Group 1, animals had been purchased and introduced into the herd, or the herds had been exposed to other forms of contact representing a risk of infection with BVDV. In the remaining 35% of the herds in this group, no explanation for the rise in BVDV antibodies in the bulk milk could be found. In this study the introduction of seropositive animals into the herd, and infection inducing seroconversion in one or more animals as the only result, seem to be the most probable explanations for the rise in antibody levels observed in Group 1.

Animals↗
PubMed1998

The effect of bovine virus diarrhoea virus on reproduction in recently infected Norwegian dairy herds.

A group of 32 dairy herds, recently infected with bovine virus diarrhoea virus (BVDV), was compared with a control group consisting of 75 BVDV free herds during a 3-year-period. Variables related to reproduction were registered. Results of multiple antibody examinations in bulk milk as well as samples of milk and blood from younger animals were used to select the herds. The incidence of abortions was statistically significantly different in the 2 groups, while the number of stillbirths, weak born calves, and congenital anomalies was not. Other variables such as percentage of non return, average number of inseminations per cow and calving interval showed during the study a trend to improve in the BVDV group, while they remained stable in the control group.

Abortion, Veterinary↗
PubMed1997

Level of viral antigen in blood leucocytes from cattle acutely infected with bovine viral diarrhoea virus.

Blood samples from 24 calves undergoing experimental acute infection with a non-cytopathogenic bovine viral diarrhoea virus (BVDV) were examined for viral antigen in peripheral leucocytes with an enzyme-linked immunosorbent assay (ELISA), and for presence of virus in blood plasma in a cell culture assay. With the antigen ELISA, low positive values were detected in leucocytes sampled on days 3-4 from two of eight animals inoculated intranasally, and on days 11-13 from three of 16 animals inoculated intramuscularly. From 22 of the animals, low titres of BVDV were detected in blood plasma obtained 2-9 days after inoculation. All other samples, drawn between 2 and 21 days after inoculation, were negative for viral antigen. All animals seroconverted 3-4 weeks after inoculation, some after having shown mild and transient signs of disease.

Animals↗
PubMed1996

Bovine virus diarrhoea virus in semen from acutely infected bulls.

The risk of spreading bovine virus diarrhoea virus (BVDV) from acutely infected animals to susceptible animals was investigated. Ten bulls from a herd with no previous history of BVDV were used. The bulls were demonstrated free from BVDV and such antibodies. Six of the bulls were inoculated intravenously with cytopathogenic virus, and 4 bulls were used as controls. Semen samples were collected during a period of 66 days after inoculation. The samples were examined for BVDV, and spermatological parameters were registered. Testes and epididymides were examined histologically post mortem. All inoculated bulls exhibited elevated temperatures between days 4 and 8 after inoculation, and BVDV antibodies were found in all of them on day 22. The control animals remained antibody negative. Non-cytopathogenic BVDV was isolated from seminal plasma from 2 bulls on day 7 after inoculation. Semen volume was significantly reduced from week 6 after inoculation. Percent abnormal sperm cells decreased in the same period. No significant differences were observed in sperm density or percentage of live spermatozoa. No pathological changes were found in the testes or epididymides.

Acute Disease↗
PubMed1995

Border disease in sheep.

The current knowledge on border disease in sheep is reviewed. This is a congenital and teratogenic disorder induced by pestivirus. The history, etiology, epidemiology, clinical aspects, and pathologic lesions at postnatal and intrauterine infections (as well as in congenitally affected animals), pathogenesis, immunity, diagnosis, and control and prevention of the syndrome are discussed.

Animals↗
PubMed1995

Ruminant pestivirus infections in animals other than cattle and sheep.

The current knowledge on infection with ruminant pestiviruses in animals other than cattle and sheep and reviewed. Natural infection is found to occur in goats, in captive and free-living ruminants, as well as in pigs. The viral agent, susceptible species, epidemiology, clinicopathologic lesions, pathogenesis, diagnosis, control, and consequences for control programs in domestic ruminants are discussed.

Animals↗