A survey of the diseases of marine turtles in northern Australia. I. Farmed turtles

Abstract

A total of 104 farmed turtles (102 Chelonia mydas and 2 Eretmochelys inlbricata) were examined for signs of chnical disease. They were obtained from the Torres Strait where they were housed in 250 1 fibreglass tanks and 50 1 plasbc basins and fed a diet of fish by islanders. Altogether, 28 diseases were diagnosed including 1 2 bactenal, 4 parasitic and 4 nutritional diseases. Less common were those of genetlc and environmental origin. Skin lesions due to biting (traumatic ulcerative dermatitis) were almost universal in farmed turtles. They were concentrated on the tips and trailing edges of the front and rear flippers and also on the neck and tail as well as the axillary and inguinal regions. Morb~dity and mortality rates of 100 and 30 %, respectively, were recorded in the first month of life. Juveniles and yearlings rarely succumbed to the disease. Cultures of lesion material yielded a variety of bacteria VIZ Vibrio alg~nolyticus, Pseudomonas fluorescens, Flavobacteriurn sp., Micrococcus sp. and Bacillus sp. Ulcerative stomatitis was the most important bacterial disease of farmed turtles after traumatic ulcerative dermatitis. It occurred as an epizootic in hatchlings 5 to 8 wk old. A plug of caseopurulent material in the oral cavity was usually the first overt sign of the disease. Debridement somebmes caused bleeding, indicating the presence of false membranes. Obstructive rhinltis and pneumonia were complications of the original condition. Turtles with these diseases showed loss of equilibrium and laboured respiration. Plugs of caseous material were lodged in the tracheahronchi and/or external nares. Focal pneumonia was characterised by nodular lesions in the apical or medial portion of the lung. Microscopic sections and cultures showed bacteria were mainly responsible. V. alginolyticus, Aeromonas hydroph~la, Flavobacterium sp. and Pseudomonas sp. were isolated from the upper and lower respiratory tract as well as the oral cavity. Fungal isolates viz PenicilLium sp., Paecilornyces sp., Fusarium sp. and Rhodotorula sp. were of secondary importance. Acid fast bacilli (Mycobacterium sp.) were seen in the lungs of 2 farmed turtles but were not isolated. Salmonellosis was diagnosed on only one occasion, when Salmonella enteritidis was isolated from the liver of a juvenile turtle. Eye lesions (keratoconjunctivitis -ulcerative blepharitis) were caused by rubbing against the side of the tank. Adenitis (salt-secreting gland infection) resulted from the introduction of forceps into the duct leading from the posterior orbit. Peritonitis was an extension of ulcerative shell disease. Pseudomonas spp. and Flavobacterium spp. were common to the last 3 hseases. Septicaemia-toxaemia was secondary to chronic bacterial and parasitic infections. V. alginolyticus, A. hydrophila and Flavobacterium sp. were isolated from the heart blood and caused toxic changes in the heart and kidneys. V. alginolyticus was cultured from a case of ulcerative shell disease and osteomyelitis. Gastritis-serositis syndrome was the most important parasitic disease of farmed turtles. Gastric and intestinal ulcers and fibrous adhesions were caused by the migration and encystment of third stage Anisakis sp. larvae from the gut lumen to the pleuro peritonea1 cavity. The eggs of cardiovascular flukes (Digenea: Spirorchiidae) were found in farmed turtles. Microscopically, the essential change was that of chronic inflammation. A slngle species of gastro-intestinal fluke was also found in farmed turtles. Cachetic myopathy was often seen in association with traumatic ulcerative dermatitis and ulcerative stomatitis in farmed turtles. Fibrous osteodystrophy was related to a diet of raw fish and intestinal obstruction was caused by the ingestion of foreign bodies. Lordosis and kyphosis were probably related to the original nest temperature. Genetic defects (albinism and mandibular microagnathia) were rare. There were 2 incidents of poisoning in farmed turtles -due to the accumulation of nitrate from Tridax sp. and contamination of food (fish) with diesel fuel.