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T Løken

Publications and source records attributed to T Løken.

34 records · Page 2Linked to original sources
PubMed1992

Pestivirus infections in ruminants in Norway.

Serological surveys in Norway have demonstrated neutralising antibodies against bovine virus diarrhoea (BVD) virus in cattle, sheep and goats. The prevalences were 18.5%, 4.5% and 3.6%, respectively. Occurrence of pestivirus-induced disease in Norway is described. Outbreaks of reproductive failure and mucosal disease have been reported, and the number of persistently-infected animals detected has increased considerably in recent years. Acute BVD occurs rarely. Border disease (BD) in sheep, first diagnosed in 1981, has subsequently been demonstrated sporadically. In goats, typical BD was diagnosed in 1982, with three later occurrences of reproductive failure. Experimental infections in pregnant goats induced a high rate of severe foetopathogenic effect. Signs and lesions in offspring were comparable to ovine BD. Similar findings were demonstrated in goats given a pestivirus-contaminated vaccine. In newborn kids, experimental infection had an adverse influence on growth and health. Persistent infection in goats is probably rare.

Abortion, Veterinary↗
PubMed1991

Cytopathogenicity of pestiviruses isolated post mortem from cattle.

Cytopathic pestivirus was isolated from different tissues of only eight of 23 cattle with mucosal disease. Three persistently infected cows were healthy until slaughter after death of all their seven offspring, out of which one of four examined demonstrated cytopathic pestivirus.

Animals↗
PubMed1991

Experimental pestivirus infections in pregnant goats.

Fifty pregnant goats, inoculated intramuscularly at different gestational stages with a non-cytopathic ovine pestivirus or a cytopathic bovine pestivirus, all developed pestivirus-neutralizing antibodies within 5 weeks of inoculation. The incidence of reproductive failure was similar for the two agents. Parturition at term with only healthy kids occurred in 13 (26 per cent) of the goats. Viable kids were not born to any of the 17 goats inoculated at about day 40 of gestation. Three of the 17 delivered dead or weak kids, seven aborted and three of seven which were necropsied during pregnancy had markedly underdeveloped and autolysed or mummified fetuses in utero, while four were barren. When inoculated at around the 60th day of gestation, two of 18 animals gave birth to only healthy kids, 12 to dead and/or weak kids, two aborted and, at necropsy, a small, decomposed fetus was found in one goat while one other was barren. In this group, one kid was ataxic and seven others had body tremors characteristic of border disease. One of the latter kids was viable. Of 15 goats inoculated at around day 100 of gestation, 11 gave birth to healthy kids only, three to dead and/or weak kids and one aborted. In 23 progeny, histological changes in the central nervous system (CNS) consisted mainly of cerebral white matter necrosis, cerebellar dysplasia, hypercellular areas in white matter and lymphocytic perivascular cuffings. All seven weak-born kids with signs of border disease had CNS lesions, particularly cerebellar dysplasia and/or hypercellular areas. Non-cytopathic pestivirus was isolated from tissues from all eight progeny examined in the 40-day inoculation group, from tissues and/or serum from 10 of 23 progeny in the 60-day group, and from four of 24 in the 100-day group. Persistent infection was demonstrated in a healthy kid, in a viable shaker and in two other kids which appeared normal at birth. Examination of offspring before ingestion of colostrum revealed pestivirus antibodies in one kid in each of the 40- and 60-day inoculation groups and in five kids in the 100-day group.

Abortion, Veterinary↗
PubMed1991

Outbreaks of border disease in goats induced by a pestivirus-contaminated orf vaccine, with virus transmission to sheep and cattle.

Five herds with a total of 276 female goats experienced severe outbreaks of reproductive failure due to a pestivirus-contaminated experimental orf vaccine given early in the breeding season. The reproductive failures comprised barrenness in 42 goats, abortion in 53 and, in 118, the birth of dead or weak kids. The incidence of female goats with such failures was 82 per cent overall, herd incidence rates ranging from 79 to 96 per cent. No progeny showed characteristic signs of border disease (BD). Microscopic lesions in the CNS were moderate, mostly characterized by hypercellularity, cell disorganization and decreased myelin content. Non-cytopathic strains of pestivirus were demonstrated in tissue or serum from two weak-born and two apparently healthy kids. Neutralizing antibodies against a bovine pestivirus were found in all 254 goats examined about 4 months after vaccination. At the end of the breeding season, all kids were removed and 74 young kids were introduced from presumably normal herds. Approximately 8 months later, 64 (86 per cent) of the bought-in kids had pestivirus antibodies. Two years after the outbreaks, such antibodies were found in all but three of 127 vaccinated goats still alive, and another 2 years later, in all 22 vaccinated goats in one of the herds. Sheep also were kept on the same five farms and cattle on one. Sheep in two of the flocks showed reproductive failure probably caused by pestivirus transmitted from infected goat offspring. A pair of twin lambs showed nervous signs and brain lesions characteristic of BD, while 17 other lambs had a very low growth rate. Virus was not isolated from any lamb. The prevalence rates of ewes with pestivirus antibodies in the two affected flocks were 33 and 72 per cent, respectively. One of nine cows aborted a pestivirus-infected foetus, and all were antibody-positive.

Abortion, Veterinary↗
PubMed1991

Pestivirus infections in Norway. Serological investigations in cattle, sheep and pigs.

Serum samples from 1,133 dairy cows (187 herds), 3,712 ewes (103 flocks) and 1,317 adult pigs (877 herds), were tested for neutralizing antibodies against the NADL strain of bovine virus diarrhoea virus. The prevalence rate of seropositive animals was 18.5% in cattle, 4.5% in sheep and 2.2% in pigs, such seroreactors being found in 28% of the cattle herds and 18% of the sheep flocks. In all three species the rate showed considerable herd and geographical variation. In cattle the seroreactor rate was similar in herds with normal reproduction and in 62 herds with problems of repeat breeding. Of 31 pig sera containing antibodies against the NADL strain, 27 were also positive in a neutralization test for antibodies against swine fever virus (Baker strain). However, all sera showed a higher titre of antibodies against the bovine strain than against the swine fever virus. It was concluded that the immune response of the pigs had been induced by ruminant pestivirus, and not by swine fever virus.

Animals↗
PubMed1991

Reproductive failure in goats in Norway: an investigation in 24 herds.

Twenty-four flocks comprising 2370 breeding goats were examined. Three hundred-and-sixty-nine (15.6%) of the goats either aborted or delivered dead kids at full term, or were barren. In 23 of the herds the rate of reproductive loss ranged from 2% to 36%, whereas in one herd all of 54 mated goats had live kids. A loss of greater than or equal to 20% was found in 9 herds comprising 799 goats. In 11 herds comprising 946 goats the rate of reproductive failure was less than or equal to 10%. The incidence of reproductive failure was higher in older goats than in those in their first or second pregnancy. The causes were identified in only about 3% of the goats that aborted. It is concluded that reproductive failure in many flocks probably is associated with non-infectious causes such as nutritional and environmental factors.

Abortion, Veterinary↗
PubMed1990

Experimental pestivirus infections in newborn goat kids.

Two experiments were carried out in which 37 healthy newborn goat kids were inoculated with a non-cytopathic ovine (BDV) or a cytopathic bovine pestivirus (BVDV) by intramuscular or intracerebral injection. No kids showed signs of disease or gross lesions which could be attributed to these viruses, but inoculated kids had lower mean growth rates than the controls. Significant histological changes in the CNS of 14 kids were restricted largely to the white matter and consisted mainly of hypercellular foci comprising microglial/histiocytic cells and mild perivascular infiltration by mononuclear cells. Varying degrees of infiltration of the myocardium by lymphocytes and plasma cells were observed. All kids remained negative for neutralizing antibodies against pestivirus until 2 to 3 weeks after infection. Titres increased during the following weeks. Pestiviruses were recovered from kids necropsied 10 days after inoculation, but not from any kids killed 20 days after inoculation or later. Non-cytopathic virus was isolated from various tissues of four kids that had received BDV and three kids that had been given BVDV. Cytopathic viruses were not recovered from any kids. Mean white blood cell counts in all kids were within the normal range at 4 and 8 weeks after inoculation. The lymphocyte response to stimulation by phytohaemagglutinin was significantly increased on both sampling occasions in the BDV-inoculated kids, while in the BVDV-inoculated animals, a similar increase was seen only at 8 weeks.

Animals↗
PubMed1990

Pestivirus infections in Norway. Epidemiological studies in goats.

During one breeding season, 2335 female goats in 39 herds in different parts of Norway were examined for pestivirus infection and for reproductive performance. Before breeding, all animals were examined for neutralizing antibodies against the NADL strain of pestivirus, 83 (3.6 per cent) positive animals in 12 herds being demonstrated. The herd prevalences ranged from 1 to 63 per cent. Antibody titres varied from 1 in 4 to 1 in 2048. Of 1816 females in 30 herds for which post-breeding information was available, a total of 178 (9.8 per cent) animals in 25 of the herds demonstrated gestation failure. Three of these goats began to produce antibodies against the NADL strain during gestation. Sera from the 83 animals with NADL antibodies were titrated for neutralizing antibodies against three additional strains of pestivirus, the highest geometrical mean titre being found for antibodies against a Norwegian bovine strain.

Abortion, Veterinary↗
PubMed1989

An outbreak of mucosal disease in a dairy herd.

An outbreak of mucosal disease (MD) was studied in a dairy herd, comprising 12 cows, 9 heifers and 18 calves. During a period of 1 month, six 5 to 8 month-old calves showed typical signs of MD. They all died or were killed in extremis after 2-8 days with progressively worsening clinical signs. Post mortem lesions were examined in one calf. Non-cytopathogenic MD virus was isolated from serum or tissues from 3 clinically affected calves and from 1 healthy heifer. All cows and heifers except for the viremic one possessed neutralizing antibodies against bovine pestivirus. According to the current MD-pathogenesis concept, the affected calves were probably infected transplacentally during the first half of foetal life with pestivirus from the persistently infected heifer in the herd.

Animals↗
PubMed1987

Experimentally-induced border disease in goats.

Twelve of 14 pregnant goats were inoculated intramuscularly with a cytopathic strain of bovine virus diarrhoea (BVD) virus at different stages of gestation. All infected goats developed neutralizing antibodies against the virus. Four nannies infected at about 40 days of pregnancy each had an empty uterus when killed after four months of pregnancy. Out of five nannies infected at about 60 days gestation, one aborted three weeks before full term; the other four were killed at about four months gestation at which time one had an empty uterus, while the uteri of the other three, contained extremely small, autolyzed foetuses and 1.1 to 1.5 l of foetal fluid. Three nannies infected at about 100 days of pregnancy produced five clinically normal offspring. Histopathological lesions were found in the central nervous system in all examinable offspring from the infected nannies, this being consistent with reported findings in cases of border disease in goats. Both cytopathic and non-cytopathic BVD viruses were isolated in these cases. Kids from two nannies infected at 60 and 100 days of pregnancy, respectively, had precolostral antibodies against BVD virus.

Animals↗
PubMedDate not supplied

Ergot from meadow grass in Norway--chemical composition and toxicological effects in sheep.

A sample of ergot from meadow grass collected in the south-western part of Norway was examined for alkaloids and dosed orally to four lambs about 10 months old. Sclerotia were dosed at a rate of 0.12-0.75 g per kg body weight per day for 4-27 days. The concentration of total alkaloids in the sclerotia was estimated to be about 0.4%. Ergosine, ergocristine, ergotamine and the three corresponding isomers were identified by thin-layer chromatography. Of the total alkaloids, ergosine and ergocristine constituted 35% each, ergotamine 15% and the isomers 5% each. Three lambs dosed outdoors in cold and wet weather all became ill, with anorexia and increased pulse rate. No symptoms nor post mortem lesions were seen in the single lamb kept indoors. On post mortem examination of the three lambs showing symptoms, hyperemic mucosae, haemorrhages, erosions and necroses in the digestive tract, most pronounced in abomasum and cecum, were demonstrated. In two lambs, slight oedema was found distally in some of the limbs and tail, but no sign of gangrene was observed.

Animals↗