Are substances which burn away the living tissues of the body, by the decomposition of their elements. They are of two kinds, viz., first, the actual cautery, consisting in the application of the burning iron, and called firing; and, secondly, the potential cautery, by means of the powers of mineral caustics such as potash, lunar-caustic, corrosive sublimate, etc.

Firing is seldom practised on the dog, but sometimes it may be had recourse to with advantage, when a very thin iron must be used. The red-hot iron is also sometimes needed to stop bleeding from warts in the mouth removed by the knife ; or in a similar way for piles.

Strong Solid Caustics are as follows: -

1. Fused Potass

Difficult to manage, because it runs about in all directions, and little used in veterinary medicine.

2. Lunar Caustic, Or Nitrate Of Silver

Very valuable to the veterinary surgeon. It should always be kept at hand in the portable wooden case made specially for it.

3. Blue Stone, Or Sulphate Of Copper

May be handled safely, and no case therefore is required. When used, it should be freely rubbed into the part affected. It is valuable for unhealthy sores, etc.

4. Corrosive Sublimate

4. Corrosive Sublimate is only required to remove warts, but can seldom be trusted to any but a practised surgeon.