Wound, draining tract or pus under the eye in a dog or cat
The typical picture: a swelling appears under the eye or on the cheek, then bursts and drains pus, the spot dries up — and some time later it all happens again. There may also be a wound or a small hole in the skin that won't heal: under the eye, on the cheek, on the chin or along the lower jaw. Antibiotics may improve things for a while, but the source remains. Often it is a diseased tooth, and until the tooth is treated or extracted, the draining tract will keep coming back.
Important note for owners
Under the eye, the infection most often comes from the roots of the upper fourth premolar — the large upper carnassial tooth (108 or 208 in the Triadan system) — or the first molar, and sometimes from the upper canine. A draining tract on the chin or lower jaw is more often linked to the lower canines, the premolars or the lower first molar (309/409).
Most common possible causes
- —A broken tooth with an exposed pulp. Even a small fracture that exposes the pulp gives bacteria a way into the tooth. The pulp dies, and a periapical abscess forms in the bone around the root tip.
- —Pulp death after an injury. A blow can damage the pulp without a visible fracture; such a tooth often changes colour.
- —Advanced periodontal disease. When inflammation spreads down the root to its tip, an endo-perio lesion develops: the infection involves both the tissues around the tooth and the pulp.
- —In cats — canines and premolars. In cats, the canines and premolars can also be the source of a draining tract under the eye or on the jaw, particularly after fractures.
- —Bites and foreign bodies. A bite wound or a foreign body lodged under the skin — such as a grass awn (grass seed) — can look very similar.
- —Skin infection or a tumour. Some skin conditions and growths also look like a non-healing wound. They can only be told apart from a dental draining tract after an examination and X-rays.
When not to postpone an exam
- ✓A swelling under the eye, on the cheek or chin that keeps coming back
- ✓A wound or hole in the skin that won't heal, or heals and then opens again
- ✓Pus draining from the wound
- ✓A broken or discoloured tooth
- ✓Your pet rubs its face with a paw or chews on one side only
- ✓The problem returned after a course of antibiotics
Urgent help needed
- ✓Rapidly increasing swelling of the face, cheek or under the eye
- ✓Swelling around the eye, a bulging eye, or sudden pain when your pet opens its mouth
- ✓Lethargy or a raised temperature
- ✓Complete refusal of food and water
What you can do at home
- ✓Gently clean the skin around the wound with saline or clean water, as your vet advises.
- ✓Don't let your pet scratch the wound: use a protective collar if needed.
- ✓Photograph the wound and the swelling and note the date — this shows how things are changing. You can send the photos for an online consultation on Telegram, but they do not replace an examination.
- ✓If your pet calmly allows it, lift the lip and look at the teeth on that side: a chip or a change in colour is an important clue for the vet.
What not to do at home
- —Don't squeeze out the pus or try to open the swelling yourself
- —Don't apply human ointments or creams
- —Don't give leftover antibiotics — they are prescribed by a vet after an examination, and on their own they will not cure a draining tract
- —Don't give human painkillers — many of them are toxic to cats and dogs
- —Don't wait for the wound to “heal by itself”: until the source is found, it will keep coming back
What diagnostics may be needed
- ✓Consultation: assessment of the wound, the mouth and the teeth on that side
- ✓Examination and probing of the teeth under anaesthesia: fractures, exposed pulp, periodontal pockets
- ✓Dental X-rays of the roots: changes in the bone around the root tip (periapical lesions)
- ✓Sometimes a CT scan may be needed — for example, when the source is not clear on X-rays
The opening in the skin is only the exit of the draining tract; the source is hidden in the bone around the root. The affected tooth may look almost intact, and changes around the root tip are visible only on dental X-rays.
Unfamiliar term in the diagnosis?If the report mentions TR, FCGS, pulpitis or a periodontal stage, the glossary explains each term briefly.GlossaryHow treatment may proceed
- ✓I choose the treatment after X-rays: the key is to remove the source of infection
- ✓Endodontic treatment (root canal treatment) if the tooth can be kept
- ✓Extraction if the tooth cannot or should not be kept
- ✓Once the source is treated, the draining tract usually heals; without that, antibiotics give only temporary improvement
- ✓Antibiotics or pain relief — only as prescribed by a vet after an examination
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Frequently asked questions
An antibiotic suppresses bacteria in the soft tissues, but it does not reach the dead pulp inside the tooth, which has no blood supply. The source remains, and once the course ends the infection finds its way out again. That is why a draining tract of dental origin usually heals only after the tooth is treated or extracted.
The roots of the upper fourth premolar lie close to the area under the eye. When the pulp dies, an abscess forms at the root tip; the pus looks for a way out and breaks through the bone and skin. This creates a draining tract — a channel between the affected root and the skin surface.
Sometimes, yes: if the tooth is stable and enough bone around it is preserved, endodontic treatment may be possible. I make that decision only after X-rays. If the tooth cannot be saved, it is extracted, and the draining tract then usually heals.
It could: bites, foreign bodies, skin infections or tumours can look similar. But a small chip or pulp death after a blow is easy to miss. That is why I recommend starting with an examination of the mouth and dental X-rays.
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