Feline dysautonomia: an ultrastructural study of neurones in the XII nucleus

Dysautonomia in dogs: 65 cases (1993-2000)

OBJECTIVE

To determine signalment, history, clinical findings, results of autonomic function testing and other antemortem diagnostic tests, and pathologic findings in dogs with dysautonomia.

DESIGN

Retrospective study.

ANIMALS

65 dogs with dysautonomia.

PROCEDURE

Case records of 68 dogs with a diagnosis of dysautonomia were reviewed; inclusion criteria included histologic confirmation of dysautonomia or clinical signs and results of pharmacologic testing consistent with dysautonomia.

RESULTS

65 dogs fulfilled all criteria for dysautonomia. Dogs from rural environments were overrepresented, and cases of dysautonomia were reported for every month, although the highest number of cases was reported in February and March. Vomiting was the most common clinical sign, followed by diarrhea, signs of anorexia and depression, weight loss, and dysuria. The most common physical examination finding was decreased or absent anal tone, followed by absent pupillary light reflexes and elevated nictitating membrane. Results of pharmacologic testing were consistent with dysautonomia, although no single test was 100% sensitive. Histologic lesions consistent with dysautonomia were found in the autonomic ganglia, brainstem nuclei, and ventral horns of the spinal cord.

CONCLUSIONS AND CLINICAL RELEVANCE

Dysautonomia is an endemic disease in Kansas, and a high index of suspicion of the disease can be made by combining clinical signs, physical examination findings, and results of pharmacologic testing.

A review of the primary dysautonomias of domestic animals

Primary dysautonomias appear to be the result of initial damage to the protein synthetic pathway of a specific neuronal population, but despite detailed morphological study of several species there is, as yet, no indication of the precise lesion or the nature of the causal agent. The very marked similarities between the species with regard to lesion type, distribution, the age group affected and the geographical restrictions of occurrence would suggest a very similar, if not common, aetiology. There is no explanation, however, for the 70 year gap between its appearance in horses and its subsequent occurrence in other species or why it is these species, with very different physiology, habits and habitats, that are affected. No reference could be found in the literature to any infectious agent or toxin causing a similar range of structural effects with a similar species specificity or lesion distribution. Many questions about dysautonomias remain. Why is the lesion distribution so specific? At what level of the synthetic pathway does the primary lesion occur? What are the unusual compounds demonstrated in "acute phase" serum from affected horses; are they a neurotoxic agent(s) and/or its metabolites, or the abnormal product of an affected animal? Why did the experimental ponies which developed autonomic lesions not become ill? When do the clinical signs appear in relation to the occurrence of the primary lesion? Why are adolescent and young adult animals most commonly affected? As the general understanding of neuronal function and the numerous factors which influence it improves, the many subtle distinctions and similarities amongst the myriad sub-populations of neurones will become clearer and common features may emerge which will link the seemingly disparate neuronal types involved in the primary dysautonomias.