Tierärztliche Fakultät - Digitale Hochschulschriften der LMU - Teil 01/07 Archiv

In the present experimental essay the effect of controlled ventilation with the UNO Micro-Ventilator? (UMV) on the mouse is examined. The UMV is a pressure controlled and volume limited ventilation device with a sinus ventilation pattern and lowflow rebreathing of the respiration gas. Not only the impact of a preoxygenation is assessed but also the effect of different respiratory rates on mice of different weight. The assessment is made with blood gas analysis, circulatory parameters and histological examinations of the lungs. The animals can be assigned to nine groups: The non-preoxygenized animals are split up in six groups and the preoxygenized ones in two groups. Additionally, group H serves as histological control group. The non-preoxygenized animals of N100 are ventilated with a respiratory rate of 100 /min (n = 6), i.e. the animals of the N130 with 130 /min (n = 6). The animals in N100L (n = 8 settings) are non-preoxygenized, weigh between 25 and 38 grams and the respiratory rate is adjusted to 100 /min. The animals of the group N100S (n = 7) which weigh between 39 and 50 grams are not preoxygenized either. In P80L (n = 7, settings) the animals are ventilated with 80 /min, are preoxygenized, and their weight varies between 25 and 38 grams. Grouped in P80S (n = 7) are animals which weigh between 39 and 50 grams. Group H (n = 7, animals) was not ventilated and serves for the histological examination. To expose the animals to as little stress as possible they are premedicated to the intubation with the completely antagonizable injectable anesthesia medetomidine, midazolam, and fentanyl (MMF). With the beginning of the anesthesia with isoflurane (the concentration of the isoflurane is 2.7 vol.-%) the injectable anesthesia is antagonized with atipamezol, flumazenil, naloxone (AFN). The anesthesia lasts 100 minutes. The A. carotis of all ventilated animals is canulated in order to measure the blood pressure and take blood samples. Besides the blood gas results (pHa, pa CO2, paO2, BE, HCO3¯) the measured parameters are the blood pressure (in mmHg) and the heart rate (in beats /min). To ascertain the normal distribution the Kolmogorov-Smirnov test is carried out. The comparison between the groups is made with the distribution-free Mann-Whitney test. The level of significance is fixed at p < 0.05 (5 %). The mice of group N130 stay in the physiological sector with their blood gas results. Animals of group N100L show a respiratory acidosis. The preoxygenized P80L and P80S require a lower respiratory rate than non-preoxygenized animals independent of their weight. The medium arterial blood pressure of all groups sinks steadily while the heart rate increases at the same time. In the histological preparations of all groups including the control groups atelectasis, perivascular edemas, congestions and emphysemas can be seen. However, on what these pathological findings are based cannot be thoroughly explained. Therefore, mice should be preoxygenized 5 minutes prior to a ventilation. Thus, a respiratory rate of 80 per minute is sufficient for all weights. If not preoxygenized, a respiratory rate of 130 /min is suggested for animals up to 39 grams and approximately 110 /min for mice over 39 grams. With these settings the UNO Micro-Ventilator is to be recommended for the ventilation of mice.

Morphological and biomechanical characteristics of the canine hip joint (articulatio coxae) Morphological and biomechanical parameters of the canine hip joint have been investigated for the first time in order to determine the long term loading of the hip joint surfaces. 86 hip joints of 43 predominantly large breed dogs (average age 6 years) were examined. By means of CT-osteoabsorptiometry (CT-OAM) the subchondral bone density was determined qualitatively and quantitatively. The exact topographic distribution of the subchondral bone density was shown in three-dimensional reconstructions of the hip joints in false colour code. The distribution pattern was regularly tricentric with bone density maxima located in the cranial and caudal aspects of the joint surfaces as well as in the roof of the acetabulum and the perifoveal area of the caput ossis femoris. The anteversion of the Os femoris was determined by a computed tomographical method. The findings allowed the assumption of a causal relationship between a reduced anteversion angle and a shift of the density maxima to the medial part of the joint surface of the caput ossis femoris. The main direction of the collagen fibres in the joint cartilage and the subchondral bone were traced by means of the split line method. The split line pattern established proof of an existing tension and bending in the acetabulum. Moreover it identified areas of compressive stress on the surface of the joint (cranial and caudal aspect of the lunate surface and the femoral head). Biomechanical parameters such as contact areas as well as distribution and amount of pressure were determined experimentally under physiological load conditions representing the three leg stance during slow walking. These data were gained by casting material and pressure sensitive film. At low loads and physiological angulation contact areas were mainly found at the peripheral margin of the cranial and caudal part of the facies lunata and caput ossis femoris. At the cranial roof of the acetabulum a joint space was evident in the loaded specimens up to 75% body weight. Under increasing loads the contact areas expanded towards the joint centre. The maximal contact pressure ranged from 8 to10 MPa under a load of 400% body weight. Areas of load transfer showed a more obvious bi- and tricentric distribution pattern than contact areas. With increasing loads areas of load transfer expanded to a uniform area. The results of this study established proof of the inhomogeneous load distribution in the canine hip joint. For the first time it was shown that the canine hip joint is not congruous as commonly assumed but maintains a physiological incongruity. This guarantees for an optimal load distribution in the joint and for a better nutrition of the joint cartilage. Further, it was shown that osteoarthrosis more often exists in those areas of inhomogeneously loaded joint surfaces which are exposed to larger mechanical stress a priori.

Disease Incidences in Dogs – Dependency on Age, Sex, Size and Breed A Retrospective Study Based upon all In-Patient Dogs at the First Clinic for Internal Veterinary Medicine in Munich 1991 – 1997 This retrospective study is based upon the case files of all in-patient dogs treated at the First Clinic for Internal Veterinary Medicine of the Ludwig - Maximillians University in Munich within the period from 1991 and 1997. Data from 6005 patients, totalling 14056 diagnoses is listed and evaluated. The sex ratio (male : female) is 1.1 : 1 (i. e. almost balanced). 10.3 % of the male and 35.3 % of the female dogs were castrated. The population was composed of 164 breeds, which were classified into 15 breed groups for the analysis. The average age of the patients increased during the period investigated. Correlations between age and sex and height and breeds, respectively, have been observed. The multimorbidity increased significantly with the age. Additionally, the height and the breed of the patients also affected it. The multimorbidity of big dogs was lower than that of small dogs. Poodles, Dachshunds and Spaniels showed the highest multimorbidity, Labradors/Retrievers the lowest one. The following observations were made: Age-related tendencies: Infectious diseases (especially virus infections) were observed predominantly in young animals as well as (endo-) parasites and inflammatory respiratory tract diseases. Young adult dogs commonly experienced poisoning and injuries. Diseases of the heart, the liver, the pancreas, the endocrine and the reproductive system, diseases of the kidneys and the eyes, variations in body weight and tumors were typical in older animals. Dermatological diseases, diseases of the ears, the nervous system, the digestive tract, the blood and the hematopoetic system as well as diseases of the lymphatic organs had a higher prevalence with increasing age. Nevertheless there are variations within special disease groups regarding the age-relationship. For example, ear parasites and the disease complex “encephalitis/meningitis/myelitis" affected predominantly young adult dogs. The age-predilection of vaginitis and balanoposthitis did not correspond to its disease group (vaginitis: decreasing incidence with increasing age; balanoposthitis: incidence decreased after age of nine). Gastroenteritis occurred less often in older dogs. Hypothyroidism was most prevalent in middle-aged dogs (six to nine years). Sex predilections: Female dogs were predisposed to variations in body weight, poisoning, endocrine diseases and also – but only slightly - to diseases of the respiratory tract. Male dogs appeared to be at increased risk for heart diseases, diseases of the nervous and the digestive system, for malformations and injuries. Infectious diseases, parasites, diseases of the reproductive and the immune system were more often diagnosed in intact than in castrated dogs. Diseases of the skin, the liver, the nervous and the metabolic system, the pancreas, tumors, variations in body weight and injuries occurred predominantly in castrated animals. Height-specific predilections: Diseases of the eyes, the liver, the heart, the digestive tract, the pancreas and endocrine diseases and deformities were more common in smaller dogs. Big dogs were prone to infectious diseases, skin, ear and circulation diseases as well as to gynecologic/andrologic, blood and hematologic diseases, diseases of the lymphatic and the immune system. Parasites and variations in body weight were also more often diagnosed in bigger dogs. Renal diseases showed no height disposition, but they were often diagnosed in giant breeds. Diseases of the nervous system occurred rarely in giant breeds. Tumors were strikingly more common in bigger than in smaller dogs. Breed predilections: The disposition of big dogs for infectious diseases and parasites correlated with the breed predilection (Greyhounds, Retrievers/hunting dogs). Pomerians, Boxers and the German shepherd were prone to dermatological diseases. Pendulous-eared dogs and Rottweilers were predisposed to ear diseases. Spaniels, Poodles and Terriers had ophthalmologic problems more often than other breeds. Bernese Mountain Dogs showed a high incidence for diseases of the kidneys and the lower urinary tract. Cocker Spaniels and Boxers developed tumors much more frequently. Poodles, Terriers, Spaniels and Dachshunds were predisposed to diseases of the pancreas as well as to diseases of the heart and the endocrine system. Terriers and Pinchers/Schnauzers often revealed diseases of the liver and the gallbladder. Hunting dogs (Irish Setters) suffered more commonly from gynecologic and andrologic diseases. Diseases of the nervous system affected especially Cocker Spaniels, West Highland White Terriers and Boxers. Brachycephalic breeds had a high incidence in deformities.

Investigation of IgG index and albumin quotient for the differential diagnosis of dogs with neurological diseases In the present study the benefit of IgG index and albumin quotient for the differential diagnosis in dogs with neurological diseases was investigated. The question whether the determination of these two parameters is a convenient extension of the conventional cerebrospinal fluid (CSF) examination was explored. The IgG index served as an indicator for intrathecal IgG synthesis, the albumin quotient as an indicator for disturbances in the blood-brain barrier. The concentrations of albumin and IgG in CSF and serum of 122 dogs were determined with the help of nephelometry, followed by the calculation of the albumin quotient and IgG index. The conventional CSF examination included cell count, cell morphology, Pandy’s test, and protein content. All 122 dogs could be categorized into five different groups according to the clinical and pathological findings: inflammatory diseases (n = 33), tumors (n = 11), disc prolaps (n = 37), orthopedic diseases (n = 20), and idiopathic epilepsy (n = 21). In 10% of the examined dogs (12 of 122), pathological findings of the cerebrospinal fluid could only be exposed with the help of IgG index or albumin quotient, with the total protein level being normal. This result was equivalent to 14% of the dogs with normal total protein levels. Among these patients were dogs with white dog shaker disease, distemper, steroid responsive meningitis arteritis, and plexus carcinoma. On the other side, dogs with increased CSF total protein had a 97% chance of increased IgG index or albumin quotient. 67% of the dogs with inflammatory diseases showed an increase in IgG index and 70% an increase in albumin quotient. In 46% of these animals both parameters were elevated. Maximum changes were observed in dogs with central European tick-borne encephalitis. Dogs with white dog shaker disease were the only ones to exhibit an exclusive increase in the IgG index. 36% of the patients with tumors showed an increase in IgG index and 64% an increase in albumin quotient. In 18% of the animals both parameters were elevated. The highest level of all IgG indices was obtained in a patient with an ependymoma. Patients with disc prolapse showed in 8% of the cases a mild increase in IgG index and in 14% a mild increase in albumin quotient, but never a combination of both. In dogs with orthopedic diseases, two (10%) had a slight increase in CSF total protein and albumin quotient, which could not be explained with the orthopedic findings and which indicated an additional neurological disease. As expected, no changes occurred with idiopathic epilepsy. Even when there were highly significant differences between the single groups of patients, one group never differed significantly from all of the others groups in both parameters – neither in absolute levels nor in the proportion of altered values. In dogs with neurological symptoms without increased levels of protein, IgG index and albumin quotient can help to identify pathological findings of the cerebrospinal fluid. In the future, the determination of IgG index and albumin quotient will be an useful extension of the routinely used CSF examination in dogs with neurological diseases.

Possibilities of early diagnosis of osteomyelitis by magnetic resonance tomography - experimental studies in rabbits Correlation of MR-images and macroscopic sections demonstrates, that anatomical structures of rabbits can be excellently visualized by MRT. Clinically used MR-systems are able to provide satisfactory resolution. Following experimentally induced osteomyelitis infected bone marrow can be detected by decreased signal on native T1-weighted and increased signal on T2-weighted images. After administration of gadolinium-DTPA marked enhancement can be observed. Detection of soft-tissue infection is superior on T2-wheigted scans showing high signal intensity. After administration of gadolinium DTPA rim enhacement provides good differentiation of abscessmembrane. Especially in earlier stages of disease (3 to 5, 8 to 12 and 12 to 19 days post infection) the sensitivity of native MRT (80%, 100%, about 67%) is superior compared to other diagnostic modalities, e.g. radiography (about 29%, about 46%, 50%), CT-scan (about 29%, about 13%, about 17%) and scintigraphy (60%, about 78%, 100%). Gadolinium-DTPA increases sensitivity (100%, 100%, 100%). At the end of the observation period bone scintigraphy provides the same sensitivity. MRT, however, is superior in detecting involvement of bone marrow and soft-tissue infection. Compared to scintigraphy and MRT radiography and CT-scan shows lower sensitivity during the whole observation period. Regional differences in detecting osteomyelitis can be recognized unsing MRT, less using other modalities. In early stages of the disease most infectious lesions are detected in the proximal femur. Explanation can be a different involvement of the femur, but also a different diagnostic potential of MRT concerning different anatomical regions. All in all MRT is an excellent tool in the diagnosis of osteomyelitis and is superior to other imaging modalities. Application of contrast material provides further improvement in sensitivity. In the clinical use fat suppression and STIR-sequence have provided further improvement. The role of MRT as a diagnostic instrument in osteomyelitis is established in clinical medicine and seems promising in veterinary medicine.

Studies on the effect of rare earth elements as growth promoter in pigs In China, rare earth elements were used in agriculture already for some decades. Rare earth elements are 17 elements which include scandium, yttrium, lanthanum and the 14 lanthanides. They were used as fertilizer in plant production and as growth promoters in animal production. Spectacular improvement of the fattening parameter daily body weight gain and feed conversion ratio of pigs were reported in the Chinese literature. In previous experiments of our working group the growth promoting effect of the rare earth elements has been proven for pigs under western feeding and housing conditions. In this thesis two feeding experiments with fattening pigs and a field trial with weaned piglets are described. In the first experiment a total of 48 pigs (German Landrace x Piétrain) were allotted to four dietary groups, 12 pigs in each group. The animals received a mixture of rare earth elements in a concentration of 0 or 300 ppm rsp. or pure lanthanum chloride and cerium chloride in a concentration of 100 ppm LaCl3 and 200 ppm CeCl3 or 200 ppm LaCl3 and 100 ppm CeCl3. Because of a disease this first study had to end ahead of schedule. In the second trial the design of the trial was the same as in the first one. During the 12 weeks of this experiment the pigs received feed, supplemented with the above described concentration of rare earth elements. The daily body weight gain in the REE group during the study period was 4 to 5 % better than in the control group, where there was no influence on the feed conversion rate. The accumulation of the lanthanides in the muscle and the liver was very low as shown in the experiments before. The analysis were made by ICP-mass spectrometry. In the serum, the levels of triiodothyronine and thyroxine were lower in the groups receiving the rare earth elements than in the control group. Thyroxine in the groups with 300 ppm REE mixture and with 100 ppm LaCl3 and 200 ppm CeCl3 was significantly lower than in the control group. In a field trial with piglets of the race Swiss Edelschwein the growth promoting effect of rare earth elements was proved by two experiments. The animals were fed with a commercial feed supplemented with a mixture of rare earth elements in a concentration of 0 rsp. 200 ppm. In the first trial for 16 days body weight gain and feed conversion ratio of the group with 200 ppm REE mixture improved by 3 % rsp. 9 % as compared to the controls. The second field trial lasted for 30 days and here, the group supplemented with 200 ppm REE mixture gained by 10 % more weight than the control group. The feed conversion ratio improved by 2 %. These results showed for the first time, that rare earth elements are able to improve the performance of the piglets under field conditions.