Just had another look at your post
A speaker won’t make any sounds unless you drive it with something.
I assume you are referring to the amplifier to drive the speaker. This also requires you to input the sound you eventually want to come from the speaker. In your case an oscillator operating at your required frequency.
In a nutshell no speaker and amplifier will just emit dog whistle sounds. You will have to generate the sounds you want.
As a matter of interest what are you intending to do with this set up. You can get dog training whistles you blow with your mouth and also low power electronic ones for just a few dollars. If you intend to run a bit of serious power around the district your neighbours may have something to say about this. At the extreme end if you intend to harm (I hope this is not the case) a dog’s hearing for any reason I don’t think you will get much response here.