36o CANINE AND FELINE SURGERY 



which can now be reduced to a very few seconds for any 

 other than the thicker parts of the body. Again, one must 

 not forget that the hairs of the coat are naturally attracted 

 by the electricity, and this will produce a pricking sensation, 

 or even a distinct shock if the tube is brought too close. 

 This point is especially to be thought of in curly-coated or 

 long-coated dogs whose coats project a slight distance out- 

 wards from the body. As a general rule it will be found that 

 the tube can be satisfactorily placed about six inches away, 

 whilst the part of which a skiagraph is wanted is laid flat 

 directly on the plate or film. For making exposures of the 

 body itself, the operator must not forget that any continuous 

 movements, such as those of respiration, are apt to blur the 

 image on the photographic plate or film ; and if it is possible 

 to utilize a fluorescent screen in these cases, matters are 

 often simplified considerably. The time of exposure can 

 also be considerably diminished by using an intensifying film. 



The fluorescent screen is placed in immediate contact with 

 the sensitive film, and the whole enveloped in opaque paper 

 and exposed so that the rays pass through the screen before 

 reaching the sensitive surface. As regards the suitability of 

 different body tissues or abnormalities for X-ray work, injuries 

 of the bony structures are more clearly demonstrable than 

 those of the softer parts, and with a lo to 12 inch coil and 

 a good interrupter, such as the ' mercury jet,' the exposure 

 needed for the limbs only averages about three seconds. 

 For the deeper-seated bones, such as the vertebras and pelvis, 

 about twelve seconds' exposure is sufficient for any ordinarily 

 thin muscular dog, such as a terrier or greyhound. For 

 obese patients or some large breed, such as a St. Bernard, a 

 few seconds more must be allowed. 



Shots, bullets, or foreign bodies of metallic origin are not 

 so difficult to locate as stones or calculi. Early pregnancy is 

 not easily demonstrated even in the cat, whose abdominal 

 walls are thin and easily penetrated. 



