The American Alligator (Alligator mississippiensis) has become a commercially important animal in the southeastern United States. It is intensively cultured for its hide and meat and generates about $4.5 million in revenues annually for Florida alligator farms. However, intensive culture stresses the animal and many diseases conditions have been detected in farm-raised hatchlings. The most common disease, Hatchling Alligator Syndrome or HAS, is believed to be caused by infection with opportunistic bacteria. The major clinical signs of HAS were runting, stunting and death (RSD) which is the usual description given by alligator farmers when contacting the veterinarian. Other workers have reported that bacterial infections are the major (about 85%) disease problems occurring in captive alligators but no one has conducted a study involving a large number of animals at different locations to determine the incidence of organisms involved. There are also no reports of clinical values associated with bacterial isolates that are of value in confirming a diagnosis. In the present study, over a 15 year period, cases presented from 25 farms which grew-out over 100,000 hatchlings were investigated. Outbreaks involving nutritional disease, intoxications, heavy parasitism, anomalies and other non-bacterial causes were excluded from the survey. Only those cases tentatively diagnosed as HAS (131 cases) were included. All of the prevalent bacterial isolates were tested against a panel of antibiotics to determine sensitivity. Three antibiotics, ampicillin, oxytetracycline and gentamicin were considered the most "practical" for disease control on the farms. Control or "normal" values for comparison were obtained from 15 animals showing no clinical signs taken from 3 farms.

Forty-five (45) clinical values were determined on blood samples from 116 cases of clinically ill alligators thought to have infections caused by opportunistic bacteria. Blood and tissue samples from clinically ill alligators were used in this study. Hematology, clinical chemistry, and protein electrophoresis were determined for most cases and microbiology of tissues (blood, lungs, liver and kidney or organs with lesions) was performed for 61 cases.

Statistical analysis (t-tests) showed that 20 of the 45 values from ill animals were significantly different from normal values. The most significant changes in the 45 clinical values determined for alligators with suspected bacterial disease were lymphopenia, hypochloremia, hyponatremia, decreased beta 1 globulins, and elevated uric acid.

Twenty genera of bacteria were found in 95% of the cases submitted for microbiology and 12 genera were found in 75% of the cases. The 12 genera isolated in highest incidence, in of occurrence, were (isolates): 1) Aeromonas (25); 2) Clostridium (23); 3) Non-enteric gram negative rod (17); 4) Corynebacterium (15); 5) Bacillus (13); 6) Pseudomonas ((11); 7) Streptococcus (11); 8) Salmonella (9); 9) Serratia (9); 10) Citrobacter (8); 11) Staphylococcus (8); 12 Edward sella (7). All of the 12 isolates were sensitive to one of the 3 "practical" antibiotics described above.

Primary viral infections as a significant predisposing cause of the opportunistic bacterial infections cannot be excluded by this study. However, viral pathogens have not been reported for the alligator and preliminary searches have not provided evidence for their presence.