234 CONTAGIOUS DISEASES. 



rally suggests itself that the brain and its membranes are the 

 seat of organic lesions. Indeed, the specific action of the poison 

 appears to be exercised, particularly in the first instance, upon 

 the medulla oblongata and the par vagura, the branches of which 

 seem to lose their natural properties ; hence the difficulty in 

 swallowing, the depraved appetite, alteration of the voice — or 

 its entire loss in the dumb form — as well as the convulsions 

 of the respiratory muscles, are all due to derangement of this 

 nerve ; and as the nervous system of the animal becomes more 

 and more deranged, complete paralysis of the respiratory muscles 

 occurs, and the animal dies from asphyxia. 



The principal post mortem appearances are oedema or con- 

 gestion, sometimes in patches, of the brain and spinal cord, 

 particularly at the base and plexus choroides, effusion into the 

 arachnoideal space, cerebral ventricles, and the cerebro-spinal 

 substance, and softening of the membranes. On the lower 

 surface of the medulla ohlowjata, at the origin of the seventh, 

 eighth, and ninth pair of nerves, the membranes are generally 

 highly injected, thickened, softened, and matted together. 

 The liver, kidneys, spleen, and the muscular system are 

 congested. The bladder is empty, and its mucous membrane 

 covered with petechise. The lungs are greatly engorged with 

 blood. The blood in the vessels is but imperfectly coagu- 

 lated, often black and tarry, sometimes bright and red, in 

 appearance. The mucous membranes of the pharynx, oeso- 

 phagus, stomach, and bowels are either greatly congested, with 

 extravasation of blood on their surface, or diffusely inllamed. 

 Patches of extravasation are particularly met with on the gastric 

 mucous membrane, and account for the hsemorrhagic vomiting 

 which is sometimes witnessed during the illness. The contents of 

 the stomach are generally of a peculiar nature, consisting of hay, 

 straw, stones — in fact, of a collection of the most incongruous 

 materials, which, owing to depraved appetite, the animal has 

 picked up during life. This appearance is of great value, as it 

 proves most conclusively that the dog has died rabid. 



The tongue is often wounded by the teeth ; its papillae con- 

 gested; and the salivary glands enlarged and vascular. In 

 " dumb madness " the congestions, more particularly those of the 

 upper part of the respiratory and digestive tracks, are developed 

 to a greater extent than in the other form of the disease. 



