----------------------------------------------------------------------------------------------------------------------------------
Aural hematoma
Introduction
The pinna is composed of a flared cartilaginous extension of the annular cartilage covered with skin. The relatively hairless skin of the concave side is more tighly adherent than the haired skin of the convex side. The pinna is supplied by branches of the external carotid artery and the great auricular artery which branches and courses up the convex aspect of the pinna. The concave aspect is supplied by branches which pass through foramina in the middle third of the pinna or which wrap around the pinnal margins. This pattern of vascular supply explains the tendency for pinnal lacerations to bleed profusely and is the reason for placing mattress sutures parallel to the long axis of the pinna when dealing with aural hematoma.
Aural hematoma
Causes
The underlying cause of aural hematoma is unknown. Various factors heve been proposed to account for the pathogenesis of the lesion itself and for the undelying cause which incites the process: most of these have been shown subsequently to be inadequate in some degree.
Association with Otodectes cynotis
60 percent of dogs and almost 80 percent of cats with aural hematoma were affected with Otodectes cynotis.
Association with otitis externa
70 percent of the dogs and 80 percent of cats were affected with otitis externa, caused by infections or foreign bodies (foxtails) in the external ear canal
Association with trauma
This is most frequently cited as the cause of aural hematoma.
Association with autoimmunity
Some peaople propose that aural hematoma had an immune-mediated, possibly autoimmune, cause.
Association with underlying hypersensitivity
Many cases of aural hematoma appear to be associated with underlying hypersensitivity and in atopy, the most common canine hypersensitivity, lesions are often present on the concave aspect of the pinnae. Certainly, otitis externa is a common manifestation of atopy, as is pruritus of the head and face.
Clinical signs
The symptoms of an aural hematoma are obvious. Depending on the severity of the problem there will be swelling, sometimes extensive. Almost every pet will either be holding the head to one side or either shaking and pawing at the affected side.
Medical Treatment
In a significant number of cases we can alleviate the hematoma by removing the fluid and injecting cortisone into the ear. The problem is that a space is left behind when the fluid is removed and this space may refill with more fluid.
This treatment is usually repeated in one week, although some cases are healed after the first week of therapy. Pets that don't heal after the second treatment need surgical correction.
The initial cause of the hematoma, usually an ear infection, will be treated simultaneously.
Surgical Treatment
It is advantageous in most cases to use medical therapy first because there is no need for general anesthesia, there is minimal discomfort to your pet, and the cost is less than surgical correction. Surgical treatment is used in those situations in which the problem is not corrected with medical therapy.
Of course the ear infection must be treated along with the hematoma.
There are several surgical techniques. The most commonly performed procedure is draining of the hematoma of fluid and blood clots. To prevent the hematoma from refilling with fluid, multiple sutures are placed in the hematoma space either vertically or horizontally, either partly through or completely through the ear flap, with or without ear cartilage removal. Sometimes bandages are applied post-operatively, sometimes not. Sutures are generally left in place for 3 weeks to allow good scarring to take place so that refilling will not occur.
None of these techniques achieve a rapid resolution and all relatively expensive in financial terms for what the owner might consider simply a large 'blood blister'. Good communication with the owner is important.
What when we do nothing?
If left alone, an ear hematoma will resolve by itself. The fluid will be re-absorbed back into the body and the ear flap will again be flat. The problem is that a lot of scarring is associated with this process and the ear is often not cosmetically appealing afterwards (a “cauliflower” ear). It can also take several months to resolve a large hematoma which may be uncomfortable for the pet. If the patient is a poor anesthetic risk it is certainly reasonable to for go surgery.
