In treating of this disease in Vol. II, page 141–2, the work of Jensen,
Perroncito and Nikolski is quoted, with the remark that “_it is
premature to specify any particular microbe as the sole cause of the
affection_.” Since the publication of that volume, Nocard, investigating
in Ireland a very prevalent and fatal affection of new born calves,
which proved fatal by “white scour” a few days after birth, or by
pneumonia one or two weeks later, identified as the pathogenic agent a
small, nonmotile, ovoid bacterium, taking the polar aniline stain,
bleaching in Gram’s solution, failing to liquefy gelatine, or to form
indol or to grow on potato. In other words it shows the general
characters of the colon group of bacteria, causative of hæmorrhagic
septicæmia, and classed as _pasteurellas_ by Trevisan and Lignieres.
This is not found in blood and lesions in all subjects, but is usually
present in pure culture in the most acute, fatal cases. Its occasional
absence later in the disease is explained, according to Lignieres, by
the power possessed by these germs of robbing the healthy tissues of
their power of resistance and laying them open to the attacks of other
microörganisms which are usually present in abundance, but are harmless
to the healthy tissues in the absence of the Pasteurella. As the disease
advances, therefore, the primary pathogenic agent (the Pasteurella) is
crowded out by the active growth of other bacteria, which accordingly
are found in complex cultures and in great variety. In his first
observations on the victims of the _white scour_, Nocard found only
these complex cultures, of which no one variety, isolated in pure
cultures _in vitro_, and inoculated, proved capable of causing the
disease. Later he found the Pasteurella (cocco-bacillus) in impure
cultures from the diseased femoro-tibial joint of one of the subjects of
the affection, and the pure cultures obtained from this were virulently
infective.
A few drops injected into the peritoneum of a Guinea pig, or veins of a
rabbit, killed in six to eighteen hours with the lesions of hæmorrhagic
septicæmia which characterize the most acute cases of _white scour_. The
blood and viscera swarmed with the microbe.
A calf one day old had 3cc. of the culture injected into the jugular,
the temperature rose in six hours, and in twenty hours the subject lay
with sunken eye, retracted abdomen, a temperature of 95° F., and having
the bed saturated with a yellowish, fœtid, fæcal liquid. Death took
place 30.5 hours after the injection and all the lesions of acute _white
scour_ were met with.
A second calf four weeks old, which had already suffered from _white
scour_ and recovered, had an injection into the jugular of 10cc. of the
same culture. In six hours he suffered a slight rise of temperature, was
dull and breathed short, but in twenty hours he was completely
recovered, full of life and appetite.
In other casual and experimental cases, Nocard found that when death
occurred within one or two days the symptoms and lesions were mainly
those of hæmorrhagic septicæmia and _white scour_, whereas if the calf
survived several days, the impaired resistance of the tissues invited
the invasion of a variety of other germs from the intestines, and
infective inflammation of the lungs, joints and other organs were
brought about by such secondary invasions.
An important question is as to the direct source of the primary
(Pasteurella) infection. The concentration of the acute cases on the
alimentary canal would strongly suggest infection through the food which
in this case means the milk. But careful bacteriological examination of
the milk of the dam of a calf that had just died of _white scour_, and
of other milk secured with careful precautions from cows in an infected
stable, showed that both were clear of the germ. Inoculations and
culture experiments were equally fruitless.
This does not exclude the probability of the contamination of the milk,
obtained under ordinary conditions, with the germ contained in the
floating barn dust, or that which was adherent to the teat and udder.
Another suggestion is that the infection is derived from the infected
womb prior to birth, but as Nocard justly says, if this were so,
abortions would be much more prevalent, as the rapidly fatal issue of
the disease would determine the prompt death of the fœtus and its
expulsion. The coincidence of abortion and _white scour_ in a herd is
not uncommon, and in such cases intrauterine infection of the fœtus is
not improbable, but in the great majority of cases no such coincidence
exists.
We are thus thrown back on infection through the raw surface of the
ruptured umbilical cord, as the rule in such cases. It may be that this
has come from the vagina or vulva, but in the great majority of cases it
is manifestly derived from the infecting bowel dejections and the dust
caused by their desiccation. The extraordinarily rapid progress and
fatal result of the acute disease, and the early abundance of the germ
in the blood and liver, suggest that the microbe traverses the umbilical
vein to the liver, and finding a congenial home in the blood is quickly
distributed through the entire body.
_Prevention_ must be based on the destruction and exclusion of the
microbe.
A thorough disinfection of the stable with mercuric chloride has not
given us uniformly satisfactory results, even when the building has been
kept apparently almost immaculately clean. This argues a renewed
infection through the fæces of the cows, yet it is the rule that the
removal of the cow to a new or unused stable a few days before calving
will usually secure the immunity of the calf. This method is however
open to the objection that the removal to such calving stable of a
succession of cows coming from infected premises soon introduces the
infection and renders it as dangerous as the place they have left. To
carry out such a plan therefore a number of new stables or sheds must be
provided to be used in succession, as they become one by one
contaminated.
Nocard confines his instructions to the antisepsis of parturition and of
the offspring:
“Cows ready to calve should be provided with dry and clean bedding until
after the birth of the calf.”
“As soon as labor sets in, the vulva, anus and perineum should be
cleaned with a tepid solution of lysol in rain water: 20 grammes of
lysol to each litre of water. The vagina should also be cleansed by
injecting with a large syringe a great quantity of the same solution
tepid.”
“As far as possible the calf should be received on a clean cloth or on a
thick fresh bedding, not soiled by urine or fæces.”
“The cord should be tied immediately after birth, with a ligature kept
in a lysol solution, and the cord amputated below the ligature.”
“The stump of the cord and the umbilicus should be washed with the
following solution:
Rain water 1 litre.
Iodine crystals 2 grammes.
Potassium iodide 2 grammes.”
“The disinfection of the umbilicus and cord should be completed by
coating them with
Methylic alcohol 1 litre.
Iodine crystals 2 grammes.”
“When the alcohol has evaporated the cord and umbilicus should be
covered with a thick layer of iodine collodion (1 per cent.) applied
with a brush. When the collodion has dried the calf may be left to the
care of the dam.”
This treatment may be changed by substituting other antiseptics, and by
prompt separation of the calf from the infected stable and dam. It is
also important to disinfect thoroughly and often the cow stable and
calf-pen, to remove instantly any calf that may show signs of scouring
or general disorder and to purify its pen and leave it unoccupied for
some time.
It should be added that the period of danger is in the first few days
after birth, and while the umbilicus is still unhealed. If scouring
should come on later it is much more amenable to treatment. A seclusion
of the calf for one week is usually sufficient to secure its escape.