Pathological findings in the tissues and blood of dogs affected in food-associated megaesophagus/polyneuropathy outbreak | Patoloģiskās izmaiņas audos un asinīs ar barību saistītā Megaesophagus/polineiropātijas uzliesmojumā skartajiem suņiem
2017
Stankevica, D., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Veterinary Medicine | Lusis, I., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Veterinary Medicine | Piginka-Vjaceslavova, I., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Veterinary Medicine;;Institute of Food Safety, Animal Health and Environment BIOR, Riga (Latvia) | Drevinska, K., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Veterinary Medicine | Ozols, A., Sensovet, SIA, Jelgava (Latvia) | Konopore, L., Hīrons, SIA, Riga (Latvia) | Matiasek, K., Ludwig-Maximilians-Universität München, Munich (Germany) | Matise-VanHoutan, I., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Veterinary Medicine;Matīses Veterinārās patoloģijas serviss, IK, Alejas, Kekava parish, Kekava Municipality (Latvia)
In Latvia during 2014-2016 there was sudden increase in number of dogs diagnosed with megaesophagus, decreased nerve impulse conduction, atrophy of muscles, and generalized weakness indicating megaesophagus/polyneuropathy (ME/PNP). Results of 56 epidemiological investigation showed that exposure to brand A dry dog food was main risk factor for developing ME/PNP. The objective of this study was to characterize changes in the tissues and blood of dogs affected with ME/PNP. In sick dogs with x-ray-confirmed ME following tests were done: haematology, serum biochemistry, and tests for vitamins B, thyroid hormones and myasthenia gravis (MG). Dogs with ME/PNP that had died were necropsied (n=32). In a subset of dogs (n=19) more extensive sampling of central and peripheral nervous system tissues was done. Dogs with ME/PNP had mild neutrophilia with left shift, lymphopenia, a slight increase in hepatic enzymes (ALT, AST and alkaline phosphatase). 15% of dogs had D.repens microfilaria. Vitamin B levels were frequently reduced. Tests were negative for MG and hypothyroidism. All necropsied dogs had ME. Most frequent lesions in dogs were PNP and skeletal muscle atrophy. Lesions in the oesophagus consisted of muscle fiber degeneration and atrophy. Nerve lesions consisted of subperineurial edema, Renaut bodies, and degenerative changes in axons and myelin sheaths. Small diameter motor nerves of hind limbs were more consistently affected than front limbs. Food-associated ME/PNP is distally enhanced neuropathy more severely affecting longest nerves in the body (vagal and sciatic nerves). Lesions are indicative of toxic polyneuropathy, but the mechanism is unclear.
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