Effect of glucocorticoids on cows suspected of subclinical infection with M. paratuberculosis

Summary

Glucocorticoids were administered to 10 heifers suspected of subclinical infection with Mycobacterium paratuberculosis. Three animals remained untreated.

M. paratuberculosis was isolated from the internal organs of 2 animals after this treatment but not from any of the control group. Delayed type hypersensitivity and lymphocyte reactivity towards Johnin and purified protein derivates of M. avium and M. bovis were depressed. A sharp increase in total leucocyte count, due loan increase in neutrophil numbers, occurred. In the three untreated animals these parameters did not change during the experiment.

A decrease of specific immunological reactivity towards M. paratuberculosis occurred, but not to such an extent that clinical disease developed.     

Investigations on live vaccines against infectious bursal disease of chicks

Summary

Four live virus vaccines against Infectious Bursal Disease (IBD) were studied with regard to their safety, immune response and applicability. None of the vaccines caused clinical symptoms or had an adverse impact on bodyweight. Differences between these vaccins were observed in their effect on the Bursa/ Bodyweight Ratio and the severity of the microscopical lesions of the bursa Fabricii. The immunosuppressive effect of IBD vaccination at one day of age on the response to Newcastle disease vaccine applied was rather low.

Three of the four vaccines induced antibodies associated with protection against challenge. Vaccination of SPF rearing chickens by drinking water at an age of 15 weeks produced an antibody response (Agar Gel Precipitin Test) whereas at an age of 23, 32 and 60 weeks it did not. Chickens of all age groups responded serologically to an intramusculair vaccination.

A correlation was found between the immunological response and the effect of the vaccines on the bursa Fabricii.     

Mortality,morbidity, and external injuries in piglets housed in two different housing systems

An investigation was undertaken to study two different types of farrowing pens, use being made of well characterized veterinary parameters for the well‐being of piglets. A housing system with a solid floor and straw‐bedding was compared with a partly metal‐slatted floor system. The veterinary parameters we used were mortality, morbidity, and external injuries in piglets. There were slight differences in mortality and morbidity rates between the two housing systems. There were big differences with regard tp the piglets” injury‐index’ of the two housing systems. The straw system was more favourable. The studies show that obervations of external injuries ('Method of Ekesbo') can be used to judge housing systems of piglets in the farrowing house.     

The interaction between plant lectins and the small intestinal epithelium: A primary cause of intestinal disturbance

Summary

The literature concerning the effects of plant lectins on the small intestinal epithelium is reviewed. It appears that after oral intake, intact plant lectins can reach the small intestinal lumen. Their binding to the mucosal surface evokes an increased synthesis of glycoproteins and a degeneration of the intestinal epithelium. The epithelial alterations may result in hyperregenerative villus atrophy and endogenous nitrogen loss. These changes ultimately can lead to less efficient feed conversion, diminished growth, scouring, wasting and death. The possible significance of plant lectins in digestive disturbances in farm animals is suggested.     

Pregnancy rate of heifers bred by an immunotolerant bull persistently infected with Bovine Viral Diarrhoea virus

Summary

Twenty four maiden heifers were bred by natural route by a specific immunotolerant bull, that was persistently infected with Bovine Viral Diarrhoea virus (BVD virus). The quality of the bull's semen was normal. Twelve heifers became pregnant in the first oestrus cycle and the remaining twelve in the second oestrus cycle. This leads to the conclusion that such persistently infected bulls may have good fertilisation results. Nevertheless, it is felt that bulls persistently infected with the BVD virus must be excluded from artificial insemination centres because of the risk of introducing BVD virus in a herd by the semen.     

Clinical Leptospira interrogans serogroup Australis serovar lora infection in a stud farm in the Netherlands

Summary

A Leptospira interrogans serogroup australis serovar lora infection in a stud farm is reported. During three successive years (1984–1986) clinical leptospirosis with a severe often rapid, fatal course was seen in 12 foals.

Clinical examination revealed severe respiratory distress, depression and pyrexia. Other symptoms were diarrhea (2), jaundice (1), and an unsteady gait (1). Morphological characteristics of the disease were massive pulmonary haemorrhage and haemorrhagicthrombotic or extracapillary glomerulonephritis with tubulonephrosis and interstitial oedema. In most foals high or increasing MAT titres to serovar bratislava were found; from one foal Leptospira interrogans serovar lora was isolated.

Serological examination of all 56 mares at the farm (August 1986) revealed antibodies to serovar bratislava in 64 per cent of the animals. These findings support the idea that Leptospira interrogans serovar bratislava and closely related strains (in this study serovar lora) may be adapted to and maintained by the horse population.     

Comparative plasma ampicillin levels and bioavailability of five parenteral ampicillin formulations in ruminant calves

Summary

Plasma ampicillin concentrations were determined in an eight‐ways crossover trial involving six ruminant calves, which were treated intravenously (i.v.) with sodium ampicillin at 15.5 mg/kg and intramuscularly (i.m.) with five different ampicillin trihydrate or ampicillin anhydrate formulations at 7.7 mg/kg. The mean plasma concentration‐time curve (C_p)after intravenous ampicillin sodium administration was described biexponentially, as: C_p = 38.8 e ‐0.0268t + 0.45 e ‐0.0058t.

Intramuscular injection, into the lateral neck, of Ampikel‐20^® and Polyflex^® resulted in 100 per cent bioavailabilities within 12 h post injection (p.i.), but the biological half‐lives (t½>) were different, being 2.1 and 3.8 h, respectively. Ampikel‐20^® produced the hïghest peak plasma drug concentrations (mean C _max:4.8 μg ampicillin/ml). After intramuscular injection of Penbritin® the mean bioavailability for the first 12 h p.i. was 63 per cent, the mean t½>, was 5.9 h, and the mean C_max was 1.8 μg/ml. Treatment with Albipen^® and Duphacillin^® resulted in low plasma ampicillin levels, which were maintained for 3 to 6 days p.i., limited bioavailability during the first 12 h p.i., and a mean t½> of 22.2 and 11.9 h, respectively. Plasma concentrations of ampicillin from four hours onwards after i.m. and s.c. administration of Ampikel‐20^® at a dose level of 15.5 mg/ kg were similar.

The duration of potentially therapeutic plasma ampicillin concentrations after administration of each formulation is presented. Pre‐slaughter withdrawal times for diseased calves are suggested for the different formulations studied.     

Oestrus control and the incidence of mammary nodules in bitches,a clinical study with two progestogens

Summary

The incidence, size and location of mammary nodules were established in 10 practices in The Netherlands by the clinical examination of bitches in which oestrus was controlled with proligestone (P), 331 animals, or medroxyprogesterone acetate (MAP), 341 animals and in 339 animals never medicated with such compounds.

In comparison with the unmedicated controls and the P‐medicated animals of comparable age the incidence of mammary nodules of all sizes was significantly increased in the MAP‐medicated animals.

There was no significant difference in nodule incidence between the P‐medicated animals and the control animals.

Based on the assumption that nodules above a certain size are most likely tumours, these results indicate that oestrus control with MAP stimulates tumour development even in animals medicated for less than four years.

The practical value of the reported differences, especially in relation to the subsequent requirement for surgical removal of tumours in bitches, medicated for oestrus control, is discussed.     

Isoenzyme studies on Theileria (Protozoa,Sporozoa). Enzyme activity associated with the erythrocytic stage

Summary

Bovine blood containing piroplasms of Theileria parva, as well as non‐injected blood, was lysed and subjected to iso‐electric focussing.

Staining for 13 different enzymes revealed parasite‐associated bands of glucose phosphate isomerase (GPI) activity, not of any of the other enzymes. There were no variations between individual donor animals in the host cell GPI bands and these bands did not interfere with the recognition of the parasite‐associated bands, so that purification of the piroplasms was unnecessary. Blood from cattle infected with T. mutans also gave parasite‐associated bands of GPI, but no such bands were seen in zymograms of blood from cattle infected with a Theileria sp. from Japan. Depending on the level of parasitaemia, up to four parasite‐associated bands were found in one strain of T. parva and up to three in two other strains. Among the disadvantages of using piroplasm material for the study of isoenzymes of T. parva is the fact that animals often die before their parasitaemia is sufficiently high, and that some strains never give rise to a high parasitaemia.