A DICTIONARY. 



281 



Pleura. — The membrane which covers 

 the lungs so closely as to appear a part of 

 their substance. 



Pleurisy, Pleuritis. — Inflammation of 

 the pleura. 



Plexus. — A network of blood-vessels or 

 nerves. 



Pneumonia. — A general term for inflam- 

 mation of the lungs. 



Poisons. — Articles wliich impede or de- 

 stroy the vital operations. Some people 

 proclaim that all food is poison ; that the 

 difference in the effect produced lies in the 

 quantity given. We deny this : good corn, 

 oats, and hay, whose nature is to nourish 

 and support the animal, can never be a legit- 

 imate cause of disease. Its excess in quan- 

 tity, and its chemical decomposition for 

 want of digestive power, are all of true food 

 that can prove injurious. On the other 

 hand, experience teaches us that opium, 

 arsenic, corrosive sublimate, tobacco, and 

 calomel are inimical to the animal organ- 

 ization, and will never change their chemi- 

 cal equivalents. A grain of arsenic will 

 always be a grain of that poison, and can 

 be detected after death : the same applies 

 to opium. A very few grains of opium in- 

 jected into the carotid artery of a dog 

 killed him in four minutes ; when the same 

 quantity was injected into a vein, the ani- 

 mal lived twenty-five minutes. When 

 injected into the bladder, it required a 

 larger quantity to destroy life. 



Again: one drop of the oil of tobacco 

 applied on the tongue of a rabbit kUled him 

 instantly; one drop applied to the same 

 organ of a cat, threw her into convulsions ; 

 two drops placed on the tongue of a squirrel 

 killed it instantly. Hence, it does not re- 

 quire much penetration in order to decide 

 what is and what is not poison. Animals 

 often get, apparently, well, although large 

 quantities of the above poisons have been 

 given. This is no proof that the poisons 

 cured them. In the early stage of the dis- 

 ease, the constitution can bear more vio- 

 lence — blood-letting and poisoning — than 

 when it becomes debilitated. This explains 

 the reason why large quantities of opium 



36 



may be given to a horse at a certain time, 

 without any perceptible effect ; at another 

 time, one-half the quantity will destroy 

 him. 



Poll-Evil. — An obstinate disease, which 

 often happens to horses. It generally pro- 

 ceeds from a blow received upon the poll 

 or back part of the head. 



Porta. — The name of the great vein of 

 the liver. 



Poultice, or Cataplasm. — The emol- 

 lient poultice may be composed of equal 

 parts of slippery elm and flaxseed. The 

 intentions to be answered by poultices are 

 relaxation and stimulation. To relax a part, 

 add to the above emollient, lobelia ; when it 

 is necessary to stimulate, use cayenne. 

 Poultices that are designed for foul ulcers, 

 in addition to the above articles, should 

 contain at least one-third powdered char- 

 coal. 



Prevention or Disease. — It is an old, 

 but true saying, that prevention is better 

 than cure, and, we may safely add, less ex- 

 pensive. 



Pricks, or Pricking. — In shoeing a 

 horse, the nail is sometimes driven in a 

 wrong direction, and the sensible parts are 

 wounded ; he is then said to be pricked. 

 When a horse has been slightly pricked, 

 and the nail immediately withdrawn, it may 

 not be followed by lameness ; but, when 

 the wound is considerable, matter will form ; 

 if the matter is not let out by paring away 

 the horn, it quickly spreads under the horny 

 sole, and upwards through the laminated 

 substance of the foot, and breaks out at 

 the coronet. (See Coronet.) To prevent 

 this, the parts, as soon as the accident has 

 happened, should be bathed with healing 

 balsam. If the horse goes lame for several 

 days, a poultice must be applied to promote 

 suppuration. 



Prim^ Vi^. — The first passages, or 

 stomach, and first intestines. 



Proband. — An instrument for removing 

 any obstruction in the oesophagus or gullet. 

 It consists of a rather flexible rod, covered 

 with leather, with a round, smooth knob at 

 one end. 



