DEAR READERS: Fleas and ticks can easily infest dogs and cats. Ticks can spread serious diseases including rickettsiosis, anaplasmosis and borreliosis (Lyme disease), while fleas -- the most common external parasite found on pets -- can transmit bartonellosis (cat scratch disease), plague, murine typhus and tapeworms.

Safe, inexpensive methods of dealing with these ectoparasites are available. (For details, see this post on my website: drfoxonehealth.com/post/preventing-fleas-ticks-and-mosquitoes.) But big pharmaceutical companies have their own toxic insecticides they developed for use in agriculture. Not content with applying these chemicals to the foods we eat, companies are spinning them off as flea and tick killers for pets -- often at grave risk.

The Seresto Flea and Tick Collar contains two active ingredients: imidacloprid and flumethrin. These insecticides are harmful to animals, to the people who pet them and to the environment -- especially when dogs wearing these collars enter a lake or stream. (For details, see drfoxonehealth.com/post/companion-animal-risks-of-flea-and-tick-insecticides.)

Now, Merck is promoting Bravecto Quantum, an injectable insecticide (fluralaner) for dogs that it claims can give protection for up to a year. The company states: "The most commonly reported adverse reactions in a U.S. field study included lethargy, decreased appetite, vomiting, diarrhea, elevated liver enzymes and pruritus. ... Fluralaner is a member of the isoxazoline class. This class has been associated with neurologic adverse reactions including tremors, ataxia and seizures. Seizures have been reported in dogs receiving isoxazoline-class drugs, even in dogs without a history of seizures.”

What more can be said beyond "beware"? The convenience of an insecticide collar, topical treatment or injection should not override safer preventive measures. I would first choose a botanical spray, such as this one, which I also spray on myself when walking my dog: earthanimal.com/product/apothecary-natural-flea-tick-herbal-bug-spray-for-dogs-people. It is infused with cedarwood and peppermint oils to produce a fresh, minty scent loathed by fleas, ticks and mosquitoes.

Also consider this oral supplement that helps repel fleas and ticks: earthanimal.com/product/apothecary-natural-flea-tick-daily-internal-powder-supplemental.

AN UPDATE ON CANINE LYMPHOMA

Lymphoma is one of the most common types of cancer in dogs today. I recall weeping upon seeing a friend's dog sitting on his lap at our local dog park: The dog's lymph glands in her neck had swollen to the size of two golf balls. My friend said that this was her last visit to the park; he was off to the vet’s to put her to sleep.

Please see this informative post from ImpriMed, a canine medical company, about some of the potential causes of lymphoma.

"There are a few (causes) that have been linked to the cancer, the obvious one being genetic predisposition. Certain breeds are more likely to succumb to lymphoma than others. Unfortunately, golden retrievers are super likely. One out of eight goldens will be diagnosed in their lifetime.

"There has also been a link found between (lymphoma and certain) garden pesticides. ... Dogs play in the grass that you use (pesticides) on. They roll around and have a great time. Then they come back inside and set out to clean themselves by licking their body that has just rolled in the grass. Lo and behold, your pet is ingesting pesticides. ...

"I’m sure it’s unsurprising, considering everything we know already about the habit, but being in a home with a smoker can cause cancer to develop in your pet. ... Secondhand smoke will make the people and animals around you sick. As a smoker, you are putting a damaging substance into your body and the bodies of those you keep closest to you."

(Full story: imprimedicine.com/blog/what-is-canine-lymphoma.)

(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: We get alerts all the time about a rabid cat they find here and there. At this point no one should inject their pets and livestock with anything until proven safe. And they have been dropping rabies vaccines from planes for the past few months in several states -- odd, don’t you think? -- S.R.E., Charlottesville, Virginia

DEAR S.R.E.: Spreading bait laced with modified live viruses has been going on for decades to help prevent rabies from spreading in wildlife communities and rural municipalities. It has proven safe and effective.

Both inactivated (killed) and modified live viruses are used in anti-rabies vaccinations, depending on the vaccine type and target species. Inactivated vaccines, typically administered via injection, are commonly used for humans and some domestic animals. Modified live vaccines are often used for oral animal vaccination programs to control rabies in wildlife. Careful monitoring of viral strains is important because they mutate and may render vaccines less effective in providing protection.

MORE CONCERNS ABOUT COVID INFECTIONS, VACCINATIONS

Studies have found that, rarely, some COVID-19 vaccines (specifically the adenoviral vector-based ones) are associated with a specific, very rare blood clot condition called vaccine-induced immune thrombotic thrombocytopenia (VITT), also known as thrombosis with thrombocytopenia syndrome (TTS). This condition is distinct from the “microclots” observed in some patients with severe, acute COVID-19 and long COVID.

See the study "COVID-19 Vaccines and Autoimmune Hematologic Disorders" by Maria Eva Mingot-Castellano et al., published in Vaccines in 2022.

FIRST HUMAN DEATH FROM NEW STRAIN OF AVIAN FLU

A Washington resident has died from complications related to H5N5 avian influenza, the first human case of this strain and the second U.S. avian flu death in 2025. The patient, an older adult with underlying health conditions, likely contracted the virus from his backyard flock of birds, according to health officials. Although there is no vaccine that protects people specifically against avian influenza, health experts say seasonal flu vaccines reduce risks. (Full story: CNN.com, Nov. 21)

For a deeper investigation about the risks of another pandemic -- while federal health and science agencies are being dismantled -- see this article co-authored by my friend and fellow veterinarian Dr. Bruce Kaplan: impakter.com/bird-flu-what-the-first-death-from-rare-h5n5-strain-reveals-about-us-public-health.

The other strain of this virus, H5N1, is infecting and killing all manner of wildlife, domestic cats, backyard poultry and those in factory farms, as well as sickening dairy cows and infecting their attendants and veterinarians.

PROTECTING PETS, BACKYARD FLOCKS FROM AVIAN FLU

Avian influenza primarily affects wild aquatic birds and domestic poultry, but backyard flocks and even pets may be at risk. To help veterinarians and the public, the AVMA has developed guidance on identifying, treating and preventing bird flu in pets and backyard poultry. Early detection is critical, so owners are encouraged to monitor their animals closely for signs of illness and consult their veterinarian if concerns arise.

Visit this page for more information: avma.org/resources-tools/animal-health-and-welfare/animal-health/avian-influenza/avian-influenza-companion-animals.

(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: I appreciated your article on the multiple harms of glyphosate. Here are two references I found that will interest you:

“Could Glyphosate and Glyphosate-Based Herbicides Be Associated With Increased Thyroid Diseases Worldwide?” by Renata Romano et al., published in Frontiers in Endocrinology in 2021.

“Hypothesis: Glyphosate-Based Herbicides Can Increase Risk of Hematopoietic Malignancies Through Extended Persistence in Bone” by Charles Benbrook et al., published in Environmental Sciences Europe in 2025. -- R.E, Wales, U.K.

DEAR R.E.: Nutrition and cognition are linked via the gut-brain axis. An unhealthy gut microbiome, especially from consuming ultra-processed foods, can have multiple effects on neural development and learning ability, and can even be associated with early onset dementia.

RISKS OF GLYPHOSATE-RESISTANT FEED FOR HORSES

Many crops and their byproducts have been genetically engineered to resist glyphosate, the active ingredient in Bayer/Monsanto’s Roundup herbicide. All horse owners should be aware because of the documented health risks to horses.

Per WildFedHorse.com: "The most common horse feed ingredients sprayed with glyphosate include: alfalfa (especially GMO alfalfa), soybeans, corn, wheat (sometimes sprayed pre-harvest to dry the crop, known as desiccation), beet pulp, canola meal, oats and barley (if not organic or non-GMO certified). Hay crops like timothy and orchard grass are less commonly sprayed, but may still contain drift or soil-based residues if grown conventionally near glyphosate-treated areas."

Since glyphosate chelates (binds) some essential minerals, the skeletal development of foals may be impaired, which could then contribute to fractures during training and racing. Buying horse feed that is Organically Certified is a responsible decision.

Horse owners and feed producers are catching on to the health and environmental benefits of the self-seeding perennial crop sainfoin, a deep-rooted, drought-resistant plant. Sainfoin can serve as a cover crop, improve soil health and provide nutrition for bees. It also has the potential to be a superfood for equines!

Per Kentucky Equine Research (ker.com): “Due to the global rise in parasite resistance to chemical dewormers, researchers are looking at alternatives. One chemical-free approach to deworming involves the legume sainfoin (Onobrychis viciifolia), which reduces fecal egg shedding of small strongyles and decreases larval motility.”

Small companion animals such as rabbits, guinea pigs, chinchillas, gerbils and hamsters benefit from some alfalfa hay or pellets, but make sure these plant products have not been treated with glyphosate.

UNRAVELING DOGS’ ANCESTRY

Please see this excerpt from the summary of a recently published study:

“Almost two-thirds of breed dogs have wolf ancestry within their nuclear genome from admixture that occurred nearly a thousand generations ago, and all analyzed free-ranging dog genomes carry some ancient wolf ancestry. Wolf ancestry correlates with traits like size, function, and personality characteristics. Altogether, the majority of dogs today have low, but detectable, levels of post-domestication wolf ancestry that has shaped their evolution and conferred unique advantages to their survival in diverse human environments.” (Full study: “A legacy of genetic entanglement with wolves shapes modern dogs” by Audrey Lin et al., published in Proceedings of the National Academy of Sciences of the U.S. in 2025.)

While this is stellar research that supports the widely held view that the domestic dog’s ancestor is the wolf, I do not accept that view, having raised and studied various wild and domesticated canids. Rather, I believe there were aboriginal landrace varieties of a species of wild bush dogs, which were taken from local forests and domesticated. These include the African basenji and the New Guinea singing dog. As people migrated, so did these early dogs. They were dispersed to other communities and cultures, where some were cross-bred with wolves.

Many of the dogs in remote tribal settlements in South India that I helped treat (at the animal refuge and hospital of my late wife, Deanna Krantz) were of a distinctive landrace type -- quite like those in Tanzania, the larger Australian dingo and the Carolina dog, also known as the American dingo.

For more details about the native dogs in India, see Deanna’s and my book, “India’s Animals: Healing the Sacred and The Suffering.”

(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.)