You may be alarmed if your pet’s eye turns red. Red eyes in pets can be caused by a variety of factors, ranging from minor irritations to serious health conditions. Understanding what may cause this condition and knowing when to seek veterinary care is important to help preserve your pet’s vision. Our Lebanon Animal Hospital team provides information owners should know if their pet has a red eye.

Common causes of red eyes in pets

Numerous conditions can cause your pet’s eye to turn red. Some common causes include:

  • Conjunctivitis — Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva, the tissue lining the eyelid and covering the white part of the eye. This condition can result in signs including redness, swelling, discharge, squinting, tearing, and rubbing at the eye. Conjunctivitis can be caused by infections, such as bacterial, viral, and fungal, allergies, or irritants, such as dust and smoke.
  • Allergies — Allergens, such as pollen, dust mites, mold, or certain foods can trigger an allergic reaction, leading to red, itchy, and watery eyes. Most pets affected by allergies also have other signs, such as itchy skin and potentially, chronic ear infections. 
  • Eye injuries — Pets are curious creatures, and sometimes their explorations can lead to eye injuries. Corneal scratches from foreign objects, such as dirt or grass, or trauma from roughhousing with a playmate can cause redness in the eye. Injuries can be serious and have the potential to get infected, so it’s important to seek veterinary attention as soon as possible if you suspect eye trauma.
  • Dry eye — Dry eye, or keratoconjunctivitis sicca (KCS), occurs when the eye doesn’t produce enough tears to keep the surface lubricated. This can lead to irritation, redness, and a thick, mucoid discharge. Dry eye is more common in certain breeds, such as bulldogs and cocker spaniels, but can occur in any pet. Without treatment, dry eye can lead to severe complications.
  • Glaucoma — Glaucoma causes increased pressure within the eye, which can damage the optic nerve, potentially leading to vision loss. Signs include redness, cloudiness, squinting, and a dilated pupil. This condition requires immediate veterinary care to prevent permanent damage to your pet’s vision.
  • Uveitis — Uveitis is the inflammation of the uvea, which is the eye’s middle layer. This condition can be caused by infection, immune-mediated disease, trauma, and systemic illness. Uveitis signs include redness, pain, squinting, and light sensitivity. If left untreated, the condition can lead to glaucoma, cataracts, and potentially blindness.
  • Entropion or ectropion — Inward-rolling eyelids (i.e. entropion) and outward-rolling eyelids (i.e. ectropion) can cause eye irritation and redness. These conditions are often seen in certain breeds and may require surgical correction if they lead to chronic discomfort or recurrent infections.

When to seek veterinary care for red eyes in pets

While some causes of red eyes in pets may be minor and resolve on their own, others can indicate serious underlying conditions that require prompt veterinary care. Here are signs you should seek veterinary attention:

  • Persistent redness that doesn’t improve in 24 hours
  • Tearing or discharge associated with eye redness
  • Eye swelling or bulging
  • Squinting or pawing at the eye
  • Cloudiness or other changes in the eye’s appearance
  • Vision loss or noticeable changes in your pet’s behavior

How your veterinarian addresses red eyes in pets

If your pet has a red eye, our veterinary team will perform a thorough ophthalmic examination that may include:

  • Fluorescein staining — This special stain highlights corneal scratches and ulcers, making them appear bright green.
  • Tear production test — To assess if your pet’s tear production is adequate, our team inserts a special paper strip under their lower eyelid and measures the tear output for 60 seconds. The distance in millimeters that tears are absorbed in the test strip in one minute represents the millimeters of tear production.
  • Tonometry — We may use a tonometer to measure your pet’s intraocular pressure to check for glaucoma.
  • Ophthalmoscopy — Using an ophthalmoscope, we examine the eye’s interior structures. 
  • Swabs or cultures — If we suspect an infection, we may take a culture to determine the causative pathogen.

Based on these findings, our team will recommend a treatment plan, which may include topical eye medications, systemic anti-inflammatory or pain medications, and in some cases, surgical intervention.

Monitoring your pet’s eyes and seeking veterinary care if you notice persistent or severe redness is important to prevent complications and ensure your four-legged friend’s eyes remain healthy and comfortable. Contact our Lebanon Animal Hospital team if you are concerned about your pet’s eye health.