MVSc

A study on the prevalence and pathology of necrosis of extremities in cattle was conducted. It was found that the disease was more prevalent in buffaloes than in white cattle. The chief clinical manifestation was necrosis of tail. A close association between mouldy paddy straw and the disease syndrome was observed. Animals observed during the study were found to be free from systemic disturbances.

The mean Haemoglobin, packed cell volume, Erythrocyte Sedimentation Rate, Total count and differential count were estimated. The data did not reveal any significant change in affected animals. Calcium, Magnesium and inorganic phosphate levels in the serum of affected animals were found to be normal. Total plasma protein level also did not show any significant variation.

The origin, distribution and features of the vascular channels in this disease syndrome were demonstrated for the first time by radiographic studies. Plain radiograph of the diseased tail revealed an increase in the density of the soft tissue at the zone of necrosis with lytic changes in the coccygeal vertebra at the level of necrosis. Arteriogram of the diseased tail revealed that the middle coccygeal artery terminated at level with the vertebra preceding the one which had undergone lysis. A large number of tortuous arterial branches originated from the artery and they supplied the soft tissue at the zone of necrosis. Venogram showed that the lateral coccygeal veins originated from the level of the diseased vertebra. Arteriovenous anastomosis was appreciated.

Histopathological studies undertaken on the necrosed tails revealed that the vascular lesions were the basis for the pathogenesis of the condition. The most conspicuous lesion was the hypertrophy of tunica media of the coccygeal arteries and consequent narrowing of the lumen. Partial or complete thrombosis with organization and canalization were observed in the arteries.Veine were found to be free from such lesions. Collateral neovascularisation was evident. Coccygeal vertebral osteolysis was observed. Radiographic studies have supported these findings. Perineural fibrosis, degeneration of nerve fibres, muscular hyalinization, were also noticed. Chronic dermatitis, hyperkeratosis, parakeratosis, acanthosis, degeneration and hyalinization of hair follicles were observed in the skin.

Samples of paddy straw collected from 14 different places in various districts were the disease had occurred were screened for fungal flora. Aspergillous, Rhizopus, Pencillium, Mucour, Alternaria, Curvularia and Nigrospora were identified. Samples were screened for trichothecenes using thin layer chromatography. Trichothecenes could not be detected.

Eventhough fusarium species of fungi could not be identified and trichothecenes could not be detected, the close association of the condition with feeding of mouldy paddy straw and pathological features observed suggest a mycotoxic aetiology. Further studies are needed to confirm the role of trichothecenes in the causation of this disease.