182 Diseases of the Circulatory System. 
palliative in the mildest forms of the disorder, the most 
useful agents being mild doses of calomel given altern- 
ately with iodide of potassium, the animal needing perfect 
quiet. 
The Pericardium or Heart-Bag surrounds the 
heart and provides the fluid which moistens the surface 
during action. It usually suffers from disease in company 
with the pleura, or lining membrane of the chest, from 
which it derives a layer, internally and externally, An 
abnormal accumulation of thin reddish-looking fluid 
(serum) is the common result, producing inconvenience 
in proportion to the quantity, such as interference by 
pressure with the functions of the heart, as indicated by 
feeble pulse, obscuration of the heart sounds, tendency to 
fainting, anzemia, local dropsies, and eventually death. 
The disease is, however, rare in the dog, but as a result 
of injury is most common, bruising, puncture, or rupture 
from violent causes being the common forms. 
Invasion by Parasites.— Canine Hamatozoa is not 
an unfrequent event in dogs of the British Islands. The 
records of other countries where malarious influences 
abound furnish more frequent evidences. Two worms 
have been recognised: Filaria immitis or Canis cordis, 
and Filaria sanguinolenta, the former being generally 
understood to be the embryonic form of the latter. 
Filaria immitis is said to be probably present in at 
least two-thirds of the dogs in the Chinese Empire, as 
estimated by microscopical examination of the blood. 
Singularly enough the embryos, though so numerous, do 
not occasion any appreciable inconvenience to the host, 
but move about briskly in a serpentine form within the 
blood-vessels. When fully developed as parent worms 
they take up their position within the heart, in some 
instances bundles or clusters of them being found, and 
individuals varying from one or two inches to six or seven 
in length. The general results of the presence of these 
worms is their interference with the valves, between 
which they may be forced by such bodily efforts as induce 
an inordinate flow of blood. The effects are seen some- 
what later, as at the end of one or two days the animal 
