The label is the law. Read your product's label before you mix or apply; the rates here come from the labels listed under Sources.
- Active ingredient
- Tetrachlorvinphos (TCVP)
- Chemical class
- An organophosphate cholinesterase inhibitor. It was first registered as a pesticide in 1966, and all crop uses were voluntarily canceled by 1987.[1][2]
- Mode of action
- IRAC Group 1B: Acetylcholinesterase inhibitors: organophosphates[3]
- Signal word
- Hartz 2 in 1 Plus Seven Month Collar for Dogs: Caution[1]
EPA's review of TCVP pet collars
EPA began registration review of TCVP in 2008, and in 2009 the Natural Resources Defense Council petitioned EPA to cancel all pet uses. EPA's 2020 revised assessment found risks of concern from TCVP dusts and powders on cats and dogs, so Hartz voluntarily canceled all its dust and powder products for pets, canceled one collar registration and switched to thinner collars that release less TCVP over time.[2]
EPA denied the petition in July 2020, but in April 2022 the Ninth Circuit found the denial unsupported on how much TCVP the collars release as dust and on the assumption that owners trim collars by at least 20%. In October 2022 EPA granted the petition for pet collars and began drafting a proposed notice of intent to cancel them.[2]
The registrant then submitted a new dust study and on-animal fur clipping studies. Using those data, EPA's September 2023 revised assessment found no residential risks of concern for adults or children, and the agency decided not to pursue cancellation of the collars. Its June 2024 interim decision requires pet product registrants to submit annual enhanced reports and annual sales information and adds risk mitigation for livestock and poultry uses.[2]
Where it is used
TCVP is formulated as dusts, pet collars, sprays, emulsifiable concentrates, feed additives, feed blocks, wettable powders, pellets and granules, and it is also applied as a perimeter treatment around livestock premises and facilities.[2]
The dog collar is unrolled and stretched to activate the insecticide, then buckled loosely enough to move around the neck; a properly fitted collar will snugly slide over the dog's head. The label says to leave 2 or 3 inches for adjustment and cut off the rest.[1]
It starts killing fleas and ticks right away. Replaced every 7 months, it gives continuous protection: it kills ticks for 5 months and aids in their control for another 2.[1]
Swimming and rain don't reduce its effectiveness, and it can be worn with a regular collar. The label recommends also treating the pet's bedding or sleeping quarters with a product registered for that use.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Hartz 2 in 1 Plus Seven Month Collar for Dogs[1] | The Hartz Mountain Corporation | 2596-84 | 14.55% | impregnated flea and tick collar | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Hartz 2 in 1 Plus Seven Month Collar for Dogs | Dogs and puppies 12 weeks of age and older | Fleas and ticks | 1 collar per dog[1] Replace every 7 months; with severe infestations it may be replaced sooner, but not more often than every 5 months. |
How to apply it, step by step
1. Protective gear
- This is a CAUTION-signal product: harmful if swallowed or absorbed through skin, and moderately irritating to the eyes. Avoid contact with eyes, skin and clothing, and don't let children play with the collar.[1]
- Wash your hands thoroughly with soap and water after handling it and before eating, drinking, chewing gum, using tobacco or using the toilet.[1]
2. Before you spray
- Don't use it on puppies under 12 weeks of age, and don't use it on a dog at the same time as, or within 30 days before or after, treatment with or exposure to other cholinesterase-inhibiting drugs, pesticides or chemicals.[1]
- Ask a veterinarian before using it on a debilitated, aged or medicated dog. If you use it on a pregnant or nursing dog, don't replace the collar until the puppies are at least 12 weeks old.[1]
- Keep the collar rolled up in its package until you're ready to put it on.[1]
3. Mixing
- There's nothing to mix. Take the collar out of the package, unroll it and stretch it, which activates the insecticide.[1]
4. Applying
- Put the collar around the dog's neck, adjust it and buckle it. It has to be worn loosely so it can move around the neck and allow for growth: a properly fitted collar will snugly slide over the dog's head when fastened.[1]
- Leave 2 or 3 inches for adjustment, then cut off the extra length and throw it away. The collar can be worn along with a regular collar.[1]
5. After you spray
- The collar starts killing fleas and ticks right away. For continuous protection replace it every 7 months; it kills ticks for 5 months and aids in their control for 2 more. With severe infestations you can replace it sooner, but never more often than every 5 months. Swimming and rain don't reduce its effectiveness.[1]
- Any collar can irritate if it is too tight, so loosen it, and remove it if the irritation continues. If signs of sensitivity appear, take the collar off, bathe the dog with mild soap and rinse with plenty of water, and call a veterinarian immediately if the signs continue.[1]
First aid
- If swallowed, call a Poison Control Center or doctor immediately for treatment advice. Have the person sip a glass of water if able to swallow, don't induce vomiting unless told to, and give nothing by mouth to an unconscious person.[1]
- On skin or clothing, take off contaminated clothing and rinse the skin with plenty of water for 15 to 20 minutes; in the eyes, rinse gently for 15 to 20 minutes, removing contact lenses after the first 5 minutes. Call a Poison Control Center or doctor for advice. The label's 24-hour line for health concerns and incidents is 1-800-275-1414, and its note to physicians and veterinarians says atropine is the antidote.[1]
Storage, spills and disposal
Safety and environmental hazards
People
Signal word CAUTION: the collar is harmful if swallowed or absorbed through skin and moderately irritating to the eyes, children shouldn't play with it, and you should wash your hands after handling it. EPA's 2016 human health assessment found risks of concern for people, including children, exposed to TCVP dusts, powders and pet collars, but its September 2023 revision, using new collar data, found no residential risks of concern for adults or children. The label also carries California's notice that the product contains a chemical known to the State of California to cause cancer.[1][2]
Pets
The label bars use on puppies under 12 weeks and within 30 days before or after a dog is treated with or exposed to other cholinesterase-inhibiting drugs, pesticides or chemicals, and says to ask a veterinarian before using it on debilitated, aged or medicated animals. Its note to veterinarians lists salivation, pinpoint pupils, incoordination, muscle twitching or weakness, vomiting and diarrhea as possible signs, with atropine as the antidote.[1]
Bees and pollinators
The collar label carries no bee or environmental hazard statement.[1]
Fish and water
EPA's 2016 ecological risk assessment found TCVP very highly toxic to freshwater aquatic invertebrates, with potential acute and chronic risk to listed and non-listed species for all registered uses, and possible risks to mammals, birds, reptiles and amphibians. The collar label says not to contaminate water, food or feed by storage or disposal.[2][1]
Common questions
- Can I use a TCVP flea collar along with another flea product?
- Not with other cholinesterase inhibitors. The label says not to use the collar on a dog at the same time as, or within 30 days before or after, treatment with or exposure to cholinesterase-inhibiting drugs, pesticides or chemicals. EPA encourages pet owners to talk with their veterinarian about which flea and tick product to use.[1][2]
- How long does a Hartz TCVP collar last?
- Seven months of continuous flea and tick protection under normal conditions; it kills ticks for 5 months and aids in their control for 2 more. Even with heavy infestations, don't replace it more often than every 5 months.[1]
- Did EPA ban TCVP flea collars?
- No. EPA granted a petition against the collars in 2022 and began drafting a cancellation notice, but after reviewing new studies it decided in September 2023 not to pursue cancellation. Its June 2024 interim decision added annual enhanced reporting and sales information requirements for pet products.[2]
- What should I do if a child chews on the collar?
- Call a Poison Control Center or doctor right away for treatment advice. The label says to have the person sip a glass of water if able to swallow and not to induce vomiting unless told to. Its 24-hour line for health concerns is 1-800-275-1414.[1]
Sources
- U.S. EPA Pesticide Product Label System, “Hartz 2 in 1 Plus Seven Month Collar for Dogs label, EPA Reg. No. 2596-84 (EPA-stamped, Mar. 25, 2026).” www3.epa.gov/pesticides/chem_search/ppls/002596-00084-20260325.pdf (accessed 2026-11-08)
- U.S. EPA, “Tetrachlorvinphos (TCVP) (last updated July 17, 2026).” www.epa.gov/ingredients-used-pesticide-products/tetrachlorvinphos-tcvp (accessed 2026-11-08)
- Insecticide Resistance Action Committee, “IRAC Mode of Action Classification Scheme, Version 11.5 (Feb. 2026).” irac-online.org/documents/moa-classification/ (accessed 2026-11-08)