NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
ENCEPHALO-MYELITIS IN AN INDIAN CAVALRY
REGIMENT
213
of the nasal passage, and the nasal mucous of infected horses is invariably infectious
while a slight catarrh of the upper respiratory tract is usually present.
It appears that, in the horse, there is more than one type of meningo-ence-
phalo-myelitis, the most important and the most specific being " Borna " disease,
which was first noted in Germany many years ago. In recent years, the amount
of literature published on this disease has been extensive and workers on it may
be divided into three schools :—German, French and American, although in other
countries there are copious records of investigation.
The workers in France have described a disease practically identical with
" Borna " disease but differing from it in certain important characters.
In " Borna " disease the important lesions are confined to the central nervous
system. There is a slight hyperaemia of the meninges of the brain and spinal cord,
and an abnormal fulness of the meningeal vessels, while punctate hæmorrhages are
seen throughout the brain substance, more especially in the grey matter. There is
a well defined perivascular infiltration around the vessels of the choroid plexus and
the small capillaries and veins, frequently extending through the grey matter.
Hutyra and Marek state that subependymal hæmorrhages may be present,
along with slight thickening of the ependyma. Exudation in the meninges is not
found, although Hutyra mentions that the choroid plexus may occasionally show
gelatinous swelling. There is, usually, a well marked mononuclear cell infiltration
in the brain substance with a certain amount of neuroglial proliferation. The most
important feature of " Borna" disease is the presence of intranuclear inclusions
known as Joest-Degen' bodies, and according to German workers, these bodies
are considered as specific of " Borna " disease as negri bodies are of rabies. As in
rabies, they are found most commonly in the hippocampal gyrus. The same
authorities state that degeneration of the cell nucleus, such as neuronophagia, is not
found in " Borna " disease in Germany.
British workers, while confirming the importance of Joest-Degen bodies, claim
that there is a definite destruction of the nucleus of nerve calls in "Borna"
disease.
In spite of numerous attempts of workers, in the past, to prove a bacterial
etiology, it is generally considered, at the present day, that the various streptococci
and diplococci which can be isolated occasionally from the brains of the diseased
horses are of no importance.
It has been definitely proved that "Borna" disease is due to a neurotropic
virus which possesses a close affinity to the viruses of vesicular stomatitis of the
horse, louping-ill of sheep, and epidemic poliomyelitis of the human subject.
214 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, III
The virus is pathogenic for cattle, rabbits, guinea-pigs, rodents and monkeys, while
cases are on record where man has been accidentally infected. It seems difficult
experimentally to infect horses with the virus, and German workers mostly incline to
the opinion that this cannot be directly done. In other countries, a successful
direct transmission of the disease from horse to horse has been effected.
The disease in America is analogous to the French form of the disease
described by Moussu and Marchand. German workers maintain that the Moussu-
Marchand form is quite distinct from their conception of " Borna" disease,
although French workers do not accept this opinion. The trend of thought would
seem to indicate that the virus producing meningo-encephalitis of the horse may
exist in an organotropic form as well as a neurotropic, and accepting this
possibility, a ready explanation can be found for the lesions which occur in the
Moussu-Marchand type of the disease. These lesions consist essentially of (1)
degeneration of the parenchymatous organs along with hæmorrhages.
Hæmorrhages also occur in the brain and spinal cord. (2) Joest-Degen bodies
are absent. (3) The nerve cells of the brain and spinal cord show definite
degenerative changes. (4) It is found difficult on intra-cerebral inoculation, if
not impossible in the majority of cases to transmit the disease.
These differences appear on a wide review of literature, to be more of degree
than of kind. Many workers mention hæmorrhages in "Borna" disease, as
well as infiltration and destruction of nerve cells.
Apart from the acceptance of Joest-Degen bodies as being an essentially
typical feature of " Borna " disease it appears difficult to accept any definite set
of p. m. lesions as being typical.
During the course of one outbreak, hæmorrhages in the brain, spinal cord and
parenchymatous organs may be present or absent. The absence of any p. m.
lesions at all is, in some cases, the most striking feature of the disease. The
lesions in the brain and spinal cord are constant in the majority of the cases,
but variations may occur. Infiltrations may be extensive around the capillaries,
or absent, in which case the brain substance shows a diffuse mononuclear infiltra-
tion. The one definite and invariable lesion seems to be a slight thickening
of the meninges, without exudation, and those changes described in the blood
vessels. In chronic cases there is a formation of new tissue in the meninges.
Referring again to Hutyra and Marek, there exist a form of enzootic spinal
paralysis of the horse which is characterized by multiple capillary hæmorrhages
in the various organs, and especially in the spinal cord. It is stated that this
disease is caused by streptococci, but in a foot note, some considerable doubt is
cast on such an etiology and the question concerning the possible relationship
ENCEPHALO-MYELITIS IN AN INDIAN CAVALRY REGIMENT
215
between this disease and " Borna " disease is raised. If we combine the p. m.
pictures of these two diseases as described by Hutyra and Marek, we get an
average and accurate picture of the disease which we have been investigating at
Multan.
Other disease possibilities have not been overlooked, and the following
observations may be made :—
1. Forage poisoning.—The most uptodate information regarding forage
poisoning in the horse is published and reviewed by Steyn, D. G. in the Onder-
stepoot Journal of July 1933. There is an essential dissimilarity in symptomology
between " forage poisoning " and the disease encountered at Multan, as well as
in the lesions of the disease which it is not proposed to discuss here. This
dissimilarity is enhanced by the fact that experimental feeding transmissions
failed both in horses and in small animals, and further-more, the disease at
Multan was not affected in any way by withholding the suspected forage for a
period. In typical forage poisoning, symptoms of meningitis, if they do occur,
are not predominant, and in the few definitely diagnosed outbreaks of forage
poisoning on record, the feeding of the suspected fodder or silage to experimental
horses succeeded in reproducing the disease in a typical form in the majority of
cases. Many outbreaks of so-called forage poisoning are actually outbreaks of
Botulism.
The possibility of Botulism has been considered. Here again, the
symptomology of pure experimental botulism in the horse is quite different from that
seen in equine encephalo-myelitis. Symptoms of lethargy, loss of co-ordination
resulting in a staggering gait, hyperaesthesia and muscular twitchings with general
symptoms of meningitis are not seen in botulism, paralysis of the tongue, a
constant feature of experimental botulism, is never observed in equine encephalo
myelitis. Neither are tissue hæmorrhages nor perivascular infiltrations seen in
botulism.
The evidence that the outbreak of the disease in the horses of the 13th
Lancers is related to, if not actually identical with, specific enzootic equine
encephalo-myelitis as occurring in other countries, may be summarised as
follows :—
In all cases of the disease, there is a definite meningo-encephalitis of a
disseminating, infiltrative, nonpurulent, lymphocytic type with predominating
vascular character. The lesions in the nervous system and the general post-mortem
features are. on a summation of post-mortem protocols, as follows :—
Subacute inflammation of the vessels of the meninges without any exudation,
accompanied by perivascular infiltration and frequent hæmorrhage. Punctate
216 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [IV, III
hæmorrhages are frequent in the brain substance and a typical diffuse mononuclear
infiltration of the neuroglia with destruction of the nerve elements is seen.
Similar lesions are present in the spinal cord. Joest-Degen bodies are not
found. Hæmorrhages occur throughout the parenchymatous organs in the
majority of cases, and there may be slight degeneration of the cells of these organs.
The lymph glands are occasionally swollen and hæmorrhagic. Gastro-intestinal
catarrh is noted in a few cases. The bladder contains a thick syrupy urine which is
frequently blood-tinged, while the submucosa is studded with hæmorrhages.
Secondary infection of the bladder consequent on urinary stasis is not uncommon,
the end result being, in protracted cases a thickening of the wall of the bladder
by a slow infiltration of granulomatous tissue.
The post-mortem appearances presented are parallel to those encountered in
American outbreaks caused, probably, by a virus of the Moussu-Marchand type.
The symptomology of the disease is, on all essential criteria, identical.
Recovered cases, in American outbreaks, tend to a permanent disability expressed
in terms of altered nervous function and structure. In the one recovered case
which was examined, there appeared no clinical disability. Definite proliferative
lesions were found in the meninges which were thickened and adherent, as well
as in the nerve cells of the brain and spinal cord. Hæmorrhages were persistent
in the ependyma, the cerebral cortex, and the internal organs, specially the
kidney.
On epidemiological considerations, the parallel is maintained. During the
course of an outbreak, one horse or a small group of horses is affected at a time.
Additional cases may occur after an interval of 7 to 10 days.
Serum from recovered horses was shown to possess some effect in lessening
the severity of the disease when given, during the course of an outbreak, in
relatively high dosage, to cases in the prefebrile phase of the disease. Even with
the onset of symptoms, serum proved useful in tiding over critical cases to the
convalescent stage, cases which might not have been expected to recover
normally. A further point of analogy is that in the Moussu-Marchand type of
the disease there is a definite prefebrile phase of about four days duration. A
similar fact was noted during the outbreak at Multan.
Opinions differ very much as to whether any drug treatment is of avail.
In German outbreaks, considerable faith is placed in the intravenous injection of
of urotropine in large daily dosage. This drug is excreted by the choroid plexus,
and its use appears rational. It was used with a considerable measure of success
in the outbreak at Multan.
ENCEPHALO-MYELITIS IN AN INDIAN CAVALRY REGIMENT
217
The disease shows a cyclic incidence.
Further evidence is adduced by the transmission experiments which were
attempted, while it is true that rabbits could not be infected by intracerebral
inoculation of nerve tissue obtained from diseased horses.
Several guinea pigs died after similar inoculations, without, however any
symptoms of the disease in question. (The nerve tissue of these cases has not
yet been examined). This finding corresponds with that of workers in America,
who failed, in the majority of cases, to reproduce the disease in rabbits, and
found that guinea pigs were more suitable for experimental inoculations, although
these animals showed no typical symptoms of the disease, apart from lesions in
the brain after death.
It has lately been found that rabbits can be infected by intraocular injection
of filtrated brain emulsion, and using the same route, horses can be infected,
although not constantly.
The French virus has only rarely succeeded in transmitting the disease when
inoculated subdurally, but that it is capable of doing so has been adequately
proved.
This fact agrees with our transmission experiments in which we inoculated
two horses with brain emulsion from a case of the disease, one subdurally and
the other into the temporal plexus, with the subsequent development of disease
symptoms of a type strictly comparable to the original disease. These symptoms
could not be ascribed to errors in technique as a definite incubation period of
nineteen days elapsed before the onset of symptoms. In experimental transmission
of the disease to horses in other countries, an incubation period of similar duration
has been noted.
Our successful result in producing the disease in horse by the intrathecal
inoculation of cerebro-spinal fluid is also in accordance with the experience of two
German workers.
Lastly although the limited time at our disposal prevented our undertaking
any filtration experiments, there is a strong presumption that the disease is of
virus origin, an opinion that is strengthened by the fact that no bacteria could be
shown, in the few cases when they were isolated from the disease, to possess an
etiological role.
The writer is of the opinion that the disease occurring in the horses of the
13th Lancers at Multan is a specific equine meningo-encephalitis probably caused
by a neurotropic filterable virus of organotropic type.
A STUDY OF THE DATA OF MILK YIELDS OF VARIOUS TYPES
OF CATTLE OBTAINED FROM THE RECORDS OF THE
GOVERNMENT MILITARY DAIRY FARMS.
III. PREDICTION OF MILK YIELDS.
BY
K. P. R. KARTHA, B.A.,
Statistical Assistant, Animal Husbandry Bureau, Imperial Council of Agricultural
Research.
(Received for publication on the 10th July 1934.)
(With one text-figure.)
The prediction of milk yields is a frequent necessity in dairy industry. The
dairyman wishes to know at times what the probable output of his stock would be
during a certain future period so as to ensure himself that his supply would
adequately meet any anticipated demand, or that he may make suitable arrange-
ments for the disposal of surplus milk. At other times he wishes to know, when an
animal has been in milk for only a short time, what its annual yield would be so
that if it is an uneconomic animal it may be culled without incurring unnecessary
expenditure on it for the whole year. Again, if two animals or two herds of
animals have to be compared from data of yields available for different lengths of
periods only it is necessary to know what these would have yielded during
identical periods of lactation. The knowledge gained in Parts I and II regarding
the properties of the lactation curve and the deductions therefrom enable such
estimates to be made as are required in the ordinary course of dairy business.
In part I, it was shown how it may be tested whether environmental conditions
like feeding, care and management of animals are such as would enable them to
produce their best. It was also shown there how an estimate may be formed of
the probable yield during a given future period when an animal has been in milk
for only a short time. This may be computed either graphically or arithmetically.
By an extension of the method it is possible to calculate the yield for a whole
lactation. This, however, presupposes a knowledge of the initial rate of milk
secretion and the rate at which it falls off. But often it is necessary to calculate the
lactation yield when one or both of these are unknown. This is especially required
in the official testing of herds. The tester is able to visit the Farms in his
jurisdiction only periodically and he has to form an estimate of the milk producing
capacity of the animals from the short time performance he records. This
makes it essential that a method should be found by which it should be possible to
estimate the lactation yield from the rate of yield at any stage in the lactation.
The rate of milk secretion at maximum is often made the basis of estimating
the total lactation yield. Prof. Tuff has found that the total lactation yield is 199
( 218 )
PREDICTION OF MILK YIELDS
219
times the maximum daily yield. Sanders finds that the ratio of the lactation
yield to the maximum weekly yield varies from 24.7 to 29.37 according to the
month of calving. From the data collected from the records of the military dairy
farms the values of this ratio (total lactation yield/maximum weekly yield) were
calculated for individual lactations in the case of a herd of buffaloes. The values
of the ratio are given in Table I. It will be seen that even when the service period
is confined to narrow limits (which more or less defines the length of lactation) the
variation in the values of the ratio is large and would introduce appreciable errors when
TABLE I.
Ratio between the lactation yield and the maximum weekly yield of individuals in the
various service period groups—Buffaloes.
Serial
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
36
36
37
38
Service period in weeks.
2—6.
22.1
23.79
16.25
28.40
25.36
24.43
2818
24.58
23.01
26.46
17.52
21.09
25.30
2003
25.46
21.47
25.90
28.96
24.49
29.05
30.07
20.45
25.95
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
6—10.
25.24
22.08
23.92
24.35
21.60
33.83
22.92
22.38
21.76
22.46
25.28
25.70
22.44
21.92
25.46
24.53
26.32
16.64
28.84
22.70
27.17
21.28
33.57
22.11
21.74
26.77
26.42
22.59
26.65
27.81
30.94
29.54
30.56
25.68
28.42
24.52
24.77
22.40
10—14.
26.53
19.93
26.37
27.88
26.59
29.95
25.32
32.81
36.63
20.74
29.17
28.34
34.41
23.86
21.59
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
14—26.
39.44
29.45
19.40
27.75
28.97
36.08
29.30
32.61
25.45
21.98
22.51
26.74
36.07
32.63
35.56
26.89
27.41
26.07
28.80
30.77
31.23
27.33
32.49
26.31
25.80
22.98
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
.....
220 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, III
applied to individuals. It has been seen in Parts I and II of this paper that the
lactation yield is a function of the maximum yield and persistency and that the
latter is subject to large variations in the case of individuals. The variation in the
value of the ratio is, therefore, obviously due to the variation in persistency. Again,
it is not enough if a ratio is found between the maximum and the lactation yield, it
should be possible to estimate the latter from the rate of yield at any stage of the
lactation.
The purpose of testing herds being to obtain a measure of their economic
efficiency as producers of milk or fat, what is often required to be estimated is the
yield over a definite period rather than the lactation yield. The magnitude
of the latter depends largely on the service period, or for that matter on the length
of lactation, and is not a reliable index of the milking capacity of the animal. If
the yield for a definite length of lactation is to be estimated it can be shown
mathematically that the value of its ratio to the rate of yield at any stage in the
lactation depends both upon persistency and the stage of the lactation.
Table II shows the values of the ratio between the yield for ten months and
the rate of yield at various stages of lactation, from 1 to 9 months after calving,
for all values of the rates of decline from 1 to 20 per cent. per month, which range,
it has been seen in Part II, includes almost all the animals studied. If the rate of
decline is known, the yield for any month of lactation multiplied by the ratio
appropriate to that month would give the total yield for ten months. If the rate of
decline is not known the best value to take would be that corresponding to the
average rate of decline for the breed to which the animal belongs. The estimate
can be further improved if use is made of the knowledge (vide Part II) of the
relation between persistency and the level of production.
If Table II is examined minutely another interesting fact is brought to light,
that would show at what stage of the lactation the estimate formed would be the
most accurate when the value of persistency is unknown. It will be seen that if
an estimate is made in the first month, the ten months' yield may be anything
between 5.27 and 9.61 times the rate of yield according to the value of persistency.
In the second month the range diminishes to 6.44 and 9.71, and in the fourth
month it is practically zero. At this stage whatever the value of persistency the
value of the multiplier is practically the same. In the 5th month the range is
narrow and from there it again widens. This fact is illustrated graphically in
222 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, III
FIG.1.
Figure I where the values of the ratio are plotted against the rates of decline for the
1st, 2nd, 4th and 5th month of lactation.
The above fact, namely, that the 4th month of lactation is the best time for
conducting a test, may be verified practically. It is obvious that the estimate
based on that month's yield would be the best which bears the strongest relation-
ship to the total yield. The relationship is measured by the coefficient of correlation
between the two. Ten months' yields were found in the case of 157 cross-bred
cows and the correlation of this was found with the yield for each of the months of
lactation from 1 to 9. The correlation surfaces for the 1st, 2nd, 4th, 5th and 8th
month are shown in Tables III to VII and the coefficients for all months are entered
PREDICTION OF MILK YIELDS
223
TABLE III.
Correlation between rate of yield one month after calving and total yield for 10 months.
10 months' yield in
100-lb.units.
Class
mid-points.
27.5
32.5
37.5
42.5
47.5
52.5
57.5
62.5
67.5
72.5
.
77.5
82.5
.
87.5
92.5
.
97.5
.
102.5
107.5
112.5
.
Total
Rate of yield in 100.lb. units. (Class mid-point).
2.5
1
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
3.5
...
1
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
4.5
...
2
1
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
3
55
...
...
1
...
7
2
1
...
...
...
...
...
...
...
...
...
...
...
11
6.5
...
...
...
...
2
2
1
2
...
...
...
...
...
...
...
...
...
...
7
7.5
...
...
...
1
1
7
7
3
1
...
...
...
...
...
...
...
...
...
20
8.5
...
...
...
1
1
3
6
4
6
5
...
l
...
...
...
...
...
...
27
9.5
...
...
...
...
...
1
2
3
7
5
5
2
2
..
1
...
...
...
28
10.5
...
...
...
...
...
...
...
1
3
5
5
1
4
3
...
...
...
...
22
11.5
...
...
...
...
...
1
...
...
2
1
1
2
2
2
2
...
...
...
13
12.5
...
...
...
...
...
...
...
...
...
...
...
1
1
...
...
3
1
...
6
135
...
...
...
...
...
...
...
...
...
...
1
1
2
1
2
1
1
1
10
14.5
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
1
1
1
4
15.6
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
...
...
...
1
16.5
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
...
...
1
2
17.5
...
...
...
......
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
18.5
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
...
1
1
Total.
1
3
2
2
11
16
17
13
19
16
12
8
11
6
8
5
3
4
157