ABSTRACTS
409
Experiments were carried out upon horses in the Finnish Army which had shown
rather wide-spread and typical malformations of the hoof wall that were suspected
to be of dietary origin. No greens were supplied to these horses and no vitamin-A could
be found in the samples of hay that was fed to them. A marked improvement, in de-
creasing order of effectiveness, was brought about by supplementary grazing, A. I. V.
silage (acidity below pH 4 ), and cod-liver oil and a vigorous growth of healthy horn
started from the coronary band.
With the exception of yellow maize, cereals are deficient in carotene or vitamin-A.
Certain cereals, such as oats, were particularly liable to ' sop up ' vitamin-A in the body
and cause symptoms to appear. These symptoms were intensified by the addition
of ergot to the cereal diet but could be prevented by including in it adequate carotene
or vitamin-A. On extending this work to lathyrism in dogs it was observed that the
neurotoxin of Akta became effective in the absence of vitamin-A and carotene. Symp-
toms of poisoning caused by cotton seed meal and certain other similar meals—convul-
sions, stiffness and blindness—in cows could be prevented by including in the ration
sources of adequate vitamin-A.
Failure of reproduction has been reported as a common symptom of vitamin-A
deficiency and it has been observed in range cattle even in the milder forms of this defi-
ciency. In the female there is complete failure or delayed occurrence of oestrus,
keratinization of the vaginal epithelium and if conception takes place, depending
upon the degree to which the uterine epithelium undergoes changes, there is either
death of the foetus and resorption, or abortion or prolonged gestation and difficult
parturition. Likewise, marked degenerative changes take place in the seminiferous
tissue of the testes in the male and these changes take place earlier than in the case of
vitamin-E deficiency. It has been observed in Germany that in cattle there was a
close relationship between the breeding ratio and the number of days annually spent
grazing. It has long been the experience of trainers and breeders that the chances of
mares holding to service are increased if service is delayed until there is grazing available.
The deficiency of vitamin-A (anti-infective) lowers individual resistance to bacterial
infections, e.g., brucellosis in cattle, and helminthic infestations of the respiratory and
intestinal tracts and other parts of the body e.g., Strongylosis in horses. It may be
due to the histological changes with the resulting loss of function in the cells of epithelial
surfaces through which the bacteria penetrate or in proximity to which the worms
reside. Probably the cells of the internal organs—liver, kidney and spleen—are also
damaged so that they are unable to suppress the secondary bacteraemia which occurs
after invasion.
It has been observed in French Indo-China that, when the ration of horses and
mules was changed from normal to one that was deficient in vitamin-A, they lost con-
dition very severely until they suffered from extreme emaciation. A number of these
animals developed eye trouble. Substances rich in vitamin-A or its precursor produced
a marked and lasting curative effect very quickly but treatment with arsenical prepa-
rations produced only a temporary improvement. Cabbage pulp, sterilized cod-liver oil
and egg-yolk were tried and the last named substance in 10 c.c. doses injected subcu.
taneously once daily was found to be the most satisfactory.