DISSECTION OF THE DOG 



The dissection of the dog is best begun with, the animal lying on its back. 

 If the subject is a female, the mammary glands should be examined as far as 

 possible before any dissection is carried out. 



Mamm;e. — The mammary glands of the dog are eight to ten in number, 

 arranged in a double row — often asymmetrical — along the ventral aspect of the 

 thorax and abdomen. When ten glands are present, they can generally be 

 designated as four thoracic, four abdominal, and two pubic. 



Though nipples are present in both sexes, mammary glands, as such, are 

 seldom demonstrable in the male. Even in the female, except during the 

 period of lactation, the mammae do not generally form very distinct projections. 



Each nipple (papilla mammae) is conical in form, covered with hairless skin, 

 and pierced at its apex by numerous (eight to twelve) openings. Each small 

 orifice leads to a milk canal (ductus lactiferus), which traverses the length of the 

 teat from a milk sinus (sinus lactiferus) at its base. 



Dissection. — Make a longitudinal incision along the mid-ventral line from 

 the middle of the neck to near the external genital parts, and a transverse 

 incision from the medial aspect of one elbow to a corresponding point on 

 the opposite limb. Two short and two long flaps of skin should now be 

 reflected. In doing this, be careful to avoid removal of the mammary 

 glands. On arriving at the base of the nipple, make a circular cut through 

 the skin so as to leave the teat uninjured and attached to its gland. In 

 turning outwards the flaps in the neck, avoid removal of the cutaneous 

 muscle which here forms a thin layer of transverse fibres. 



If the mammary glands are not active the gland-tissue will be scanty and 

 form merely a thin layer under the skin. Generally the thoracic glands are 

 separate from each other, while those over the abdomen are continuous. The 

 character of the glands is much more obvious during lactation, when they 

 form a continuous, lobulated sheet stretching from the oral border of the 

 pectoral muscles to the neighbourhood of the external genital parts. 



Dissection. — Remove the thoracic mammary glands and define the pectoral 

 muscles. Then proceed with the dissection as in the male. 



