7 weeks old is way too young to be fixed. It is not giving a dog a chance to mature at all!
Please also take into account the long-term consequences of waiting to speuter within the shelter environment.
In a shelter you have two choices:
A: Speuter at an early age (pediatric spay/neuter)
B: Keep the pet in a shelter environment during its impressionable weeks where it should be getting love, attention, socialized and being taught manners and potty trained, then speutering at adolescence... knowingly preventing that many more animals from being adopted during that 6 month period of time.
There is a shelter in our area (no-kill) that will not perform pediatric spay or neuter. Because of this, they are unable and often unwilling to accept puppies and kittens. On the rare occasions that they actually have room for these animals, they keep them until they are 6 months of age. As a result, it is not uncommon to see 2-3 year old pets that are being adopted for the FIRST TIME having spent the first years of their lives in the shelter environment.
When I worked at the shelter in Omaha where kittens were spayed at 2 pounds regardless of age, and puppies at 8 weeks or 2 pounds, whichever was sooner, the puppies and kittens were rarely in the adoption wing for more than a week. At our local shelter, young, impressionable, energetic animals are no more adoptable than the adults because they're held until 6 months of age, and therefore can stay in the shelter environment for years. This is FAR WORSE in my opinion... the thought of any animals spending years in a cage is absolutely abhorent to me...
Our clinic often accepts foster/orphan kittens because this shelter doesn't have space due to this policy, but this "No Kill" shelter will accept the kittens "for euthanasia due to lack of space" and owners are often reluctant to do this so they go looking for someone else.
This shelter also refused to adopt out two 8 week old kittens to one of our BEST clients even when they offered to pre-pay for the spay/neuter surgeries for the two kittens. Those two kittens are still in the shelter, and that client adopted a pair of orphans from us instead... and they never miss a vaccine appointment or decline any care whatsoever... and have not for 8 years. Even a phone call from the hospital owner (a well respected veterinarian in the community for 30 years) vouching for the quality of care of these owners gave would sway the shelter from adopting out these two kittens prior to 6 months of age. It was a sad situation for everyone...