Chapter 1
WHY DEWORMERS MUST BE REPEATED
Understanding the 21-Day Worm Life Cycle
ROUNDWORMS
Deworming medications kill adult worms living in the intestine. They do NOT kill migrating larvae in tissues.
If you give only one dose, immature worms will survive and mature later.
HOW ROUNDWORMS DEVELOP IN KITTENS
Roundworm larvae are passed through the mother’s milk.
A nursing kitten ingests larvae every single day while nursing.
Each larva takes approximately 21 days to mature into an adult worm.
This creates a rolling maturation cycle.
WHAT “ROLLING MATURATION” MEANS
If a larva is ingested on:
Day 1 → It becomes an adult worm on Day 21
Day 2 → It becomes an adult worm on Day 23
Day 3 → It becomes an adult worm on Day 24
Day 4 → It becomes an adult worm on Day 25
This continues daily as long as exposure continues.
There is not one “batch” of worms. There is a continuous wave of worms maturing every day.
VISUAL EXAMPLE
Larva Ingested → Adult Worm Appears
1 → 21
2 → 23
3 → 24
4 → 25
5 → 26
6 → 27
7 → 28
8 → 29
9 → 30
10 → 31
11 → 32
12 → 33
13 → 34
14 → 35
15 → 36
16 → 37
17 → 38
18 → 39
19 → 40
20 → 41
21 → 42
22 → 43
23 → 44
24 → 45
25 → 46
26 → 47
27 → 48
28 → 49
This pattern continues forward.
WHY WE DEWORM EVERY TWO WEEKS
Example kitten schedule:
3 weeks of age
5 weeks of age
7 weeks of age
Continue every 2 weeks until 12 weeks (when big enough we switch to a topical that lasts for 4 weeks)
Each treatment kills the worms that have matured since the previous dose.
Because larvae mature over a 3-week window, at least three treatments are required to clear the cycle.
KEY TAKEAWAYS FOR FOSTERS
All dewormers must be repeated.
Medications kill adult worms only.
It takes approximately 21 days for larvae to mature.
Nursing kittens are exposed daily.
Missing doses allows worms to continue cycling.
FELINE DEWORMING QUICK REFERENCE
Label-Based Information Only
Dose by current weight (kg).
Confirm product concentration before dosing.
PYRANTEL PAMOATE (Strongid® 50 mg/mL suspension)
Indication (label):
Removal of large roundworms (Toxocara cati) and hookworms (Ancylostoma spp.)
Minimum Age (label):
No specific minimum age listed on most 50 mg/mL suspension labels. We start at 3 weeks old because it take three weeks for round worms to mature and the medication kills mature worms. Dosing sooner will not kill the roundworms.
Dose (label):
5–10 mg base/kg (commonly administered as 10 mg/kg)
For 50 mg/mL suspension:
10 mg/kg = 0.2 mL/kg
≈ 0.09–0.1 mL per lb
Retreatment (label):
Repeat as necessary to eliminate reinfection.
FENBENDAZOLE (Panacur® 10% Suspension – 100 mg/mL)
Indication (label):
Removal of roundworms (Toxocara cati) and hookworms (Ancylostoma tubaeforme)
Minimum Age (label):
Safe for use in kittens (no specific lower age restriction stated on label)
Dose (label):
50 mg/kg once daily
For 100 mg/mL suspension:
50 mg/kg = 0.5 mL/kg
≈ 0.23–0.25 mL per lb
Duration (label):
3 consecutive days
(Note: Giardia use is extra-label in cats. Treat for 5 consecutive days if Giardia suspected)
DRONTAL® (Praziquantel + Pyrantel)
Indication (label):
Removes tapeworms, hookworms, and roundworms
Minimum Age (label):
Kittens 2 months of age or older
Dose (label):
Based on body weight (tablet chart required)
Retreat needed. This is a cocktail medication. Pyrantel needs to be given every 2 weeks for three rounds.
TAPEWORMS IN CATS (dewormers used listed below this explanation)
How They Infect and Their Life Cycle
The most common tapeworm in cats is Dipylidium caninum.
Cats do not get tapeworms directly from other cats. They get them by swallowing an infected flea.
HOW INFECTION HAPPENS
A flea larva in the environment eats tapeworm eggs.
The tapeworm develops inside the flea as it matures.
The flea jumps onto a cat.
The cat grooms itself and swallows the flea.
The tapeworm is released in the intestine.
It attaches to the intestinal wall and grows into an adult worm.
No flea, no Dipylidium tapeworm.
LIFE CYCLE TIMING
After a cat swallows an infected flea:
The tapeworm attaches in the small intestine.
It matures in about 2–3 weeks.
Segments (proglottids) begin to shed.
Those segments look like small rice grains around the anus or in bedding.
Each segment contains egg packets.
When the segment dries out, it breaks open and releases eggs into the environment.
Flea larvae then ingest those eggs, and the cycle continues.
KEY POINTS FOR FOSTERS
Tapeworms require fleas for transmission.
Cats do not get Dipylidium just from being near another cat.
If you see rice-like segments, the cat had fleas at some point.
Deworming without flea control can lead to reinfection.
OTHER TAPEWORMS
Another common tapeworm in cats is Taenia taeniaeformis.
Cats become infected by:
Hunting and eating rodents.
Ingesting infected intermediate hosts.
Indoor-only cats are much less likely to have Taenia.
IMPORTANT DIFFERENCE FROM ROUNDWORMS
Roundworms are transmitted:
Through mother’s milk.
Through contaminated soil.
Directly from the environment.
Tapeworms are transmitted:
Through an intermediate host (usually a flea or rodent).
Tapeworm prevention requires flea control, not just deworming.
DRONCIT® (Praziquantel)
Indication (label):
Removal of tapeworms (Dipylidium caninum, Taenia taeniaeformis)
Minimum Age (label):
Kittens 6 weeks of age or older
Dose (label):
5 mg/kg (oral tablet or injectable form per label)
Retreatment (label):
Single dose effective for labeled parasites.
CESTEX® (Epsiprantel)
Indication (label):
Removal of tapeworms (Dipylidium caninum, Taenia taeniaeformis)
Minimum Age (label):
Kittens 7 weeks of age or older
Dose (label):
BOTTLE SPECIFIC. USE THE LABEL IN YOUR KIT
Retreatment (label):
Single treatment effective for labeled parasites.