Treating otitis in dogs with two formulas: a comparative study
What is otitis in dogs?
Otitis is a disorder that occurs frequently in dogs and cats, characterised by epithelial inflammation of the external auditory canal and pinna. It is one of the leading reasons for consultation at the veterinary clinic and can affect up to 20% of dogs and 6% of cats. The pathogenesis of external otitis can be broken down into primary causal factors, predisposing factors and perpetuating factors and it is typically a combination these factors that determines the overall clinical picture.
How can it be identified?
The clinical signs of otitis in dogs include tilting of the head and frequent shaking, evident pain in the area, moderate to severe pruritus, unpleasant odour, inflammation, aggression when trying to treat the affected ear, exudation and superficial pyoderma in surrounding areas.
Predisposing and perpetuating factors
The predisposing factors make the animal more susceptible to otitis but are never a direct cause of inflammation. They include:
- Moisture in the ear canal.
- High ambient temperature.
- Iatrogenic irritation due to the application of solutions.
- Obstruction of the ear canal (neoplasia, polyps).
- Systemic diseases.
As for perpetuating factors, these are secondary factors stemming from the primary cause which can sustain the inflammatory response even after the resolution of the primary cause. They include:
- Bacterial infections (Staphylococcus, Proteus, Streptococcus and Pseudomonas spp.).
- Fungal infections (Malassezia and Candida spp.).
- Hypertrophy of the epithelium.
- Otitis media.
- Hypersensitivity to topical drugs.
- Iatrogenic (treatment errors).
Treating otitis in dogs
When treating otitis in dogs, besides specific treatment, patients also need supporting treatment through diet and bathes with special shampoos.
In general, the treatment should eliminate the primary cause, control opportunistic bacterial and fungal infections, and keep the ear canal clean and dry, by means of different methods depending on the severity of the clinical picture. Such methods include the use of ceruminolytic agents, topical corticosteroids and even cleansing of the canal under general anaesthesia in severe cases.
Once clean, the ear should be treated with the appropriate agent – acaricide, antifungal or antibiotic – depending on the primary cause. A parenteral and/or oral route can be used in addition to the topical route to help resolve the process. Each pathogen that causes otitis must be treated with a different medication, so it is essential to identify the causal agent in the dog’s ear for successful treatment.
The following measures relate to the targeted treatment of the primary cause:
- Foreign body removal.
- Topical insecticides including ear drops or ivermectin (200–400 µg/kg sc); repeat after 15 days when treating otodectic otitis in dogs and cats.
- Topical and systemic corticosteroids for allergic otitis externa.
- Systemic corticosteroids at immunosuppressive doses in otitis associated with autoimmune diseases.
- Topical corticosteroids, antibiotics and antifungals combined with ceruminolytic, cleansing and astringent drops for seborrhoeic otitis or otitis associated with endocrine disorders.
Regarding treatment of the cause, a phase III clinical study was published in 2015 which compared the efficacy and tolerability of an otic suspension based on the combination of marbofloxacin/clotrimazole/dexamethasone (MCD) against a standard topical treatment.
The authors analysed a total of 140 dogs with clinical signs of acute or subacute otitis externa and identified Staphylococcus, Pseudomonas, Enterobacteriaceae and Malassezia spp. as causal agents. Another sample was also taken in case of failure or relapse and another from dogs with a Pseudomonas infection (on day 14).
The method involved one group receiving MCD and a control group treated with a standard topical treatment called Surolan (containing polymyxin B, miconazole and prednisolone), assessing the efficacy and tolerability at days 7 and 14, and, where applicable, day 28 for dogs treated for more than 14 days.
They found that both treatments produced similar outcomes in terms of efficacy, with a cure rate of 58.3% for MCD and 41.2% for Surolan, and although both medications were equally well tolerated, MCD was superior in terms of pain relief, reduced pus and odour, and improved response rate and researcher assessment on day 14.
With respect to support treatment, both diet and special shampoos are key factors in improving the dog’s condition.
Using a shampoo like Atopic Care Shampoo speeds up the recovery process. It has anti-irritant, restructuring and antiseptic properties, so it is indicated for treating otitis in dogs.
Regarding nutrition, we recommend using the Atopic Care diet.
Canine otitis externa has an excellent prognosis in uncomplicated cases where the primary cause is known and can be treated. If it is accompanied by predisposing and/or perpetuating factors, then the prognosis is less positive.
