Gastrointestinal system stimuli

Most patients with systemic sclerosis have Raynaud s phenomenon, where the digits tarn white, followed by a bluish color, which is then followed by reddening in response to an appropriate stimulus. Usually the precipitating event is cold temperatare or emotion. The pallor is due to vasospasm, the bluish color is from ischemia, and the reddish color is caused by a reactive hyperemia. Raynaud s phenomenon is a common manifestation of other syndromes, and most patients with Raynaud s phenomenon do not have systemic sclerosis. Approximately 50% to 80% of patients with systemic sclerosis have gastrointestinal symptoms, and 75% to 90% of patients have esophageal dysmotility. 

Ill-health can reduce the intake of both ruminants and non-ruminants. Contrary to popular opinion, infestations of gastrointestinal parasites tend to reduce intake, presumably because the interference with digestive function overrides any metabolic stimulus arising from a reduction in the absorption of nutrients. There is also evidence that stimulation of the animal s immune system, as happens with parasite infestations, may be responsible for a reduction in food intake. Infestations with external parasites, such as ticks, also reduce intake. 

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