Botryomycosis of the Udder 975 



gland becomes much swollen because of the maturing of an ab- 

 scess preparatory to its rupture. The gland may become so 

 swollen, tense, and sensitive that the animal shows pain, ex- 

 pressed by lameness in the hind limb of the corresponding side. 



There is usually some edema in the subcutaneous tissues of the 

 udder and neighboring parts. As a rule, but one-half of the 

 gland is involved . After a few days the niatured abscess ruptures 

 and discharges a small quantity of pus, and there remains for a 

 period of time an inconspicuous fistulous opening, from which a 

 very small quantity of pus exudes. The mouth of the fistula 

 sinks deeply into the skin by retraction of its scar tissue. If a 

 probe be inserted into the fistula, the canal is found tortuous, but 

 one may be able to follow it for a distance of two to six or more 

 inches. After a time the fistula heals, and later another small 

 abscess forms in some other portion of the gland, and ruptures, 

 to be followed by another fistulous opening. In some cases there 

 may exist, at one time, two, three or more fistulous openings, 

 from each of which a very small quantity of thick pus is dis- 

 charged . 



The general health of the patient is not apparently affected. 

 The diseased gland continues to grow, and may attain a very 

 large size. 



The disease is chronic, and shows no tendency toward spon- 

 taneous recovery, but rather continues from year to year. 

 There is little tendency for the disease to pass beyond the capsule 

 of the gland and involve neighboring tissues. Vennerholm states 

 that it may extend to the thigh or perineum, and may thus cause 

 marasmus and the death of the animal. 



The differential diagnosis sometimes offers difiiculties. A gray 

 mare, entered in our clinic, presented symptoms which made it 

 difficult to determine whether she was suffering from botryomy- 

 cosis, melanosis or a malignant new-growth. The affected half 

 of the gland was enormously enlarged, and the animal showed a 

 distinct cachexia and was very stiff in her movements. Explor- 

 ing the pelvic cavity and posterior portion of the abdomen pef 

 rectum, we found that the growth extended up through the in- 

 guinal ring into the peritoneal cavity. An unfavorable prognosis 

 was given, and the animal was destroyed, whereupon it was 

 found that the gland was invaded by a malignant melanom, and 



