There are conficting website on the world's biggest dog Zeus.
When you do a google on the world's biggest dog.
Seems like there are 2 version circulating in the internet.
One is a video of the dog pictured together with a horse and another is a picture of a dog with black patches without any other things in the picture for reference.

Is this just people trying to cash in on the high search volume on Google?

However, i did manage to find a picture of the award winning dog for 2009 Dog Parade Contest Photo.  Out of all the sites found on google. This site seems the most Authentic