Clinical and pathological findings associated with congenital hypovitaminosis A in extensively grazed beef cattle.
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.


METHODS
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.


CONCLUSIONS
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.
Hill
Bd
B
Department of Primary Industries and Fisheries, Animal Research Institute, Locked Bag 4, Moorooka, Queensland 4105, Australia. bruce.hill@dpi.qld.gov.au
Holroyd
Rg
R
Sullivan
M
M
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001766:Blindness / Q000662:veterinary; D002417:Cattle; D002418:Cattle Diseases / Q000151:congenital* / Q000401:mortality / Q000473:pathology; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D009751:Nutritional Requirements; D006109:Poaceae / Q000009:adverse effects / Q000737:chemistry; D011247:Pregnancy; D011793:Queensland / Q000453:epidemiology; D014802:Vitamin A Deficiency / Q000151:congenital / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D014811:Vitamin E Deficiency / Q000151:congenital / Q000401:mortality / Q000473:pathology / Q000662:veterinary*