DEAR READERS: According to a scientific study by Scott J. McGrane and associates, cats have receptors in their taste buds that detect umami, the savory flavor found in meat -- and tuna in particular. In cats, as in humans, the umami receptors are triggered by a combination of amino acids and nucleotides. Cats’ taste buds seem to be particularly attuned to histidine and inosine monophosphate: compounds that tuna contains in high amounts.

In tests, 25 cats were given their choice of plain water or water flavored with various umami compounds. The histidine/inosine monophosphate flavor “was one of the most preferred combinations,” said McGrane. “It really seems to hit that umami sweet spot.” (Full study: "Umami taste perception and preferences of the domestic cat [Felis catus], an obligate carnivore," published in Chemical Senses, summarized on Science.org, Aug. 25)

"Why cats have a hankering for tuna in the first place remains a mystery," says the Science.org writeup. After all, cats "evolved in the deserts of the Middle East about 10,000 years ago, where fish of any kind was unlikely to be on the menu."

Indeed, there are few, if any, fish in deserts! But I checked other research reports and solved this “mystery.” The domestic cat is a descendant of Felis lybica, the African wildcat. Wildcats hunt primarily mice, rats, birds, reptiles and insects. It is likely that the insects in wildcats' diet contain the same amino acids and nucleotides that cats like to eat, as would the insectivorous reptiles and birds that consume these insects before being consumed by the cats.

So tuna likely contains similar nutrients to the ones cats have enjoyed since their early days in the desert. However, because of mercury and other contaminants, and the fact that many cats are allergic to fish, I do not advise feeding tuna to cats. We should be helping the oceans restore their natural biodiversity, currently under threat from climate change and the overharvesting of marine life for human consumption and livestock feed.

Cat food manufacturers are certainly aware of cats' affinity for tuna, using it to make their products more appetizing. But also, we may soon see high-nutrient ingredients derived from farmed insects being added to cat and dog foods. They are approved in Europe for pet foods, and also as food additives in various products for human consumption.

DEAR DR. FOX: I was reading an article on PETA’s website regarding the drawbacks of cat trap-neuter-release (TNR). You were quoted as saying, “It is time to work for responsible solutions.” I was wondering if you had any thoughts on what those responsible solutions might be. The communities outside of Las Vegas are looking for answers to this issue. -- D.H., Las Vegas

DEAR D.H.: First, I wish all veterinarians and everyone involved in cat rescue and rehabilitation would read the excellent study by Bailey H. Eagan and associates that was published in the Journal of the American Veterinary Medical Association in September ("Daily gabapentin improved behavior modification progress and decreased stress in shelter cats ...").

It should be noted that all these caged cats had double-compartment portalized enclosures with separate litter box, bed and "hide box," which I consider most important in reducing fear.

An alternative is group housing (after vaccinating, neutering, and screening the cats for disease and parasites). Shy cats see other cats interacting with caregivers and soon come around and can be adopted out eventually. Those who do not can become permanent residents in these enclosed cat sanctuaries. No cats should be released outdoors to fend for themselves, which can put their health and lives at risk, as well as public health and wildlife. Cats are predators and will decimate local populations of songbirds and small mammals.

See these related posts on my website: drfoxonehealth.com/post/outdoor-cats-wildlife-and-human-health and drfoxonehealth.com/post/releasing-cats-to-live-outdoors-humane-environmental-and-one-health-concerns.

(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 DrFoxOneHealth.com.)

DEAR DR. FOX: The new NexGard Combo topical treatment for cats appears to have caused horrific problems for my 15-year-old cat, Whitey.

In the worst spur-of-the-moment decision of my life, I let the vet apply this treatment to him. She had just run his blood work, and said that one marker from the kidneys was a little high (though she didn't seem too concerned about it). He was also anemic, and in case the anemia was caused by parasites, I made the poor decision to have Whitey dewormed.

This combo product was clearly not tested on elderly cats with health problems. On the fourth day after application, he was no longer his normal self. He slipped and fell off the table where he always jumped to lick my elderly mother's plate after she was finished eating. And at his food bowl, his feet started slipping and sliding underneath him. He stopped eating, completely lost the use of his legs and died within two weeks.

It's obvious to me that this product needs a warning label that includes elderly or diseased animals. Animals that lived a dignified life deserve a more dignified death. -- N.M., New Orleans

DEAR N.M.: I see from the photo you sent me that your cat was indeed a beauty. I'm noting that the photo was taken outdoors, which can always put cats at risk from fleas and various infectious diseases. But if the attending veterinarian did not find any evidence of fleas on your cat, or parasites in a stool sample, prescribing the NexGard Combo was an unwarranted shot in the dark.

Considering your cat's age, I would have done additional tests for kidney function. Cats with chronic kidney disease can develop nonregenerative anemia when their kidneys produce less of a hormone called erythropoietin, which helps the bone marrow produce red blood cells.

Tell me, did the veterinarian check for fleas and parasites in Whitey's feces?

I am so saddened by your loss, and am once more dismayed by the cavalier actions of the many veterinarians who prescribe these antiparasitic drugs. They can have harmful, even fatal, consequences.

N.M. REPLIES: Whitey had been born under a house near ours and sheltered under it until he was a young adult, so he never would have been happy being an indoor-only cat. I noticed behavior changes in him last spring, including increased drinking and urination and not wanting to go outside. However, the health problems of the elderly people in our home took precedence, and I was not able to take him to the vet until August.

I don't know if she checked Whitey for fleas, though I don't think he had any at the time. But I know she didn't take a stool sample.

I had hoped Whitey could recover at home, with me continuing to hand-feed him. I would have tried to hospitalize him if I had a greater amount of trust in veterinarians.

I know the vet didn't intend to harm my cat, but I wish she would have explained the product she was going to use. I didn't know she specifically used NexGard until I got home and looked at the bill. I had never heard of any of the neurological problems caused by similar products in dogs.

DRAMATIC RISE IN PET SURRENDERS, EUTHANASIA

According to the Shelter Animals Count database, 37% more dogs were euthanized from January to July this year than in the same period last year. Animal adoptions and reclamations have failed to keep pace with surrenders and abandonments. Housing instability and the suspension of spay/neuter programs during pandemic shutdowns have contributed to overcrowded shelters, some of which are now focusing on helping people keep their pets. (Full story: Axios, Aug. 30)

The shortage of affordable pet-friendly housing is contributing to a record number of pet surrenders, animal shelter administrators say. Dog owners looking for homes to rent are encountering breed restrictions, weight limits, high fees and complete pet bans. And natural disasters have destroyed lots of housing this year, leaving people and animals alike homeless, says Laurie Garrison with the Central Vermont Humane Society. (Full story: National Public Radio, Sept. 7)

(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 DrFoxOneHealth.com.)

DEAR READERS: The following is a post from pet food safety advocate Susan Thixton of truthaboutpetfood.com regarding Martha Stewart's new line of pet foods.

Thixton writes: "The press release states, 'Stewart is leveraging her passion for home cooking and healthy nutrition, as well as her passion for pets, to create Martha Stewart Pet Food. "My pets mean the world to me, which is why I insist on feeding them delicious whole ingredients like real chicken, fish, cage-free eggs, and nutrient-dense grains and vegetables," Stewart said.'

"But Martha Stewart's new pet food line is not made with all whole-food ingredients (that she 'insists' on feeding her own pets). Instead, her pet foods are highly processed, made with feed-grade ingredients. And her 'new' pet foods are not new formulas ... they are disappointingly similar to many other brands of pet foods (but strikingly more expensive).

"The Martha Stewart pet food line consists of three dog foods and two cat foods, only dry/kibble pet food options. All five pet foods include feed-grade processed ingredients such as meat meals, pea protein, dried egg product and multiple dried vegetables. When these processed ingredients are processed again in the pet food, they become an ultra-processed pet food."

I concur fully with what Thixton has written. For more details, go to truthaboutpetfood.com/martha-stewarts-disappointing-new-pet-food.

DOG BREED HEALTH INFORMATION RESOURCE

Nationwide insurance company has developed a digital platform called The Pet Health Zone, which is designed to provide pet owners with breed-related health information based on more than 40 years' worth of claims data. At launch, the platform was drawing on data from more than 12 million Nationwide claims. It can help pet owners watch for signs of illness and make informed decisions in collaboration with their veterinary care team, says Dr. Jules Benson, chief veterinary officer at Nationwide. (Full story: AVMA News, Sept. 4)

ADOPTED SHELTER DOGS DO WELL WITH TIME, UNDERSTANDING

Researchers reported in PLOS ONE that most people who had adopted a dog from a shelter were highly satisfied with their decision. While some returned dogs to shelters, the ones who kept their dogs said the new pets had adjusted "extremely or moderately well" to their new environment. Many respondents reported seeing increased aggression toward strangers, excitability, training difficulties and touch sensitivity in their new dog after the first week, but separation-related and attention-seeking behaviors declined over time. No respondents reported "poor" or "terrible" behavior. (Full story: HealthDay News, Aug. 28)

DEAR DR. FOX: While I was packing up my apartment, I found my copy of your book "The Healing Touch for Dogs." It could not have come at a better time.

My dog Georgie is a rescue pug, approximately 12 years old. He has been diagnosed with degenerative myelopathy and is now in the middle stages. I love him, and I am devastated. Seeing his decline is overwhelming some days.

Georgie walks with the help of Biko Bands, and his attitude is so wonderful that you would never know he has this horrific disease. I give him a massage down the sides of his spine, plus on his hind legs, and I give him reiki treatments. He is on vitamins and herbs to slow the disease's progression.

He does not like swimming (it actually makes him vomit), and we don't have access to acupuncture. Please advise if you know of anything else I can do to help him and keep him with me longer. -- A.K., Queens, New York

DEAR A.K.: So sorry to hear about Georgie's spinal problem. You will find detailed information here: sevneurology.com/blog/4-things-about-pug-myelopathy.

You may be close to a veterinary neurology specialist who can determine if this condition is constrictive or degenerative myelopathy. Surgery can be very expensive, and recovery takes time; alternatively, many dogs with degenerative spinal conditions enjoy some quality of life when they learn to use a K-9 cart. A sling under Georgie's belly that you hold up while walking would also make activity easier.

Pugs, along with other flat-faced breeds like the English and French bulldogs, have suffered from poor breeding practices and lack of progeny testing to keep track of health issues later in life. This has caused much suffering for these popular breeds, and unanticipated costs and concerns for their owners.

REMEMBERING A CARING VETERINARIAN

Veterinarian Mike Cranfield, the retired director of animal health, research and conservation at the Maryland Zoo, died after possibly contracting West Nile virus, according to zoo officials. As executive director of the Mountain Gorilla Veterinary Project -- now called Gorilla Doctors -- Cranfield implemented One Health programs to benefit gorillas in Uganda and the Democratic Republic of Congo, along with the people living and working near their habitats. (Full story: WJZ-TV Baltimore, Aug. 31)

(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 DrFoxOneHealth.com.)