DEAR DR. FOX: Three years ago, I adopted Sadie from an animal rescue organization. They told me she had just turned 1, but based on her weight gain, I would guess she was closer to 6 months when I adopted her.

She weighs about 30 pounds now. I specifically looked for a smaller dog because my previous dog weighed almost 60 pounds, and I couldn't lift him in his last days with me.

I found out after I agreed to adopt her in early October that Sadie had spent the summer at a no-kill shelter. After I brought her home, she was shy and afraid of most things in the first few days.

As soon as she realized she was staying with me forever, Sadie found her voice. Now she barks whenever my neighbor's dogs are outside. More troubling is her behavior when she gets outside and her doggy pals or my neighbor are outside, too. Sadie gets in a zone and runs circles around my yard. She has worn out a path along about 20 feet of the fence line, another 10 feet along my bromeliad patch and about 10 feet in front of my carambola tree.

When I try to call her to stop running, she ignores me and continues to run. I tried to prevent her from this obsessive behavior by putting down lava rocks and some pavers along the fence, but she continues to run in circles.

I think she gets enough exercise. We walk every morning for about 1.5 miles, and I play ball with her at least once a day. How can I break her of this obsessive habit of running in circles? -- J.S., Lake Worth, Florida

DEAR J.S.: This kind of obsessive-compulsive behavior can result from a dog being confined and frustrated or anxious for an extended period of time. It has elements of an addictive behavior, because running produces feel-good neurochemicals such as brain cannabinoids.

What your dog may want and enjoy is some regular, daily off-leash playtime in a safe area with other dogs. Check for doggy play groups in your area or ask about a friendly neighbor's dog coming over.

Possible pharmacological treatment with fluoexetine may help, or you can try St. John's wort, which a veterinarian familiar with psychoactive herbs may prefer to prescribe. A calming herbal supplement called @Ease elevates brain serotonin and is available from petzlife.com.

Keep me posted on your dog's progress.

DEAR DR. FOX: I have just returned from the Bwindi Impenetrable National Park in the southwest corner of Uganda, where many of the world’s remaining mountain gorillas live.

Having heard that germs can jump from humans to gorillas with ease, often with devastating consequences, our small group all brought surgical masks to wear -- not because we didn’t think the guides would supply masks, but more for our own personal hygiene in case theirs were being reused.

We were surprised to find that not only were we the only people in the group wearing masks, but the guides, guards and other tourists had no idea of the risk. We were allowed to get within touching distance of the animals.

Have I been misinformed? Is there no threat from germs to these incredible creatures? -- F.C., Golden Valley, Minnesota

DEAR F.C.: I greatly appreciate your vigilance and sensibilities. This is a problem wherever tourists come into close contact with wildlife that could be infected by potentially lethal strains of illness -- influenza virus in particular -- be they the penguins of Antarctica or the gorillas of East Africa.

The genetic relatedness of mountain gorillas and humans has led to concerns about interspecies transmission of infectious agents. Human-to-gorilla transmission may explain human metapneumovirus in two wild mountain gorillas who died during a respiratory disease outbreak in Rwanda in 2009. Surveillance is needed to ensure survival of these critically endangered animals, of whom fewer than 900 exist in the wild.

It is enlightened self-interest for the tourism industry to wake up to this serious issue and take immediate steps to provide footwear covering, face masks and gloves for their wildlife-visiting clients. Local guides may feel that the gorillas and other wildlife are not at risk because they often enter and raid villages for food, and make indirect contact with indigenous peoples hunting and tending their livestock in their dwindling habitats. All such tourism companies should dedicate a significant percentage of their profits to conservation and support of organizations such as Conservation Through Public Health, founded by veterinarian Dr. Gladys Kalema-Zikusoka (ctph.org) and gorillaconservationcoffee.org. All who are concerned with gorilla protection and conservation can donate to them with the endorsed assurance of the International Primate Protection League.

An essential aspect of wildlife conservation is to limit contact between wild species and people, indigenous and tourist, and domestic animals -- dogs, cats, livestock and poultry -- to prevent the transmission of a number of communicable diseases.

The ultimate protection of gorillas and other endangered species and their habitats calls for a united environmental nation’s armed paramilitary police force to prevent poaching and all forms of human encroachment, coupled with more effective family planning, since our species has become an infestation on planet Earth. (See Population Connection, popconnect.org, for more information.)

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.net.)

DEAR DR. FOX: I have a 13-year-old female Chorkiepoo (a Chihuahua-Yorkie-poodle mix). She is spayed and has a heart murmur. She takes furosemide, theophylline and enalapril daily. She mostly eats baked chicken thighs and sometimes canned Purina Beyond dog food.

My dog likes to eat dirt. I have to be careful with commercial potting soil, because she will eat that, too. I asked the veterinary technician if she had ever heard of this, but she hadn't and had no idea why my dog would do this. I heard that people with a condition called "pica" eat things like laundry starch due to a vitamin deficiency.

Any ideas as to what causes this? Is there anything I should do about it? -- P.R., Ste. Genevieve, Missouri

DEAR P.R.: I am surprised that the vet tech with whom you spoke seemed clueless about this common condition in animals -- dogs in particular.

Geophagia (eating dirt) is a normal behavior insofar as animals, including humans, will develop this form of pica when they are anemic or have some digestive problem or other internal issue that may be relieved by consuming some dirt. Some animals will carefully select the kind of dirt, possibly to get an infusion of soil bacteria that can help with digestion or of various minerals that will correct some deficiency or imbalance.

I doubt your dog is being properly nourished, so I would give her digestive enzymes, which a teaspoon of shredded unsweetened pineapple in her food would provide. Also, try a couple of good-quality probiotic capsules; a tablespoon of live, plain organic yogurt or kefir; and a crushed pediatric multivitamin and multimineral tablet. I would also urge you to transition your dog to my home-prepared diet, as posted on my website, DrFoxVet.net, reducing the grain amount by 50 percent.

Most important with the kind of dog you have is good dental care. Chronic oral disease can lead to a variety of health complications if it's not addressed.

DEAR DR. FOX: I have visited your website, and with your academic background, you are surely qualified to speak about environmental and conservation issues. But is this right for your Animal Doctor column, which I thought was an advice column for pet owners? -- R.E., Silver Spring, Maryland

DEAR R.E.: From my perspective, how we treat the natural environment ultimately affects the health and well- being of companion animals as well as our own species. Considering environmental issues and conservation of healthy ecosystems and their restoration and protection -- long ignored by organized medicine -- are now essential aspects of the One Health movement, which is now being embraced by health professionals and long advocated by the veterinary profession.

PETS CAN PREVENT ALLERGIES AND OBESITY IN CHILDREN

According to Canadian researcher H.M. Tin and associates, having one or more mammalian species in the home during and after pregnancy gave infants higher levels of beneficial gut bacteria (Ruminococcus and Oscillospira), which have been linked to lower rates of allergy and obesity in children.

Early-life exposure to household pets has special benefits for infants following caesarean delivery. Additionally, potentially harmful Streptococcaceae, associated with normal vaginal birth, were substantially and significantly reduced by pet exposure.

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.net.)

DEAR READERS: The Clean Label Project completed a study of over 900 pet food products from 71 brands. Products were screened for over 130 toxins. See cleanlabelproject.org/product-ratings/pet-food for more information and handy infographics about the results.

In my opinion, the high and concerning levels of lead, cadmium, arsenic, pesticides, nickel, chromium and mercury in some pet foods, and the low levels in others, can be traced to the kinds of animal parts and byproducts being recycled into pet foods.

I am referring to the vast tonnage of factory- and feedlot-raised animals and fish killed and discarded as unfit for human consumption; remains of euthanized horses; and hundreds of thousands of worn-out milk cows, exhausted breeding sows and spent laying hens. The older the animal, the greater the bioaccumulation in the bones, livers and other body parts. By inference, the safest animal parts come from those killed at an early age. This enormous fraction from the animal industries is widely used by the pet-food industry to recycle the low-cost animal remains of a carnivorous culture that still refuses to accept the adverse health and environmental consequences of including beef as a dietary staple.

The Clean Label Project's rating of pet foods, according to pet-food consumer advocate Susan Thixton, raises some suspicion by giving many waste-ingredient pet foods high ratings. Regardless, this is an alarm bell to the pet-food industry and to pet owners and veterinarians. The older the farmed animals are and the higher in the marine food chain the fish are, the more loaded with these and other toxic chemicals they will be. This is a classic example of environmental and food-chain contamination due to our continued, collective sins of omission and commission with regard to social responsibility and effective planetary stewardship.

DEAR DR. FOX: Large dogs have larger brains than small dogs. Are large dogs potentially smarter than small dogs? -- R.P., Washington, D.C.

DEAR R.P.: It would be logical to assume that the bigger the brain, the greater the intelligence, but biologically, it has more to do with the ratio between body size and brain size.

Small dogs have more compact bodies and brains than large dogs and are relatively equal in terms of overall intelligence. Intelligence tests, as I detailed in my book "Superdog," are compounded by animals' motivation and cognitive abilities, attention span and how easily they are distracted.

Domesticated animals generally have smaller brains than their wild counterparts of similar body size. Poor nutrition in early life and prenatally can impair brain development and later cognitive abilities in humans and other animals.

Being raised in physically, emotionally and intellectually stimulating environments may, as biologist Charles Darwin theorized, account for the larger brains seen in some species compared to their domesticated counterparts.

CATS FED DRY FOOD ONLY MAY HAVE ELEVATED DIABETES RISK

A survey of the owners of more than 6,700 cats in Sweden found a higher risk of feline diabetes in cats fed primarily dry food than in cats fed mostly wet food, researchers reported in the Journal of Veterinary Internal Medicine.

Obesity was a key risk factor, but the dry food link to diabetes held among normal-weight cats, and the animals were also more likely to have feline diabetes if they ate a lot of food, primarily stayed indoors and got minimal exercise.

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.net.)