How do I introduce a new pet to my grumpy old pet?

Your household already has a ruler. They sleep 18 hours, tax you in snacks, and glare like you parked in their spot. Now you’re bringing home a new roommate. This can work. You just need a plan that respects the senior’s feelings, protects the newbie’s confidence, and bribes everyone fairly with healthy, portion-controlled treats.

The no-drama, yes-friendship plan

Set the stage
Give each pet their own territory first. One room per pet. Separate bowls, beds, litter boxes, toys. For cats, add a tunnel or cube so they can observe without being seen. For dogs, create a comfy “place” bed outside high-traffic zones.
Shop tunnels and cubes: https://snarkyhumans.com/collections/pet-toys-1

Scent first, then sight
Swap blankets and toys so they learn each other’s smell before a single stare-off. Rub a soft cloth on cheeks and shoulders, then place it near resting spots. For cats, park a scratch box between rooms so both deposit and read scent in a safe way.
Cardboard scratch options: https://snarkyhumans.com/collections/pet-toys-1

Tiny windows of hello
Use gates, carrier doors, or a cracked door to allow quick, upbeat glimpses. Keep early sessions short. End while both are calm. If either stiffens, tail-flicks, or pupils go dinner-plate, reset with distance.

Pay them for manners
Use high-value, limited-ingredient treats in very small amounts. One or two pieces or a small handful of broken bits across a session is plenty. Reward calm glances, sniff-and-retreat, and parallel chilling.
Dog lineup: https://snarkyhumans.com/collections/dog-treats
Tank’s Freeze Dried Chicken Meatballs on Amazon: https://www.amazon.com/Snarky-Pets-Delights-Preservatives-Grain-Free/dp/B0F13YTRV6/ref=sr_1_4?sr=8-4
Cat treats: https://snarkyhumans.com/collections/cat-treats-1/products/kitty-nibbles

Rotate flavors to keep motivation high
Chicken today, beef liver tomorrow, salmon after that, peanut butter hearts on the weekend. Freeze-dried means big flavor in tiny portions so your senior doesn’t gain a retirement belly.

Work the energy, not the furniture
Before intros, give each pet a short workout. Dog: brisk walk or fetch. Cat: five-minute chase session through a mesh tunnel. Hamster hour at 3 a.m. does not count.
Mesh tunnel playhouse: https://www.amazon.com/Snarky-Pets-Collapsible-Crinkle-Windows/dp/B0DZ449831/ref=sr_1_3?sr=8-3
Chonky Cat Playground: https://www.amazon.com/Snarky-Pets-Chonky-Cat-Playground/dp/B0FFFCZSC8?ref_=ast_sto_dp

Protect your stuff while they negotiate
Redirect claws to a dense cardboard scratcher. Redirect zoomies to a bed “place.” Keep a stain and odor remover handy for stress accidents. Hair roller for your sanity before guests arrive.
Stain & odor remover and rollers: https://snarkyhumans.com/collections/pets

Raise the difficulty slowly
Parallel hangouts on opposite sides of a room. Short, positive sessions. Then shared sniff around the yard or hall. Meals on opposite sides of a barrier. Finally, free time together with escape routes available.

When the grump grumps
Interrupt gently. Guide the senior back to their bed. Pay one tiny treat for choosing calm. Give the newbie a foraging puzzle so they feel clever instead of cornered.

Why this works

You respect territory, communicate in scent, meet biological needs before social needs, and pay for the behaviors you want. That turns “new intruder” into “new neighbor,” which is all most grumpy legends really need.

What to buy and why

Healthy freeze-dried dog treats for training and weight management
https://snarkyhumans.com/collections/dog-treats

Limited-ingredient cat treats for picky or sensitive stomachs
https://snarkyhumans.com/collections/cat-treats-1/products/kitty-nibbles

Interactive cat toys and eco-friendly scratch boxes
https://snarkyhumans.com/collections/pet-toys-1

Cleanup crew for the transition period
Pet stain and odor remover, pet hair remover roller
https://snarkyhumans.com/collections/pets

Separate spaces. Scent swap. Short, paid hellos. Exercise first. Rotate freeze-dried treats in tiny portions. Give cats tunnels and scratchers. Give dogs a place bed. Keep it boring, then celebrate the first nap within three feet of each other like you won the Super Bowl.