size: 5036KB - Crocodile Specialist Group

109
Fuigol and other dermar,?ir - dermatitis, other than that caused by pox, is a condition that has
recently gained importance. It can occur in slaughter stock, as well as other age groups, and
therefore hide quality may be affected. Ulcerative or crusting dermatitis, seen ;b;wn lesions
between the ventral scales, and excoriation of the epidermis in the intertriga are presenting
features. Ophthalmia may also be present. Mortality may ocour in severe cases: especially whe;
the nares are blocked by exudate. Dermatophiluslike bacteria are demonstraied'histologically
insome lesions, while Fusarium spp. and other mycelia-producing fungi have been isolated in
culture. A number of factorc are believed to be responsibie for thiJsyndrome, and they include
lapses in the standard of hygiene, the type of housing now used on most farms and nutritional
factors. Tmuma atld pox may also be imponant.
Nutritional osteomalacia - is still seen on some farms evety year, despite adequate inclusion
of calcium and vitamin D1 in the diet. Osteomalacia ofthe veriebrae can result in compression
of the spinal chord and posterior paresis. Sudden death also occurs in well grown individuals
liom low levels of calcium in the blood, and subsequent tetany. Because vitamin anzuyses
cannot be routinely undertaken in Zimbabwe, it has not been possible to confirm if loss of
vitamin potency in the premix is responsible fbr some cases of this syndrome. Certainly,
calcium levels in supplements are fbund, at times, to be considerably lower than the stated
analysis.Jhere is some evidence to suggest that crocodiles which are marginally deficient in
Vitamin Dr do benefit from exposure to sunlight which chemically actiuateJ any p.ecursors of
Vitamin D which may be present in the diet. The relative role of these fictors requues
elucidation.
Vitamin E/selenium deJiciency - this is a nutritional deficiency which has recently been
recognised in Zimbabwe. It has occurred only where a diet of fi:h is fbd and causes typical
steatitis (yellow fat disease), as recognised elsewhere (Latsen et. al., 19g3). Indoor housing
appears to have contributed to the development ofthis condition because the high temperarures
and humidity in these facilities cause rapid decomposition of the fish plus oxidation of the fat.
A special vitamin E/selenium additive tbr inclusion in fish diets wa; fo.mulated because rhe
standard vitamin/mineral premix is not usually added to fish.
God - this was rarely seen on Zimbabwe crocodile farms until the last two years. The reason
for the recent increase in incidence and the pathogenesis ofthe condition are not proven but are
believed to be associated with the supplemenration of higher levels of calcium (up to 2,5% on
a dry matter basis) in rm attempto correct nutritional osteomalacia. The kidneys may become
very distended with accumulated urates, resulting in destruction of most of the parencnyma.
Less common is the accumulation of urates in the peri-articular tissue.
In conclusion, while disease plays much less of a role in the economics of crocodile farming
than was the case ten yeats ago, there are a number ofconditions that still require investigation
and, at times, vigorous control measuies. The veterinarian's inputremains imiortant, espeiially
to inorease the efficiency of production in an industry whose viability is no\ropen to quesuoD.