This page has information about every episode Spot appeared in or was mentioned. I know of 8 episodes of The Next Generation and 1 movie.
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TNG Episode #85  Data's Day  Stardate 44390.1
A typical day in the life aboard the Enterprise-D as seen through the eyes of Data. In this episode can we see Keiko for the first time, who marries Miles O'Brien and most important, we can see Spot for the first time. Spot has no name yet in this episode, but we hear his name in "In Theory", the next episode Spot appearred in.
. data feeds Spot    

TNG Episode #99 In Theory  Stardate 44932.3
Data tries to experience a romantic relationship. We see Geordi bringing Data's cat back who was escaped from his quarters. Geordi named the cat Spot, so that is his name from know on.
.  Geordi brings Spot back  

TNG Episode #131 Schisms Stardate 46154.2
Aliens from another time continuum kidnap Enterprise-D crew members. In this episode we can hear the famous poem "Ode to Spot" told by Data. Spot him(her)self did not appear in this episode.
.  Data tells the poem  

TNG Episode #134 A fistful of Data's Stardate 46271.5
A holodeck malfunction traps Alexander, Worf and Troi in the ancient American West, where everyone else is a replica of Data.After an malfunction parts of Data's memory integrates in some part (the holodeck) of the ships computer. This is the reason while Riker is saying parts of Data's poem instead of the doctors play. Also we see Spot refusing his food and is mentioned that all replicators are making catfood.
 Riker saying Spot poem  Data trying to feed Spot  All replicators make catfood 

TNG Episode #151 Timescape Stardate 46944.2
The Enterprise-D and a Romulan ship are frozen in time, moments away from an explosion that will destroy both ships.This episode opens with Riker in sickbay having scratches on his head. It appears Spot did that. At the end of the episode Riker enters Data's quarters, but is first making very sure that Spot is not around. Data tells him that Spot is sleeping. Spot is not seen in this episode.
 Riker "likes" Spot?   Riker suspicious  .

TNG Episode #158 Phantasms Stardate 47225.7
The Enterprise-D is plagued by interphasic parasites that attack the crew and affect Data's dream program, giving him nightmares.In this episode we see Data looking at Spot while he/she is sleeping. Data is studying the reactions of Spot while he/she is asleep. We also see Worf taking Spot with him to watch over him because Data is afraid of doing Spot any harm.
 Data watching Spot Sleeping  Worf takes Spot   Data playing with Spot

TNG Episode #161 Force of Nature Stardate 47310.2
The Enterprise-D is disabled by two scientists trying to prove that warp drive is damaging the very fabric of space. This episode established a Federation-wide "speed limit" of warp 5.We see Geordi trying to Get Spot while he/she is under Data's bed. Next we see Geordi and Data talking about Spot. Geordi thinks Data should train Spot. Finally we see Data trying to train Spot.
 Spot under bed  Talking about Spot  Data trains Spot

TNG Episode #171 Genesis Stardate 47653.2
A cure for a simple flu becomes a disease that causes the crew to regress into their evolutionary forbearers.First we see Spot in Sickbay examined by doctor Crusher because Spot is pregnant. We also see Barclay and Spot together because Data asks him to watch over Spot. Finally we see the kittens of Spot and Spot changed in a very strange being.
 Spot in sickbay  Spot likes Broccoli  Spot has kittens

Star Trek Movie #7 Star Trek Generations Stardate 48650.1
Captain Jean-Luc Picard and Captain James Kirk meet in a time nexus and combine forces against a scientist who is jeopardising the lives of milions of people. At the end of the movie after a crash of the Enterpirse-D saucer Data finds Spot and is very happy.
.  Data finds Spot .