562 Veterinary Medicbie. 



number of these localities lie 011 magtiesiaii limestone or are 

 supplied with water that has percolated tlirough this, so that at one 

 time the excess of magnesia and the lack of iodine were held to 

 be the main causative factors. This contention cannot be sus- 

 tained in all cases, so that the disposition is, at present, to 

 attribute the disease to some unknown poison. This unknown 

 poison may be present in districts apart from the magnesian lime- 

 stone, 3'et the disease is so frequently seen upon this formation 

 that its presence must always be looked upon with suspicion as a 

 probable bearer of the poison, and waters bearing its products are 

 unsuited to the victims of goitre. 



Pathological Anatomy. Sometimes the swelling of the gland 

 which appears during catarrh or pharyngitis will subside on 

 recovery. In other cases it remains as a distinct hypertrophy. 

 This is usually an increase of the parenchyma and dilatation of 

 its follicles with an albuminous fluid {hypertrophic goitre) . This 

 may affect one lateral lobe or both. In other cases the fibrous 

 tissue mainly increases and the gland becomes hard and resistant 

 {fibrous goitre). In other cases the individual follicles become 

 distended, and may even break into each other forming a large 

 cavity or several with liquid contents (cystic goitre). In other 

 cases there is a great increase of tlie vascular network of the gland 

 so that blood alone is obtained on puncture (varicose goitre). 

 Tumors of all kinds may be found in the gland, thus ency.sted 

 adenoma, sarcoma and melanoma in horses, carcinoma in old 

 dogs. 



Symptoms. In horses there may be swelling of one lateral lobe 

 of the gland or of both, reaching individually the size of a hen's 

 egg or the fist, or larger. Cadeac cites cases that weighed 4 lbs. 

 In dogs, cattle, sheep and especially in sivine, the two lobes are 

 much more closely connected, and the disease affecting both, 

 together with the commissure, the whole may be resolved into 

 one uniform swelling, much larger than in the horse relatively to 

 the size of the animal, often covering the whole front of the neck, 

 and extending into the chest. Cadeac mentions cases in the dog 

 in which the mass weighed 4 lbs. 



The smaller swellings appear in the solipeds on the two sides of 

 the larynx, and in other animals more in front. They are 

 mobile, but rise somewhat with the larynx in swallowing, and are 



