130
Common Diseases of Young Calves
they occur, because by the time they attract attention the parasitic infestation
in a herd may have become heavy and have reached a serious stage :—
1. Damp and low-lying places provide an ideal place for the development
of worm larvae and the breeding of intermediate hosts of certain worms.
Such places should, therefore, be avoided or drained. Ditches which cannot
be drained properly may be filled in with earth.
2. Keep the young stock which are more susceptible to parasitic infesta-
tions away from the older animals which are often carriers of parasites and
from the infected grazing areas used by them.
3. In order to avoid over-stocking, which is liable to increase parasitic
infestation, keep calves in small batches, according to age, in separate pens.
4. Paddocks for calves should be used in rotation. The ground should
be ploughed and used for cultivation when not required as a paddock. This
procedure will kill the worm eggs and larvae.
5. Frequent removal and proper disposal of the excreta is necessary. It
may be stored in a pit and used as manure in fields that are under cultivation.
6. Watering and feeding troughs should be kept clean and be at a higher
level than the ground in order to avoid contamination.
7. Build up the resistance of the herd and that of the new progeny by
feeding the cows on nutritious and well-balanced diet, paying special attention
to its vitamin and mineral contents.
8. Obviously affected animals should be isolated from the rest and the
premises should be thoroughly cleaned and disinfected. Animals in both lots
should be given a suitable treatment with vermicides.
9. Regular drenching of the stock with vermicides, as recommended
later, helps a great deal in keeping the parasitic infestations on a farm under
control.
(i) Parasitic bronchopneumonia.—This is caused by a thread-like round
worm, known as Dictyocaulus viviparous, which is of the thickness of twine
and is about 1½ to 5 inches in length (Plate XII, fig. 1). The parasite inhabits
the trachea, bronchi and lungs whence the worm eggs are coughed up and
swallowed. In the intestine the eggs hatch and young larvae are passed out
in the faeces. Under favourable conditions of moisture and temperature
these larvae survive and are swallowed by other animals along with the grass
and reach the lungs via the blood stream.
The common symptoms are nasal discharge, paroxysms of cough with
expulsion of mucus which is sometimes mixed with blood and always contains
worms and their eggs. The coughed-up mucus may be swallowed and passed
out with the faeces, thereby spreading the infection on the pastures and farm
premises. The animal gradually loses condition and becomes anaemic and
its respiration becomes accelerated. Swellings may appear on the dependent
parts of the body. The affected lung shows patches of consolidation with worms
and their eggs in the air passages. The condition can be diagnosed by observ-
ing the symptoms and examining the parasite and the eggs, under the micro-
scope, in the coughed-up mucus and nasal discharge (Plate XII, fig. 2).
For the control of this parasitic infestation, the affected animals should be
isolated and the infected premises vacated. Low-lying places and ditches
should be avoided. The animals should be fed liberally on nourishing diet