Spontaneous primary myopathies in domestic mammals: a review

Equine atypical myopathy: a review

Atypical myopathy (AM) is an acute rhabdomyolysis syndrome that occurs at irregular intervals in grazing equines. An increasing number of outbreaks have been reported in recent years, including some from countries where the disease has not previously been diagnosed. In this review, clinical and other details of outbreaks of AM are analysed to better define its epidemiological profile. Potential aetiologies are discussed, the short clinical course of AM is described and the main biochemical and pathological findings are considered. Recommendations for medical management are suggested, based on a review of clinical reports. Biochemical and histopathological findings have been integrated in order to characterise the physiopathology of AM. There is an ongoing requirement to record new cases of this syndrome, ideally through an epidemiological network.

Protein folding pathology in domestic animals

Fibrillar proteins form structural elements of cells and the extracellular matrix. Pathological lesions of fibrillar microanatomical structures, or secondary fibrillar changes in globular proteins are well known. A special group concerns histologically amorphous deposits, amyloid. The major characteristics of amyloid are: apple green birefringence after Congo red staining of histological sections, and non-branching 7-10 nm thick fibrils on electron microscopy revealing a high content of cross beta pleated sheets. About 25 different types of amyloid have been characterised. In animals, AA-amyloid is the most frequent type. Other types of amyloid in animals represent: AIAPP (in cats), AApoAI, AApoAII, localised AL-amyloid, amyloid in odontogenic or mammary tumors and amyloid in the brain. In old dogs Abeta and in sheep APrPsc-amyloid can be encountered. AA-amyloidosis is a systemic disorder with a precursor in blood, acute phase serum amyloid A (SAA). In chronic inflammatory processes AA-amyloid can be deposited. A rapid crystallization of SAA to amyloid fibrils on small beta-sheeted fragments, the 'amyloid enhancing factor' (AEF), is known and the AEF has been shown to penetrate the enteric barrier. Amyloid fibrils can aggregate from various precursor proteins in vitro in particular at acidic pH and when proteolytic fragments are formed. Molecular chaperones influence this process. Tissue data point to amyloid fibrillogenesis in lysosomes and near cell surfaces. A comparison can be made of the fibrillogenesis in prion diseases and in enhanced AA-amyloidosis. In the reactive form, acute phase SAA is the supply of the precursor protein, whereas in the prion diseases, cell membrane proteins form a structural source. Abeta-amyloid in brain tissue of aged dogs showing signs of dementia forms a canine counterpart of senile dementia of the Alzheimer type (ccSDAT) in man. Misfolded proteins remain potential food hazards. Developments concerning prevention of amyloidogenesis and therapy of amyloid deposits are shortly commented.

Epidemiological aspects of cerebrospinal elaphostrongylosis in small ruminants in northern Norway

Pathology records from the State Veterinary Laboratory for Northern Norway were used to examine the association between the occurrence of cerebrospinal elaphostrongylosis (CSE) in small ruminants and summer temperature and rainfall in northern Norway. From 1968 to 1993, Elaphostrongylus rangiferi induced CSE was diagnosed in six sheep and 30 dairy goats from 28 different herds in northern Norway. The animals were received for autopsy during 11 different winters. The occurrence of CSE was associated with high mean temperatures during the preceding summers. Further information on clinical CSE and potential risk factors of the disease was obtained from small-ruminant farmers in northern Norway in 1989 and 1991, using a questionnaire. Clinical CSE was defined as posterior paresis without any evidence of brain disturbances or cranial nerve dysfunctions. The survey showed that epidemics of CSE may occur in goat herds while the occurrence of CSE was sporadic in sheep herds. Disease incidence in affected goat herds varied between 0.8 and 8.2%. CSE was associated with the presence of reindeer in the pasture area and occurred in the first, third and, especially, the fourth quarter of the year.

Dyserythropoiesis, polymyopathy, and cardiac disease in three related English springer spaniels

A polysystemic disorder was observed in three related English Springer Spaniel dogs that demonstrated regurgitation from an early age, slowly progressive temporal muscle atrophy with partial trismus, and less pronounced generalized skeletal muscle atrophy. All dogs exhibited moderate dyserythropoietic anemia, polymyopathy with megaesophagus, and varying degrees of cardiomegaly. The prevalence, etiology, underlying pathomechanism, and possible mode of inheritance remain to be elucidated.