I saw a patient yesterday, a 2 year old beagle. We’ve been seeing said beagle and her brother their entire lives. And for the past 18 months we’ve been telling the owners: “Your dogs are fat. You need to control their diet or they’ll just keep getting fatter. Here’s a diet plan for them, follow the diet plan and your dogs should be fine.”
We’ve given out diet plans, we’ve given out charts mapping the dogs’ weights, we’ve given out free bags of diet food and measuring cups to go with it.
Yesterday the female weighed in at 45 pounds. A beagle her age and size should weigh 25 pounds at the most. 20 pounds would be ideal.
Yesterday the male weighed 56 pounds. That’s an appropriate weight for a full grown black lab. A beagle his age and size should weigh about 30 pounds.

And I said flat out: “Your dogs are grossly obese. If they continue at this rate they might live to be five years old, but I doubt it.”

I gave them a diet plan, a simple piece of paper that lists how much food to feed each dog and how frequently. I didn’t give them another bag of diet food because I know for a fact that they didn’t follow my recommendations the last time so there’s no point in me wasting the money to hand them another bag of food when it’s not going to do any good.

It’s hard for a person to restrict their diet. In the first world we have free will, enough money, and overample resources enough that dieting is a billion dollar industry in this country.
How hard is it for a dog to diet? If one person is in control of what the dog eats, even if it’s a whole family of people responsible for what the dog eats, how hard is it to come to an agreement that the dog eats only what is recommended? The dog doesn’t have any say in the process and certainly doesn’t have the resources to do anything about it if they don’t like it.

When it’s been made as easy as is possible for you, when you have gotten a freebie as a starter, and especially if you’ve been told that your dog is going to die if you don’t modify their diet why not do it?
Hubris? Stupidity? Stubbornness?
I know people aren’t reasonable, but sometimes the sheer unreasonability of my species overwhelms me.