Auricular (ear)

Definition

A tumor that is attached by a pedicle or stem.

Clinical Signs

May observe any of the following:

• Initial signs of upper respiratory illness with sneezing, or wheezing, and or show signs of an ear infection with or without head tilt.
• A foul odor coming from the ear or see pus.
• A pink to red edematous growth at the opening of the ear canal.
• Bleeding that may occur if polyp ruptures.

*Note: for additional information on recognizing various signs of pain or discomfort refer to: Signs of Pain In Rats.

Etiology

Polyps are generally benign pedunculated (stem or stalk) or sessile growths. They can be found as a singular formation or in grape-like clusters in the nasopharyngeal passages, and the auditory ear canal. The polyp’s appearance may depend upon the type and location. Their etiology is not clearly understood, but is believed they may be idiopathic (without clear pathogenesis or cause), attributed to an autosomal dominant trait (familial), or from an underlying disease process.

It is further believed that chronic inflammation, along with swelling and edema of mucous membranes give rise to polyps, and occurs when normal cell proliferation is altered. It is this proliferation that causes immature epithelial cells to accumulate and form a tissue mass. The increase in the size and the weight of this tissue mass leads to the polyp becoming suspended by a stalk.

Although seemingly rare in rats nasopharyngeal and auricular (ear) polyps can occur, and may emanate from the Eustachian tube having originated in the middle ear. The reason for this is that rats, as well as other animals and humans, can have inflammation and swelling with granulated tissue build up from a chronic middle ear infection due to upper respiratory illness.

Signs of respiratory illness or ear infection often are seen weeks before the rat’s owner is actually able to just see the tip of the body of the polyp just inside the ear. Surgical intervention in larger animals, though helpful, does not always preclude the return of polyps, especially if the polyp is not able to be completely removed. In rats with auricular polyps, the surgical procedure if at all feasible is geared at debulking the polyp, since to remove the entire polyp including its base is virtually impossible in this size of animal. It is for this reason that they are treated medically with topical or systemic steroids to reduce inflammation, along with a broad-spectrum antibiotic for any secondary infections as appropriate.

In addition to polyps being found in nasopharyngeal passages and the middle ear, other sites where they may arise are vascular organs like the uterus and the rectum.

Figure

• Fig. 1: Auricular polyp in a 1½-year-old rat (Lukkas)

Diagnostics

Physical assessment may show pale, edematous, mucosally covered mass, or if in the ear canal wax/pus formation with a pale to pink mass protrusion.

Assess for unrelenting ear or upper respiratory infection with or without waxy to mucopurulent foul odor or discharge at ear.

Treatment

Removal of the growth including base and stem, or if not feasible then removal of as much as possible. One should be aware that the growth may return.

Recommended post-op analgesia if surgery is an option:

• 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 more information on analgesics, and NSAIDs refer to the Rat Medication Guide.

Additional treatment options

May treat with a topical steroid like Tresaderm drops, or a course of systemic corticosteroids such as prednisone, or dexamethasone.

May require additional broad-spectrum antibiotic (e.g., enrofloxacin/Baytril) if infection or abscess also present.

For more information on medications refer to the Rat Medication Guide.

May need to consider euthanasia if tumor effects quality of life.

Nursing Care

• Provide high calorie foods or food supplements such as Nutri-Cal Paste, canned Ensure, soy or soy formula if necessary. Include multi-vitamin supplement (can be found in pet store) if food intake is poor.
• Medicate as prescribed with corticosteroids if surgery not an option.
• If increased signs of swelling, drainage, or odor, seek assistance of a veterinarian.

In the event of surgical debulking of polyp:

• Provide hospital cage during recovery, or 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.
• Encourage fluid intake while recuperating, such as water, 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.

• If condition precludes comfort or quality discuss euthanasia with veterinarian.

Outcome

• A reduction in pain, swelling, odor.
• Increased comfort and mobility.
• Increased quality of life.
• Emotional support for those having to consider euthanasia for their rat.

Prevention

• Do regular physical checks of your rat/s weekly to maintain health.
• Seek veterinarian care if your rat is ill, and treat appropriately for signs of illness.
• Early detection of growth while still limited, improves quality of life.