Mammary teats

The number and location of mammary glands varies with species from two, e.g. human, goat and sheep, to 14-16 for the pig. Each gland is anatomically and physiologically separate and is emptied via a teat. 

For the mammary fat pad injection, a small incision is made toward the midline of the teat using a scissors (a scalpel also works well) (Fig. 8.2A, B). The mammary fat pad is exposed in the incision by inverting the tissue using a finger and shding the needle into the fat pad immediately under the teat (C). A blister forms at the site of injection that is translucent and relatively fragile. For this type of injection, slower injection rates are recommended. When the inoculum has been injected, the needle is withdrawn and the incision is closed with sterile wound clips (D). Removal of the wound clips is usually not necessary since they usually fall out with 1-2 weeks. If, however, the clips remain, they pose no adverse threat to the animal or the tumor. 

Fig. 8.3. Key steps involved in oithotopic mammary fat pad injections. An incision is made medially to the teat under which the fat pad will be exposed (Panels A and B). The fat pad is externalized by inverting the skin using a finger (Panel C). The needle is inserted into the fatty tissue below the teat and inoculum injected. Panel D shows the mouse following closure of the incision with wound clips. As noted in Fig. 1, coloration is distorted due to room lighting, flash and sterile hood lighting...

Phytophotodermatitis was reported in pigs allowed to graze in a field of parsley. Vesicles with erythema and skin fissures were reported on the snouts, ears, and mammary gland teats (Griffiths and Douglas 2000). Acute photosensitivity was reported in a flock of ostriches exposed to parsley. Avian photosensitivity was confirmed by experimental reproduction of the typical lesions in ducks (Perelman and Kuttin 1988). 

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