Lab animals and pets getting fatter

0somuchbetter0

Wow...maybe I've got the fat virus!? Kidding...I know only I am responsible for my weight battles. But this article is very interesting. Could definitely change perspectives...

http://www.scientificamerican.com/article.cfm?id=lab-animals-and-pets-face-obesity

Lab Animals and Pets Face Obesity Epidemic
Animals in human care are fatter than they were 20 years ago.

By Alla Katsnelson

It's not just people that are getting fatter.

A statistical analysis of more than 20,000 animals suggests that the obesity epidemic is spreading to family pets, wild animals living in close proximity to humans, and animals housed in research centers--perhaps indicating that environmental factors beyond diet and exercise are at least partly to blame for expanding waistlines.

David Allison, a biostatistician at the University of Alabama at Birmingham and lead author on a study published online November 24 in the Proceedings of the Royal Society B, stumbled across the trend while looking for a relationship between body weight and longevity in a population of marmosets housed at the Wisconsin National Primate Research Center in Madison. He decided to take a closer look. He and his colleagues examined changes in weight in a total of 24 populations (12 male and 12 female), drawn from 8 different species, including primates and rodents used for research, domestic cats and dogs, and urban feral rats. About half of the data in the analysis comes from rodents that had been used between 1982 and 2005 in the control arms of studies run by the National Toxicology Program, which assesses safe exposure levels for various chemicals.

The researchers tracked the animals' percentage weight gain per decade, as well as animals' odds of being obese. Because there were no clear guidelines for what animals should weigh, the authors defined obesity as the weight above the 85th percentile in each group at the earliest time point for which they had data. Both the percentage increase in body weight and the odds of an animal being overweight in a given population showed a strong trend upwards, and although the shift was statistically significant in fewer than half of the groups when they were analyzed individually, it was highly significant when all of the groups' figures were lumped together.

"Now, we don't know why these increases occurred, but it invites some very interesting speculation," Allison says.

The surge in human obesity is generally attributed to an increasing consumption of calories and a decrease in physical activity. "But maybe there are other things that are important -- because those things can't be acting on the marmosets, or the rats and mice in the National Toxicology Program," he says.

In some cases, the explanation might be obvious: the more than 40 percent jump in body weight in feral rats scavenging on the streets of Baltimore may reflect the increasing richness of their diet as they feed on our more calorie-dense refuse.

In other cases, hidden factors might be at play. For example, toxins that disrupt the endocrine system could be leaching into the water supply, or particular pathogens might be having a widespread effect on mammalian metabolism, Allison says.

Fat virus?

Nikhil Dhurandhar, an obesity researcher at the Pennington Biomedical Research Center in Baton Rouge, La., has shown that a human adenovirus called AD36 raises body-fat levels in animal models such as chickens and rodents. What's more, he found that obese humans were three times more likely to be infected with the virus than non-obese people--and heavier individuals in both groups tended to be infected. Dhurandhar reported these findings in a 2005 paper on which Allison was a co-author.

The current study is conceptually important, Dhurandhar says, because "it draws attention to having to look at the environment and how that is changing, instead of only focusing on lifestyle in a person".

However, Jaap Seidell, a nutrition and health researcher at the VU University Medical Center in Amsterdam who has studied the link between weight gain in pets and their owners, contends that the data presented in the study could be explained by lifestyle factors.

"This is an interesting collection of data, but it's very difficult to interpret them," Seidell says. Pets and feral animals might very well be subject to changes in our eating patterns, and there isn't enough information to conclude that the captive animals are exempt from such influences, he adds. Other factors may also have changed. For example, over the past 30 years the number of rodents housed in each cage may have altered -- which could very well affect the amount of exercise they get.

"I think they are trying to deflect the attention from restriction of physical activity and high-energy foods," Seidell says.

The paper includes the statement that Allison "has received grants, honoraria, consulting fees and donations from numerous food and pharmaceutical companies, litigators, and non-profit and government entities with interests in obesity-related matters". However, Allison stresses that this particular study was not financed by any company.

And Seidell does acknowledge that certain environmental factors could be affecting body-weight cycles in humans and other animals. In the wake of climate change, for example, some animals have stopped hibernating and others have shortened their seasonal migration routes.

The current study, however, is not rigorous enough to pinpoint whether such factors were responsible, he says. "I think it's worthwhile to do such a study in a systematic way," he says.

0somuchbetter0

No one interested? I think this says a lot about our "obesity epidemic" in the developed world.

k8blujay2

That has a lot to do with the owners over feeding their pets and not providing opportunities for exercise. We have one cat that is fat... however, that's because she eats the dog food AND her food... I can seperate the cats food (we have two) by putting one up higher (the fat cat can't jump up onto higher structures than the counters). However, we have a 2 year old dog and another cat that are both on the skinny side of normal.

GetSoda

I'm going to just cut out all the writing, garbage, nonsense and do what the weight loss industry is doing anyway:

It's not your fault you are fat. Now give me money.

ze_hombre

The simple answer is this bit:

A statistical analysis of more than 20,000 animals suggests that the obesity epidemic is spreading to family pets, wild animals living in close proximity to humans, and animals housed in research centers

We as a species are very efficient at making food. Wild animals are not able to find, hunt, or graze enough food to become obese. All animals, us included, will eat as much food as we can because over the millenia it was beneficial (hunter gathers never knew where the next meal was coming from). Now that we can just drive to the corner store and get food has thrown that balance off.

0somuchbetter0

True. One of my dogs, a street mutt we picked up in Africa, was thin for the 5 years we lived there (eating home made "dog food" from local ingredients)...then got chunky when we moved back to teh U.S. (store-bought dog food).

But what about the lab animals? Here's an excerpt from another article, more about the "fat virus" and the role of temperature (climate change?):

But other findings are more mysterious. Rats, mice and primates (four types were analyzed in this study) in laboratories are fed a highly controlled, known diet that has remained relatively constant over time. Why are these animals getting fatter?

Perhaps for some reason they're choosing to eat more of what they are offered or are somehow changing how they metabolize it, he said.

Allison pointed out at least three potential contributions to this and the other observations: endocrine disrupting chemicals, pathogens such as a virus, and/or changes in temperature where the animals are kept.

There is evidence to support a role for each of these in obesity. The endocrine-disrupting chemical tributyltin, for instance, which is added to marine paints to prevent growth of aquatic life on ship hulls and other places, has been shown to make mice fatter, Allison said.

Meanwhile, several types of animals have been shown to gain weight when injected with a virus known as adenovirus-36, indicating that pathogens may play a role in some cases of obesity.

As for temperature, Allison pointed out that hog farmers know that it's easier to fatten pigs if you keep the temperature just right: not so cold that the pigs need to expend energy to keep warm, and not so hot that they reduce their appetite. Homes are probably kept at more neutral temperatures today than in the past, and labs may also have better temperature control, he said, which may be part of the story.

Allison came upon the findings by accident. He was looking at the data for a population of lab marmosets and noticed that the weight of the marmosets appeared to be increasing. Intrigued, he looked for similar data available for other mammals, eventually gathering information on the 12 populations used in the study, which he divided further into males and females to make 24 separate analyses.

In all 24 groups, Allison's team found that animals' weight increased over periods that spanned at least ten years and often more.

http://news.discovery.com/animals/fat-pets-obesity-weight.htm

fishgutzy

Dogs can't get fat unless the owner over feeds them junk.
Given the proper food dogs don't naturally get fat.
Our pit bull Mastiff mix has a voracious appetite. But she doesn't get fat. She is still growing and will until she reaches about 24 months. We feed our dogs grain free dog food. Products like Blue Buffalo.

Never had a fat cat.

tumblyweed

GMO