Prevent tick-borne disease with time-sensitive interventions

In this dvm360 interview, Susan Little, DVM, PhD, DACVM (Parasitology), breaks down when common tick pathogens transmit and what clinicians and owners can do to stop them. She explains which infections can transfer within hours versus the 24 to 48 hour window for Lyme and Babesia, demonstrates gentle, effective tick removal, and outlines why continuous systemic tick control and selective vaccination are the most practical defenses. Watch for clear, actionable advice you can use at the clinic or share with clients.

Transcript

Susan Little, DVM, PhD, DACVM (Parasitology): So, I'm Susan Little. I'm a veterinarian and a parasitologist. I worked in academia for 30 years teaching veterinary students at the University of Georgia and Oklahoma State University. I still am active as a veterinary parasitologist, but I'm focusing more on continuing education for veterinarians and technicians and just sharing my love of parasites around the world. Here at the Fetch Conference in Long Beach I'm presenting on perfect timing—timing of transmission of tick-borne infections—because one of the most common questions we get from pet owners and that I get from veterinarians is,how long does a tick have to feed in order to transmit an infection? It's a complicated question, and I'm really excited that BI invited me here to share about that topic.

The thing with tick-borne infections is that it varies so much. It depends on which tick and which infection. Even within the same tick–pathogen system we see differences in different experimental models in terms of how long the tick has to feed to transmit infection. So there aren't hard-and-fast rules, but there are some general trends. The rickettsial infections—like Ehrlichia, Anaplasma, and Rickettsia species (Rocky Mountain spotted fever agent)—are all transmitted within that first day of tick feeding. Anywhere from 3, 6, 12, to 24 hours those pathogens can be transmitted from tick to host.

For Borrelia burgdorferi, the agent of Lyme disease, it takes longer—at least 24 to 48 hours of tick feeding before transmission to the host typically occurs. So we have a window of opportunity there to kill the tick before it can transmit infection. The same is true with Babesia—about 24 to 48 hours before the organism in the tick has matured enough to be transmitted to the host. Again, that gives us an opportunity to kill the ticks before they transmit infection.

To remove a tick that's already attached to one of our patients, the recommendation to clients and staff is gentle, steady rearward traction. Our goal, of course, is not to snap it off because we don't want to leave mouthparts in the skin. If you do leave mouthparts, it's not a disaster—it's just a foreign body in the skin, similar to a splinter—but ideally we remove the entire tick. I say “steady rearward traction” because we don't want to compress the tick and express its contents into the feeding site or onto our hands.

We also recommend using a tool—forceps, tweezers, or a tick-removal tool (a small spoon-like tool with a slot that lets you scoop under the tick without compressing it). If you're going to use your hands, gloves are always recommended in practice because we don't want tick contents to get into hangnails or any open cuts on the hand. Once the tick is removed, transmission stops, but there may already have been exposure; so it's important to counsel the owner about ongoing tick control. What we always say is: every pet, every month, all year long. Pets need continuous tick control to prevent the next tick from completing its feeding on the host.

A seropositive dog that appears asymptomatic always presents a quandary in practice. We have to sort out what that positive test means and whether the dog would benefit from antibiotic treatment. It's now recommended by CAPC, AAFP, and ACVIM to test dogs annually for antibodies to tick-borne infections. Because of that, we find many dogs that are seropositive but clinically normal.

The first thing I encourage is to delve a little deeper into the patient and confirm they are truly asymptomatic. We want to pull additional laboratory work. For a dog that's antibody-positive to Borrelia burgdorferi (Lyme), we would look carefully for evidence of proteinuria that might suggest the dog could be developing Lyme nephritis and might benefit from antibiotic treatment. I also suggest getting a really good history from the owner. If they tell you that their three-year-old lab has suddenly become much quieter and more subdued, that suggests to me the dog might be painful. Often, it's not clinically obvious because the dog is stoic, so it's up to us to sort that out and decide whether treatment is indicated.

If you see antibodies to Ehrlichia or Anaplasma, then for those pathogens we're going to run a CBC and a serum chemistry profile and look for the classic thrombocytopenia, maybe some anemia, or even pancytopenia if it's severe ehrlichiosis. Large granular lymphocytes are common in ehrlichiosis. On serum chemistry we look for evidence such as hypergammaglobulinemia.

The possibility of local (autochthonous) transmission of Borrelia burgdorferi by Ixodes scapularis is even more important now because more pets in more places are being infected. We used to think Lyme was contained to the Northeast and the upper Midwest and maybe some spots along the West Coast, but we now know it's endemic and actively transmitted in places like Tennessee, Kentucky, the Carolinas, and throughout West Virginia.

For preventing tick-borne infections, we really have to focus on the ticks. We do have vaccines for Lyme in dogs, which is fantastic. If we get a robust OspA response to that vaccine, the dog will be protected from infection from Borrelia. But that's just one infection—there are so many tick-transmitted pathogens, some described and some not yet recognized. By keeping pets on tick control—every pet, every month, all year long—we're limiting the time a tick can feed and therefore limiting transmission.

Some products are labeled to prevent transmission of Borrelia burgdorferi by killing Ixodes scapularis—for example, NexGard or NexGard Plus has FDA label claims for prevention of transmission of Lyme in certain contexts—so that can be reassuring. But there are many different infections transmitted by ticks, and systemic tick control with the isoxazoline class (the “-laner” compounds, e.g., fluralaner) is really the cornerstone of any tick control program.

If a pet lives in an area and for a few months the tick pressure is extremely high—for example, in the Southeast and south-central states when Lone Star ticks are abundant in spring, or in the Northeast and upper Midwest in October–November when Ixodes activity is high—you might consider adding a second, topical product for those intense months in addition to the systemic isoxazoline. But year-round systemic protection is important.

As veterinarians we're always trying to balance providing appropriate care without overtreating. When we find antibodies to a tick-borne infection, that's an invitation to a conversation with the owner: get the history and the additional lab work so that if the patient has clinical disease we treat appropriately and they recover. We also need that information so we can advise the client on what to do going forward to make sure it doesn't happen again. Whether it's antibodies to a tick-borne infection or actually finding a tick on the pet, something has failed in the prevention system and we want to make sure the pet is protected with a tick-control product going forward.

If the pet is on an isoxazoline (a “-laner”) the ticks do have to feed to acquire the drug and be killed. It's helpful to show owners a dead tick: an attached tick that is dry and crunchy and whose legs come off if you flick it—it's not a healthy tick. That shows the dog or cat is likely protected from infection because the tick was killed, which is exactly what we want the product to do. Helping owners understand how the tick-control product they're using actually works is, I think, a real service to them.

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