PALISADE WORMS. 403 



artery, in which case, the obstruction is called an embolus. Owing 

 to obstructions thus formed, the part usually supplied by the artery 

 becomes more or less paralysed, with the result, in the case of the 

 intestines, that flatulent colic is produced, on account of fermen- 

 tation taking place in the delayed food. On the formation of an 

 embolus, there is an unmediate attempt at the restoration of the 

 circulation by side branches of the vessels. We then have a race 

 between the " collateral circulation " and the colic, which will be- 

 come cured if the function of the part becomes restored before the 

 resulting pain or flatulence has produced fatal consequences, or 

 before twist or invagination (pp. 420 and 421) of the bowel has 

 taken place. These emboli may produce weakness or diminished 

 freedom of action of the hind quarters. 



After the immature worms have undergone another stage of deve- 

 lopment in their respective aneurisms, they again launch them- 

 selves into the blood stream, and by its means they reach the intes- 

 tine, under the mucous membrane of which they again form cysts ; 

 become adult; and emerge into the intestine, to which they attach 

 themselves and produce eggs. 



As a rule, these aneurisms are not found in foals younger than 

 three months old, and are more frequent in aged horses, than in 

 young ones. 



The dangers due to the presence of palisade worms in the arteries 

 are : embolism, and rupture of the wall of the aneurism, in which 

 case there will usually be fatal bleeding into the abdominal cavity, 

 with rapid failure of the physical powers and bloodlessness of the 

 mucous membranes. 



Although these emboli give rise to no characteristic symptoms^ 

 we may suspect their presence when we find that the horse is liable 

 to colic without any errors of diet being to blame, and when 

 the seat of pain appears to be far back, as will be shown by the 

 animal crouching behind and, if obliged to walk, getting his hind 

 legs under him as much as possible. Often, when the animal seems 

 on the point of death, with the surface of his body very cold, 

 he will take a sudden change for the better, owing to the collateral 

 circulation becoming established, and will rapidly mend. In the 

 treatment of this form of worm colic, I would advise a drench of 

 a pint of linseed oil, and 2 oz. of turpentine, followed, if necessary, 

 by an ounce of chlorodyne in a pint of water, or half an ounce of 

 the extract of Indian hemp. Besides the symptoms of colic caused 

 by embolism, the presence of the worms in the intestines gives 

 rise to more or less inflammation of the bowels, diarrhoea, gene- 

 rally, of a foetid and sometimes bloody character, and slight attacks 

 of colic. The diarrhoea, disturbance of the functions of digestion 

 and circulation, and drain on the constitution by the presence of 



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