Pet-Med Urinary Spray uses Apis, Benzoic acid, Berberis vulgaris, Cantharis, Equisetum, Sarsaparilla, Terebinthina, and Uva ursi. The main reason they are combined here is to support urinary tract comfort in pets, especially when there is irritation, frequent urination, incontinence, or obvious discomfort.
The extra value in the blend is that it can combine remedies commonly used for burning, urgency, bladder irritation, and urinary tract support.
This also helps explain why uva ursi is a well known herb for urinary support, and cantharis is one of the best known homeopathic remedies for burning urinary discomfort.