Whilst searching for past threads on this, I see that you had the same problem in 2009 and I'm wondering what your Vet advised you then.
Here's a link about ME in baby rabbits
Internal Diseases of Rabbits
Mucoid Enteritis
Mucoid enteritis affects rabbits of 7-14 weeks of age. The exact cause of mucoid enteritis is unknown, but it is similar to that of weaning enteritis. Recent works suggest that a dysautonomia (abnormal functioning of the autonomic nervous system, equivalent to "grass sickness" in horses) may be responsible for this disease. It is caused by changes of cecal pH that are associated with disruption of the normal cecal flora (portion of large intestine). It is a disease of young rabbits, just beyond weaning age (7-14 weeks) which is the age when the cecal microflora are becoming established and are vulnerable. Mortality is common. In up to 60% of cases there may be an accompanying pneumonia. Death is primarily due to dehydration. In older rabbits an enteritis associated with mucus production is more likely to be part of the "enteritis complex" rather than classic "mucoid" enteritis and mortality is lower. Mucoid enteritis is rarely seen in rabbitries that feed a high fiber diet and avoid excess of grains, proteins and fats.
Clinical signs include loss of appetite, lethargy, weight loss, diarrhea, excessive thirst, possible gritting and grinding of teeth, rough coat, bloat (sloshing belly), constipation and passing of jelly-like mucoid material from the bowels. Great pain is exhibited through sitting humped up, sometimes over the water crock and grinding of teeth. Temperature is subnormal.
Treatment of Mucoid Enteritis
Treatment includes fluid replacement either by injection under skin or orally with an electrolyte solution such as Lectade. Withholding solid food for 24 hours is usually recommended, then feeding stemmy alfalfa hay or similar roughage instead of pellets. Vegetable baby food can be given by syringe or orally. Drugs such as Metoclopramide and Cisapride are sometimes given.
Prevention of Mucoid Enteritis
The provision of a high-fiber diet and a gradual introduction to the pelleted ration at weaning. A probiotic such as Avipro can be dissolved in the drinking water at this vulnerable time.
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