To Nancy Hartman concerning vaccine reactions: I will defer the clinical aspects of this question to Dr. Brown, but I can address what is going on with this ferret. Most likely what you are seeing, with collapse shortly after vaccination and bloody stools is indeed a vaccine reaction, also known as immediate anaphylaxis. This is a very uncommon event in domestic animals, but it does happen. ( I have heard a number - approximately 1 in 10,000 cases attached to several vaccines, but as that comes from drug companies, I don't know how reliable that is.) For immediate anaphylaxis to occur, an animal has to be sensitized to a component of the vaccine sometime previously. When the component is re-injected into the animal, a severe allergic response is initiated by certain cells in the body which are primed to respond to that specific ingredient. The cells that are the trigger are mast cells, which line blood vessels. When they are stimulated by antibodies that have bound with the allergen - they release chemicals that cause marked dilation and leaking from the blood vessels in the area in which they are located. They can also cause marked constriction of the airways, furthering the distress to the patient. Anaphylaxis can range markedly in severity, from a small wheal or pain at the injection site, to hives, to, as in this case, marked systemic vascular dilation and shock. Blood generally pools in the intestinal tract in ferrets in shock, and often a small to moderate amount will leak into the lumen of the colon, resulting in the passage of blood. In no way should this be interpreted as colitis, and it is generally a transitory phenomenon (if the animal survives). Generally, if the animal is supported with fluids and some nursing care, they recover fully. Vaccination reactions are an unfortunate fact of life for veterinarians. There is generally no way to predict which animals will be affected, unless there is a history, as there is no in this animal. My suggestions would be to NOT vaccinate with the same product next time. A heavy dose of antihistamines may prevent a recurrence; I've used them in dogs and horses in the past with a history of vaccine reactions to good effect. (Histamine is the substance the mast cells release upon unsuspecting blood vessels...) Maybe Dr. Brown can enlighten us as to her experience with vaccine reactions in ferrets.... Bruce Williams, DVM [log in to unmask] [Posted in FML issue 0778]