Literaturdatenbank
Literaturdatenbank |
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Jacobson, E. R., & Homer, B. L. (1995). Health problems of wild populations of desert tortoises, gopherus agassizii, in the southwestern united states. Annual Conference - American Association of Zoo Veterinarians, 1995, 68–69.
Added by: Sarina Wunderlich (12 Dec 2010 20:43:06 UTC) |
| Resource type: Journal Article BibTeX citation key: Jacobson1995a View all bibliographic details  |
Categories: General Keywords: Gopherus, Gopherus agassizii, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Testudinidae, Veterinärmedizin = veterinary medicine Creators: Homer, Jacobson Collection: Annual Conference - American Association of Zoo Veterinarians |
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| Abstract |
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Testudinidae In 1988, desert tortoises (Gopherus agassizii) with upper respiratory tract disease (URTD) were seen in the Desert Tortoise Natural Area (DTNA), Kern County, California.2 In 1989, a detailed survey of the DTNA and nearby areas in the Rand Mountains and Freemont Valley indicated that 43% of 468 live desert tortoises encountered on the sections surveyed showed signs of this disease.4 Additionally, carcasses of 627 tortoises were recovered from the sampled areas. Since first being seen in desert tortoises in the DTNA, desert tortoises with URTD have been seen in multiple locations throughout the Mojave Desert of southern California. Desert tortoises with URTD have also been seen in the Las Vegas Valley, Nevada, the Beaver Dam Slope, Utah/Arizona, and the Sonoran Desert, Arizona. Pathologic studies of 17 ill desert tortoises from the DTNA and one ill desert tortoise from Utah indicated that major microscopic lesions were confined to the upper respiratory tract (URT) of ill tortoises.2 Electron microscopic studies revealed small (350 to 900 nm), pleomorphic organisms resembling Mycoplasma in close association with the surface epithelium of the URT of ill tortoises. A Mycoplosma-like organism was cultured from the nasal passageways of four ill tortoises and was ultrastructurally similar to the pleomorphic organism present on the mucosa in tissue sections. The species name proposed was Mycoplasma agassizii; strain PS6 is the type strain.5 In a recent transmission study, this organism was demonstrated as the cause of URTD in the desert tortoise.1 High mortality rates and a shell disease originally described as shell necrosis were observed in the population of desert tortoises in the Colorado Desert, on the Chuckwalla Bench Area of Critical Environmental Concern, Riverside County, California, USA.3 In a retrospective review of photographic slides of desert tortoises from the Chuckwalla Bench, the disease was evident in 1979 when tortoises on a permanent study site were first photographed. In those tortoises where sequential photographs were taken, the most severe lesions were seen in 1988. While the disease was present on the carapace, plastron and thickened forelimb scutes, the plastron was more severely affected than other areas of the integument. The lesion commenced at seams between scutes and spread toward the middle of each scute in an irregular pattern. Shell biopsies of nine affected tortoises were evaluated by light microscopy. No inflammatory infiltrates were in the lesions and while bacterial organisms were identified in tissue sections, they were superficially located and were considered to be secondary invaders. For the most part, the epithelial cells which formed a pseudostratified layer under affected portions of each scute remained intact. While the location and histological appearance of the lesion was compatible with a dyskeratosis and was suggestive of either a deficiency disease or toxicosis, the exact cause of the disease could not be determined. Pathological evaluations of 22 desert tortoises, received over a 31-month period from the Mojave and Colorado deserts of California and the Sonoran Desert of Arizona indicated a variety of problems. Seven of these tortoises had shell lesions typical of cutaneous dyskeratosis. Three tortoises had respiratory tract disease, one with fungal pneumonia and the other two with lesions typical of mycoplasmosis. Septicemia was seen in two tortoises, of which one had a cutaneous fungal infection secondary to being entombed within its burrow. Another tortoise had lesions associated with a burn injury. Osteopenia of the shell was seen in two cases.
Added by: Sarina Wunderlich |