A wound drain is a tube that a vet places in a wound so fluid can leave it. After surgery, fluid can build up in the empty pocket under the skin (often called dead space). A drain helps carry that fluid away so it does not collect in the wound [1].
Do not pull, cut or remove a drain yourself. If you have any question about your pet’s drain, ask your vet.
Why vets use drains
Vets often place a drain after surgery that leaves a large pocket under the skin, for example after a lump is removed and the skin is closed over the gap [1]. Whether a pet gets a drain, which kind and for how long depends on the wound, what the surgeon finds during the operation and how much empty space is left [1].
For how vets decide whether to close a wound or leave it open, see stitched or left-open wounds in dogs and cats.
The two kinds of drain
Drains come in two main kinds. A passive drain is a soft tube that lets fluid flow out of the wound on its own. An active drain is a closed system that uses gentle suction to draw the fluid out [1].
Passive drains can let germs travel back up into the wound, and they can irritate the skin around them [1]. In a study of dogs that had skin flap surgery, wounds with a passive drain broke down more often than wounds with an active drain. The authors think suction drains may deal better with the empty space and the fluid in it [1]. Your vet will choose the kind of drain that suits your pet’s wound.
How long a drain stays in
In that dog study, drains usually stayed in for about a week, though some came out after a few days and some stayed in for two weeks or more [1]. The surgeon decides when the drain comes out [1].
Some pets go home with a suction drain still in place. In a study of 101 dogs and cats with this kind of drain, pets sent home with the drain had more problems than pets whose drain was taken out before they left the hospital. Most of those problems were minor and easy to manage, and going home meant a shorter hospital stay [2]. Problems seen with drains at home include the tube slipping out and discharge from the wound [1].
Your vet will decide when the drain can come out.
At home, as directed by a vet
- do not pull, cut or remove the drain yourself;
- follow your vet’s instructions for the drain and any bandage exactly;
- do not give your pet human or leftover medicines unless your vet says so;
- go back for any recheck your vet books.
For more on dressings over a wound, see bandages on dogs and cats.
When to see your vet
Your vet checks the drain and the wound to judge when the drain can come out [1], so keep every recheck your vet books.
See your vet if:
- the drain slips out or comes loose [1];
- you have any question about the drain, the fluid or the wound;
- anything about your pet or the wound worries you or you are unsure about it.
The bottom line
A wound drain lets fluid leave a wound so that it does not collect under the skin. Drains work either on their own or with gentle suction, and your vet decides how long one stays in.
This article is for general information only and does not replace advice from your veterinarian. If you have any question about your pet’s drain or wound, ask your vet.
Sources
- Boonwittaya N, Noonoi P, Prawadwin S, Thengchaisri N. Retrospective comparison of axial pattern and subdermal plexus flaps in canine reconstructive surgery: Surgical outcomes, complications, and factors associated with wound dehiscence. Veterinary World. 2026;19(6):2393-2405. CC BY 4.0. https://pmc.ncbi.nlm.nih.gov/articles/PMC13392620/
- Lu HY, Wright TF. Evaluation of complications and long-term outcomes associated with 101 dogs and cats discharged with and without subcutaneous active closed-suction drains (2014-2022). J Am Vet Med Assoc. 2023;261(10):1510-1517. PubMed abstract. https://pubmed.ncbi.nlm.nih.gov/37330225/