162 VETERINARY SURGICAL THERAPEUTICS. 
these troubles continue their action, the sick fall and soon die in 
convulsions, 
Most of the subjects affected with over-heating have withstood to a 
high degree the influence of the solar radiation, and, in the generality 
of cases, one is in the presence of a complex morbid state in which, 
according to the given troubles prevailing, three forms can be recog- 
nized : 1, Cerebro-spinal, essentially characterized by sigus of a great . 
hyperzemia of the nervous centers; 2. Cardiac and syncopic, killing by 
arrest of the heart; 3. Pudmonary, characterized by anxiety and exces- 
sive dyspnoea, which kills by asphyxia. 
Dogs fixed softly in wooden frames and exposed to the sun when 
the heat was 25° to 28° in the shade, taken after three-quarters of an 
hour with trepidation and chronic convulsions, become comatose and 
die quickly. (Vallin, Vincent.) * By over-work, experimentally real- 
ized in making animals walk on a mobile wheel placed in a room 
heated 50° to 60°, death takes place after an hour or so. (Laveran, 
Reynard) *. 
The experiments made by Colin upon large animals have shown that 
if, by exposure to the sun, the hyperemia of the superior regions of the 
body takes place with rapidity at a degree somewhat elevated, the central 
temperature rises only slowly and in very limited proportion. On the 
contrary, in the case of small animals, the central heat reaches quickly 
the degree incompatible with life. ‘The wool of the sheep does not 
protect him from heat any more than from cold; in animals of this 
species which were experimented on in a yard surrounded by very 
warm walls, the central temperature did not rise much above 41°C. In 
conditions where accidents from overheating take place, the hypera- 
mia does not result except from the outside temperature : it is due also to 
the superexcitation of animal caloricity, resulting from muscular action, 
respiration, and other fundamental modifications. Overheating has 
numerous degrees and various forms, according to its effects upon a 
larger or smaller number of functions or of organs. It may extend to 
cerebral congestion, cerebro-spinal congestion, or to other visceral con- 
gestions to incipient asphyxia, anesthesia, syncope, and to other 
troubles which invite rather than exclude each other.* (Colin.) 
Prophylactic rules are suggested by the etiology. Animals must not 
be submitted to long exposure under a burning sun, or to excessive 
work in a high temperature. If they must work under a burning sun, 
their heads ought to be protected with leaves of trees, a cap, or other 
objects ad hoc. In Bulgaria, as soon as the heads of Russian horses 
1 Vallin, Bullet. Acad de Med., 1894, p. 640. 
? Laveran & Reynard, Bull. Acad. de Med. 1894, p. 501. 
3 Collin, Bull. Acad. de Med., p. 28. 
