Chronic phalaris toxicity in eastern grey kangaroos (Macropus giganteus).

CASE REPORT: Seven eastern grey kangaroos (Macropus giganteus) grazing pastures including Phalaris spp. in Victoria showed neurological deficits characterised by ataxia, head tremors and collapse. Gross examination of the brains and spinal cords of affected kangaroos showed a greenish discolouration in several regions of the grey matter. Histologically, intracytoplasmic accumulation of pigment granules was detected in the neurons, most prominently in the thalamus, brainstem and ventral horns of the spinal cord. Pigment granules were positive to stains used for identification of melanin, including Fontana-Masson stain and Schmorl's reaction. CONCLUSION: The combination of clinical signs and obvious neuronal pigmentation is consistent with chronic Phalaris spp. toxicity, a condition well documented in domestic ruminants.

Phalaris arundinacea (reed canarygrass) grass staggers in beef cattle.

Four adult mixed-breed beef cows from a cow-calf operation in West Virginia were referred to the Virginia-Maryland Regional College of Veterinary Medicine in March 2009 with weakness, ataxia, hind limb paresis progressing to lateral recumbency, and death within 2-3 days. Histologically, there was accumulation of light brown, granular pigment in neurons of the ventral gray horns of the spinal cord (more severe in thoracic and lumbar sections), brain stem, and pons, resulting in distortion and bulging of the cell body and displacement of the Nissl substance, suggestive of Phalaris sp. grass toxicosis. The most severely affected cow had accumulation of dark green-brown pigment in renal tubular epithelial cells. Reed canarygrass (Phalaris arundinacea) was identified in pastures, and the concentration of tryptamine alkaloids in new leaf blades was approximately 0.2% on a wet weight basis. These alkaloids are serotonergic receptor agonists, resulting in neurologic "staggers" in ruminants. Delayed onset times of up to 4-5 months have been reported in sheep after removal from Phalaris sp. pastures. Distribution of pigment in serotonergic tracts of the midbrain, brain stem, and spinal cord with Phalaris sp. toxicoses is distinct and differs from lipofuscin. Electron microscopy confirmed that the pigment was not lipofuscin. From these findings, a diagnosis of delayed P. arundinacea toxicosis was made. Over a 2-month period, 18 cows died with similar clinical signs.

Acute and chronic nervous signs in cattle associated with Phalaris angusta poisoning in Argentina / Sinais nervosos agudos e crônicos em bovinos na Argentina associados à intoxicação por Phalaris angusta

Phalaris angusta is a South American natural grass that produces poisoning in sheep and cattle in Argentina and Brazil. Phalaris spp. can produce unrelated forms of poisoning in ruminants, acute and chronic syndromes. The objective of this paper was to describe an outbreak of acute and chronic Phalaris nervous syndrome in 53 of 980 fattening steers and heifers in a farm of Buenos Aires province. On September of 2006 the animals developed nervous signs and died after 3-5 days. The herd was removed to a phalarisfree pasture. Three months later (on December) 15 new clinical cases developed in the herd. Necropsy performed in one affected calf showed neither grossly nor microscopic changes. Microscopically, there were no major alterations in tissues. Nervous signs had been described in some field cases where neither pigment deposition nor axonal degeneration could be detected. Clinical findings displayed by affected cattle after consumption of Phalaris angusta pastures resemble those observed by other authors in Phalaris staggers. This is the first report in Argentina where both syndromes were seen in the same herd.

Phalaris angusta é uma gramínea originária da América do Sul, que causa intoxicação em ovinos e bovinos na Argentina e Brasil. A intoxicação pode ocasionar quadros nervosos agudos ou crônicos, independentes um do outro. O objetivo deste trabalho é descrever ambos os quadros (agudo e crônico) da intoxicação por Phalaris em um rebanho de 980 garrotes em engorda na província de Buenos Aires. Em setembro de 2006, 53 animais desenvolveram sinais nervosos e morreram após um curso clínico de 3-5 dias. O rebanho foi trocado para uma pastagem sem Phalaris. Em dezembro, alguns animais apresentaram diarréia, depressão e perda progressiva de peso. Quando eram forçados a se movimentar, os sinais progrediam para incoordenação dos membros torácicos, impossibilidade de se manter em pé e decúbito lateral. Havia perda de peso e os animais morriam após um curso clínico de 5-7 dias. Não foram observadas lesões macroscópicas nem histológicas nos animais com as duas formas da doença. Os sinais clínicos observados são semelhantes aos observados em outros surtos de intoxicação aguda ou crônica por Phalaris angusta.