As incredible as it may seem, the canteen or Feldflasche was not issued to the cavalry even though it had been standard issue piece of equipment for the rest of the German Army prior to 1914; this is something that so far has been inexplicable. It was not until September 14, 1914 that the issue of canteens to the cavalry was made. Initially, a modified version of the the standard 1907 pattern canteen with a shoulder strap was issued. This was similar to what was issued to the field artillery. Later on, the cavalry was issued with the same model issued to all other branches of the German Army.
Below in Nos. 8 and 9 are pictures of the artillery canteen. No. 8 is basically a 1907 pattern infantry canteen with a harness and shoulder sling while No. 9 is the same for a 1915 pattern infantry canteen:
Finally, below are pictures of the 1915 version of the artillery canteen. Like the infantry version, materials shortages mandated a change in June 1915 with the introduction of the 1915 pattern, which was made from steel that was tin plated on both sides. A cork stopper was used rather than a machined screw-top. What is especially interesting about the examples below is the use of an ersatz sling.