These are my suggestions on what to do when your find a stray pet. This assumes that the pet is not acting strangely or aggressively. If a stray is aggressive or possibly rabid, my advice is to call animal control. For advice on saving reasonably calm strays, read on.
If the animal is injured, take it to the vet. If you aren’t willing to pay for a vet visit, take the pet to the shelter (or find someone willing to foot the bill). If the owner isn’t found, you will have to pay for the vet bill.
It’s important to know that you don’t have to call animal control to pick up a friendly, uninjured pet. You don’t have to take a found pet to a kill shelter. You have an obligation to report it found, but you may keep the dog or cat at your home if you like. This is especially important if your local animal control is a high kill shelter, or if it has a reputation for being unclean or unsafe. On the other hand, be realistic. Don’t keep a stray you can’t take care of, as tempting as it may be. Don’t use all your finances on its medical bills, and don’t bring it home if your landlord forbids pets.
You must call animal control (or whoever deals with lost and found animals in your area) and file a found pet report. If you skip this step, you are stealing the pet and are at risk of being arrested. It only takes a few minutes. File the report. The shelter or a vet’s office will also scan for a microchip. It’s 2019. Just because the dog lost his collar doesn’t mean that the owner can’t be found
It may be relatively easy to find the owner. The pet may have a collar with owner’s information. If it has a rabies tag, the number on the tag can probably be traced by a vet’s office to the owner. You can try walking door to door in the neighborhood to see if anyone recognizes the pet. You can make flyers to post in the area the pet was found (this will be effective if the owner lives nearby and is searching for their pet). You can post on Facebook groups (lots of cities have lost and found pet groups).
If the pet is uninjured, friendly, and it seems unlikely that the owner will be found soon, it may need a bath, brushing, nail clipping, or flea treatment. Groomers are an option if you aren’t prepared to take care of these steps. Personally, I always keep nail clippers, flea shampoo, and brushes ready for just such an occasion. I also keep spare food bowls, collars, a surplus of pet food, and a room in my house that can be used to quarantine flea-ridden pets, because I’m the crazy animal lady and my dear husband is very supportive.
Chewy.com has all sorts of pet supplies and free shipping on orders over $49!
Sort out your priorities. Look at the animal in front of you. What should be done first? You may need to feed the pet and give it water before anything else can be done. (Beware feeding it too much too fast, or allowing an overheated animal to drink a lot of very cold water. Basically, all changes should happen slowly or the animal could go into shock.) It may be so covered in fleas that you can’t take it into your house until a trip to the vet has been taken and a flea pill has begun working. If it has been obviously abused, you may want to call animal control or the police instead of the number on its collar. Every situation is different because every animal is unique. Judgement calls will have to be made. For example, if a stray cat has a runny nose and is sneezing, you shouldn’t bring that cat into a house with healthy cats.
Once the animal is comfortable (the right temperature, flea free, fed, watered, clean, and mat-free), the best thing to do is let it rest and get used to its surroundings. Presumably, a lot of changes just happened. It may be agitated, or it may seem chill. Even if the pet seems chill, be understanding, kind, and gentle. Take note of any health problems or potential health problems you notice. Were there so many fleas that the animal may be anemic? Does it have diarrhea? Does it have worms? Does it have any cuts or sore spots that you noticed during the bath?
If the owner isn’t found in several days, or if it seems very unlikely that an owner will be found, the pet will need a trip to the vet. It should be given vaccines if it didn’t have a rabies tag. It may require a special diet to gain weight. It may have worms. The vet may suggest a heartworm test and heartworm prevention. The vet may catch an injury you missed (cats, especially, are very good at hiding pain, and their skin often hides puncture wounds).
Hopefully, the pet can be reunited with its owner.
If not, you will be well on your way to owning a new pet. Welcome to the crazy animal people club.
Resources
http://www.lostdogsflorida.org/found-dog.html
https://pets.webmd.com/cats/guide/upper-respiratory-infection-cats#1
https://www.petmd.com/blogs/nutritionnuggets/jcoates/2013/oct/the-right-way-to-feed-dog-that-has-been-starved-30937
(I am a Chewy.com affiliate and will earn money if you buy something on that website after clicking that link. Just a legal FYI. I really use them and think they’re awesome!)