It’s been known for decades that animals such as chimpanzees seek out medicinal herbs to treat their diseases. But in recent years, the list of animal pharmacists has grown much longer, and it now appears that the practice of animal . . . → Read More: Animals can pick items from the environment to reduce disease, Is this self medication?]]> 29 April 2013
Self-medication in animals much more widespread than believed

It’s been known for decades that animals such as chimpanzees seek out medicinal herbs to treat their diseases. But in recent years, the list of animal pharmacists has grown much longer, and it now appears that the practice of animal self-medication is a lot more widespread than previously thought, according to a University of Michigan ecologist and his colleagues. Animals use medications to treat various ailments through both learned and innate behaviors. The fact that moths, ants and fruit flies are now known to self-medicate has profound implications for the ecology and evolution of animal hosts and their parasites, according to Mark Hunter, a professor in the Department of Ecology and Evolutionary Biology and at the School of Natural Resources and Environment. In addition, because plants remain the most promising source of future pharmaceuticals, studies of animal medication may lead the way in discovering new drugs to relieve human suffering, Hunter and two colleagues wrote in a review article titled “Self-Medication in Animals,” to be published online in the journal Science. “When we watch animals foraging for food in nature, we now have to ask, are they visiting the grocery store or are they visiting the pharmacy?” Hunter said. “We can learn a lot about how to treat parasites and disease by watching other animals.”

Much of the work in this field has focused on cases in which animals, such as baboons and woolly bear caterpillars, medicate themselves. One recent study has suggested that house sparrows and finches add high-nicotine cigarette butts to their nests to reduce mite infestations. But less attention has been given to the many cases in which animals medicate their offspring or other kin, according to Hunter and his colleagues. Wood ants incorporate an antimicrobial resin from conifer trees into their nests, preventing microbial growth in the colony. Parasite-infected monarch butterflies protect their offspring against high levels of parasite growth by laying their eggs on anti-parasitic milkweed. Hunter and his colleagues suggest that researchers in the field should “de-emphasize the ‘self’ in self-medication” and base their studies on a more inclusive framework. “Perhaps the biggest surprise for us was that animals like fruit flies and butterflies can choose food for their offspring that minimizes the impacts of disease in the next generation,” Hunter said. “There are strong parallels with the emerging field of epigenetics in humans, where we now understand that dietary choices made by parents influence the long-term health of their children.” The authors argue that animal medication has several major consequences on the ecology and evolution of host-parasite interactions. For one, when animal medication reduces the health of parasites, there should be observable effects on parasite transmission or virulence.

For example, when gypsy moth caterpillars consume foliage high in certain toxic compounds, transmission of viruses between the caterpillars is reduced, facilitating moth outbreaks. In addition, animal medication should affect the evolution of animal immune systems, according to Hunter and his colleagues. Honeybees are known to incorporate antimicrobial resins into their nests. Analysis of the honeybee genome suggests that they lack many of the immune-system genes of other insects, raising the possibility that honeybees’ use of medicine has been partly responsible — or has compensated — for a loss of other immune mechanisms. The authors also note that the study of animal medication will have direct relevance for human food production. Disease problems in agricultural organisms can worsen when humans interfere with the ability of animals to medicate, they point out. For example, increases in parasitism and disease in honeybees can be linked to selection by beekeepers for reduced resin deposition by their bees. A reintroduction of such behavior in managed bee colonies would likely have great benefits for disease management, the authors say.

Science Daily
April 29, 2013

According to the World Health Organization, more than two-thirds of Americans are overweight or obese. And it’s not just humans who are packing on the pounds. Our furry companions are plagued . . . → Read More: Molecular techniques in pet obesity research]]> First anti obesity diet based on the concepts below is now available
29 April 2013
Molecular techniques in pet obesity research

According to the World Health Organization, more than two-thirds of Americans are overweight or obese. And it’s not just humans who are packing on the pounds. Our furry companions are plagued by an obesity epidemic of their own. More than 50 percent of the dogs and cats in the United States are overweight or obese. In a new paper on pet obesity in the Journal of Animal Science, University of Illinois professor of animal and nutritional sciences Kelly Swanson and his colleagues describe how nutrients and biological compounds in foods can affect gene expression in animals. Their field, called nutrigenomics, offers new insights into the why and how of companion animal obesity. There are many reasons for the uptick in pet obesity, but they stem from the domestication of cats and dogs, Swanson said. Because most pets no longer hunt or compete for their food and do not mate — as a result of having been spayed or neutered, the typical dog or cat of today has a much smaller need for energy than the typical wild dog or cat of yesterday, he said. When a person or an animal consumes more food than the body needs, the excess energy is converted into fat that is stored in adipose tissue. These fats can then be converted back to an energy source during fasting or times of food scarcity.

Adipose tissue secretes more than 50 substances known as adipokines, cell-signaling molecules that are involved in metabolism, immunity and inflammation, the authors write. Two of these adipokines, leptin and adiponectin, increase or decrease, respectively, within obese or insulin-resistant subjects. The excess adipose tissue that develops in pets often leads to chronic disease and a shorter lifespan, Swanson said. While a new diet or exercise regime may help relieve some of these symptoms, a better understanding of the molecular underpinnings of pet obesity could further increase the quality of life for household animals. “There are a lot of issues that contribute to pet obesity, but we’re focusing on the animal biology side of it and trying to use some of these tools to learn things we couldn’t learn in the past,” he said. New tools that allow the researchers to determine how pet obesity affects gene expression within these animals offer promising new insights. These new approaches mark a huge change from the traditional approach to studying obesity, said Maria de Godoy, a postdoctoral researcher in the Swanson lab. “What we are trying to do is change the emphasis of how to look at obesity,” she said. “Our focus is to manage obesity, but if we can, the ideal situation is to prevent it.” De Godoy believes nutrigenomics are the key to unlocking the best ways to treat pet obesity. “Pet owners see the animals just putting on weight, but metabolically speaking, there’s a lot of stress on the animal that is carrying excess weight. The genomic measures are really interesting because we can understand how they change if the animal becomes obese,” de Godoy said. “We want to know at what point we can intervene and hopefully prevent the development of obesity or help the animals so that they don’t have the complications that they currently do.”

Science Daily
April 29, 2013

Related Stories COMING UP: Daniel Promislow talks to Quirks & Quarks, April 6 at noon on CBC Radio One External Links Summary of study, . . . → Read More: Larger dogs age faster, more prone to cancer]]> Larger dogs age faster, more prone to cancer
CBC News Posted: Apr 5, 2013 4:53 PM ET Last Updated: Apr 7, 2013 12:59 PM ET Read 104 comments104

Related Stories
COMING UP: Daniel Promislow talks to Quirks & Quarks, April 6 at noon on CBC Radio One
External Links
Summary of study, why large dogs age faster
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Small dogs have an average life span of about 10 to 14 years, while larger dogs may live only five to eight. (Eduardo Munoz)
Why is it that tiny terriers and Chihuahuas tend to outlive big, robust Great Danes and mastiffs? An analysis of thousands of veterinary hospital records may have uncovered the answer.

“What we found was that large dogs are actually aging at a faster rate, so large dogs appear to actually be … falling apart faster than small dogs,” said Daniel Promislow, a Canadian professor of genetics at the University of Georgia, in an interview with Quirks & Quarks that airs Saturday.

Promislow was discussing the results of a study he co-authored, published in this month’s issue of the journal The American Naturalist, which relied on records of 80,000 dogs that died at 30 veterinary hospitals in the U.S. and Canada in recent decades.

Previous studies have shown that while small dogs typically live to the age of 10 to 14, and can reach the ripe old age of 20, larger breeds had an average lifespan as short as five to eight years.

COMING UP Daniel Promislow talks to Quirks & Quarks, April 6 at noon on CBC Radio One

The new study, which was led by Cornelia Kraus at the Laboratory of Survival and Longevity at the Max Planck Institute for Demographic Research in Rostock, Germany, found that a major reason for the differences was that cancer is much more common in large dogs.

Promislow suggested that may be because humans may have inadvertently selected for characteristics that predispose large dogs to cancer, such as rapid growth, while breeding them for larger size.

The fact that larger dogs don’t live as long as smaller dogs is surprising in a way, because species of larger animals, such as whales and elephants, tend to live longer than smaller species such as mice.

On the other hand, Promislow points out, whales and elephants have many more cells than smaller animals, which would theoretically create more opportunities for cancer to arise.

“Presumably,” he added, “they must have evolved some special defence mechanisms against cancer.”

Those mechanisms likely evolved via natural selection over the very long period of time that these larger species evolved.

Most dog breeds arose through selection by humans over a much shorter period of time.

“It’s really an evolutionary blink of an eye,” Promislow said, “and the protective mechanisms haven’t had a chance to catch up.”