there is such thing as a silver cartiage
why you cant find it because it is not called a "silver cartragie"
ok if you have heard of action replay it is made my the say company
the silver cartiage is called dog trainer it is like a action replay for nintendogs
ok go to 
http://us.codejunkies.com/news_reviews.asp?c=US&cr=USD&cs=$&r=0&l=1&i=
8838&p=17&s=8
this is what the company has to say
 

Dog Trainer - the Perfect Companion for Nintendogs...


 

The world's going wild for Nintendogs, and with Datel's amazing Dog Trainer, you can blow
the games wide open right from the start. 

With Nintendogs, you can train a virtual pet to do your every bidding. With the Nintendo
DS's touch-screen and microphone, you can touch and talk to your pooch, and it responds
just like a real dog. As you play, new features and bonuses become unlocked, and you can
swap things with other Nintendogs fans who own a different version of the game. Or you can
grab yourself a copy of Dog Trainer, Datel's devious device that gets to the heart of all
three Nintendogs releases - that's Labrador Retriever & Friends, Miniature Dachshund
& Friends and Chihuahua & Friends trained and tamed, with Super Mario 64 DS thown
in as a bonus! 

Dog Trainer is incredibly easy to use. Just plug it into your DS, and insert the game
cartridge into your Dog Trainer unit. You're then offered the chance to transfer a game
save to your cart, a save that opens up your game. And what excellent game saves they
are...

Dog Trainer offers the following saves for every version of Nintendogs:

• ALL DOGS
A fresh save (at the beginning) with ALL dogs in the kennel, including the 18 standard
breeds plus two extra, Jack Russell and Dalmatian.

• ALL DOGS + CASH
As above, plus you have $999,999.99 to spend!

• ALL DOGS + EVERYTHING
As above, but you have all toys, all sports items, all accessories, all care products, all
music, all clocks, all misc. items and all interiors!

• FRESH SAVE + CASH
A fresh save (at the beginning) but you have $999,999.99 to spend! Only the standard
breeds are available at the start.

• ALL ITEMS
A fresh save (at the beginning) with $999,999.99 to spend but you have all toys, all
sports items, all accessories, all care products, all music, all clocks, all misc items.
Only the standard breeds are available at the start.

• BANJO WITH EVERYTHING
A pre-created Jack Russell called 'Banjo'.  He has access to all toys, all sport items,
all accessories, all care products, all music, all clocks, all misc. items, all interiors.


• BANJO WALKS FOR AGES
When planning Banjo's walking route the distance meter is huge! He has access to all toys,
all sport items, all accessories, all care products, all music, all clocks, all misc
items, all interiors. 
  
 
 
 
 

And that's not all. As a special bonus, your Dog Trainer also gives you the following
saves for the amazing Super Mario DS, one of the greatest games yet to arrive on
Nintendo's happening handheld:

• ALL STARS
All 150 stars have been collected.

• ALL CHARACTERS
Mario, Luigi and Wario have been unlocked.

• CHARACTERS & HATS
Mario, Luigi and Wario have been unlocked and their hats available in the levels.

• CHAIRS, HATS & DOORS
Mario, Luigi and Wario have been unlocked and their hats available in the levels.  All
locked doors and Star doors are open.

• LOTS UNLOCKED
Mario, Luigi and Wario have been unlocked and their hats available in the levels.  All
locked doors and Star doors are open.  All 150 stars have been collected.

• ALL UNLOCKED
Mario, Luigi and Wario have been unlocked and their hats available in the levels.  All
locked doors and Star doors are open.  All 150 stars have been collected.  In the Rec
Room, you can play all the minigames. 

All this is only possible with Dog Trainer, which is coming soon. Watch this space for
details...<table class="table_ch"></table>