When most people think about fleas, they think about their pets. The old adage that “If you lie down with dogs, you will get up with fleas” used to be a common warning. Because of this, many people assume that if they are not getting bitten, their pet doesn’t have fleas.
However, the truth is that fleas can be everywhere and anywhere in our home. They prefer the warmth and fur of a dog or cat as the ideal location for a hearty meal and a place to lay eggs. While humans can get bitten, this is not common as we don’t make a good host. Most of us simply lack the body hair that fleas like to hide in…most of us.
Common Things We Hear
When we see your pet for an exam, we always ask very specifically: “What flea control product are you using?” The most common replies we hear are:
- “They don’t have fleas.” * “They are indoor-only.” * “We only use it during the summer.” The reason we recommend year-round protection despite these answers is that fleas are world-class hitchhikers and experts at breaking into your home—regardless of the season.
The Flea Haven of Western WA
In Western Washington, we rarely get cold enough or hot enough outside to kill off a flea population. Below freezing temperatures of low 30 degrees Fahrenheit or very hot temperatures above 95-100 degrees Fahrenheit, may kill fleas outside after several days’ worth of those temperatures.
- The “Fake” Sleep: During cold snaps, fleas in their cocoons might appear to be “sleeping,” but they are actually just waiting. They are perfectly protected in that pupae stage until the weather shifts.
- The Climate-Controlled Home: Even when it’s tough for them outside, fleas thrive once they get indoors. Our heaters in the winter and air conditioning in the summer create a perfect, stable environment for them to grow and multiply 365 days a year.
Where do they come from?
The short answer is: Outside. Our lawn, the bushes, and the woods around Lacey are teeming with fleas.
The Wildlife “Delivery Service”: We live in an area rich with wildlife, and every animal that passes through our yard is a potential carrier. All those wild bunnies hopping across the lawn? They have fleas. The deer that wanders through? They have fleas. Squirrels, raccoons, coyotes, rats, and mice—they are all perfect hosts.
How They Get Inside:
Egg Drop: When a flea lays 40–50 eggs per day on a passing bunny or squirrel, those eggs roll off like tiny salt grains into our grass or onto our porch. Every time we go outside, we can track eggs and larvae into our house on our shoes, our clothing, or even in bags of potting soil. They are so small we don’t even notice them.
The “Spider” Rule: Adult fleas can crawl through the smallest cracks under our door or in our wall. If a spider or an ant can get in, a flea (which is much smaller!) certainly can too.
The 5% Rule: Doing the “Flea Math”
It is estimated that the adult fleas we see on our pet are only 5% of the total population in our environment. The other 95% are eggs or larvae hiding under the couch, in the carpet fibers, or in the cracks of our hardwood floor.
Think about it this way: If a single flea lays 40–50 eggs per day, and we have just 10 fleas in our home, that is 500 eggs being dropped into our carpets every single day. By the time we actually see one flea on our dog’s back, there are likely hundreds more in various stages of life waiting for their opportunity to jump on a host.
The Indestructible Cocoon
- The Larvae: For 4 to 18 days, larvae live on “flea dirt” (fecal matter from adult fleas) or even dead human skin cells.
- The Pupae: This is the cocoon stage, and they are virtually impossible to kill, even with professional sprays or chemicals. They can lie dormant for up to 7 months.
- The Hatch: They only hatch when they feel vibration, heat, or CO2—signals that a host, like your dog or cat, is nearby.
Not All Medications Are Created Equal
One of the most confusing parts of flea control is that every medication works differently. The active ingredients depend entirely on which product you choose, and they serve different purposes:
- Adulticides: These products are designed to kill the adult fleas that are currently biting your pet.
- Insect Growth Regulators (IGR): These don’t kill the adults; instead, they act like “birth control” for fleas, preventing eggs and larvae from maturing.
What Doesn’t Work (And Why)
It’s tempting to grab a quick fix at the grocery store, but when it comes to Washington fleas, many “tried and true” methods are falling short:
- The “Old Guard” (Frontline/Advantage): Because these have been used for decades, local flea populations have adapted and built up a resistance. We frequently see pets covered in fleas despite being “on” these products. The fleas that had genetic mutations allowing them to survive Frontline or Advantage lived to reproduce, passing that resistance down. Today, many regional flea populations simply aren’t bothered by these specific chemical classes found in these products anymore. Both of these products are topical. They sit in the oil glands of the pet’s skin and coat, and the flea has to absorb the chemical through contact to die. Even though these products claim to be waterproof, frequent bathing, swimming, or using harsh grooming shampoos strips the natural skin oils that hold the medication. If the oils are stripped, the product loses its efficacy long before the 30-day mark.
- Diatomaceous Earth: While many people swear by this “natural dust,” it is rarely effective as a standalone treatment and is incredibly messy. In order to have the greatest success, it must be applied by a professional.
- Flea “Bombs”: The mist often fails to reach the dark, tucked-away places where larvae hide. Plus, they don’t touch those indestructible pupae.
- “Natural” Remedies: Garlic, essential oils, or cedar chips aren’t enough for a high-infestation area. In fact, garlic can be toxic to your pets.\
- Flea Shampoos: They kill the fleas currently on your pet but have zero lasting effect.
What Actually Works (The Professional Approach)
Because of these widespread resistance issues, veterinary medicine has largely shifted away from older topics and toward the Isoxazoline class of oral medications (like NexGard, Simparica, Credelio, or Bravecto).
These are prescription-only chewables that enter the pet’s bloodstream. When a flea bites, it gets a lethal dose instantly. Because this drug class is newer, fleas have not developed widespread genetic resistance to it, and because it’s internal, it can’t be washed off in the bath.
For these products to be effective, the flea actually has to bite the pet. Because of this, you may still see a few fleas on your pet as they hatch from your carpet and jump up for a meal. Don’t panic! Once they bite, the medication goes to work. This prevents them from living long enough to lay more eggs, effectively breaking the cycle.
How To Stop an Infestation
- Treat EVERY Pet: If your dog is treated but your “indoor-only” cat isn’t, the cat becomes a “reservoir” that keeps the infestation alive.
- Vet-Kem (specifically their Siphotrol premises sprays) is a heavy hitter for home infestations because it uses a “two-pronged” chemical approach. It contains both fast-acting adulticide with a long-lasting Insect Growth Regulator (IGR). Not only killing adults within minutes but stops the growth of larvae so they cannot become adults to bite or reproduce.
Since Vet-Kem contains powerful chemicals, application requires strict
safety protocols:
- Prep the Safe Zones: Remove all pets (dogs, cats, birds) and humans from the area before spraying. Permethrin can be highly toxic to cats when wet, so keeping cats completely out of the treated rooms until the spray is 100% dry is an absolute must.
- Cover the Food Gear: If you are spraying under or around the refrigerator, ensure any exposed pet food bowls, water dishes, or human food prep areas are completely covered or moved.
- Let It Dry and Ventilate: Leave the treated rooms and allow the spray to dry completely (usually 1 to 2 hours depending on humidity) with windows open or ventilation fans running before letting the pets back into the space.
- The Power of the Vacuum: Vacuuming tricks the cocoons into hatching early, so they jump onto your treated pet and die. CRITICAL STEP: Empty the canister or discard the vacuum bag outside in the trash immediately. Fleas can escape out of the vacuum bag, or the trash can inside, allowing the freshly hatched adults to reinfest your home.
- Hot Water Laundry: Wash all bedding in the hottest water possible to kill larvae and eggs.
Don’t wait for the itch! Whether you live in a gated community or have a “couch potato” pet, protection is the only way to keep your home flea-free. Call us at Mountain View Veterinary Hospital today to find the right plan for your family.