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.)

DEAR READERS: I sent the following note of support to the growing list of professional scientists and signed a letter to secure the expansion of the Cascade-Siskiyou National Monument, enacted by President Obama on Jan. 12, 2017, and now threatened by the new administration:

“Across the North American continent, this and other bioregions rich in biodiversity need CPR (conservation, protection and restoration). Spiritually, these places are sacred. Scientifically, they are unique habitats rich in animal and plant diversity essential to sustain our need for clean air and water and to help correct and stabilize climate change. Economically, they are a biobank for society, not only for tourism, but also for biologics and microbiota of potential medical, agricultural and other industrial use. Ethically, they are monuments of Earth's creation that society must cherish -- if not for nature's sake, then at least out of enlightened self-interest.

"Environmental CPR of all federal- and state-owned and -leased lands should be a top national security issue and priority. If we do not secure the present, there can be no future.”

I would add that educationally, these natural national monuments are galleries and libraries of inspiration and information. But we will not have a jungle for the last of the tigers or forest for America’s lions a generation from now if planetary CPR is not adopted by every nation-state, kingdom and principality. The health of one affects the health of others. A United Environmental Nations paramilitary force to police and protect the last of the wild from annihilation by the rich and poor alike may be our last hope. Activist organizations like Sea Shepherd and Greenpeace cannot do it alone.

Young children must be informed as to why it is in everyone’s best interests to care for all animals and the environment and what they can do to help. Regrettably, major organizations like the Humane Society of the United States and the American Society for the Prevention of Cruelty to Animals have reportedly pulled out of supporting humane education. But my friend Jane Goodall has set up environmental and humane education programs in many schools around the world (visit rootsandshoots.org for more information), as have others concerned about animals and the natural environment. These include the National Humane Education Society (nhes.org/education-2); my daughter Camilla Fox’s Project Coyote (projectcoyote.org/programs/keeping-it-wild); and one of my former graduate students, Marc Bekoff, (search "Rewilding Our Hearts: Building Pathways of Compassion and Coexistence").

All educators need to engage young minds with these concerns and sow seeds of hope for their own good and for the revolution in planetary consciousness, conscience and conservation. Wisdom speaks when we listen with our hearts and when we empathize with fellow creatures.

DEAR DR. FOX: Recently, my pug started acting strangely: circling, drooling, watery eyes, torticollis; I believe she wasn't seeing correctly, if at all, at times. I took her to the vet.

At first they suspected toxicity of some kind, but all her blood work came back 100 percent normal. They now suspect encephalitis. They started her on prednisone, phenobarbital and doxycycline and released her the same afternoon. I gave her another phenobarbital at around 10 that night, and by 1 a.m., she was acting almost completely normal. She has continued to act normally, aside from the occasional throwing the head back a few times a day.

She was spayed and vaccinated a few days before this all started. I read an article about vaccines possibly triggering this. I was wondering if there was any way other than an MRI to diagnose this disease. She's still acting fairly normal except for being rather lethargic, which is not like her or any 2-year-old pug, for that matter.

I would like to know exactly what was wrong and do whatever I can to help her or prolong her life or make sure she doesn't suffer if she does have this disease. She hasn't had any seizures that I know of. She is so cute and fun and usually full of life. -- M.T., Hobbs, New Mexico

DEAR M.T.: Considering the time between her being vaccinated and the onset of neurological problems, I would suspect she has a vaccinosis, an adverse reaction to whatever vaccines she was given.

It is not advisable to vaccinate an animal who is ill or subjected to the stress of general anesthesia for any major surgery as for spay/neuter. The vaccinations should have been done three to four weeks prior to or after surgery, but for convenience sake, this protocol is not always followed.

The treatment prescribed is satisfactory, but she must be slowly weaned off the prednisone and not suddenly taken off of it. Give her probiotics to help correct any adverse consequences to her gut bacterial flora from the antibiotic. For good measure, I would add a few drops of fish oil to her food and up to a tablespoon daily of coconut oil, which may help stabilize brain function and can help prevent seizures.

NEW YORK CONSIDERING BAN ON FELINE DECLAWING

New York legislators are considering a bill that would make their state the first to ban the declawing of cats. Some countries and a number of U.S. cities ban the procedure, but the New York State Veterinary Medical Society argues declawing must remain a last resort for families that might otherwise take their cat to a shelter.

(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: We’ve known for years that dogs can be good models for human research.

In 2009, researchers at the University of Missouri, in collaboration with scientists at the Broad Institute, found that degenerative myelopathy (DM), an older-onset disease in dogs that can lead to paralysis, is similar to ALS (Lou Gehrig’s disease) in humans. This can be diagnosed through a diagnostic tool that measures biomarkers that are released into spinal fluid and blood in humans.

In a strange twist to the One Health initiative, human diagnostic tools are showing promise in diagnosing the sister disease in dogs -- we’re actually helping our “best friends.”

Now, Dr. Joan Coates, a veterinary neurologist, has proven the test helps with DM. You can read more about it on our website, munews.missouri.edu/news-releases/2017/0503-biomarker-test. The team is now seeking dogs with DM to test out a type of gene therapy that could show promise in helping to slow the progression of ALS in people. I thought you’d like to share this news with your audience. -- J.S., Research News Strategist, University of Missouri, Columbia

DEAR J.S.: Thanks for the information.

Veterinarians and caregivers of old dogs, please note this clinical research request, which may ultimately lead to some more effective treatment and possible reversal of this and other degenerative diseases of the nervous system. Finding out the causes would be a better path to prevention. Some of the causes may be due to human influences, such as from pesticides, vaccinations and mercury and lead poisoning. There are genetic and autoimmune factors and reactions to spontaneous infections, such as influenza or other viral or bacterial infections that make prevention a challenge on many fronts -- political and economic.

DEAR DR. FOX: I have an unusual problem with one of our two cats, and I'm not sure what to do.

We've had our 7-year-old shorthair Olivia since she was a year old, and she has always been skittish when people pet or stroke her head. She tends to shy away when people pet her at any time, and I think I now know why.

Her fur seems to be conductive -- more so than any other cat I've seen -- to static electricity buildup. I know in the drier winter months, I can feel sparks when I pet her, and I'm careful for that reason. But this morning, I saw something that may explain why she shies away so much when her head gets stroked.

It was still dark when I woke up, and I immediately reached down to pet Olivia's head -- and her head lit up like a Christmas tree! I thought I was seeing something, so I did it again, and although I did not feel any static discharge, her head "flashed" for an instant. It was a definite white light from a static discharge that surrounded the top of her head and completely enveloped her ears.

Poor kitty! No wonder she's skittish. I imagine this has been happening for some time and I just never noticed due to the darkness. Our other cat -- a longhair -- never experiences static problems.

Do you have any suggestions short of putting a collar on her with a grounding chain? -- G.S., Brandon, Vermont

DEAR G.S.: For some reason yet to be determined, some cats have more of a problem than others building up a static charge and then receiving a shock when petted.

Dry weather and walking on synthetic-fiber carpets and bed covers can make the problem worse, and interfere with cats' eating and drinking when they get shocks from their food and water bowls. It may help to set a damp towel on the floor beside the cat's bowls, litter box and doorway floor areas to "ground" the cat and take away the built-up static charge.

(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.)