The cases of navel ill resulting from infection before birth can not
well be guarded against. By keeping mares, advanced in pregnancy, in
good physical condition, the fetus will be expelled immediately upon the
opening of the uterine cavity.

Once the infection of the navel cord has set in, the cord should not be
ligated but should be washed in a disinfectant solution and a
veterinarian called for the subsequent treatment.

INFECTIOUS ANEMIA OR SWAMP FEVER.

By JOHN R. MOHLER, V. M. D., _Assistant Chief, Bureau of Animal
Industry_.

Infectious anemia of horses, known also by a number of other names, as
swamp fever, American surra, malarial fever, typhoid fever of horses,
the unknown disease, no-name disease, plains paralysis, and pernicious
anemia, has recently been the subject of much investigation. The cause
of the disease has now been definitely determined as an invisible virus,
which is capable of passing through the pores of the finest porcelain
filters, like the infection of foot-and-mouth disease, rinderpest, hog
cholera, and similar diseases. The disease is most prevalent in
low-lying and badly drained sections of the country, although it has
been found on marshy pastures during wet seasons in altitudes as high as
7,500 feet. Therefore proper drainage of infected pastures is indicated
as a preventive. It is also more prevalent during wet years than in dry
seasons. It usually makes its appearance in June and increases in
frequency until October, although the chronic cases may be seen in the
winter, having been contracted during the warm season.

_Cause._--It has been conclusively proved that infectious anemia is
produced by an invisible filterable organism which is transmissible to
horses, mules, and asses by subcutaneous inoculation of blood serum. The
virus which is present in the blood may be transmitted to a number of
equines in a series of inoculations by injecting either the whole blood,
the defibrinated blood, or the blood serum which has been passed through
a fine Pasteur filter, thus eliminating all the visible forms of
organismal life, including bacteria, trypanosoma, piroplasma, etc. This
virus has also been found to be active in the carcass of an affected
animal 24 hours after death.

Following the injection of the infectious principle there is a period of
incubation which may extend from ten days to one and one-half months, at
the end of which time the onset of the disease is manifested by