121
Horse No. XLVI.—(i)
Inoculated subcutaneously with 2.0 c.c. rat's blood, hæmatozoa numerous.
Swelling attained a maximum on 5th. day, remained stationary for three days, and finally disappeared
on the 18th day. (ii) Inoculated with 1.0 c.c. Horse Surra blood, taken 9½ hours post mortem. No
swelling at seat of inoculation until the 5th day ; maximum attained on 8th, reduction on the 9th day,
when hæmatozoon first discovered in the blood.
Horse No. LVIII.—(i)
Inoculated subcutaneously with 2.0 c.c. rat's blood, hæmatozoa very
numerous. Swelling at seat of inoculation increased up to 5th day; remained stationary, as regards its
dimensions, up to the 8th day, and became reduced in size, finally disappearing on the 22nd day. (ii)
Inoculated with 1.0 c.c. Horse Surra blood, obtained 5 hours post mortem ; hæmatozoa previously
swarming. The swelling at. the seat of inoculation increased until the 6th day, when it measured
7× 6 inches, and raised 1½ inches above the surrounding tissues. The hæmatozoon was discovered
in the blood on the 10th day, concurring with the reduction in size of the tumour.
The average period of incubation of Surra in 15 horses inoculated with ante-mortem blood,
containing the hærnatozoon, extended over a period of 5.78 days, and with blood drawn during an
intermission of the disease 8.7 days; while in 14, inoculated with blood drawn on an average 7.46 hours
post mortem, the latent period was 9 days. In the cases now recorded, injected with soiled rat's blood
on one or more occasions, followed by negative results, and subsequently inoculated with Horse Surra,
the latent periods also occupied varying periods according to the source from which the virulent blood
was obtained.
In No. XII, ante-mortem, hæmatozoa numerous, latent period 6 days as against 5.78 days in the
above-mentioned instances.
In Nos. XIII and XLVIII, ante-mortem, taken during intermissions, latent periods 8 and 10 days,
average 9 days as against 8.7 days.
In Nos. XLVI and LVIII, drawn 8½ and 5 hours post mortem respectively, the latent periods
were 8 and 9, average 8.5 days as against 9 days.
From the above it will be at once observed that the subcutaneous injection of blood, containing
the hæmatozoon of the rat on one or two occasions, although followed by marked local manifestations
at the seat of the injection, had practically no effect on the period of incubation of the subsequent
attack of Surra in horses.
SUBCUTANEOUS INOCULATION WITH THE BLOOD OF DIFFERENT ANIMALS
INOCULATED FROM THE RAT.
Result Positive.
Horse No. LXIX.—Inoculated
with 0.5 c.c. blood, containing swarms of hæmatozoa, taken from
the cow. The swelling at the seat of inoculation was perceptible on the 3rd day, increased to P.M. on
the 4th, remained stationary on the 5th day. From the appearance of the organism in the blood, size
of tumour reduced, disappeared entirely 10th day.
SUBCUTANEOUS INOCULATION WITH THE BLOOD OF DIFFERENT ANIMALS, WHICH HAD BEEN PRIMARILY
INOCULATED FROM HORSE XCI (Rat excrement ingestion).
Horse No. XCV.—Inoculated
with 0.7 c.c. Guinea Pig blood, hæmatozoa very numerous. The
swelling at the seat of inoculation increased until the 5th day. The reduction in size of the tumour
and first appearance of the organism in the blood occurred on the morning of the 6th day.
The period of incubation of Rat Surra in experimental cases was much more prolonged than in
the case of Horse Surra, the maximum being 63 and the minimum. 13 days. The average time which
elapsed, between inoculation and the first appearance of the hæmatozoon was about thirty-one days ;
but it immediately returned to the normal period, 7 to 8 days, when a second horse was inoculated with
the blood of the first affected. When a third animal was inoculated with the blood of the second the
latent period became still more reduced, viz., to five days.
It will be unnecessary to re-capitulate the symptoms of Surra in equines produced by the
simultaneous inoculation of soiled blood obtained from the rat, for in those animals which survived
the appearance of the hæmatozoon in the circulation for more than a few days, the characteristic features
of the disease were similar to those described under Equine Surra, as occurring in the spontaneous and
inoculated forms of the disorder. In several cases, the course of the disease was considerably accelerated,
death taking place within forty-eight to one hundred and twenty hours after the trypanosoma had been
discovered in the blood. There can be no question that this form of Surra acquired from the rat
produces in the horse a most virulent type of infection, consequently no time is allowed for the develop-
ment of the characteristic symptoms which are so marked a feature in the more chronic cases of the
same malady.
In this volume the pathological changes found at the autopsies have not been analysed at length, as
in Volume I. Short accounts of the conditions found post-mortem accompany each case and will
be seen on reference to the respective Appendices
B 2204—31