Derm's dirty Dozen, The top chronic, recurrent cases destined to cause frustration - DVM
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Derm's dirty Dozen, The top chronic, recurrent cases destined to cause frustration


DVM360 MAGAZINE


Hyperplastic otitis externa/media I shiver when a Cocker Spaniel walks into my examination room and the owner complains of a "chronic ear infection".Why? These cases are extremely frustrating and often result in failure, especially when it involves Pseudomonas. The most important thing to remember is the hyperplasia resulting from the inflammation and infection can perpetuate the problem. Hyperplasia of the epidermal glands can accompany the primary otitis and make matters worse.

The causes of otitis (especially in the Cocker Spaniel) are many and usually include anatomy, allergy, hypothyroidism and primary seborrhea. These underlying causes can initiate the infection, but the resulting hyperplasia and microbial overgrowth perpetuate it.

The first thing to do is to take a thorough history and perform a good examination. An examination includes performing otoscopy and evaluating the integrity of the tympanum membrane (TM). Once the TM is ruptured, otitis media is diagnosed. Cytological evaluation of the otic exudation is crucial. This may involve obtaining a sample from deep in the vertical canal or middle ear. I base prognosis and treatment upon many things, including the results of otic exudate cytology. Any cytology demonstrating rods should be cultured (aerobic culture and sensitivity).

Treatment includes corticosteroids administered orally and topically if hyperplasia is moderate to severe. Pending results of culture and if numerous rods are visualized upon cytology, I prescribe either aminogylcosides or fluoroquinolones-containing otic preparations with corticosteroids (when hyperplasia is evident). Besides the readily available topical fluoroquinolone or aminoglycoside-containing otic preparations, the following recipes can aid in the treatment of refractory gram-negative or Pseudomonal otitis.
  • Amikacin otic: 15 cc Amikacin (injectable amikacin 50mg/ml) mixed with 15 cc sterile water.
  • Prepared ophthalmic drops (neomycin/-polymyxin/gramicidin) used as an otic product with or without dexamethasone.
  • Prepared ophthalmic drops containing tobramycin with or without dexamethsone.

Pseudomonas is uncommonly cultured from cases of chronic otitis and can be difficult to treat. Treatment can include the above topical otic preparations but always should include appropriate oral antibiotics (choice based upon culture and sensitivity). These can include the fluoroquinolones (enrofloxacin and ciprofloxacin) at dosages of 20 mg/kg/day or marbofloxacin at 2 mg to 5 mg/kg/day. Most often, cases of otitis externa are treated for three to four weeks, and otitis media are treated for four to eight weeks. Unfortunately, if medical management fails, surgery (total ear ablation with or without bulla osteotomy) is advised.

  • Disease 4:

Eosinophilic granuloma in the cat Apparently in the cat, studies have shown that early-age onset cases tend be genetically based and not curable. I found this to be true. Cases that start later in life can be allergic in origin and curable.

Eosinophilic granuloma manifests in several forms. The classic presentation is the so-called rodent or indolent ulcer. This ulcer (which is usually accompanied by swelling) occurs on the upper lip unilaterally or bilaterally and can be confluent. Most cats are unaffected by this ulcer and seem to go about life without any problem. My opinion is that Main Coon cats, the Siamese breeds and other exotic breeds are predisposed early in age with onset of disease. The so-called granuloma also can involve the trunk, paw pads or the caudal thighs (linear granuloma). Some of these cats effected with haired-skin granuloma are pruritic.

In the late age of onset cases (and even in a few of the early age in onset cases), it is worth pursing underlying allergy as a primary cause. My opinion is flea allergy is the most-common cause of these eruptions. Atopic dermatitis and food allergy are two very uncommon causes of indolent ulceration and eosinophilic granuloma formation.

Treatment can include oral and injectable corticosteroids. Luckily, feline patients tolerate corticosteroids well, so I usually prescribe either oral triamcinolone or dexamethasone. I prefer oral corticosteroids, as the injectable forms are unpredictable in the onset of effect and duration. I also specifically prefer oral triamcinolone, as dexamethasone can cause diarrhea. Dosages of triamcinolone are similar for most average 5 kg cats. Tapering dosages of 0.75 mg twice daily are usually sufficient over two to three weeks to resolve most cases. Occasionally, bacterial colonization occurs (especially on the lip) and antibiotics can help or even resolve these lesions. Cyclosporine at 5mg/kg/day has been used as alternatives to corticosteroids. I have also used injectable gold and chlorambucil therapy in the treatment of refractory cases of eosinophilic granuloma in the cat with some success.


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