Dogs and cats “are responsible for 25 percent to 30 percent of the environmental impact of meat consumption in the United States,” according to new research from the University of California at Los Angeles. Some studies have shown vegetarian diets can suffice with adequate protein and vitamin D.

Studies like this make the headlines every few years. They put numbers to common sense -- which, today, is a rare commodity. But advocating for making cats vegetarians and dogs vegans is unethical and inhumane; they can be harmed by diets that are not biologically appropriate.

The vast tonnage of meat-industry byproducts and condemned animal parts that are recycled into pet food often make cats and dogs ill. It is we humans who must transition, for environmental, economic and health reasons, to vegetarian and vegan diets. A first significant step is to avoid beef, pork and most seafoods.

I would beware of other “studies” that conclude companion animals do not really serve as co-therapists or provide health benefits to their owners/guardians and to children in the family. This is the next step, as I see it, to denigrating the keeping of animals as companions (as distinct from disposable commodity “pets”). In keeping people connected and concerned about animals and nature, companion animals can be seen as threats to a host of vested interests bent on animal and environmental exploitation.

Keeping animals as companions is seen by many as self-indulgent and as a waste of money and resources, putting the needs and interests of dogs and cats and other animals over those of starving and sick children and the poor. But this guilt/shame-making falls down when reason and empathy prevail. The fact is that animal rescue and humane education are positive virtues of a civil society. Animals are one of the best antidotes for anthropocentrism, which can lead to disassociation from other animals and the natural environment -- with disastrous consequences. Animal companions offer us salvation and a way to grace.

DEAR DR. FOX: I have a problem with my almost 5-year-old Shih Tzu, a rescue dog. We got him when he was 2 months old: cute and playful. But at about 6 months of age, he became aggressive. At first, it was with food and toys, and I said, “OK, we can train him.” After some training, he was fine with sharing his toys. Then came the aggressiveness when petting him.

If you pet him too long, especially on top of his head, he snaps -- and I mean a full-on bite. My vet said four things: Send him back, give him away, put him on meds or put him down.

He attacks my husband and knocked him down twice (with my husband laughing). It’s not really funny; the poor dog seems depressed. I think he is bipolar. Is there help for him? Our last Shih Tzu was a very gentle soul; she passed six years ago from cancer. Our Bo is nothing like her. -- L.V., Fort Myers, Florida

DEAR L.V.: You certainly do have an issue living with a “bipolar” dog, as you put it -- a diagnosis that is not far off the mark.

There are some breeds and individual dogs who show sudden and unpredictable aggression associated with low levels of serotonin in their brains. So I advise you to raise this issue with your veterinarian.

This should be an interesting educational journey for your family into the relatively new realm of nutrigenomics, as per the review article posted on my website, drfoxvet.net. A change in diet to one with biologically appropriate ingredients that are USDA Certified Organic and labeled Non GMO Product Verified would be a first step. Free-range organic turkey meat would be especially good for your dog, since turkey meat is high in tryptophan, the biological precursor of serotonin. I also recommend supplementation with synthetic concentrates of tryptophan or theanine, another precursor of serotonin from plants, coupled with nutraceuticals providing essential fatty acids and the building-block for dopamine, another brain- and behavior-modulating neurochemical.

You and your veterinarian might also want to consider therapeutic botanical supplements such as St John’s wort, aromatherapy with essential oils of lavender and cedar, and massage therapy as per my book, “The Healing Touch for Dogs.”

(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: As noted in an earlier column, the Animal Legal Defense Fund filed a class-action lawsuit this past July against Petland, claiming that it defrauded customers by “guaranteeing” the health of puppies it knew were prone to illnesses and other defects. Now Petland’s puppies, according to officials with the Centers for Disease Control and Prevention, have passed on a bacterial infection to people.

Campylobacter, a common cause of diarrheal illness that can spread through contact with dog feces, has been contracted by people in Wisconsin, Florida, Ohio, Kansas, Missouri, Tennessee and Pennsylvania. Campylobacter infections were reported between September 2016 and August 2017 in 12 patients who were Petland employees, while anther 27 had come in contact with a Petland puppy. Nine people have been hospitalized since last September, but no deaths have been reported. More than 200 cities and counties now have laws that ban pet shops from selling so-called “puppy mill puppies,” Petland being the only major national chain selling dogs from commercial breeders.

DEAR DR. FOX: Thirteen years ago, we rescued a young female cat who had apparently been dumped. She was in poor shape, starving and full of fleas.

We took her to a vet for complete care and spaying. The vet suspected the cat’s mother may have been malnourished when pregnant with her.

At home, we fed her well, but she remained obsessed with food, especially fats. She would watch as we unpacked groceries and steal away with butter or cheese and eat it. At the same time, she was given to sudden bursts of violent behavior, as though having flashbacks. We assumed that she had been abused. Without warning, her pupils would dilate and she would launch herself at one of us, often aiming for the face. I warded her off many times by holding a pillow at arm’s length, which she ended up clinging to. Legs were a target, also; seven months after taking her in, we reluctantly had her declawed.

Gradually, she became socialized and settled into being a sweet kitty, and remained so for years. However, now she is reverting to violence. There are still no children or other animals inside, or even nearby, to trigger aggression. All will seem well, then suddenly she attacks and bites, drawing blood and, in one case, causing an infected wound. The attacks are increasing.

We are at a loss to explain this reversion to hostile behavior and don’t know how to handle the situation. Any guidance you can provide would be greatly appreciated. -- C.K., Fredericksburg, Virginia

DEAR C.K.: The saga of your poor cat, and you, is indeed distressing.

You did follow my first principle of responsible companion animal care: Any time there is a change in behavior, consult with your veterinarian. It is regrettable, but understandable, that the only treatment was to remove your cat’s claws. This mutilation can make cats feel more vulnerable, and then they are more likely to bite.

I agree with you that her sudden aggressive behavior when you first adopted her was possibly related to earlier traumatic experiences, a case of post-traumatic stress disorder indeed. But where there is sudden and unpredictable aggression with biting, in a cat or any animal brought into the home who has been outdoors, possible contact with a rabid animal must be considered. Certainly the attending veterinarian would have ruled out this possibility when you took your cat in for treatment after rescuing her.

The craving for fat is very curious indeed. Cats do need animal fats that contain omega-3 fatty acids, and many cat foods, especially dry kibble, are deficient. They are essential for several organ and system functions, including the brain.

I would give her a sardine or two a day (canned, in water), for a start. Also, since some dogs with low levels of brain serotonin can have attacks of psychotic rage, a supplement like PetzLife’s @-Eaze to elevate your cat’s serotonin may also help.

Second, odors can trigger cats to attack. One woman was cornered in her bathroom by her Siamese cat after she put on a new perfume (which contained the anal gland secretions of Ethiopian civet cats, held in captivity in small cages and subjected to repeated anal gland curettage). Perhaps you have a new deodorant or other toiletry product with a scent that disturbs your cat. A room diffuser dispensing organic essential oil of lavender may help calm all of you. Fresh or dried organic catnip has a tranquillizing effect on some cats, and your cat may enjoy a pinch in the early evening.

It is possible that her thyroid gland is hyperactive, which can also account for sudden aggression. This should be checked. If that is not the issue, and sardines and other suggestions do not help her enjoy a normal life without having these almost seizurelike episodes, discuss trying psychotropic medication with your veterinarian to reduce anxiety and possible brain seizure activity. Older cats do develop dementia, and chronically painful conditions like arthritis can bring on aggression, but rarely to the intensity shown by your cat.

(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: We are all moved by the rescue efforts on behalf of people’s dogs and cats when natural disasters like hurricanes and forest fires strike their communities. But what of farm animals out on the range, in corrals and sheds, or confined to stalls, cages and pens?

Generally, they must fend for themselves, which means millions of animals out in the open suffer and die around the world from droughts, floods and extreme temperatures. Those kept in confinement on factory farms, where we are talking about billions of poultry and pigs worldwide, are most often left where they are, or released to fend for themselves.

One farm animal welfare investigator wrote to me, stating: “Producers (in the United States) either release or let animals drown, because producers can be reimbursed for the bulk of their losses under the USDA’s Livestock Indemnity Program.” There is little chance of rushing them to slaughter, because most slaughtering facilities are running at full capacity every day to meet the public demand for meat. While we cannot control the weather, we can control our appetites. We can help reduce this population of vulnerable animals already suffering on factory farms and out on the range by choosing to eat fewer -- or none -- of them.

There is a growing scientific consensus that our appetite for meat, coupled with our ever-increasing numbers, are arguably the biggest drivers of climate change and natural disasters, and certainly of wildlife and habitat decimation.

DEAR DR. FOX: Our 50-pound dog, Mo, around 10 years old, had a vestibular incident early in the morning 18 days ago.

He had all the major symptoms -- sudden onset of loss of balance, disorientation, head tilt and irregular jerking eye movements -- and he also threw up three times. I understand it is like vertigo for dogs, especially old ones. We rushed Mo to the emergency clinic, where they gave him medication for the upset stomach, meclizine for the dizziness and IV fluids. The next day, our regular vet also prescribed Zeniquin just in case he still had an ear infection. (Mo had had an ear infection several weeks before the incident and was treated with Gentizol, which I have since read can contribute to vestibular incidents.)

Before the incident, we knew there was something brewing because Mo started having accidents in the kitchen, which he had never done before. Blood and urine tests indicated he was in great shape, but the incident let us know that there was a definite problem.

Mo is doing much better now. He still has his head tilt, but his big problem is at bedtime, when he gets very restless and appears disoriented. We have added night-lights, and our vet prescribed trazodone to help calm him down, but it hasn’t worked. He has also started having accidents in the kitchen during the night again. I finally tried Dramamine last night, and he was able to sleep for six hours. However, when he woke up at 4 a.m., he was restless again and started roaming the house and whining.

Do you have any suggestions to help us get through the night? My wife and I are getting large bags under our eyes and feel really bad that our best friend is uncomfortable. -- P.N., St. Louis, Missouri

DEAR P.N.: You give a very clear description of this old-dog middle-ear condition, which is relatively common and usually associated with an earlier ear infection. It can sometimes be prevented with optimal nutrition.

He now seems to be showing signs of anxiety, which could have been triggered by the intense vertigo and nausea that this condition brought on. Since the trazodone has not helped, discuss increasing the dose with your veterinarian, or try Valium.

He may be also be showing early signs of dementia or cognitive dysfunction, which you should raise as a possibility with the attending veterinarian. Supplements such as fish oil and coconut oil have multiple benefits for older dogs. Also try 3 to 6 milligrams of melatonin at bedtime. Another treatment worth trying is prescription medication selegiline (1 mg/kg).

Many older dogs become restless because of the constant pain of arthritis. Others become anxious because they need to be taken out more often to urinate, as a result of drinking more water due to kidney disease. Both of these common old-animal issues need to be considered. Slippery floors can also be hell for older dogs, so you may need some new, secure carpets.

My book “The Healing Touch for Dogs” will give you advice on how to help him relax and feel secure while enjoying the therapeutic benefits of a full-body massage.

(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.)