Append numbers up to a length?

I'm normally running hashcat on WPA and naturally passwords containing less than 8 chars are simply rejected. Is there any built-in way to, for instance, append characters only to the to-be-rejected passwords to make them candidates?

For example, if the dictionary contained the word "dog", I'd like hashcat to try, say, "dog12345" to reach the minimum length.

I looked into rules and masks, and as far as I can see, they wouldn't be the right tools for this.