Myopathie der Labrador Retriever: neuromuskuläre Veränderungen bei kranken und klinisch gesunden Hunden

Gegenstand und Ziel: Die erbliche Myopathie der Labrador Retriever (LM) ist eine autosomal rezessive Krankheit, die bei schwarzen und gelben Tieren beiderlei Geschlechts und unterschiedlichen Alters vorkommt. Um der Frage nachzugehen, welche Rolle die LM in der hiesigen Labradorpopulation spielt, wurden seit 1998 am Institut für Neuropathologie der Universität Düsseldorf Muskel-und Nervenbiopsien von 121 Labrador Retrievern untersucht. Hunde: Die Tiere gehörten zu zwei Untersuchungsgruppen. Gruppe I (Einsendungen) umfasste 63 Labrador Retriever unterschiedlicher Herkunft aus Deutschland, Schweiz, Italien und Portugal mit Symptomen einer Myopathie. Gruppe II (Zuchttiere): Im Rahmen einer genetischen Studie wurden 58 miteinander verwandte Labrador Retriever aus einer Zucht in der Schweiz untersucht, nachdem dort bei zwei Welpen LM nachgewiesen worden war. Ergebnisse: Gruppe I: 17/63 (27%) hatten eine degenerative Myopathie vom Typ der Labrador-Myopathie, 8/63 (13%) metabolisch-mitochondriale Veränderungen, 33/63 (52%) andere (überwiegend neurogene oder entzündliche) Myopathien und bei 5/63 (8%) wurden keine pathologischen Veränderungen in Muskel und/oder Nerv nachgewiesen. Gruppe II: Zwar hatten nur sieben Tiere der Zucht klinische Symptome, doch wies die Mehrzahl morphologisch und histochemisch nachweisbare neuromuskuläre Veränderungen auf, nämlich 37/58 (64%) solche vom Typ der LM, darunter auch die Eltern und die sieben Geschwister der beiden Welpen, und 11/58 (19%) vorherrschend metabolisch-mitochondriale Veränderungen. Schlußfolgerungen: Die vorliegende Untersuchung zeigt, dass (a) die Verbreitung der erblichen Myopathie und deren Erfassung ein ernst zu nehmendes Problem beim Labrador Retriever darstellt und (b) neben der »klassischen« erblichen Typ-2-Myopathie der Labrador Retriever möglicherweise noch eine zweite, metabolisch-mitochondriale Form der Myopathie besteht, die Ähnlichkeiten mit einer anstrengungsabhängigen Myopathie bei Labrador Retrievern in den USA aufweist.

[Tetanus in cats: 3 case descriptions]

Three cats with spasticity on one leg or on all four limbs were presented between 1996 and 1998 at the Department of clinical veterinary medicine, Section of neurology, Vetsuisse-Faculty of Bern. The presumptive diagnosis was tetanus. A focal form was present in two cases and generalised tetanus in one cat. All cats had a history of injury at the affected legs respectively at the neck. The first clinical signs were seen between two days and three weeks after injury. The bacteriologic examination of serous fluid from the site of injury revealed an infection with Clostridium. EMG in one cat during anaesthesia showed motor united potentials (MUPs) on the spastic leg. All patients received antibiotics (Penicillin, respectively Amoxicillin/Clavulanic acid and Metronidazol). Supportive aid were initially sedation, wound revision and in one cat nutrition through oesophageal sonde. In a second phase physiotherapy was performed. All three animals were significantly better after a couple of weeks, two cats were without symptoms after eight and five weeks respectively.

Genetic aspects of Labrador Retriever myopathy

Labrador Retriever myopathy (LRM) has become a relatively common muscular disease. The objective of our prospective study was to determine by segregation analyses a plausible mode of inheritance within a Labrador Retriever population. Therefore we performed neurological examinations, as well as electromyographic and histopathological evaluations of 58 closely related dogs. Seven dogs with an average age of 27.8 months had clinical signs consistent with LRM including exercise intolerance or fatigue. The diagnosis was based on neurological deficits and confirmed by histopathological results of muscle biopsy. We found in all cases obvious differences in fiber calibre size associated with texture disturbances. In addition, we found 41 clinically normal dogs with histological findings consistent with LRM. Three genetic models, the major gene, the mixed inheritance as well as the environmental model, were evaluated by segregation analyses. They were applied to an extended pedigree including 164 non-randomly ascertained related Labradors. According to phenotype the clinically examined dogs were divided into two different data sets. One data set distinguished between clinically normal and abnormal dogs, the second data set between histopathologically normal and abnormal dogs. We concluded that the clinical form of LRM is transmitted by a major gene and controlled by an autosomal recessive mode of inheritance. Furthermore, for expression of the subclinical form an additional gene or an environmental factor is responsible. Our findings suggest that LRM is similar to limb-girdle muscular dystrophy in man and therefore, may be used in the future as an animal model.

Longissimus dorsi muscle diameter, backfat thickness, body condition scores and skinfold values related to metabolic and endocrine traits in lactating dairy cows fed crystalline fat or free fatty acids

An experiment was performed using 18 dairy cows with > or = 2 lactations from parturition until week 20 of lactation to investigate the effects of feeding rumen-protected crystalline fat (group A) or free fatty acids (group B) compared with a control group not fed supplemental fat or fatty acids (group C). The feeding effects studied were those on milk yield and composition, body weight (BW), body conditions scores (BCS), skinfold values (a measure of subcutaneous fat tissue thickness), backfat thickness and longissimus dorsi muscle diameter (measured by ultrasound), as well as on blood plasma metabolic and endocrine traits. Fat and fatty-acid feeding reduced roughage intake. Net energy and protein balances during the first week of lactation were negative. Milk yield was similar in all groups, but concentrations of milk fat were reduced in group B and of milk protein in groups A and B. BW, BCS, skinfold value, backfat thickness and longissimus dorsi muscle diameter similarly decreased in all groups until weeks 8-12. Concentrations of glucose and fructosamine decreased transiently during early lactation, whereas levels of beta-hydroxybutyrate, urea, total protein and albumin increased reversibly and similarly in all groups. Concentrations of creatinine decreased similarly in all groups until week 4 and those of nonesterified fatty acids until week 12. Triglyceride concentrations increased continuously until week 18, whereas concentrations of phospholipid and cholesterol increased until week 10 and then remained elevated. Triglyceride, phospholipid and cholesterol concentrations were higher in group B than in groups A and C throughout the experiment. Concentrations of insulin, insulin-like growth factor-1, thyroxine and 3,5,3'-triiodothyronine started to increase after the first 6-8 weeks of lactation, while those of growth hormone were transiently low in week 16. None of the hormones exhibited group differences. In this study rumen-protected fat or fatty-acid supplementation failed to improve the energy and protein balances during early lactation and did not affect milk yield, likely due to decreased roughage intake. BCS, skinfold values and backfat ultrasound measurements of subcutaneous adipose tissue mass and of longissimus dorsi muscle diameter indicated mobilization of fat tissue and protein mobilization in early lactation and were mirrored by typical changes of metabolic and endocrine traits.

Genetic aspects of idiopathic epilepsy in Labrador retrievers

A study was undertaken to define the mode of inheritance of idiopathic epilepsy in Labrador retrievers in Switzerland. Seven hundred and ninety-two pedigree certificates from a population of healthy and epileptic dogs from 11 generations were evaluated. Forty-four different families (giving a total of 55 epileptic dogs) were included. Most patients showed generalised grand mal seizures and the onset was within one to three years in 41 per cent. Males were no more affected than females and the gender ratio between epileptic and control animals was not significantly different (P > 0.05). Additionally, there was no difference in average total inbreeding coefficient between both sexes, or with respect to age of onset of seizures. The increased manifestation of seizures in some subpopulations and the repeated occurrence in different families of the same sires suggested that there was a genetic basis for the condition in the breed. Results of pedigree analyses and from use of the binomial test support the hypothesis of a polygenic, recessive mode of inheritance. However, only an objective test-mating programme is likely to define the exact mode of inheritance.

[Convulsions in relation to polycythemia: literature review and case description]

Polycythemia--characterized by an excessive number of erythrocytes--is a rare disease in the dog with a chronic progressive course and unspecific symptoms. There are several forms: a primary, a secondary adequate or a secondary inadequate polycythemia. The clinical workup is done step by step and after stabilization of critical patients, the remaining therapy must address the primary cause. We report on a five year old male Leonberger dog suffering from secondary, inadequate polycythemia. He was presented with apathy, gait disturbances and disorientation. On the basis of the diagnostic workup a pathological process in the kidneys was postulated. Initially focal seizures became generalized later, most probably because of formation of a forebrain thrombus with secondary hypoxia. Even after emergency treatment the general state deteriorated. The course indicated possible sepsis. Because of the critical picture with secondary complications and the poor prognosis, the dog was euthanised. The histopathological results showed T-cell renal lymphoma and secondary injury to the forebrain.

Clinical, epidemiological and treatment results of idiopathic epilepsy in 54 labrador retrievers: a long-term study

The records of 54 labrador retrievers with idiopathic epilepsy were reviewed. Exogenous factors played a minor role in the transmission of the epilepsy. Prodromal phase and aura were present in the majority of the dogs with generalised seizures. The ictal phase was characterised by long-lasting automatisms. Approximately half of the dogs had seizures more than once a month: the remainder ranged from one every two months to one every 12 months. The average frequency in dogs with generalized seizures (n = 49) was one every 65 days and in dogs with partial seizures (n = 5) one every 205 days. Long-term follow-up was performed in 46 dogs, 37 of which followed a strict treatment protocol. Possible causes for the large variations in treatment results were analysed. One goal was to identify objective aspects enabling a realistic prognosis prior to treatment. Animals with a high age at onset of seizure (mean, four years) showed an excellent outcome, even if treatment began late. Dogs with low frequency rates and low total numbers of seizures responded well to therapy if treated as early as possible.