THE ANATOMY OF ABDOMINAL AND RECTAL PALPATION
In the previous chapter the process of abdominal palpation was described, together with the examination of most abdominal organs. The remaining organs are now considered, together with the information that may be obtained from digital examination via the rectum.
Although the right kidney cannot be found in most dogs, the caudal pole of the left one is generally identifiable. Indeed, in some dogs, generally of the larger breeds, the left kidney “floats” as both kidneys normally do in cats.
The dog’s bladder can be found extending forward from the pubic brim; when grossly distended, it lies over a large part of the abdominal floor. Micturition may be induced by gentle compression through the abdominal wall, which is a procedure not free from risk if performed incautiously. The bladder of the cat is located more cranially than that of the dog, well forward of the pubic brim. The prostate, notoriously variable in size and position (p. 468), may sometimes be palpated between the pubic brim and the bladder (Figure 15-27).
The empty uterus cannot normally be palpated. The gravid uterus is readily identified at certain stages of pregnancy by its beaded form or general enlargement or by the recognition of individual fetuses. The separate loculi (p. 465) within which the embryos initially develop are largest about the beginning of the 6th week (bitch), but this stage is soon followed by that in which the horns are uniformly swollen. A little later, individual fetuses may be palpated, although it is not always possible to make an exact count when the litter is large. The gravid uterus may affect the position of other abdominal organs markedly. It always occupies the most ventral position in the abdomen because it contains no gas; therefore it is heavier than most freely movable abdominal organs. In advanced pregnancy it may almost fill the ventral half of the abdominal cavity.
Digital examination per rectum, a procedure possible only in subjects of a certain size, may provide additional information.
In addition to revealing the tone of the anal sphincter and the condition of the rectum and its mucosa, digital examination may be used to explore the pelvic skeleton for evidence of fracture or deformity. The anal sacs may be palpated and their content expressed with the aid of a finger within the rectum. The only other visceral organs that may usually be examined are the urethra and the prostate in the male and the vagina in the female. Evaluation of the prostate requires consideration of its size, consistency, and symmetry. In large dogs the gland may be out of reach, but the prostate and the neck of the bladder may be made more accessible by coordinating the rectal examination with manipulation of the abdomen to press the caudal abdominal contents toward the pelvic entrance.Palpation of the abdominal wall of the laterally recumbent animal will reveal the position of the superficial inguinal ring, from which the spermatic cord may then be traced toward the scrotum in the male. The location of the ring is determined by recognition of its tense medial crus, which may be traced over the abdominal wall from the origin of the pectineus muscle (which forms the conspicuous swelling on the medial surface of the thigh). The superficial inguinal lymph nodes lie a little cranial to the ring. They are contained within the fold of skin that supports the prepuce in the male but are more difficult to find in the bitch, especially the parous bitch, because they lie deep to the inguinal mammary gland. In perineal hernia the pelvic diaphragm fails to support the rectal wall, which stretches and deviates. In this condition it is possible to deviate the inserted finger to the side of the hernia.