Definition

Inflammation or infection of the uveal tract of the eye consisting of the iris, ciliary body, or choroid. It may also originate in the retina.

Clinical Signs

May see any of the following:

• Excessive blinking
• Watering of eye(s)
• Inflammation of eye(s)
• Pain/sensitivity to light
• Hyperemia (an excess of blood) in conjunctiva
• Lens may have a milky appearance

Etiology

The uvea is the middle layer or vascular coat of the eye. It lies just under the cornea and consists of the iris (the color seen around the pupil of the eye), the ciliary body (structure containing muscle behind the iris, that helps to focus the lens of the eye), and the choroid (the layer of blood vessels that line the back of the eye). These structures make up the uveal tract and supply nutrients to the eye. When these areas become inflamed, it is called uveitis.

Uveitis is classified as: anterior uveitis involving the iris, the ciliary body, or both; posterior uveitis involving the choroid; and panuveitis which involves all three of those structures.

Anterior uveitis is further defined as acute (sudden and of short duration) or chronic (long duration or reoccurring), and granulomatous (a chronic inflammation resulting from a concentric layer of cells causing a lesion) or nongranulomatous.
In nongranulomatous anterior uveitis, pain, redness, light sensitivity, and loss of vision can occur, and usually occurs in one eye.
In granulomatous anterior uveitis, the eye may be less sensitive and mildly inflamed.
In cases where anterior uveitis is severe, conjunctival hyperemia (blood), a layer of white cells (hypopyon), and fibrin (a white filamentous protein), is usually present.
In severe unilateral anterior uveitis, where treatment with use of medications is unable to control pain (seen in rats as continued blinking watery eye, persistent scratching at eye), surgical enucleation of the eye may be the course of action.

In posterior uveitis, inflammatory lesions may be found in the choroid or the retina. In severe posterior uveitis, gradual degeneration with clouding of the vitreous (a transparent gel that fills the eye from the iris to the retina) may be present in both eyes.

Panuveitits is where inflammation or infection involves the entire uveal tract.

The causes of uveitis can be many. Anterior uveitis, involving just one eye, can result from trauma, intraocular neoplasias, or intraocular helminths (parasites). If both eyes are involved, it may be the result of systemic bacterial infections, or viral infections such as (SDAV).

In cases where uveitis is left untreated, secondary complications such as glaucoma, cataracts, retinal detachment, and permanent blindness, can occur.

Diagnostics

Obtain history.

Visual assessment.

Visualization with an ophthalmoscope.

Treatment

Therapy may consist of topical mydriatics (speak to veterinarian regarding mydriatics) to maintain pupillary dilatation and movement depending on location of the uveitis.

Topical corticosteroids or systemic corticosteroids (if nonbacterial) such as prednisone, or dexamethasone , or prostaglandin inhibitors such as aspirin, or flunixin meglumine to reduce inflammation and swelling.

Where corneal ulceration is present topical drops with corticosteroids should be discontinued to prevent increased damage to the eye.

If a bacterial agent is believed to be involved include topical or systemic antibiotics.

Surgical enucleation of eye if treatment is not effective in resolving infection and inflammation, or if persistent pain is involved.

In the event of surgery, the following post-op analgesia may be given:

• For severe pain or first 24 hours post-op: Buprenex (buprenorphine), or Torbugesic (butorphanol).
  

• For mild to moderate pain: Banamine (flunixin meglumine), Metacam (meloxicam), or carprofen. Do not use if a corticosteroid has already been prescribed.
  

• *Note: for pain not controlled by the use of an NSAID (e.g.Banamine, meloxicam, or carprofen), alone, consider alternating or co-administering with a narcotic (e.g., buprenorphine or butorphanol) or narcotic-like (e.g., tramadol) medication.

For information on medications listed, and dosages, see the: Rat Medication Guide.

Nursing Care

• Always wash hands before and after cleaning to prevent spreading the infection to your rat’s unaffected eye, or to other rats in the household.
• If only one eye is involved prevent drainage from the affected eye contaminating the unaffected eye.
• When cleaning eyes with a cloth, do not use a back-and-forth cleaning motion across eye, but clean from inner aspect of eye to the outer portion of the eye to prevent reintroducing infection.
• Use disposable cloths to clean eyes or wash used cloths after each use.
• Use medications as prescribed and for length of time prescribed.
• If condition does not improve or becomes worse notify your veterinarian.

In the event of surgery for enucleation:

• Provide hospital cage during recovery and if there are concerns that their cage mates may groom sutures or wound site.
• Provide clean bedding daily such as felt, soft t-shirt type material or ink-free paper towels. Avoid using material such as terry cloth type towels that can ravel. Also avoid litter-type bedding, post-op, until healed to prevent the chance of wound contamination or infection.
• Provide additional warmth to maintain body temperature within normal limits. It is essential that the rat does not become overheated or dehydrated. The rat should also be able to move away from the heat source if it becomes uncomfortable. If the rat is unconscious or immobile extreme care must be taken to keep the heat low and stable.
  • You can use an isothermic product that is heated in the microwave such as SnuggleSafe®. Make sure to follow the product directions carefully and wrap in a towel before placing in the cage. SnuggleSafe® will provide heat for 12 hours before needing to be reheated. Other similar types of products may vary in re-heat time. Check directions for individual product.
  • If using a heating pad (good for long term use) use only the low heat setting, put a thick towel in between the pad and the cage bottom, and place beneath a corner of the cage.
  • If none of these options are available you can use a plastic bottle filled with hot water, and wrapped in a towel, in the corner of the cage.
• Medicate for post-op pain as needed.
• Provide high calorie foods or food supplements such as Nutri-Cal Paste, canned Ensure, soy or soy formula, during recuperation.
• Encourage fluid intake while recuperating, such as water, or Jell-O water, or electrolyte replacement drinks such as Pedialyte or Gatorade which can be found in local grocery stores.
  • Please note that Pedialyte is only good refrigerated for 24 hours after opened, but can be frozen as ice cubes and thawed as needed.
  • *Note: a juicy type of fruit also provides an additional fluid source in the diet

Outcome

• Inflammation/drainage resolves
• Eye(s) appear normal
• Healed surgical site if enucleation performed

Prevention

• Keep the cage environment clean.
• Rinse cage(s) well following use of disinfectants or cleaning solutions.
• Keep housing environment in a draft free area.
• Use dust free litters.
• Do not smoke in or around where rats are housed.
• Treat all respiratory illnesses promptly.