At autopsy, the only conspicuous gross 
lesions noted were in the prescapular lymph 
nodes. The right node contained a dry necrotic 
cent ei' about 2 cm. in diameter; the left pre- 
scapular node contained a mass of thick pus. 
The greatest tick concentration on infested 
sheep is usually along the lower neck, brisket, 
and navel areas. In a tick-transmitted in- 
fed ion the prescapular nodes are the ones most 
likely to show involvement.) 
The following tissues were used for inoculums: 
hone marrow, brain, kidney, liver, prescapular 
lymphatic node, muscle, and spleen. Four 
mice were used for testing each tissue. 
All test mice remained well and, except for 
those injected with brain emulsion, were 
discarded after 30 days. Three of the four 
test mice injected with brain tissue died the 
day after inoculation. The fourth died on the 
seventh day with lesions suggestive of tularemia. 
A culture of P. tularensis was established from 
subsequent transfers. 
The other lamb was killed and autopsied on 
July 8, approximately 1 month after the height 
of the epizootic. At this time it weighed 60 
pounds and had completely shed its fleece. 
'Phe following lesions were noted at autops} r : 
The right prescapular node was enlarged 
and contained a thin-walled pocket at one 
extremity that was filled with dry greenish 
exudate. The left prescapular node was slightly 
enlarged and contained a small tract of dry 
necrotic material. The peritoneal cavity con- 
tained about 100 cc. of amber-colored fluid 
with strands of fibrous residue. The surface 
of the liver and the peritoneal surface of the 
diaphragm showed multiple small fibrous tags. 
There were multiple contiguous fibrous ad- 
hesions on the spleen capsule. The left lobe 
of the liver had a small strip and small focal 
areas of necrosis. Two lymph nodes in the 
omentum along the lesser curvature of the 
abomasum showed dry, caseous nodules, the 
largest of which was about 3x2 cm. and almost 
entirely replaced the node. The intermediate 
lobe of the right lung showed an area of ate- 
lectasis. These lesions suggest an earlier bac- 
terial infection with resulting peritonitis. 
The following tissues were tested for infection 
by maceration and injection into mice (4 mice 
were used for each tissue): brain (3 samples), 
right and left prescapular node, precrural 
Public Health Monograph No. 28, 1955 
node, omental node, liver, peritoneal fluid, 
spleen, kidney, heart muscle, lung, bone marrow, 
and muscle tissue. No infection resulted in 
the test mice. 
On July 22, two convalescent lambs were 
selected from flock D at Bellevue, Idaho, for 
transport to the laboratory and autopsy. 
Serum samples from both were positive for 
tularemia at diagnostic titers. Both lambs 
had badly broken fleeces. 
One lamb was killed and autopsied August 1 , 
approximate^ 3 months after the epizootic 
had affected the band. It was an especially 
small animal and weighed only 48 pounds. 
The following conditions were noted: 
The peritoneal surface of the rumen and 
abomasum was slightly roughened. The vis- 
ceral surface of the rumen showed a caseous 
nodule about 6 mm. in diameter. There were 
several small, white subscapsular foci on the 
liver, and a few yellow necrotic streaks. One 
omental node was enlarged and contained 
several discrete yellowish necrotic areas and 
a caseous mass about 8 mm. in diameter. 
In this lamb the prescapular nodes were 
apparently normal, in contrast to the other 
three, which had enlarged nodes containing 
dry necrotic or caseous masses. 
The following tissues were tested for infec- 
tion by maceration and injection into mice: 
prescapular nodes, liver, spleen, kidne}', lung, 
omental node, muscle, brain, and bone marrow. 
Test animals injected with kidney emulsion 
died of tularemia, and a culture of P. tularensis 
was established. A retest of this kidney tissue 
after 7 days’ storage in a refrigerator again 
produced tularemia in test mice. All other 
tissues tested gave negative results. 
The other lamb was autopsied on August 12. 
It weighed 71 pounds. The following condi- 
tions were noted: 
The fleece had shed on the lower sides and 
belly. A 1-cm. subcutaneous abscess contain- 
ing thick greenish exudate was present at the 
point of the right shoulder. The right pre- 
scapular node was enlarged about 2 times and 
contained a small pocket of necrotic exudate 
The left prescapular node contained a thickly 
walled-off cavity 1 cm. in diameter filled with 
green caseous exudate. There was a fibrous 
band about 3 cm. long between tin- diaphragm 
and the liver at a fissure between liver loin - 
9 
