6 Steps to Treating Ears

Two Basset hounds from the same home were referred with bilateral ear infections. Patient 1 was a tricolor, spayed female; patient 2 was her daughter, a lemon colored intact female. Both dogs were in severe distress as noted upon external manipulation of the ear canals whereas their general demeanor was otherwise unaffected. The owners were concerned about a contagious problem since both dogs were affected.

History revealed periodic, recurrent bouts of otitis that incompletely responded to a variety of medications. Both dogs had a profound, fruity "hound dog" odor which at times was associated with excessive greasiness which PE interpreted as mild seborrhea oleosa secondary to Malassezia as seen typically in this breed.

PE : Examination with a video vet scope revealed Patient 1 and 2 to have severe bilateral otitis externa. Patient 1 had a severe erythematous pinna, with multiple crater-like ulcers in the lateral and horizontal canals. Patient 1 had bilateral swelling of both vertical canals to the extent that further exam and treatment required sedation.

The discharge was black and waxy in Patient 2 while Patient 1 was profuse, hemorrhagic and mucopurulent. Cytology of patient 1 and 2 done with a modified Wright's demonstrated Malassezia pachydermatis while Patient 2, also showed numerous rods interpreted as most likely Pseudomonas. Patient 2 showed bilateral rupture of the tympanic membrane. I standardly find cytology more rewarding than culture and sensitivity.

DD: The differential of OE is extensive and discussed in other publications. These dogs had various problems complicated b y primary, predisposing and perpetuating circumstances. For brevity sake, we will accept that this breed has extensive ear problems for a variety of reasons. In this case, a primary keratinization disorder predisposed Cutaneous and otic Malassezia which in 1 dog also was complicated by rods presumed to be Pseudomonas.

Step 1 ( See chart) was initiated in Patient 2. Step 4 was initiated in Patient 2. Topical Malassezia was treated in both dogs by using a n acetic/boric acid shampoo twice weekly as well as daily drenching with a leave-on, dry-on acetic-boric acid Conditioner.

Re-exam in 14 days revealed totally normal ear canals in Patient 2. Clinical signs as well as discharge were absent. Step 1 maintenance cleansing was suggested every 3.5 to 7 days.

Patient 1 had reduced inflammation, no exudation, mild erythema, occasional pin point ulcers (evidence of a sever reduction in size). The vertical canal was wider. Continuation of the same treatment was suggested for up to 2-3 months.

It can not be stressed enough that the underlying cause of ear disease must be thoroughly and comprehensively sought. While not mentioned in these cases due to the propensity of Basset Hounds to have primary otitis externa, it is not uncommon for this and other breeds to require a "pruritic clinical trial" (See "Itchy Head to Toe", SA Melman, Vet Forum, 7/97).

The creation of the Gemish serves many purposes. 1). It is non-ototoxic; 2) acetic and boric acid together are cidal to Pseudomonas in 60 seconds, Staphylococcus and Streptococcus in 5 minutes and Malassezia; 3) Baytril penetrates well and has a broad antibacterial spectrum. One negative for fluoroquinolones is that they are just 1 mutation away from being resistant. Other drugs (in terms of excellent in-vitro activity) like aminoglyco sides are inactivated by a n acid pH, ototoxic, not stable or insoluble in an acid solution.

The 6 steps to treating ear disease is a practical, clinical method to plug into one of the most common clinical problems veterinarians face ever day.

How to clean an ear: Apply approximately one (1) teaspoon (5 ml) of the acetic/boric acid into the ear canal and massage thoroughly. Some people occlude the canal with a small amount of cotton during this process to protect against drenching should the pet shake its head. For maximum benefit, allow the solution to remain for at least 5 minutes before attempting to manually clean. Clean the ear by stuffing wads or balls of cotton in the ear and massaging so the debris sticks to the cotton. An applicator stick may be of assistance where repetitive cleaning is required. In dry and/or irritated ears with little debris and/or wax, the cotton may become irritating. In these cases, a tiny bulb or a water pick can be helpful.

In problem ears, the frequency of this process may be increased to one (1) to three (3) times daily. Should medication be necessary, apply after cleaning. A previously little known fact to remember is that with most acidifying ear the ear will be acidified and therefore may inactivate some commonly used drugs like aminoglycosides (amikacin, gentamycin). In those cases, either waiting 4 hours or applying alkalinizing agents will be of assistance. One alkalinizing agent that the literature reports to have primary antimicrobial is Tris-EDTA (Triz-EDTA^TM, DermaPet, Inc, Potomac, MD 20854). To use Triz-EDTA, one should follow the above instructions in how to clean an ear only substituting the alkalinizing Triz-EDTA solution. Repeating Steps 3 and 4 should then be more rewarding.

Step 2. Step 1 (see shampoo therapy) once daily, plus treat twice daily with the "Gemish".

Gemish

12 ml of DermaPet Ear/Skin Cleanser
2 ml of Baytril injectable
6 mg of dexamethasone sodium phosphate (for solubility)
a. Some people add .5-1 ml of medical grade DMSO
b. Some people add ivermectin for a topical treatment.

Step 3a. Step 2 plus a systemic antibiotic such as a flouroquinolone (Baytril) at double the recommended dose.

Step 4. Step 3 plus ear cleansing under anesthesia. Visualization of the ruptured ear drum or swollen tympanum should confirm otitis media. After careful and thorough cleansing and removal of "debris", infuse Baytril and dexamethasone** directly into the tympanum. In the case of a strangulated canal, with a 1 1/2 inch 20 gauge needle, inject approximately 1/2 ml of depomedrol (depending on the size of the pet) as deep as you can between the skin and the cartilage of the ear canal. If a corticosteroid injection is not done then, if there is significant erythema or exudation, then place the dog on short term (7-12 days) short acting corticosteroids. At this stage, some people do culture and sensitivity.

Step 6. Using DermaPet® TrizEDTA Ear/Skin Cleanser clean the ear thoroughly (see instructions) daily for 7-21 days. This is an alkaline solution with a pH of 8***. In many cases, daily cleansing is all that is necessary. If Pseudomonas is suspected and/or otitis media is present then use the appropriate systemic and topical antibiotic after cleansing.

Step 7. Surgery. This is if Step 4 fails and/or calcification of the ear canal is evident.

* There is no simple method of diagnosing cutaneous Malassezia. Do a topical treatment in cases where Malassezia otitis is confirmed by cytology.

** the use of corticosteroids is multifunctional. While we are most familiar with it's anti inflammatory properties, in the case of OM, the reduction in the viscosity of the tympanic exudate is a noteworthy goal.

*** There are reports in the literature of primary microbiocidal properties of tris-edta, particularly to Pseudomonas. Those reports also indicate the evidence for potentiation with antibiotics which otherwise are ionactivated by other acidifying ear cleansers.