In addition to routine samples, tissues should be frozen for possible bacterial, fungal, or viral cultures. At this time, a thorough history and a collection of animals for diagnostics and necropsy can be obtained. This also allows observation of the feeding and water change practices. A visit to the ranch or farm should be performed during feeding time to avoid additional stress to the animals. One should not underestimate these observations because most workers are well tuned to the daily routine and behavior of the animals. In commercial operations, the workers may notice excess food remaining from the day before, which is sometimes followed by a perceived change in the behavior of the animals. These include anorexia, lethargy, and death.
The first signs of illness in captive crocodilians are usually nonspecific in nature. Overcrowding, handling, excessive noise, diet changes, water and air quality, temperature irregularities, and more should all be considered as predisposing or confounding factors of disease.Īnorexia, Lethargy, and Acute Mortalities 1 Enough evidence exists to suggest that stress plays an important role in the physiology of crocodilians, and it may indeed predispose them to illness. 3, 4, 5, 7 Factors that influence stress in crocodilian and reptile species are reviewed by Rooney and Guillette. In addition, an argument is made for immunosuppression on the basis of changes observed in the white blood cells. 7 Catecholamines, glucocorticoids, glucose, and lactate have been implicated in the stress response of crocodilians. provide an overview of the physiology and endocrinology of stress in crocodilians.
2 Studies in crocodilians have evaluated the stress associated with restraint, long-term corticosterone implants, cold shock, and stocking densities.
The autonomic nervous system, the hypothalamic adrenal axis, neuropeptides, neurotransmitters, and neuroimmunologic mediators all have a role in the response of the immune system to stress. Stress has been defined as “a physiological answer to a perceived threat that includes, but is not restricted to, increased adrenal secretion.” 1 Stress is also thought of as any event that challenges homeostasis, and likely the response to that challenge involves more than an adrenal response. Stress and immunosuppression are often underlying factors for many diseases affecting captive crocodilians.
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