Unfortunately, in the majority of countries, states, provinces, districts, etc., legal action in cases of animal cruelty and mistreatment is very limited. I volunteer at my local Humane Society, and it's quite disheartening. The OSPCA officer and another member of the shelter's staff took part in a massive farm seizure. Dozens of farm animals were seized from horrible conditions, and hundreds of hours went into trying to help these animals. The judge ruled in favour of the abusers, and ordered the OSPCA to hand the animals back over to their abusers. The OSPCA had tons of evidence showing the animals were clearly abused, but all the abusers had to do was promise they would actually start feeding the animals on a regular basis, muck out their stalls more than once a year, and not cause the animals any "unnecessary" suffering.
Also, the OSPCA officer recently seized a cockatiel from terrible conditions. The house was full of dogs, cigarette smoke, wood smoke, and budgies. The cockatiel had plucked her neck and part of her head (I know it sounds like PBFD, but I think she's just been using her foot to pluck or has been rubbing the feathers off). Anyways, I was talking to the officer and she's really frustrated because she can't legally do anything to get them to hand over the rest of the bird's. Honestly, the laws we have suck. Seriously, I could repeatedly punch a puppy in front of a dozen witnesses, but as long as there wasn't any physical evidence (broken bones, cuts, bruises, video), the case would be thrown out.
There's countless cases of animals being mistreated, but nothing that can be legally done about it. Look at the wool industry. Bad, bad things are done to the sheep. Ever hear of ag-gag laws? In many states, it is ILLEGAL to document abuse against farm animals. How about the goose down industry? Look up "NIH baby monkey experiments." Also, we've been fighting for years against the use of (live) animals in military trauma training.
Remember, if you see the Amish or Mennonites abusing animals (puppy mills, starvation, beating, etc.), nothing can legally be done. Your local animal welfare officers already know about it, but our laws don't apply to them. The Mennonites run puppy mills, and nothing can be done about it. The police can politely ask them to stop running puppy mills, but that's about it. Legally, nothing can be done to stop a member from the Amish or Mennonite community from abusing an animal. Sometimes, if something can't be done legally...well, remember the Underground Railroad? Those people were criminals. Everything they did was illegal. But was it wrong? Now, before anyone says anything, I'm not suggesting anyone should ever personally intervene (aside from calling the cops and yelling at the abuser to step away from the animal). It's dangerous and illegal. If the law's on the abuser's side, there's nothing you can do. Legally, speaking.
Anyways, in most cases, the law is on the side of the perpetrator, not the victim. If it were a human being abused, that's a different story. A non-human animal? Well, under the law, they're considered property. Historically speaking, only white males who own property are considered persons.
If you see animals being mistreated, or suspect they're being mistreated, contact your local animal shelters, animal protection officers, PETA, and animal rights groups.
I know a lot of people don't like PETA. I'm a member and I've heard all the "bad" stuff about them. I can say that 99% of that stuff is false and is actually propaganda spread by groups who profit from the exploitation of animals. You don't have to agree with all their methods, but you have to admit that they've helped countless animals. Look up their success stories. Did you know that GM used to use live pigs and ferrets in crash tests? PETA ended that. Did you know that POM, the juice manufacturer, carried out deadly experiments with rats and mice until recently? PETA intervened. Yes, PETA did euthanize a lot of animals from shelters. But what you don't know about those shelters is that they were actually animal hoarders. Most of the animals in these facilities were gravely ill, suffering from malnutrition, dehydration, parasites, infections, and diseases. The other animals that PETA took from shelters were taken so that they could be humanely euthanized. Many shelters can't afford to humanely euthanize the hundreds of animals who are never adopted. Instead, many shelters use DIY methods. PETA will go to these shelters and take these animals so they can be humanely euthanized by qualified individuals (vets, trained staff, etc.), using injections.
Anyways, when "conventional" methods don't help animals, PETA is often an animal's last hope. You don't have to be a fan of them, but PETA will fight for the rights of every animal, and they won't give up. Even if it takes more than a decade, they'll keep fighting. No matter how small it may seem.
Oh, and if a moderator sees this, instead of deleting what I wrote, please just edit it to make it more family-friendly. I'm not trying to force my beliefs on anyone, trying to start a flame war, shock, or offend—I just want to make people aware that sometimes, the law just isn't there to protect animals in need. Sometimes, you have to be the one who makes a difference for animals, whether it be contacting your local newspaper or radio station, passing out petitions, contacting PETA, or contacting your local government representative.