Pet Factsheets

Red eye - hyperaemia

Red eye is a non-specific term used to describe an eye that appears red due to illness, injury, or other conditions. It can be common and occurs when blood vessels in the eye rupture and the white area of the eyeball (sclera) appears red.  Veterinary advice should always be sought urgently when the rabbit's eyes appear red or different in any way. Some of the potential causes are less serious and occur commonly; others are rare but generally more serious.

What are the signs of red eye?

An increased blood flow or intraocular haemorrhage can produce a deep red colour of the sclera and the rabbits eye appears red and blood shot.

Other ocular clinical signs are ocular discharge, excessive blinking (blepharospasm) or bulging of the eye (exophthalmos). The rabbit may also present impaired vision, nasal discharge and swollen eyelids.

More general clinical signs depend on the underlying cause and they can be anorexia, lethargy, gastrointestinal stasis and even bruxism (painful tooth grinding).

Is my rabbit susceptible?

All rabbits can develop red eye although it is more commonly seen in New Zealand White rabbits.

Red eye is a sign of irritation that can be cause by several problems. Conjunctivitis is a common disorder causing red eye that can result from allergies and bacterial or viral irritants and can sometimes occur as a side effect of a respiratory tract infection. Red eye can also develop due to uveitis caused by Pasteurella, E. cuniculi or Staphylococcus infections.

Other common ocular conditions that can cause red eyes are glaucoma and corneal irritation (keratitis). Rabbits that suffer from dental diseases can also develop abscess behind or into the eye that will eventually irritate the eye. Haemorrhage into the eye can also be caused by a knock to the head or eye area. This can be hard to determine since the injury may not have occurred when the owner was present. These rabbits may also exhibit neurological problems due to brain injury.

How is red eye diagnosed?

Your vet may need to investigate and run several tests in order to determine the cause of rabbit red eye. This may include not only a thorough ophthalmological examination but also more general tests such as blood test and radiographic examination.

Most common tests performed in case of red eye are:

  • Tonometry:  measures the pressure in the eye and can diagnose glaucoma and other related disorders.
  • Schirmer tear test: detects dry eye, a condition which can also lead to conjunctivitis and red eye.
  • A blood test for E. cuniculi: although useful, a positive result will not be conclusive that E. cuniculi is the underlying cause of the red eye.
  • Fluorescein stains: aim to rule out ulcerative keratitis, which can be a cause of red eye.
  • General anaesthesia: to examine the teeth and skull.
  • Radiography: x-rays to assess the rabbits tooth roots and rule out abscess. 
  • Ultrasonographic examination of the eye: to exclude other potential causes.

Can red eye be treated?

Depending on the cause, most of the time red eye can be treated.

Mild conditions such as conjunctivitis and keratitis can often be treated with topical treatments, applying eye drops directly into the eye. Other causes may instead require longer treatment.

If the rabbit has been diagnosed with E. cuniculi, the rabbit will require a long-term treatment with fenbendazole (a drug used to treat infections with parasitic worms) and supportive treatment for any other symptoms caused by this disease.

Dental disease is also a long-term problem that requires repeated anaesthesia to remove sharp edges on the molar teeth, possible tooth extractions and surgical removal of associated abscess.

Glaucoma may require surgery and long-term medication, as well.

What is the prognosis?

If the underlying cause can be identified and treated or managed then the rabbit's prognosis is good, especially if the cause is mild and relatively easy to treat, such as conjunctivitis.

Other causes may require longer and even life-long treatment, but if the rabbit is kept comfortable and pain free, then there is no reason to euthanase the rabbit.

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