Acute or chronic inflammation of the epithelium of the external auditory canal in dogs, sometimes accompanied by auricular disease or otitis media, mainly manifested as ear itching, auricle and ear canal erythema, excessive secretions and odor in the ear, and may purulent and foul smell in severe cases , and even hyperplasia occludes the ear canal. Causes include:primary causes (allergies, parasites, foreign bodies, endocrine and tumors,etc.), causes (pseudointermediate Staphylococcus, Pseudomonas, Malassezia and other microorganisms), susceptible causes (variety susceptibility, excessive ear hair, abnormal glandular tissue, etc.) and persistent causes (ear canal stenosis, auditory canal mucosal hyperplasia, fibrosis, otitis media, etc.).
The case in this article uses compound miconazole ear drops as an external treatment drug for the ear canal, which can effectively control the external symptoms caused by microorganisms such as coccus and Malassezia, and is safe and well tolerated. The case is sorted as follows.
1. Case information
- Name: Sis
- Varieties: Samoyed
- Age: 8 years old
- Gender: female (sterilized)
- Visiting time: 2022.9.25
2. Medical history investigation
- Problems in consultation: Severe scratching of the right ear
- Chief complaint: The dog scratched his ears 10 days ago, and the scratching was serious. He took it to the pet store for 2 anti-inflammatory injections. After the second medication, there was no improvement. 3 days ago, the scratching became serious and he was transferred to our hospital. There is no other at home. The dog usually takes bath care at home, and took oral medicine in vivo for deworming six months ago. At present, the spirit and appetite are normal, and it has been 10 days since he came to see the doctor when he found the problem.
3. Physical examination
BCS5/9 had good body condition, normal capillary refill time, and normal skin tone.
BW: 24KG, T: 38.2℃, HR: 110 times/min RR: 24 times/min, MM: Pink
On auscultation, the heart rhythm was normal, no obvious heart murmur, no obvious abnormality on palpation of the abdomen, pain on palpation of the right external auditory canal, purulent secretions, foul odor, slight erythema on the left ear, and no obvious secretions. There was no obvious reddening and skin lesions on the whole body.
Test items: otoscopy, cytology, blood tests were not performed because there were no systemic lesions.
The eardrum was intact, the ear canal erythema, and the cytological examination showed a large increase in cocci and Malassezia. The diagnosis direction was canine otitis externa.
4. Diagnosis and Treatment
Ear canal erythema, purulent discharge, and a large increase in microscopic cocci and Malassezia were diagnosed as otitis externa.
Choose the matching ear canal cleaning agent and external medicine for the ear canal, wash and apply the medicine every day, and take the lead to avoid secondary infection caused by excessive scratching.
1.External use: ear canal cleaning agent 1 time/d for 5 consecutive days
2.External use: compound miconazole ear drops once a day for 5 days
After the 5th day of treatment, the right ear had no obvious redness, swelling and ear canal secretions, no odor, no phenomenon of scratching the ear and shaking the head, and the ear canal basically returned to normal.
For cases with obvious swelling or stenosis of the ear canal, irrigation should not be performed. After antibiotics and corticosteroids are used to reduce the swelling, use an otoscope to observe, and then give corresponding therapeutic drugs. In the treatment of ear diseases, glucocorticoids are mostly prednisolone, 0.25-0.50 mg per kilogram of body weight, orally twice a day for 7 to 14 days; after that, the status of external auditory canal infection should be re-evaluated to determine whether additional administration is required 7 to 14 days of treatment, or tapering until discontinuation. When the ear canal is blocked due to skin hypertrophy and hyperplasia, resection of the lateral wall of the external auditory canal or total external auditory canal resection can be performed according to the degree of the lesion.
5. The monitoring of otitis externa
Otitis externa is an inflammatory reaction of the skin of the external auditory canal and is a common disease. Studies have shown that allergies (atopic dermatitis and food allergy) are the most common causes of chronic otitis externa in dogs. After the treatment and recovery, it is necessary to clean the ear canal regularly, pull out the foreign body (ear hair) in the ear canal in time, prevent water from entering, observe whether there is a recurrence after the drug is stopped, and return to the doctor one week after the drug is stopped. Recurrent seizures in dogs after treatment discontinuation require a thorough evaluation of the underlying cause (eg, allergy).
The normal ear can resist biofilm formation and resist the overgrowth of bacteria and yeast due to the internal cleaning mechanism, normal cerumen gland secretions and the antibacterial effect of the normal microflora, but with the development of otitis externa, The self-cleaning function of the ear canal is gradually lost, resulting in slow removal of microorganisms, accumulation of debris and exudates, abnormal earwax composition, and wavy epidermis promoting biofilm formation, resulting in repeated deterioration of the disease course. Once the infection cycle is established and the normal balance mechanism of the ear canal is broken, otitis externa will easily continue to develop into chronic otitis externa regardless of the underlying cause.
7. Home care
Due to the L-shaped structure of the dog’s ear canal, the ability to “ventilate and drain” inside the dog is not very good, and it is easy to accumulate earwax and lead to the growth of microorganisms, thereby causing otitis externa caused by bacterial and fungal infection. Therefore, it is particularly important for animal owners to take daily ear canal care at home. Ear canal cleaning is an important part of managing otitis externa, and ear canal cleaning should be performed regularly in dogs prone to otitis externa to prevent recurrence.
Otitis externa care:
- Clean the ear canal with ear canal cleaner for 5 to 10 minutes, then wipe the ear canal with a sterile cotton ball or suction ear ball to dry the ear canal. Then instill the medicine into the ear canal.
- The ear canal drops are generally used 1 to 2 times a day for 5 days.
Commonly used pharmaceutical ingredients are mainly antibacterial drugs, antifungal drugs and glucocorticoids, etc., and the dosage forms are mostly water or ointment. Common ear medicines on the market include florfenicol and metronidazole ear drops (mostly used for ear canal infections caused by Gram-positive bacteria, negative bacteria and anaerobic bacteria). From the composition of these drugs, we can see their different pharmacological effects in the treatment of otitis externa. According to the feedback of clinical data, the use of preparations containing aminoglycoside antibiotics in the treatment of otitis externa should be avoided, and some dogs may experience adverse reactions.
Most acute otitis externa can be managed with ear cleaning and topical antimicrobial/glucocorticoid products. However, the treatment and management of chronic otitis externa first need to be based on a comprehensive assessment of the underlying causes such as primary factors, predisposing factors, and persistent factors in specific cases, so as to start relevant tests, such as skin examination, cytological examination, and bacterial culture. , ear imaging examination, otoscopy, etc. If the course of the disease continues, it will enter a vicious circle, increasing the complexity of treatment and the probability of treatment failure. Uncontrolled otitis externa may be related to a variety of factors, including: lack of understanding of the pathophysiology of chronic otitis externa, failure to control the primary cause, lesions at the end of the disease course, organic matter/microbe/foreign body/biofilm in the ear canal, medication Ineffective course and dose, otitis media, drug resistance, improper monitoring and care.Chronic recurrent otitis externa relies on more thorough methods such as cleaning the ear canal, systemic and topical therapy with antibacterial therapy, and anti-inflammatory therapy based on the accurate identification of multiple causative factors to solve the problem and prevent recurrence.