Biomedical subjects
Publications and source records attributed to C D König.
An ELISA was developed for the detection of antibodies to the exotoxin of Corynebacterium pseudotuberculosis. Experience with the test for control of caseous lymphadenitis in goats in the province of Gelderland is discussed.
The results of the first four years of the Dutch national voluntary maedi-visna control program, which was launched on January 1, 1982, are presented. At the end of the observation period, 1711 breeding flocks representing 70% of the registered breeding flocks participated. The program is based on accreditation of flocks that have passed two successive serological tests with an interval of six months between and post-accreditation tests every 12 months. The flocks have to conform to a set of specific regulations. Sheep sold from such flocks receive a certificate stating that their origin was accredited. A total of 1212 flocks gained accreditation. Of these flocks, 29.5% were free from infection from the beginning, 35.6% were created by total replacement of the original stock, 19.6% employed repeated testing and culling of positives, and 15.3% were created by artificial rearing of colostrum-deprived lambs. A total of 22 flocks lost accreditation due to detection of 36 seropositives. These positives and their progeny were culled, and all flocks regained accreditation after passing the two negative flock tests required. In a total of seven flocks, an unusual course of events during the pre-accreditation stage was observed; this was mainly attributed to late seroconversions and uncommon degrees of horizontal transmission. The results indicate that this certification yields a substantial guarantee of freedom from maedi-visna virus and they indirectly show that the basic design of the program has been adequate.
A chondroma localized in the last two ribs at one-third of the distance from the spinous process to the sternum, and approximately 35 cm in diameter, is reported. The ewe was about four to five years of age and in fairly good condition. Apparently it was a rare case; a condition of this type was not previously reported in the Netherlands. Only two cases of chondrosarcoma (also in the costal arch) out of 129,981 autopsies are reported (1).
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A prospective study was done to examine the extent to which the 'regulation concerning the method of examining milk using the Coulter counter' was also applicable to sheep's milk. This was found to be the case, provided the milk is previously mixed with a Vortex mixer for 0.5 minutes. In view of the studies done by others, the threshold value was reduced to 4.5 mu. The levels recorded by this method were readily reproducible. Any statement regarding the relationship between the cell counts recorded and the cells actually present in the milk cannot be based on these studies.
Little is known of udder health in sheep in the Netherlands. The present study represents an effort to gain some insight into this matter. For this purpose, test samples were taken during the period from March 6, 1981 to April 17, 1981, on sixteen commercial farms in the province of Gelderland, on which there were a total number of 936 nursing ewes; this was done again during the period from June 22, 1981 to June 25, 1981, final sampling being done during April 1982, though this was confined to animals showing poor udder health in the year before. Cell counts were made by an adjusted method using the Coulter Counter. The cell counts recorded were higher than those reported in the literature. Of the samples examined, from 20 to 25 per cent contained more than 2,000,000 cells per ml. Cell counts were high during the early period of lactation, subsequently diminished and then increased again about the time of weaning. Moreover, cell counts increased with age and possibly, though not significantly so, with the number of suckling lambs. Bacteriological examination shortly after lambing was positive in 7.3 per cent of the ewes and 4.1 per cent of samples of udder halves.
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A field trial to study the practicability and efficacy of maedi-visna control in sheep by artificial rearing of lambs was carried out during the lambing season of 1979. Lambs were immediately separated from the dams at birth, deprived of ovine colostrum, and reared isolated from the parent flock. Bovine colostrum was given instead of maternal colostrum. Eleven farms participated in the experiment. All flocks were severely infected with maedi-visna virus: 63-100% of the ewes were seropositive as demonstrated by ELISA. Artificially reared lambs were serologically tested and positives culled at the age of 6, 12, 18, 24, 30 and 36 months. Only very few positives were found: 1/389, 1/376, 0/337, 1/223, 1/192 and 0/144, respectively. The first two sero-positive lambs occurred in one flock, and it could be ascertained that both had mistakenly been given ovine colostrum probably containing maedi-visna virus. No explanation, other than sub-optimal hygiene and isolation, could be found for the two sero-positive sheep that turned up in another flock at 24 and 30 months of age although, transplacental infection cannot be entirely excluded. It is concluded that artificial rearing of ovine colostrum-deprived lambs is an effective and practicable method for the control of maedi-visna in sheep. The method appears particularly useful when valuable genetic material has to be salvaged.
Antibiotic concentrations were determined in the lacrimal fluid of sheep following subcutaneous application of penicillin/dihydrostreptomycin into the lower eyelid, and intramuscular administration of spiramycin base, tiamulin, and oxytetracycline formulations. The penetration of penicillin and dihydrostreptomycin into the lacrimal fluid was poor. The spiramycin and tiamulin concentrations in the lacrimal fluid were 10- and 4-fold higher than in the serum. The peak spiramycin concentration in the lacrimal fluid was 3.4 +/- 0.8 microgram/ml at 8 h post injection (p.i.) and the drug could be detected at least 72 h p.i. For tiamulin and oxytetracycline (OTC) peak concentrations of 1.53 +/- 0.70 and 1.88 +/- 1.9 micrograms/ml, respectively, were achieved in the lacrimal fluid and these drugs could be detected 25 to 30 h p.i. The OTC and tiamulin concentration-time curves for lacrimal fluid and serum were parallel, whereas for the spiramycin appearance in the lacrimal fluid was delayed.
In a comparative study the clinical efficacy of five different treatments of keratoconjunctivitis infectiosa ovis (KIO) were tested, namely an intramuscular injection of chloramphenicol base (dosage 15 mg/kg), spiramycin base (Suanovil dosages 10 to 25 mg/kg), oxytetracycline (Engemycine Forte, Terramycin LA, dosages respectively 5 and 10 mg/kg), tiamulin (Dynamutulin, dosage 10 mg/kg) and subcutaneous injection of procaine penicillin G, benzathine penicillin G. and dihydrostreptomycin in the lower eyelid. It appeared from these field trials that spiramycin base, oxytetracycline and tiamulin had a clearly positive effect on the clinical course of 'pink eye', although with tiamulin there was only a temporary effect (high percentage of relapses). In view of the field data the following dosage schemes are, for the time being, advised: spiramycin base (Suanovil), and oxytetracycline (formulation with a good biological availability) both 20 to 30 mg/kg and, if necessary, to be repeated on days 5 and 10 after the first intramuscular injection. The dosage scheme advised for tiamulin is 20-30 mg/kg to be repeated on day 3 and if necessary on days 6 and 9 after the intramuscular injection. In mild cases it is sufficient to rub the eyes with for example oxytetracycline eye-ointment, a few times a day.
The occurrence of keratoconjunctivitis infectiosa ovis (KIO) in the Netherlands was reported by Hofland et al. in 1969 for the first time. At present the disease is well known in the Netherlands. Nevertheless there are still questions about the causative agent and the most effective and easiest therapy. Most authors suppose that the disease is caused by Colesiota conjunctivae, although others mention infections by other chlamydia, Mycoplasma conjunctivae, Mycoplasma ovipneumoniae, Acholeplasma oculi and a wide variety of bacteria. The diagnosis can be made on the basis of the symptoms and the detection of the agent in conjunctival scrapings. The bacilliform bodies can be found in conjunctival smears in the cytoplasm (Giemsa, Stamp). Many therapies are used topically, parenterally or orally. Locally used eye-ointments must be effective against Colesiota; antimicrobial drugs administered by injection must be effective against the latter and also provide a sufficient cell tissue penetration with excretion into the lacrimal fluids. Injections have proved to be easier to administer, especially in serious outbreaks, but such outbreaks are exceptional (18). Some therapies have been evaluated in small scale experiments (28) as well as in field trials (17).
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A herd of sixty-two veal calves was studied to determine whether there was a relationship between neonatal diarrhoea and infections with rotavirus, bovine coronavirus, Salmonella and K99-positive E. coli. Examination of the animals was negative for salmonellosis. Clinical findings and serological testing did not suggest that K99-positive E. coli was a factor in aetiology. Bovine coronavirus was isolated from the faeces of a small number of calves, only a few of which were affected with diarrhoea. A few faecal samples were found to harbour bovine coronavirus as well as rotavirus. Rotavirus was isolated from the faeces of a large number of calves; excretion of the virus was only associated with diarrhoea in some cases. A definite conclusion could therefore not be drawn from the findings, although they suggested a possible role of rotavirus in the aetiology of neonatal diarrhoea of veal calves.
The effect of treatment with clenbuterol on lambing during the period from 9 p.m. to 5 a.m. was studied in a field trial in sheep, which was continued for twenty-two days. The date of tupping was not known. The sheep were divided into an experimental and a control group, each numbering 106 animals. Animals of the experimental group were assessed every day at approximately 7.30 p.m., using a system of scoring for the development of udders and vulvae, and were treated with oral administration of 200 micrograms of clenbuterol when the findings suggested that parturition would occur that night. Seventy-nine animals of the experimental group lambed. twelve of them lambing during the night (two of these had been treated in the evening before lambing); of the group of controls, seventy-two lambed, twenty-three doing so during the night (difference significant: P greater than 0.05). The difference in the number of lambings during the night between treated and untreated animals was highly significant (P less than 0.001). Side-effects of clenbuterol were not recorded. The amount of clenbuterol used in the group of controls was: 3.49 tablets/lambing sheep, 5.03 tablets/treated sheep and 5.02 tables/treated and lambing sheep. This high consumption rate is attributed to the fact that the date of tupping was not known as well as to the defectiveness of the criteria on which the decision to treat or not to treat was based.
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After Nematodirus battus infection had been detected in sheep imported from Britain into the Netherlands in January 1978, Dutch lambs and sheep on seven farms in the Province of Gelderland were also found to be infected with N. battus later in 1978. The possible origin of the infection was investigated. Three flocks had been in contact with British sheep, two farms were trading farms, one farm had purchased its sheep from various sources a few years previously, on another the cause continued to be obscure, recently purchased rams possibly having played a role in this case. Severe infections were not (sor far) observed. It was difficult to differentiate between clinical symptoms of N. battus infection, if any, and those due to coccidiosis which was diagnosed in a number of flocks.