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This study reports on two Hanwoo (a native Korean breed of cattle) calves, a 3- and 6-month-old presenting with diarrhea, anorexia and blindness. Ophthalmoscopic examination revealed bilateral papilledema in both calves. Reverse-transcription polymerase chain reaction tests for bovine viral diarrhea virus, rotavirus and coronavirus were all negative. The levels of serum vitamin A in the two affected calves were 0.317 µg/dl and 0.481 µg/dl, respectively. These values are much lower than the normal vitamin A levels; therefore, the calves were diagnosed with hypovitaminosis A.

A group of beef cattle in eastern Alberta was investigated due to sudden onset of blindness after grazing on standing corn in mid-winter. Fumonisin-producing Fusarium spp. were isolated from the corn. Blindness was due to an optic nerve degeneration suspected to be secondary to fumonisin mycotoxin.

Objective: To determine the cause of exceptionally high mortality (41.4%) in perinatal calves on a beef cattle property 50 km south-west of Julia Creek in north-western Queensland., Design: Investigations were based on clinical assessment of affected calves and laboratory analysis of pre- and postmortem specimens taken from 12 calves aged from 6 to 36 h of age., Methods: Associations between gross and histopathological findings and biochemical analyses conducted on serum and tissue samples were examined in relation to clinical observations., Results: Clinical signs varied, but commonly included mild to severe ataxia, difficulty finding a teat and sucking, blindness (partial or complete, as judged by avoidance of obstacles) and depression with prominent drooping of the head. Gross and histopathological findings included herniation of the cerebellar vermis through the foramen magnum, squamous metaplasia of interlobular ducts in the parotid salivary glands and Wallerian degeneration of the optic nerves. Biochemical analysis of serum and liver samples available from four of the calves revealed low or undetectable levels of both vitamin A and vitamin E., Conclusion: Although vitamin E is known to have a sparing effect on vitamin A, the role (if any) played by deficiency of this vitamin was uncertain. The combination of clinical signs, postmortem findings, histopathological features and biochemical findings indicate that gestational vitamin A deficiency was highly likely to have been an important contributor to perinatal calf mortalities in this herd.

A young, partially blind Holstein steer was affected by mild cerebral atrophy. Formalin-fixed cerebral gray matter was diffusely yellow brown. Microscopically, there were eosinophilic, autofluorescent granules primarily in the cytoplasm of cerebral neurons. There was also extensive retinal atrophy with complete loss of the rod and cone layers. Ultrastructural examination of affected cerebral neurons revealed a mixture of granular osmiophilic and lamellar patterns in the cytoplasmic storage bodies. This suggests the existence of neuronal ceroid-lipofuscinosis in the Holstein breed.

A new, fatal mycotoxicosis of cattle has been recognised in north-western Australia. A feeding trial confirmed the toxicity of a previously unknown species of Corallocytostroma that grows on Mitchell grass (Astrebla spp). The disease has been colloquially named 'black soil blindness' because its most prominent features are its confinement to pastures on black soil, and blindness and death of affected animals. Over 500 cattle have died and considerable subclinical disease in present. Above average wet season rainfall and extended growing seasons may explain the emergence of the fungus. The disease is important because cattle production in large areas of Australia utilise Mitchell grass pastures.

The after-effects of a serious lead intoxication were studied. This intoxication was caused by contaminated feed. Calves and cows of two dairy farms were examined up to half a year after the incident with the contaminated feed in October 1989. Clinical signs were observed and blood samples were taken. Blood parameters like zinc-protoporphyrin (ZPP), haemoglobin, RBC, WBC, MCV, haematocrit, MCHC, and the blood lead levels were analysed. Cattle of one of the most afflicted farms showed severe effects of lead intoxication: blindness, muscle twitching and hyperirritability. Two animals died. Forty percent of the affected cows had to be slaughtered. The ZPP levels in calves of this farm were still elevated after six months. The zinc-protoporphyrin level in blood seemed to coincide better with the clinical signs than the blood lead level. Animals with less than 3 mg ZPP/l RBC showed no irreversible effects of the lead intoxication. It is suggested that ZPP could be a useful predictor for the after-effects of lead intoxication.

A case of eye infection in a heifer was reported with bilateral blindness, cornea opacity, excessive lachrymation and nasal discharge. Treatment with 6-10 drops of a 10% solution of levamisole resulted in a complete recovery, a total of 127 adult Thelazia rhodesii being recovered from the eyes.

Central blindness in a 3.5-year-old crossbred steer was evaluated by electrodiagnostic techniques. When admitted the steer was depressed, head pressed, and circled to the left. Ptosis and absence of menace response were seen with the right eye, while the left eye was normal; direct and consensual pupillary light responses were normal in both eyes. Brainstem auditory evoked potentials and electroretinograms were essentially normal. The flash visual evoked potential (VEP) was greatly reduced upon stimulation of the right eye, while no VEP peaks could be recognized after flash stimuli were presented to the left eye. The amplitude of the electroencephalogram was depressed over right occipital cortex. Multiple brain abscesses were detected on postmortem examination adjacent to the left thalamus, in the left caudal cerebrum, and right frontal cerebrum. Corynebacterium pyogenes was cultured from abscess exudate; however, no origin for the infection could be determined. Both eyes were microscopically normal. The thalamic abscesses were postulated to have produced the EEG depression. Correlations between the VEP abnormalities and the abscess locations are discussed, based on proposed central nervous system generators of the VEP.

Poisoning of dairy cows and of calves by metaldehyde is reported. The clinical signs, post mortem and toxicological findings are described. Confirmations of the diagnoses was obtained by biochemical estimations. It would appear that a dose as low as 0.2 g/kg in adult cattle, and even less in calves, can be lethal.

Blindness attributed to vitamin A deficiency afflicted 47 out of 197, and 15 out of 29 new-born dairy calves on 2 farms. Other clinical signs included doming of the forehead, thickening of the carpal joints, incoordination and weakness. Gross lesions in 8 of the calves examined consisted in hydrocephalus and thickened occipital and sphenoid bones. In 4 of these calves the optic nerves were constricted as a result of a reduction in size and dorsoventral narrowing of the optic canals. Microscopical changes in the optic nerves were characterized by necrosis, demyelination and fibrosis. Oedema or gliosis of the optic disc occurred in some of the calves. Retinal lesions included atrophy and gliosis of the ganglion cell layer and the nerve fibre layer. Three of the calves showed focal retinal dysplasia with occasional rosette formation.

Clinical, ophthalmoscopic, and histopathologic findings of vitamin A deficiency in a group of 535 feedlot cattle are described. Liver vitamin A content and results of histologic examination of ocular and osseous (optic canal) tissue confirmed the diagnosis. Blindness was the only clinical sign observed. Even though the steers and heifers in this feedlot were approximately the same age and were fed the same ration for an equal period, none of the heifers had overt clinical signs of hypovitaminosis A. Production of vitamin A by the bovine corpus luteum may account for the sexual dimorphism observed in vitamin A-deficient cattle.

The prevalnece and severity of IBK in a group of Shorthorn and crossbred (approximately 50% B. indicus) cows, steers and calves were observed during a 31-month period, from November 1970 to May 1973, in North Queensland. In both the wet summer and dry winter seasons, IBK prevalence was significantly higher for all classes of Shorthorn than crossbred animals. Prevalence was consistently highest during the wet summer months (peak February-March). Ninety-six per cent of Shorthorn cows contracted IBK and 53% severe IBK, compared with 53% and 7% respectively, of crossbreds. Permanent and temporary blindness occurred in 3% and 10% of Shorthorn cows, but not crossbreds were affected. The implications of these findings are also discussed.

Blindness and convulsions were the predominant clinical signs in a group of feedlot steers inadvertently fed a vitamin-A deficient diet. Although vitamin A had been added to the feed at the time of preparation, it was believed that the vitamin A had been destroyed by heat, humidity, and minerals mixed in the feed. Feedlot heifers fed the same high-grain diet were clinically normal, and one heifer from which a blood sample was obtained had normal serum vitamin A content. The ingestion of sparse grasses and weeds found along the fence row of the heifers' pens was thought to have provided sufficient vitamin A to these animals. This episode demonstrated the importance of monitoring vitamin A and vitamin A precursor concentrations in stored feeds, especially those stored under adverse conditions and those fed to animals ingesting only a high-grain diet.

An outbreak of amaurosis and paresis was observed amongst sheep, and occasionally cattle, which had been grazing on pastures consisting mainly of Helichrysum argyrosphaerum DC. A similar syndrome was produced by feeding the suspect plant to sheep, thereby providing proof if its toxicity. Although none of the sheep became blind and only one developed paralysis, typical sponly lesions were detected in the brains and optic fasciculi of all the experimental animals. The lesion had specific predilection sites, such as the white matter around the lateral ventricles, the optic tracts plus chiasm, the pyramidal tracts and the brachium pontis. Enlargement of the optic fasciculi furthermore gave rise to malacia, papilloedema and retinal changes. Some aged sheep developed cataracts approximately 2-3 months after the initial outbreaks of amaurosis had occurred. Circumstantial and histopathological evidence suggests that the cataracts may be due to chronic Helichrysum poisoning, but this could not confirmed in the present investigation.

An outbreak of ataxia, blindness, respiratory disease and kerato-conjunctivitis occurred in October 1972 in a beef feedlot in Cyprus. Fifteen animals died and 10 that were severely ataxic were slaughtered; many animals became blind. There was no opportunity to isolate virus when the disease was active but in March and October 1973 infectious bovine rhinotracheitis (IBR) virus was isolated from cattle after they had been treated corticosteroids to stimulate virus excretion. It is probable that IBR virus caused the disease. This is the first report of the isolation of IBR virus from cattle in Cyprus.