How to Put On a Seresto Collar (Step by Step)
Posted by Flea Collar Direct on Nov 5th 2026
A Seresto collar only works well if it fits well: snug enough to stay in contact with your pet’s skin and coat, loose enough to be comfortable. Here are the label directions, step by step.
Step by step
- Open it right before use. Take the collar out of its protective pouch only when you are ready to fit it. Use one collar per pet.
- Unroll and check. Unroll the collar and make sure no pieces of the plastic connectors are left on the inside.
- Buckle. Insert the end of the collar through the buckle.
- Use the two-finger rule. Adjust it around the neck, not too tight and not too loose. Two fingers should fit comfortably between the collar and the neck.
- Trim. Pull the excess through the loop(s) and cut it to no more than 1 inch (2 cm) beyond the loop. On a growing puppy or kitten, leave extra length.
- Wash your hands with soap and cold water after fitting.
After fitting
- Leave the collar on continuously for 8 months, then replace it.
- Check the fit from time to time, especially on growing pets.
- Don’t attach a leash to the Seresto collar; the label says it may break. Use a separate collar or harness for walks.
- Pets new to collars may scratch at it for the first few days. Slight hair loss or mild skin reactions where it sits may occur and usually clear within 1 to 2 weeks without removing the collar.
- If you see a more serious reaction, remove the collar and contact your veterinarian.
| Collar | For | Pet weight | Minimum age | Collar length |
|---|---|---|---|---|
| Seresto Small Dog | Dogs & puppies | Up to 18 lbs. (8 kg) | 7 weeks | 15 in. |
| Seresto Large Dog | Dogs & puppies | Over 18 lbs. (8 kg) | 7 weeks | 27.5 in. |
| Seresto Cat | Cats & kittens | Any | 10 weeks | See label |
Frequently asked questions
How tight should a Seresto collar be?
Two fingers should fit comfortably between the collar and your pet’s neck.
How much should I cut off?
Trim the collar to no more than 1 inch (2 cm) past the loop, leaving extra on a growing puppy or kitten.
Can I use the Seresto collar as a walking collar?
No. The label says not to attach a leash because it may break the collar.
Information from the EPA-registered Seresto product labels. This is general product information, not veterinary advice; always read the full label and ask your veterinarian about your pet’s health. Flea Collar Direct is an independent retailer, not affiliated with Elanco. Seresto is a trademark of Elanco or its affiliates.