Definitely you can repair or bypass the sliding switch on your battery‑operated dog toy. I’ll explain three safe options, from easiest to most proper
Easiest Fix: Bypass the Switch (Always ON)
If you just want it to run when batteries are installed, you can bypass the switch.
YOU CAN FOLLOW THIS MY STEPS ON HOW TO BYPASS
STEP 1: Open the toy to access the wires going to the switch.
STEP 2: You will see two wires attached to the sliding switch.
STEP 3: Remove them from the switch (or leave them if the switch is broken).
STEP 4: Twist the two wires together tightly.
STEP 5: Wrap them with electrical tape.
I hope this completes the circuit and the toy will run continuously.
TAKENOTE:
The dog will be always ON when batteries are installed you will need to remove a battery to turn it off.
SECOND WAY TO REPLACE THE SWITCH ( MY SURE OPTION)
Sliding switches are cheap and easy to replace.
What you need to achieve this
Small soldering iron (or someone who has one)
Replacement SPST slide switch
Make sure you follow this step:
Firstly Remove the broken switch. Then solder each of the two wires to the new switch terminals. Then Mount the switch back in the toy.
This will restores proper ON/OFF function.
If you want, send me a photo of the broken switch so I can tell you exactly which type you need.
My last temporary repair (No Soldering)
If a small piece of the slider is missing and it still clicks inside, you can: Use a toothpick, tiny piece of plastic, or pen cap piece glued onto the switch to act as a new slider knob. Then use super glue sparingly , don’t glue the switch shut.
This works if the internal switch mechanism still works, and only the physical slider tab is missing.
Ramsey, since we don't know exactly what toy you have, we'd need more information in order to help. Please add pictures of your dog and some close-up photos of the switch itself. If you've opened it up, we'd like to see what the switch is mounted on; with that information we may be able to locate a suitable replacement switch. It's unlikely you'll be able to find just the part of the switch that's missing as most manufacturers don't provide parts for things like that.
Adding images to an existing question
by Jerry Wheeler
I moved your comment back into your question, as iFixit software doesn't allow pictures to appear in comments. Thanks for adding those!
by Jerry Wheeler