unfortunately alot of symptoms for many diseases are exactly the same and only a necropsy can definitively answer the question of cause of death (and only then if a full scala of histological testing is done )....
A chicken s immune system is totally dependent on their nutrition and their ability to absorb the nutrition from their feed. When a chicken is cold or heat stressed or stressed it will eat and drink less ... all its efforts go into keeping it cool or warm... this affects their nutritional status which in turn affects their immune systym. When on top of that (subclinical ) disease or worms are additional stressors on the birds system then they can go downhill quite quickly.
http://poultry-health.com/fora/inthelth/hoerr01.htm
(Intestinal Integrity and the Impact of Losing It)
http://edis.ifas.ufl.edu/vm104
(Interrelationship of
excerpt:
"....Stress: Its Effect on Nutrition and Immunity
Anyone wishing to understand the interrelation between nutrition and immunity has to also understand that the stress response in the bird has an important influence on the above interrelationship. A three-way interrelationship exists among stress, nutrition and immunity and it is because of this that this paper emphasizes all three of these important factors that influence overall poultry performance.
The word stress means different things to different people and because of this, stress has been difficult to define. Stress is brought about by stress-producing factors, called stressors. It is important to be able to distinguish between a stressor and stress. Stress is the nonspecific response that the body of an animal has to any demand made upon it. An animal is under stress when it has to make extreme functional, structural, behavioral, or immunological adjustments to cope with adverse aspects of its environment (Curtis, 1983). A natural environment is composed of various potentially hostile stressors. Animals that are able to cope with the stressors to which they are exposed are those that will perform best in stressful situations. In nature, stress is the rule not the exception--after all, complete freedom from stress is death (Selye, 1973). Survival depends on the severity, duration, and interaction of the environmental stressors and the animal's physiological and behavioral ability to respond and adapt to them (Harvey et al., 1984). Once an animal perceives a stressor, its immediate response is usually behavioral (Friend an Dellmeier, 1986). It will tend to move away from the unpleasant stimulus. Depending on the severity and nature of the stressor, the autonomic nervous system responds, followed by a neuroendocrine response. These biological responses can eliminate or reduce the potential effects of the stressor by changing either the animal's relationship to the stressor or its perception of the stressor. If these responses are not successful, a pathological state may be induced that can result in decreased performance or a disease state.
Many of the problems in the poultry industry today are a direct result of the bird having to cope with one or a combination of stressors in the environment. Poor management is one of the greatest causes of stress in all types of poultry. The exposure to disease agents, poor nutrition and exposure to immunosuppressive agents also contribute to reduced performance. Poultry must be managed correctly in order to minimize the effects of stress on their performance and health. Successful identification and correction of problems in the poultry house and in the diet will benefit the bird. This paper will review some of the nutritional factors related to stress in poultry...."
ETA:
Remember your basic supportive care:
1)If your bird is ill during times of cold or heat stress adress that environmental factor
2) A bird will die of dehydration quicker than what is causing it to be ill (most quick weight loss in birds is caused by dehydration > when a bird is ill they stop drinking)
3) Give a good general daily formulation supplement like AviaCharge 2000 > you can give a supplement to this if needed.
