I tend to agree with others that if they got taken they were likely being abused. I'm sure it's similar to CPS where things have to meet a certain criteria before an action is taken. Likely, they saw neglect and then told them to take the pets to the vet. They likely then didn't.
I have a tale of two neighbors. My neighbor that was my friend, told me about how our other neighbor, her friend, was extremely depressed because her dog just died. I was a bit confused, because she had just lost a dog a few months back. And before that she had lost a dog about a year ago. So it was either really poor luck, or something was going on to have 3 dogs die in a year. She kept beating around the bush but I got my friend to admit that her friend thinks it was one of her pitbulls that was killing the other dogs. Her solution was to keep going to the pound and getting more dogs and internally she'd make excuses like "Well this one is a girl, or this one is much smaller and not a threat, or well the dog was already kind of sick anyway".
I was irate. She was basically murdering dogs as far as I could see it. But I didn't have any proof. I mean what can you even do? The pounds are so full and desperate they don't really look into owner's past, especially in a big city with multiple shelters.
Anyway, my friend was mad at me for being mad at her friend and made me swear I wouldn't say anything.
Thankfully, it didn't matter. Both of my neighbors (my ex friend too) moved shortly after that conversation and I don't speak to either of them but it still pisses me off.
All that said, it was still a betrayal by your friend assuming your friend didn't see things you were choosing to ignore.