In this article:
- What is Rickettsia finnyi?
- How is Rickettsia finnyi treated?
- What other illnesses can ticks spread to dogs?
- How can I protect my dog from ticks?
- Which ticks carry Rickettsia finnyi?
Anyone with a dog—or anyone else who spends time outdoors in the summer—knows that ticks are a risk, and can expose you and your best friend to illnesses like Lyme disease.
And researchers are still discovering new tick-borne bacteria that can make dogs sick. In November of 2025, a team at the North Carolina State University College of Veterinary Medicine published a paper in the journal Emerging Infectious Diseases about one of them: Rickettsia finnyi.
Here’s what’s to know about it, and how you can best protect your dog as you enjoy the warm weather this summer.
What is Rickettsia finnyi?
In 2018, a team of researchers at NC State’s Vector-Borne Disease Diagnostic Laboratory (VBDDL) received a blood sample from a Colorado dog named Finny.
Analysis revealed the presence of DNA from a foreign pathogen, and DNA sequencing suggested “a novel species,” said Barbara Qurollo, DVM, senior author on the paper and an associate research professor of clinical sciences and co-director of the VBDDL.
Between 2018 and 2019, she and her team identified the same mystery species in two more dogs through submitted blood samples. With her paper’s publication, this bacterium was officially dubbed Rickettsia finnyi after Finny, the dog in whom it first surfaced. (Finny has since passed away due to unrelated causes.) Dr. Qurollo and her team studied data from 17 dogs infected with this bacterium. Since its initial discovery, it’s been detected in 19 dogs total, most of them residing in the southern and midwestern US. And its DNA has been detected in the lone star tick (Amblyomma americanum), which is distributed throughout those regions.
R. finnyi is just one species of bacterium within the broader category Rickettsia. Rickettsia can’t live outside of host organisms, but thrive within ticks and dogs. Dr. Qurollo said there’s currently no evidence that infected dogs directly transmit R. finnyi or other Rickettsia pathogens to other dogs or people; ticks transmit bacteria to dogs when they feed on their blood.
What are the signs of R. finnyi infection in dogs?
Rickettsial bacteria cause illnesses like Rocky Mountain spotted fever, Brazilian spotted fever, and Mediterranean spotted fever; there are more than 25 of this type of tick-borne, spotted-fever group. According to the paper, the most common signs in the dogs infected by R. finnyi studied were lethargy, fever, and low platelet count in the blood (thrombocytopenia). These signs are similar to those of Rocky Mountain spotted fever, which is usually caused by the pathogen R. rickettsii.
Signs of this illness include:
- Fever
- Lethargy
- Lameness
- Loss of appetite
- Vomiting
- Weakness
- Swelling
- Rash
- Pain
How is Rickettsia finnyi treated?
Some good news: This infection is curable.
“This bacterium appears to be susceptible to doxycycline, the same antibiotic used to treat Rocky Mountain spotted fever,” Dr. Qurollo said. Doxycycline is a common antibiotic that treats infections throughout the body, and the length of treatment may last from one to four weeks, according to Brian Collins, DVM, Diplomate of the American Board of Veterinary Practitioners, with the Cornell Richard P. Riney Canine Health Center.
Early detection is critical to prompt treatment, and most dogs treated with antibiotics for Rocky Mountain spotted fever recover. But Dr. Collins added that various health complications and even death are possible, due to treatment starting too late or to individual differences between dogs. If the antibiotics aren’t sufficient, dogs may require additional treatment in the form of intravenous fluids and drugs like corticosteroids.
What other illnesses can ticks spread to dogs?
There are many different types of ticks. These include the previously mentioned lone star tick; deer ticks (aka black-legged ticks); brown dog-ticks; and American dog-ticks.
All these parasites carry different types of bacteria, which can cause diseases like Lyme, ehrlichiosis, anaplasmosis, and babesiosis in humans and dogs. (Again, dogs and humans cannot transmit these diseases to each other directly—though you could, for example, catch Lyme from a tick that’s crawled off of your dog and onto you.)
There may be months between a tick bite and signs of infection. If your dog shows any signs of illness, take them to the veterinarian, especially because signs of tick-borne disease may resemble signs of other illnesses. Dr. Collins also said it’s possible for dogs to be infected by more than one type of tick-carried bacteria in what’s known as co-infection; this can result in more serious illness.
How can I protect my dog from ticks?
Protecting your dog from ticks is a lifelong endeavor. Commonly associated with high elevations, wooded areas, and tall grasses, ticks live in most places. But the risk of your best buddy picking up a tick is much higher when you’re out hiking in the forest than when you’re walking through a city.
Your first line of tick protection comes in the form of preventatives. Oral and topical medications as well as collars are extremely effective, and can even be used at the same time. While every product comes with its own guidelines, many of them are administered monthly. You can also vaccinate your dog against Lyme disease starting at 4 months. Talk to your veterinarian about which options make sense for your dog.
None of these preventatives are 100% effective, so it remains crucial to check your dog for ticks after walks. “Ideally tick checks would take place after each trip outside,” said Dr. Collins. These checks must be thorough: “It’s necessary to inspect everywhere, including between toes and in ears.”
When checking your dog for ticks, use the feel test. By simply running your hands and fingers over your dog’s skin, you may be able to feel the tick. Ticks often feel firm, like a wart. Start at your dog’s head and work your way toward their tail. Concentrate on these areas:
- Head—including around eyes, inside and behind ears, and under chin
- Neck, including under the collar
- Feet, including bottoms of paws and spaces between toes
- “Armpits” where the front legs meet the body
- Under their tail
If your dog won’t abide a tick check, incorporate treats, praise, and toys to gamify the process.
If you do find a tick, don’t remove it with your bare hands; this can result in incomplete removal, and infection may still occur at the site of the wound. You also risk becoming a new host to these disease-causing bacteria.
Instead, use a tick-removal tool from the pharmacy or pet store, or a pointed pair of tweezers to remove the entire tick—body, head, and teeth. Spread your dog’s fur, pinch the tick as close to the skin as possible, and very slowly and gently pull up. Once your dog’s been de-ticked, clean the bite area with rubbing alcohol and wash your hands. If your dog wasn’t on preventatives, Dr. Collins recommended calling your veterinarian to see what other steps you should take. And if the skin shows redness or oozing, those are potential signs of infection that merit a call to the vet, too.
Which ticks carry Rickettsia finnyi?
Researchers are not 100% sure which ticks carry this bacterium. Dr. Qurollo said that “an important next step is confirming the tick species responsible for transmission.” The lone star is a good lead, but scientists still need definitive transmission studies.
Summer is among the best times for outdoor adventures with your dog. Taking every precaution to prevent them from contracting R. finnyi and other tick-borne illnesses will give you peace of mind and make it easier to embrace the best parts of the season together.
The post There’s a New Tick-Borne Bacterium Infecting Dogs appeared first on The Farmer’s Dog - Digest.
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