Malignant oedema associated with blood-sampling in sheep

Clinical of two marsupials, a bird, and a reptile. Vet Pathol 1997;34:615-618. 17. Filippich LJ, Bucher AM, Charles BG. Platinum pharmacokinetics in sulphurcrested cockatoos (Cacatua galerita) following single-dose cisplatin infusion. Aust Vet J 2000;78:406-411. 18. Ramsay EC, Bos JH, McFadden C. Use of intratumoral cisplatin and orthovoltage radiotherapy in treatment of fibrosarcoma in a macaw. J Assoc Avian Vet 1993;7:87-90. 19. Coppoc GL. Chemotherapy of neoplastic diseases. In: Adams HR, editor. Veterinary Pharmacology and Therapeutics, Iowa State University Press, Ames, 1995:1028-1049. 20. Bruss ML. Lipids and Ketones. In: Kaneko JJ, Harvey JW, Bruss ML, editors. Clinical Biochemistry of Domestic Animals. Academic Press, San Diego, 1997:83-116. 21. Watson TDG, Barrie J. Lipoprotein metabolism and hyperlipidaemia in the dog and cat: a review. J Small Anim Pract 1993;34:479-487. 22. Hochleithner M. Biochemistries. In: Ritchie BW, Harrison GJ, Harrison LR, editors. Avian Medicine and Surgery: Principals and Application. Wingers Publishing, Lake Worth, 1994:223-245. 23. Johnstone AC, Jones BR, Thompson JC, Hancock WS. The pathology on an inherited hyperlipoproteinaemia in cats. J Comp Pathol 1990;102:125-137. 24. Hoekstra KA, Nichols CR, Garnett ME, Godin DV, Cheng KM. Dietary cholesterol-induced xanthomatosis in atherosclerosis-susceptible Japanese quail (Cotunix japonica). J Comp Pathol 1998;119:419-427. (Accepted for publication 1 January 2001) Malignant oedema associated with blood-sampling in sheep WE MORRIS, FA UZALa, FR FAT TORINI b and H T ERZOLO c Animal Health Unit, T he National Institute of Agricultural Technology, CC 277, (8400) Bariloche, Argentina Malignant oedema is a fatal disease of several animal species, produced by one or more members of the Clostridium genus. We report here a case of malignant oedema in a 1-year-old Friesian sheep after a blood sample was collected from the jugular vein. Clostridium septicum and Clostridium sordellii were isolated from the lesions and also demonstrated by a fluorescent antibody test. This report stresses the need for maintaining a clean environment for animals and for strict hygienic measures during procedures that generate wounds, together with immunity acquired by proper vaccination, for prevention of malignant oedema. Aust Vet J 2002;80:280-281 M alignant oedema is an acute, fatal disease of domestic and wild animals that follows contamination of wounds by one or more members of the Clostridium genus. 1-3 Major reported predisposing factors for malignant oedema in sheep are shearing, docking, marking and parturition.4 Although theoretically any skin wound can allow access of clostridia to an animal, we are not aware of any reports of malignant oedema in which blood sampling using hypodermic needles was the predisposing factor. T his is a case report of malignant oedema in sheep related to blood sampling. Case report A 1-year-old Friesian ewe was submitted to the Animal Health Unit of the National Institute of Agricultural Technology, Bariloche, Patagonia, Argentina for necropsy. T he sheep was from a flock of 200 animals from a dairy farm in the El Bolsón area, also in Patagonia. T he ewe was kept with 11 aPresent address of corresponding author: California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California Davis. 105 W Central Ave, San Bernardino, CA 92408, USA. E-mail: fuzal@cahfs.ucdavis.edu bPrivate practitioner, Bariloche, Argentina cThe National Institute of Agricultural Technology, Balcarce, Argentina 280 others in a shed and fed on lucerne hay, concentrated pellets and water ad-libitum. T he straw bedding was not regularly changed and was heavily contaminated with manure. Blood samples from all 12 animals were taken from the jugular vein for routine brucellosis testing by a veterinary surgeon, using a new 18 g, 50 mm long, sterile disposable needle for each animal. T he skin was neither clipped nor disinfected at the puncture site. T he sheep had been vaccinated at approximately three months of age with two doses of an aluminium hydroxide vaccine containing toxoids and biomass of Clostridium septicum, Clostridium chauvoei and Clostridium perfringens types C and D (Investigaciones Biológicas SA, Florida, Provincia de Buenos Aires, Argentina). A booster dose of the same vaccine had been given to the sheep 3 months previously. One animal was found dead the morning following bleeding. T he rest of the flock remained clinically normal. A necropsy was performed within 6 to 12 hours of death. Several smears were prepared from subcutaneous and muscular tissues of the neck. Some of these smears were stained with Gram and others were subjected to a direct inmunofluorescent antibody test (FAT ) for C chauvoei, C sordellii, C septicum and C novyi, as described by Sterne and Batty.5 International reference strains of these clostridia were used as controls for each fluorescent preparation. T he fluorescent antibodies were from Pragma (Kent, England). Samples of subcutaneous exudate and muscle from the neck were aseptically collected and inoculated onto 5% sheep-blood agar and incubated both aerobically and anaerobically at 37°C for 48 hours. Sub-samples of the same specimens were also inoculated into cooked meat medium and incubated anaerobically at 37°C for 48 hours. T he isolates were identified by conventional biochemical techniques and also by the FAT mentioned above.5 Tissues were also collected from muscle of the neck and thymus, and fixed in 10% neutral buffered formalin, embedded in paraffin wax, sectioned at 4 µm, and stained with haematoxylin and eosin and Gram. Aust Vet J Vol 80, No 5, May 2002 Clinical On necropsy the animal was in very good physical condition. Severe swelling was observed externally in the neck and head. T he skin on the swollen area showed blue discoloration, and crepitation was evident in the subcutaneous tissue. Severe diffuse haemorrhagic and gelatinous subcutaneous oedema was observed in the head and neck. T he distribution of this oedema was concentric to three pin-point haemorrhagic lesions in the skin of the area where the blood-sample was taken, around the left jugular groove. Gram positive bacilli were observed on the Gram-stained smears from muscle and subcutaneous tissues. T hese bacilli were sporulated or non-sporulated and pleomorphic. T he FAT on subcutaneous tissue and muscle smears gave positive results to C septicum and C sordellii. Each fluorescent antibody preparation stained its corresponding control and none of the others. C sordellii and C septicum were isolated from the subcutaneous tissue, while C sordellii was also isolated from the muscle. Histological examination of muscle revealed severe coagulation necrosis of muscular fibres, proteinaceous oedema in between the muscle fibres with abundant basophilic bacilli, and a moderate neutrophilic infiltration. T he thymus had diffuse haemorrhage and necrosis of the medulla. oedema in sheep in Patagonia,6 most vaccines in Argentina do not contain such antigens. In the present case, C sordellii antigen was absent from the vaccine used and this alone is enough to explain the infection by this microorganism. However, the animals were vaccinated against C septicum ; the presence of this microorganism in the infection could have been related to a suboptimal vaccination procedure, to an individual lack of immune response or to an unusually high challenging dose. Clostridia are ubiquitous microorganisms that are frequently present in the environment of sheep, but malignant oedema due to minor skin injuries such as the one produced by a needle in this case are not usually reported. Iatrogenic transmission via contaminated needles, dehorning equipments, milking or other veterinary practices has been reported in other diseases such as bovine leukaemia and caprine arthritis-encephalitis. 7,8 Hygienic measures taken to prevent malignant oedema are also effective in preventing these and other conditions. T his report stresses the need for maintaining a clean environment for animals and for strict hygienic measures during procedures that generate wounds, together with immunity acquired by proper vaccination for prevention of malignant oedema. Discussion Malignant oedema is caused by local proliferation and production of toxins by one or more of the following microorganisms: C septicum, C novyi, C chauvoei, C sordellii and C perfingens.5 T he disease occurs after the introduction of bacteria through skin wounds together with the creation of anaerobic conditions in the area.5 In the case presented here, the distribution of the lesion concentric to several pin-point lesions, presumably the result of several bleeding attempts, suggests that the portal of entry was the wound caused by the needle. Because the needle used was initially sterile, it is likely that the contaminant microorganisms were on the wool and/or the skin of the animal and that they were admitted into the subcutaneous and muscular tissues during the bleeding procedure. Heavy contamination of the shed with faeces, presumably carrying numerous clostridial spores, could, in turn, have been responsible for heavy contamination of the sheep fleece and skin. Possible predisposing factors for this unusual case were the unhygienic conditions of the shed where the sheep were housed and a suboptimal immune status of the animals. Although C sordellii has previously been isolated in a case of malignant Aust Vet J Vol 80, No 5, May 2002 Acknowledgments T he authors thank Ms Elma Vidal for excellent technical assistance and Ms Patricia Lopez for typing this manuscript. T his work was carried out with support from Fondo Nacional para la Ciencia y la Tecnología (PICT – 01-3591), Argentina. References 1. Dennis SM. Perinatal lamb mortality in Western Australia. 4. Neonatal infections. Aust Vet J 1975;50:443-449. 2. Lewis CJ. Clostridial diseases, In: Martin WB & Aitken ID, editors. Diseases of sheep. 3rd edn. Blackwell Sciences, Oxford, 1999;131-143. 3. Uzal FA, Assis RA, Chang Reissig E. Malignant oedema in a guanaco (Lama guanicoe). Vet Rec 2000; 147:336. 4. Blood DC, Henderson JA, Radostitis OM. Medicina Veterinaria. 8th edn. Nueva Editorial Interamericana, México, 1986;586-609. 5. Sterne M, Batty I. Pathogenic Clostridia. Butterworts, London, 1975;78-95. 6. Vanelli SA, Roberts RG, Uzal FA, Moreira AR. Clostridium sordellii asociado a un caso de gangrena gaseosa ovina. Vet Arg 1996;13:421-422. 7. Johnson R, Kaneene JB. Bovine leukaemia virus and enzootic bovine leukosis. Vet Bull 1992;62:287-306. 8. Rowe JD, East NE. Risk factors for transmission and methods for control of caprine arthritis encephalitis virus infection. Vet Clin N Am: Food Anim Pract 1997;13:35-52. 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