Bay Area tick season runs backwards. Adult western black-legged ticks emerge with the first autumn rain, peak in January, and are largely gone by summer. They can carry Lyme, though only a small share locally do. A tick generally has to stay attached a day or more to pass anything on, which is why a nightly check works.
Everything you learned about tick season is wrong here
If you moved to San Carlos from almost anywhere east of the Rockies, you learned that ticks are a summer problem. You check the kids after a July hike, you stop thinking about it in October, and you put the whole subject away until spring.
That calendar is wrong on this side of the country, and it is wrong in a way that leaves people unprotected for the six months that actually matter.
The adult western black-legged tick, which is the one San Mateo County residents meet most often through winter and spring, does not wait for warm weather. It becomes active in the fall, in late October and early November, and its appearance is tied directly to the first real rain of the season. Numbers climb from there, peak around January, and then fall away until adults are rare or absent by June and July.
So the moment to start paying attention is not Memorial Day. It is the first weekend the trails smell like wet oak.
Which tick, and what it actually carries
The western black-legged tick is the local carrier of Lyme. That sentence makes people picture a far higher risk than the numbers support, so it is worth being precise about both halves of it.
The district that monitors ticks in San Mateo County has tested tens of thousands of them, and it finds the Lyme bacterium in about six tenths of one percent of adult western black-legged ticks. That is a very low number. One tick on your dog is not an emergency and is not a reason to panic. The smaller spring nymphs run several times higher, closer to two percent, which is why the spring check matters more than most people assume.
But a low per-tick chance stops being reassuring when the exposure repeats. A dog who walks the same grassy trail edge four times a week from November through March is not having one encounter, and the ticks you never find are the ones that stay attached long enough to matter. The risk here is cumulative, not dramatic. That is exactly the kind of risk a routine beats and vigilance does not.
Ticks in this area can also pass on other infections, and a heavy burden on a small dog or a kitten is a problem in its own right regardless of what the tick is carrying.
Where they are, and where they are not
Ticks do not drop out of trees. They do not jump and they do not fly. They sit on the tips of grass and low vegetation with their front legs out, waiting for something to brush past, and that behavior tells you exactly where the risk concentrates.
It is the edges. The eighteen inches of tall grass and leaf litter on either side of a trail, the margin where oak woodland meets a path, the shaded brushy strip at the bottom of a slope. San Carlos is ringed by this habitat: the open space above town, the oak and grassland trails, the creek corridors, the brushy edges of the neighborhood parks.
What follows from that is the single easiest change you can make. A dog walking down the middle of a fire road is at far lower risk than the same dog weaving through the vegetation on the shoulder. Keeping to the center of the trail, on leash, through the wet months is worth more than most of what people buy.
The flip side: a paved walk down El Camino Real is not where this happens. You do not need to think about ticks on the sidewalk. You need to think about them after the trail.
Why the day-or-more attachment window is the whole strategy
Here is the fact that makes a simple habit genuinely protective. A tick that has only just attached has usually not passed on the Lyme bacterium yet, because transmission of Lyme generally requires the tick to stay attached and feeding for a day or more. Some of the other infections ticks carry here move faster than that, which is the reason to take one off as soon as you find it rather than counting on a day as a safe allowance.
That window is your margin. A tick found and removed the same evening has, in most cases, not had time to do the thing you are worried about. A tick that rides home unnoticed, stays on for three days, and drops off on its own is the one that mattered, and you never saw it.
So the goal is not to avoid every tick. That is not achievable on a Bay Area winter trail. The goal is to find them the same day. Everything below is in service of that.
How to actually check a dog
Looking is not enough, because an unfed adult tick is the size of a sesame seed and a spring nymph is closer to a poppy seed and most of them are somewhere you cannot see. Use your fingertips, flat against the skin, and feel for a small firm bump. Work against the lie of the coat rather than with it.
Go where they prefer, which is thin skin and sheltered spots:
- Ears, inside and along the edges, and the folds behind them.
- Head, muzzle and around the eyelids.
- Under the collar, which is one of the easiest spots to miss. Take the collar off to check.
- Neck, chest and the armpits.
- Groin and belly, including the inner thighs.
- Between the toes and in the webbing, and around the pads.
- Under the tail.
Do it the same evening, in good light, with the dog somewhere comfortable. On a long-coated dog a comb helps. The whole thing takes two or three minutes once it is a habit, and it pairs naturally with the check you should already be doing for grass seeds after a trail walk. Our guide to foxtails and grass awns covers that side of it, and the two checks are the same two minutes.
Cats need this too, including indoor cats. Cats who go outside pick up ticks the same way, and they are harder to find under a dense coat. Indoor-only cats are not entirely out of it either, because ticks travel inside on shoes, on bags and on the dog. Check your cat’s head, ears, neck and chin.
Getting one off without making it worse
Use fine-tipped tweezers. Get them as close to the skin as you can, grasp the tick itself rather than its swollen body, and pull straight out with steady, even pressure. Do not twist, do not jerk, and do not stop halfway. Then wash your hands and the bite area.
If a small piece of mouthpart stays behind, leave it. It is not carrying anything, and digging at the skin to extract it does more harm than the fragment does. The spot may stay slightly raised and pink for a few days, which is normal.
Put the tick in a sealed bag or a small container and write the date on it. If your dog becomes unwell weeks later, having the tick and the date turns a vague history into a useful one.
The folk methods all make things worse, and this is the part worth being firm about. Do not burn it with a match. Do not smother it in petroleum jelly, nail polish, alcohol or essential oil. Do not try to make it back out on its own. When these were actually tested, none of them got the tick off, and every minute spent waiting for one to work is another minute the tick stays attached and feeding, which is the one variable you control. Stressing a feeding tick may also make it bring gut contents back into the bite. Tweezers, straight out, done.
What to watch for afterward, and over what timescale
This is where people get caught out, because the signs do not follow the bite closely. They usually show up two to five weeks after the bite, and sometimes later than that, long after you have forgotten the walk.
Call us if you see any of these in the weeks and months after a tick:
- Lethargy and a dog who is suddenly flat or reluctant to do things they like.
- Fever, shivering, or a dog who feels hot and seems unwell without an obvious reason.
- Off food.
- Lameness that shifts. This is the characteristic one. A limp that is in one leg, then settles, then turns up in a different leg a week later is a pattern worth telling us about specifically. Owners often dismiss it because it keeps getting better.
- Swollen or sore joints, or a stiff, hunched way of moving.
- Swollen glands.
- Drinking and urinating noticeably more, vomiting, weight loss, or puffiness around the limbs or face. That combination points at the kidneys and is the one not to sit on.
- Pale gums, or bruising and bleeding that does not fit anything.
None of these is specific on its own, which is why the tick history matters so much. Mention it even if it feels irrelevant and even if the tick was months ago. It changes what we look for and it saves a round of guessing.
Sorting this out is blood work rather than an examination finding, and our pet diagnostics run on site, so the rapid screening test and most blood panels come back while you are still here rather than days later. A small number of specialized panels go to an outside laboratory and take longer, and we will tell you which. Our pet diagnostics page covers what that includes. Anything the results turn up is handled by our medical services team.
Prevention, and the part people get wrong
Year-round prevention is the backbone, and the mistake is seasonal thinking. People stop at the end of summer, which in this climate is the month before the risk actually begins. In this climate the parasite calendar never really closes, and stopping at the end of summer means stopping the month before tick risk actually begins. That applies to indoor cats as much as to dogs, since what comes inside arrives on shoes and on other pets.
What suits your animal depends on their species, their size, how they live and how much trail time they get, so it is worth working out together rather than guessing off a shelf. Our preventive care visits are where that gets worked out, and our preventive care page explains what a visit covers.
The rest is free and makes a real difference. Keep to the middle of the trail through the wet months. Keep your own grass short and clear leaf litter and brush away from where your animals lie down. Check the same evening, every time. And keep checking in January, which is the peak and the month everyone has stopped thinking about it.
Our hours, and what to do when we are closed
We are open Monday through Saturday, 9:00 AM to 8:00 PM, and we are closed on Sunday. A tick you have found should come off the same evening, and that is a job you can do at home with tweezers using the steps above rather than something to hold until we open. Bring it in if you would rather we did it and we are open, but do not leave it attached overnight waiting for us. A dog with a shifting limp can wait for a regular appointment.
What should not wait is a dog or cat who is collapsing, struggling to breathe, has pale or white gums, is bleeding and will not stop, or has gone from a little flat to seriously unwell in a few hours. If any of that happens on a Sunday or after we close at 8:00 PM, go directly to an open emergency veterinary hospital and call them on your way rather than waiting for us to open. Our emergency and urgent care covers the same thing during our own hours, and urgent appointments are available every day we are open.
Common questions
I found one tick on my dog. How worried should I be?
Not very. Around half a percent of adult western black-legged ticks in San Mateo County carry the Lyme bacterium, and a tick found and removed the same day has usually not been attached long enough to pass Lyme on. Take it off properly, keep it with the date written on the bag, and carry on. The thing worth changing is the routine, not your evening.
My dog is on prevention. Do I still need to check?
Yes. Year-round prevention does a lot of the work, but it is not a force field, and nothing stops a tick climbing on in the first place. The nightly check is what catches the one that got through. Think of them as doing two different jobs rather than one job twice.
Can my cat get Lyme?
Very rarely, at least in any way you would see. Cats pick up ticks readily and should be checked, but illness from Lyme is essentially not described in cats the way it is in dogs. The practical concern with cats is the tick burden itself and the fact that a dense coat hides them. Check the head, ears, neck and chin, and do not assume an indoor cat is exempt.
Can I catch something from my dog’s tick?
Not from your dog directly. Your dog cannot pass Lyme to you. But a tick that rode home on your dog can climb onto a person, so handle the removal with the tweezers rather than your fingers, wash afterward, and check yourself after the same walk your dog just did. You were both in the same grass.
The tick is swollen and gray. Does that change anything?
It tells you it has been attached a while, which is useful information rather than cause for alarm. Remove it the same way, grasping as close to the skin as possible rather than squeezing the engorged body, and note the date. Then watch over the following weeks for the signs above and tell us the tick was already full when you found it.
When can I stop checking?
You do not really stop. Adults thin out around June, but the spring and early-summer nymphs are the stage more likely to be carrying the Lyme bacterium here, and they are small enough to miss. So this is a year-round habit with two reasons behind it: the winter adult peak, from the first rain through to about March, when you will find the most ticks, and the spring nymph window, when the ones you find are likelier to matter.
Speak to the team at Revive Veterinary Care
If you have found a tick you would rather we removed, your dog has a limp that keeps moving around, or you want to get year-round prevention sorted before the rain starts, call us. We are closed Sunday and we close at 8:00 PM, so if your pet becomes seriously unwell outside those hours, go to an open emergency veterinary hospital and call ahead before you leave.
Published by the team at Revive Veterinary Care.
This article is educational in nature and is not a replacement for hands-on assessment of your own pet by a veterinarian.
Revive Veterinary Care
718 El Camino Real, San Carlos, CA 94070
Phone: (650) 750-0777
Email: hello@revivevetcare.com
Hours: Monday through Saturday 9:00 AM to 8:00 PM; closed Sunday