Fact: Dogs love balls.
Another fact: When male dogs are missing their testicles, their abnormal testosterone levels can affect their dominant behavior, according to a National Institute of Health clinical study.
And this week, the inventor of Neuticles -- surgically implanted prosthetic testicles -- told HuffPost Weird News that dogs psychologically and emotionally need their testicles, whether or not the sex organ is actually pumping the pup full of testosterone.
Gregg Miller, who invented Neuticles in 1995 and helped plan the first procedure to implant the solid silicone self-esteem boosters, says dogs know when their testicles are removed during castration.
"Of course the dog knows a familiar part of his body is missing -- he misses them," Miller told HuffPost. "With Neuticles, he doesn't know anything has changed. For a male dog, his little things down there are his favorite part of his body. He needs them. Dogs are very smart."
Of course, any inventor of a fake testicle is going to tell people that patients need his product. But the NIH study may give some insight into what an animal is thinking after he's neutered.
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A total of 12 male rhesus monkeys were picked at birth for the study, in which six were gonadectomized (surgically castrated) and six were left to grow a pair.
For control purposes, surgeons implanted Neuticles into the castrated monkeys to avoid "any obvious visual differences" between them and the intact monkeys.
The study found that the intact monkeys "displayed a decrease in subordinate behaviors and an increase in dominant behaviors, which ultimately related to a rise in social status and rank in the dominance hierarchy." The study didn't say whether the monkeys sporting Neuticles would have been more or less dominant than castrated monkeys, nor did it ever mention dogs.
But Miller has his theories.
"I've spoken to thousands of pet owners through the years who have experienced for themselves their beloved pet acting and functioning exactly the same after being Neuticled," he said,
Pet owners who didn't get implants reported that their dogs "appeared depressed and different."
He said that there have been more than 500,000 successful Neuticle procedures in all 50 states since the product launched. Prosthetic testicles in pets -- even plastic surgery -- have grown in popularity, to a point where even reality star Kim Kardashian Neuticled her pooch, Rocky, on an episode of "Keeping Up With The Kardashians."