Navicular disease is associated with intraosseous hypertension and venous stasis.

Although core decompression by drilling is an accepted treatment regimen for similar

conditions in humans, no experimental results exist concerning its application in the

equine navicular bone and its physiological effects.

During an in vitro study, the effects of decompression drilling of various drill bit sizes and

drill channel numbers on the intraosseous pressure and the 3-point bending breaking

strength of isolated navicular bones were studied and correlated to the bone mineral

density (BMD).

Core decompression significantly reduced the intraosseous pressure response to stresstest-

injections. A significant correlation existed between response to stress tests and

BMD. The drill channels did not significantly reduce the 3-point bending breaking

strength, regardless of their size and number.

In the course of the second part of the investigation, core decompression was carried

out arthroscopically in navicular bones of 6 healthy horses. The procedure was

performed in both front limbs staged by 3 weeks. The venous, arterial, articular and

intraosseous pressures were recorded before and after drilling, after intraosseous stress

– test- injections as well as 3 resp. 6 weeks after core decompression. Postoperative

lameness was assessed subjectively and using force plate gait analysis before inclusion

of the animals into the study as well as 1, 3 and 6 weeks post operatively. Navicular

radiographs were taken prior to acceptance of the horses into the program, immediately

after surgery and at week 1,3,6,9 and 12. Fluorochrome bone – labeling was performed

by alternating intravenous administration of oxytetracycline and calcein green every 3

weeks starting at day 0 (first surgery). The animals were sacrificed following a 12 week

observation period. The navicular bones were isolated, the bone mineral density was

measured and bone histology was performed on undecalcified sections using Toluidinblue

and von Kossa/McNeill stains in addition to the unstained fluorochrome slides.

Core decompression significantly reduced the intraosseous pressure response to stresstest-

injections. The effect decreased over the course of the observation period. A

significant correlation existed between response to stress tests and BMD.

114

No significant lameness was observed after the first 5 days following surgery. The drill

defects were clearly visible on tangential radiographs for the entire study period.

Histology revealed an almost complete seal of the drill channels with fibrous tissue and

woven bone at the time of sacrifice, 12 weeks after surgery. Significant remodeling and

neovascularization was demonstrated in the vicinity of the surgery sites.

In conclusion core decompression of the equine navicular bone appears to be a safe

procedure in regard to breaking strength and postoperative lameness score. It

significantly decreased intraosseous pressures following stress tests in healthy horses.

As the direct decompression effects of the procedure are short – lived due to the rapid

healing of the drill channels, its possible long – term effects, which might be extended by

the neovascularization, as well as its efficacy in the treatment of horses with navicular

disease remain to be assessed.

The objective of this study was to investigate anatomical and biomechanical parameters of the canine capal joint in order to determine the physiological situation of articular loading. 121 carpal joints of 61 dogs of varying age weighing more than 20 kg were examined. The joint angle of the carpal joint was measured in 50 standing dogs.

Long term tensile stresses of the articular cartilage and the subchondral bone were determined by the split line method. The distal articular surface of the radius showed two different types of split line patterns, a clear transverse orientation or one singular attractive point at the dorsal rim of the articular surface. The split lines at the dorsal aspect of the radius diverged towards its distal end, which is an evidence of a transverse strain of the articular surface during loading. In all joints compressively loaded regions were located especially in the dorsal parts of the articular surfaces. The articular surfaces of the second carpal bone showed two different split line patterns depending on the weight of the dogs. The palmar aspects of the proximal articular surfaces of the metacarpal bones showed evident transverse tensile stress.

The silicon cast method was used to determine the contact areas and Fuji pressure sensitive film to determine the contact pressures at different loading steps. In all joints of the carpus the contact areas increased nonlinear with an increasing loading rate. They never included more than 50% of the convexe articular surface. Contact areas in the antebrachiocarpal joint always were larger than those of the midcarpal and carpometacarpal joint at the same loading step, the latter being nearly identical for each loading step. Because of the hyperextension the antebrachiocarpal contact areas were located close to the dorsal edge of the articular surfaces, while in the midcarpal and carpometacarpal joint they reached further palmar. The centres of the contact pressures corresponded closely with the centres of the contact areas. Greater pressures in the antebrachiocarpal joint were located medially, in the midcarpal joint they were equally distributed over the whole articular surface, while in the carpometacarpal joint they were found laterally.

The long term loading situation of the articular surfaces was investigated by means of computertomography-osteoabsorptiometry (CTOAM). Individual CT-datasets were matched onto one target joint surface. Thus the mean values of all bone density measurements of the subchondral bone could be visualized. Areas of high bone density were very consistent and coincided with the location of high compressive load in the split line investigation and the contact areas. In the antebrachiocarpal joint, areas with high bone density were found dorsomedially. In both the midcarpal and carpometacarpal joint they were more equally distributed over the joint surfaces. With increasing age the subchondral bone density increases as well. Furthermore the bone density maxima are more clearly demarcated in older animals.

The joint angle of the carpal joint of standing dogs showed a significant correlation with the age of the animals. Body weight and breed did not have any influence.

From the biomechanical point of view the distal radioulnar ligament is a tensile loaded structure which connects radius and ulna distally and inhibits a separation of the two bones in stress. Moreover it increases the congruence of the antebrachiocarpal joint and thus is stressed with compressive forces.

Because of the physiologic hyperextension and valgus-angulation of the carpal joint the articulation with the greatest range of motion, the antebrachiocarpal joint, is loaded unilaterally. Due to the limited range of motion in both the midcarpal and carpometacarpal joint the load is equally distributed over the articular surface in these two joints.

Anhand von histologischen, immun- und lektinhistochemischen

Untersuchungen wurde die Entwicklung des Eileiters beim Rind analysiert. Hierbei wurden sowohl die Bildung und Differenzierung des Müller Ganges als auch des pränatalen Eileiters untersucht.

Umsetzung der Anforderungen der EU an registrierte Betriebe ab 2006 hinsichtlich Umsetzbarkeit und Verbraucherschutz

Staphylococci in the facemasks of workers in mince-meat-production by the example of two southern German meat factories

In this study a microbiological survey was made about facemasks taken from two EU-accredited meat processing factories in southern Germany. In factory A 110 masks from 44 meat workers were examined. This examination took place between April 2002 and January 2003. For comparison 51 masks of one day of production were taken in factory B. For both factories a survey was made of the bacterial flora, particularly regarding the coagulase-positive staphylococci which were contained in facemasks used during the processing of mince meat. The masks which went into the examination were compulsively used by all the staff of the mince-meat-production including dissection. At factory A 43% of the persons belonging to the mince meat processing, whose masks were examined were carriers of coagulase-positive staphylococci, compared to 64% at factory B. But the statistical spread of results, especially for coagulase-positive staphylococci, was significantly higher at factory A than at factory B. The results of the facemask of certain workers at this factory were also comparatively higher. There were also detectable interrelations between the total plate count and coagulase-positive staphylococci and the function and gender of the meat workers. Meanwhile there were no detectable interrelations between bacterial counts and possible seasonal influences.

Despite of remarkably high results found in the facemasks of separate meat workers no negative influences on the microbial quality of the mince meat could be observed, which makes the wearing of facemasks in mince meat production appear to be a simple way of avoiding contamination. If it is not possible to provide a good hygienic management or if separate staphylococcal isolates occur in the facemasks of certain meat workers as well as in the corresponding mince meat, an intranasal treatment with mupirocin could be considered for these persons. An noncritical application of antibiotics is not recommended due to the risk of creating resistances.

7. Summary

Tatjana Miller

Influence of Rare Earth Elements on fattening pigs and calves

In China rare earth elements (REE) are used as growth promoters in the animal production for almost 40 years.

In recent studies of our group the ergotropic effect of the rare earth elements was tested with pigs, poultry, rats and fish in different dosages also under western feeding conditions.

The best effects could be obtained with pigs. The daily weight gain in relation to control thereby could be increased over up to 12 %. At the same time the feed conversion ratio in the raising and mast phase decreased.

In the first part of the this work the influence of rare earth elements as citrate on the daily weight gain was examined in a field trial with fattening calves. In the second part of the work the effects of REE and the phytogenic additive on pigs were examined.

In a first feeding study with 312 male calves of the mark cattle race, divided into groups of 26, a mixture of rare earth elements was supplied to the animals in a concentration of 200 mg/kg daily by milk exchanger. No positive effects could be observed on the daily weight gain.

In a second feeding experiment 80 piglets of the race German land race x Piétrain were evenly divided after sex and weight in four groups of 20 animals, and a mixture of rare earth elements in a concentration of 300 mg/kg, phytogenic additives in a concentration of 1000 mg/kg and a combination of both in same dosage was added during a period of 138 days.

The additive of rare earth elements with male animals caused an average body weight increase by 3,4 %, whereby no improvement in the body weight development was to be observed with the female animals.

An increase of the average body weight in [kg] by the supplementation with phytogenic additives could be observed around 3,1 % with female animals and around 1,8 % with male animals.

The use of a combination of REE and phytogenic additives did not obtain an increase of the average body weight with the male animals, but on the other hand showed an increase with the female animals around 2,7 %.

Thus it could be shown that both, rare earth elements and phytogenic additives, might have a positive effect on the body weight gain. A cumulative effect was not observed.

An intact embryo-maternal communication in the pre-implantation period is particularly critical for establishment of pregnancy and early embryonic losses have been identified as the major cause of reproductive failure in cattle. Thus, to gain deeper insight into this complex embryo-maternal crosstalk, a combination of subtracted cDNA libraries and cDNA array hybridization was applied to identify mRNAs differentially regulated genes in the bovine endometrium by the presence of a conceptus. One cDNA library was constructed according the suppression subtractive hybridization method (Diatchenko et al., 1996) with minor modifications; a second cDNA library was constructed of subtracted cDNA purchased from the vertis Biotechnologie AG. As biological model endometrial tissue samples of monozygotic twins (generated by embryo splitting) collected at day 18 of gestation were used, which is a unique possibility to eliminate genetic variability as a factor potentially affecting the results of gene expression analyses. Array hybridization was carried out using 33P-labeled cDNA probes obtained from five monozygotic twin pairs. Sequence analysis revealed 87 different genes or mRNAs, respectively, which displayed a difference in signal intensity of 2.0 fold or more in at least four out of five twin pairs. Eighty genes corresponded to genes with known or inferred function, either the bovine gene or the human orthologue. For 7 mRNAs a match with bovine ESTs was obtained only. For nine selected genes the expression in the bovine endometrium was quantified by the use of quantitative real-time RT-PCR to verify the results obtained by array hybridization and to perform more precise quantitative measurements for these genes. Overall, the results of array hybridization and real-time RT-PCR correlated very well.

Almost half of the identified genes are known to be stimulated by type I interferons reflecting the response to IFNt, which is the pregnancy recognition signal in ruminants. Of particular interest among the interferon stimulated genes is ISG15, one of the most markedly upregulated genes in the present study, which is hypothesized to stabilize intracellular endometrial proteins through conjugation processes. For the ISG15ylation system mRNAs of four potential components (IFITM1, IFITM3, HSXIAPAF1, and DTX3L) were found in addition to ISG15 and UBE1L, and in situ hybridization revealed similar mRNA expression patterns of these genes. It is therefore suggested, that modification of endometrial proteins through ISG15ylation plays a fundamental role in the IFNt signaling.

A classification of the identified genes according to their assignment to Gene Ontologies revealed the orchestrated interaction of various processes and mechanisms with regard to the preparation of the maternal endometrium for embryonic implantation. As particular interesting, genes were identified involved in modulation of the maternal immune system at the humoral and cellular level, cell adhesion, cell communication, regulation of transcription, cell differentiation, cell growth, and cell proliferation. These findings underline that an intense embryo-maternal dialogue takes place during the pre-implantation period, which culminates in a receptive endometrium prepared for implantation of the conceptus.

To conclude, this is the first study of its kind for cattle in the pre-implantation stage of embryonic development and revealed the orchestrated upregulation of genes important for embryonic implantation during the pre-implantation period in the bovine endometrium. The presented results provide new starting points for detailed investigations of the embryo-maternal dialogue by which the endometrium is prepared for conceptus attachment.