Dog bite injury (around the eye)

Key points at a glance

Key points of this condition

• Dog bites injure about 4.5 million people each year in the United States, and the tissues around the eye are injured in 4% to 17% of cases.
• The main injuries are eyelid lacerations, canalicular lacerations, traumatic ptosis, and orbital fractures, while open globe injury is extremely rare.
• Canalicular lacerations occur more often in dog bites than from other causes, and repair within 48 hours after injury is desirable.
• The infection rate in the head and neck is low, at less than 5%, but despite the rich blood supply, attention is needed for the risk of infection spreading into the skull.
• The key to preventing infection is thorough wound irrigation (at least 150 mL), which can reduce the infection risk by up to 90%.
• The first-line antibiotic is amoxicillin-clavulanate for 3 to 5 days.
• For orbital fractures, early surgery (within 14 days) leaves residual enophthalmos in 20%, whereas delayed repair (after 6 months) reaches 72%.¹⁾

1. What is a dog bite (periocular)?

Periocular trauma caused by a dog bite. It mainly involves eyelid lacerations and canalicular injuries, and rarely is complicated by open-globe injury or orbital fracture.

In the United States, about 4.5 million people are bitten by dogs each year. About 20% of these require medical care (CDC), and emergency department visits account for about 1% of all injuries. Annual medical costs exceed $100 million in the United States. More than 50% of children are said to be bitten by a dog at some point in their lives. Injury to the periocular tissues occurs in 4% to 17% of cases.

15.55% of dog bites are from stray dogs, and severe injuries from stray dogs are reported at 0.97% versus 1.91% for owned dogs. Only about 20% of all cases are reported. About 50% of the dogs that bite are euthanized, and about 60% of dogs that are not euthanized bite again within 3 years.

Q How often is the area around the eye injured when someone is bitten by a dog?

A

Periocular tissues are injured in 4% to 17% of cases. In attacks to the central face, periocular injury occurs in up to 17%. Young children have a higher risk because they are small and their faces are at about the level of a dog’s mouth.

2. Main symptoms and clinical findings

Subjective symptoms

• Pain, swelling, and bleeding around the eye: caused by direct tissue damage from the bite.
• Tearing: caused by impaired tear drainage due to canalicular injury.
• Double vision: caused by entrapment of the extraocular muscles or displacement of the eyeball due to an orbital fracture.
• Nausea and vomiting: may occur as a vagal reflex associated with an orbital fracture.
• Numbness of the nasal ala and upper lip: due to injury of the infraorbital nerve.

Clinical findings

At least two puncture wounds from the upper and lower incisors are characteristic. The main clinical findings are listed below.

• Eyelid laceration: ranges from superficial to full-thickness lacerations. Be sure to check for levator rupture.
• Canalicular laceration: occurs more often in dog bites than from other causes. Lower canaliculus > upper canaliculus > both. If accompanied by medial canthal tendon rupture, the punctum is characteristically displaced laterally.
• Traumatic ptosis: caused by rupture of the levator muscle and levator aponeurosis.
• Orbital fracture: incidence is less than 5%. The nasal bone, maxilla, and orbital bones may be affected. Age under 2 years, large dogs, and severe bites are risk factors.
• Open globe injury: extremely rare. It is thought to be because the blink reflex protects the globe.

Lachman classification

The Lachman classification is used to assess the severity of dog bites.

Stage	Severity of injury
I	Superficial
II	Skin and underlying muscle
III	Traumatic loss of deep tissue
IVA	III + vascular/nerve injury
IVB	III + bone/organ injury

3. Causes and risk factors

Dog bites occur as a combination of abrasions, puncture wounds, lacerations, tissue loss/avulsion, and crush injuries.

High-risk dog breeds: German Shepherd, Doberman, Pit Bull Terrier

Victim risk factors:

• Age: About three-quarters are children under 9 years old. Toddlers are at higher risk of facial injury because they are small and their motor skills are not yet fully developed.
• Sex: More common in males.
• Underlying condition: ADHD

Situational factors:

• Toddlers are often injured by dogs they know (such as family pets).
• Older children and adults are more often injured by unfamiliar dogs.
• With attacks to the central face, periorbital injury occurs in up to 17%.

Prevention and daily care

• When approaching a dog, avoid sudden movements, and keep your distance when the dog is showing warning signs.
• Be careful not to leave a small child alone with a dog.
• After a dog bite, seek medical care promptly and have a specialist check for any injury around the eye.

Q Which dog breeds are more likely to cause periocular bites?

A

German Shepherds, Dobermans, and Pit Bull Terriers are listed as high-risk breeds. However, situational factors (young children, familiar dogs, attacks to the central face) have a greater impact on the risk of periocular injury than the dog breed.

4. Diagnosis and Examination Methods

Initial assessment procedure

1. Rule out life-threatening injuries first (prioritize the full body examination).
2. Perform eye injury assessment first. If there is globe rupture, it takes priority over eyelid treatment.
3. If opening the eyelids is difficult, pull back the eyelids with a Desmarres retractor and observe with a handheld slit lamp.

Laceration assessment

• Check the location, depth, foreign bodies, and tissue loss.
• Check for levator muscle rupture: Always check in eyelid lacerations.
• Check for canalicular laceration: Always suspect it in lacerations medial to the punctum.
• Confirm canalicular rupture: Confirm with irrigation or probing. Be careful, because if irrigation is done carelessly, fluid can leak into the surrounding tissue and make surgery more difficult.
• In bruising lateral to the eyebrow, keep traumatic optic neuropathy in mind and check light perception.
• Severe pain and nausea are signs that suggest a trap-door orbital fracture.

Imaging studies

• CT: For extensive wounds or puncture wounds of the maxillofacial area, perform maxillofacial CT. Also perform CT when a foreign body is suspected.
• MRI: Consider when injury involving the eyeball, orbit, or head and face is suspected.

Q How do you confirm canalicular injury after a dog bite?

A

In eyelid lacerations medial to the punctum, suspect canalicular rupture. Diagnose with irrigation (inject saline from the punctum and confirm passage into the nasal cavity) or probing (pass a probe through the canaliculus to identify the cut ends). If there is also rupture of the medial canthal ligament, a characteristic finding is lateral displacement of the punctum.

5. Standard treatment

General principles

After prioritizing life-saving treatment, proceed in the order of cleansing → wound exploration → wound closure. In the initial phase, limit treatment to simple wound closure and make room for staged surgery.

Infection prevention

Wound irrigation

Amount of irrigation: 150 mL or more (reduces infection risk by up to 90%)

Equipment: 30 mL syringe + 18G catheter

Note: Povidone-iodine is generally not recommended

Prophylactic antibiotics

First choice: Amoxicillin-clavulanate for 3 to 5 days

If penicillin allergy: TMP/SMX, clindamycin, ciprofloxacin, azithromycin

Timing of wound closure: Early closure is recommended for head and neck. If antibiotics are given, closure may be delayed for up to 24 hours

Wound debridement: Avoid eyelid debridement as much as possible. Remove only crushed or contaminated tissue.

Vaccines:

• Rabies vaccine: administer only when infection is strongly suspected.
• Tetanus vaccine: administer to patients with unknown vaccination history, immunodeficiency, or an incomplete initial 3-dose series.

Surgical repair of eyelid lacerations

• Infiltration anesthesia: 0.5–1.0% lidocaine with epinephrine
• Irrigation and foreign body removal: normal saline. Fine foreign bodies are removed under the operating microscope.
• Hemostasis: bipolar coagulation for arterial bleeding
• Minor lacerations: taped closed after disinfection and pressure hemostasis
• Suturing procedure for eyelid margin and tarsal lacerations:
  1. Temporary suturing with 6-0 nylon
  2. Tarsal plate suturing with 6-0 nylon
  3. Bulbar conjunctival suturing
  4. Align the lash line and gray line, then suture the skin (7-0 nylon)
  5. Posterior lamella is repaired in this order: tarsoconjunctiva → Müller’s muscle and levator → medial and lateral canthal tendons
  6. Eyebrow and nasal root are closed with buried 6-0 nylon sutures
• Levator rupture: If the rupture is obvious, suture it. If it is unclear, observe for up to 6 months after injury.

Repair of canalicular laceration

Repair within 48 hours after injury is preferable. Even if only one canaliculus is lacerated, canalicular reconstruction is the basic approach.

• Anesthesia: General anesthesia is preferred. If local anesthesia is used, add an infratrochlear nerve block.
• Surgical technique:
  1. Insert a bougie
  2. Expose the wound with a hook and 4-0 silk traction suture
  3. Search for the ends (milky white to gray-white, ring-shaped)
  4. Insert a silicone tube and guide it into the nasal cavity
• Canalicular wall suturing: 8-0 Vicryl or nylon
• Repair of associated injuries: Horner muscle laceration → suturing, medial canthal ligament laceration → repair
• Postoperative care:
  • Antibiotic + steroid eye drops
  • Remove skin sutures after 5–7 days
  • The first irrigation test is performed about 2 weeks after surgery
  • Remove the silicone tube after leaving it in place for 1–2 months
  • For 2–3 months after removal, check with irrigation every 2 weeks

Management of orbital fractures

• In pediatric closed fractures with extraocular muscle entrapment: indication for emergency surgery
• Reconstruction of open fractures: reconstruct the orbital wall with absorbable implants such as PLLA or silicone sheets.

The relationship between timing of surgery and prognosis is shown below.

According to Courtney DJ et al. (2000), early repair within 14 days leaves enophthalmos in only 20%, whereas delayed repair after 6 months or more leaves enophthalmos in 72%¹⁾. Also, only one-third improve diplopia with delayed repair¹⁾. The infection rate reaches 40% when purulent sinusitis is present, and is about 15% with an intraoral approach¹⁾. Prophylactic antibiotics are given within 3 hours after injury or at the start of surgery¹⁾.

Open globe injury

It is extremely rare. Treat it before eyelid procedures.

Points to note during treatment

• If irrigation testing for a canalicular laceration is done carelessly before surgery, fluid may leak into the surrounding tissues, making it difficult to find the cut ends during surgery.
• If levator rupture is unclear, urgent suturing is not necessary, and 6 months of follow-up is recommended.
• Delayed repair of an orbital fracture greatly increases the risk of persistent enophthalmos and diplopia. Early referral to a specialist is important.

Q What is the most important thing for preventing infection after a dog bite?

A

Thorough wound irrigation is the most important step. Irrigating with at least 150 mL of saline using a 30 mL syringe plus an 18G catheter can reduce the infection risk by up to 90%. In addition to irrigation, give prophylactic antibiotics with amoxicillin-clavulanate for 3 to 5 days.

6. Pathophysiology and detailed mechanism of onset

Mechanism of injury

The injury occurs as a combination of abrasions, puncture wounds, lacerations, tissue loss/avulsion, and crush injuries. At least two puncture wounds from the upper and lower incisors are typical.

Mechanism of canalicular injury

Injury occurs when the eyelid is stretched, creating shear force. In indirect injuries, the tear occurs more toward the nasal side, making repair more difficult.

Mechanism of open-globe injury

This occurs when the mandible enters the orbit (inferomedial side). Because of protection by the blink reflex, it is extremely rare.

Pathophysiology of infection

The infection rate in the head and neck is low, at less than 5%. A rich blood supply helps protect against infection, but the valveless venous system can allow spread into the skull, so it can still become severe.

The oral cavity of dogs contains more than 64 kinds of bacteria. The main causative organisms are shown below.

Pasteurella multocida

Pathology: One of the most important causative organisms in acute infections after bites.

Features: Causes severe pain and rapid abscess formation.

Antibiotic susceptibility: Susceptible to amoxicillin-clavulanate.

Capnocytophaga canimorsus

Pathology: Causes necrotizing infection and fulminant sepsis.

Feature: May become severe in immunocompromised patients (such as after splenectomy).

Course: If diagnosis is delayed, it can be fatal.

Other major commensal bacteria: Streptococci, Staphylococci, Moraxella, Corynebacterium, Neisseria. Note that it can present as a polymicrobial infection and often includes a high proportion of anaerobic bacteria.

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8. References

1. Courtney DJ, Thomas S, Whitfield PH. Isolated orbital blowout fractures: survey and review. The British journal of oral & maxillofacial surgery. 2000;38(5):496-504. doi:10.1054/bjom.2000.0500. PMID:11010781.
2. Desai AN. Dog Bites. JAMA. 2020;323(24):2535. PMID: 32573671.
3. Snook R. Dog bites man. Br Med J (Clin Res Ed). 1982;284(6312):293-4. PMID: 6800436.