Dechra Pharmaceuticals has received FDA approval for Ostiserene, a novel single-dose treatment for canine otitis externa that combines marbofloxacin, terbinafine, and dexamethasone in an otic suspension. This new medication represents a significant advancement in treating challenging and recurrent ear infections in dogs.
"With Ostiserene, we will leverage the proven track record of marbofloxacin, now as part of a single-dose, long-acting solution for the treatment of challenging and recurrent canine otitis externa," said Laura Olsen, president of Dechra North America. "This addition not only expands Dechra's dermatology offerings, it also adds a convenient, broad-spectrum option for veterinarians to use with confidence on their most challenging patients, ultimately fortifying the special bond that people share with their dogs."
Comprehensive Formulation Targets Multiple Pathogens
Ostiserene contains 15.1 mg marbofloxacin, 22.7 mg terbinafine (equivalent to 25.5 mg terbinafine hydrochloride), and 2.01 mg dexamethasone, along with inactive ingredients including mineral oil and paraffin. The product is specifically indicated for otitis externa associated with susceptible strains of yeast (Malassezia pachydermatis) and bacteria (Staphylococcus pseudintermedius) in dogs.
The formulation strategically combines a higher-tier antibiotic with antifungal and anti-inflammatory components, making it particularly suitable for persistent and difficult-to-treat cases. Marbofloxacin, already FDA-approved for bacterial infections in dogs and cats, provides proven antimicrobial efficacy against common otic pathogens.
Clinical Efficacy Demonstrated in Field Trials
Ostiserene's approval follows a rigorous clinical evaluation against a vehicle control in a randomized, masked field study involving 232 client-owned dogs with otitis externa across the United States. By day 30 of the trial, 71.3% of dogs treated with Ostiserene showed clinical improvements in key symptoms including ulceration, redness, swelling, and exudative discharge, compared to just 26.3% in the control group.
The treatment requires only a single application per affected ear, administered by a veterinary professional. All dogs, regardless of size or weight, receive the same pre-measured dose, ensuring accurate administration every time.
Challenging Condition Requires Tailored Approaches
Otitis externa remains one of the most common yet challenging conditions in veterinary dermatology, requiring individualized treatment approaches.
"I think treating otitis externa is so challenging because there's no one size fits all remedy. It's very case-dependent, patient-dependent, client-dependent," explained Julia Miller, DVM, DACVD, in a previous interview about the condition. "It's difficult because you have to be able to pivot and MacGyver things... The lack of a simple easy answer is what makes it so tricky."
Expanding Treatment Options for Veterinarians
Ostiserene's approval comes shortly after Dechra's launch of DuOtic (terbinafine and betamethasone acetate otic gel), an antibiotic-free treatment for yeast-driven otitis externa that received FDA approval in March 2024. Unlike Ostiserene, DuOtic is specifically designed for cases where Malassezia is the primary pathogen, supporting antimicrobial stewardship by avoiding unnecessary antibiotic use.
"It's exciting to have an antibiotic-free otitis externa product specifically designed for Malassezia infections," noted Rusty Muse, DVM, DACVD, regarding DuOtic. "As a profession, we have had to use antibiotics in ears that don't need them for too long. Now, with DuOtic, we don't have to."
Administration and Availability
Veterinarians should note that Ostiserene is not approved for use in cats, and it's recommended to restrain canine patients during administration to minimize post-application head shaking. The product will be available through select veterinary distributors later this year.
With these two new products, Dechra has significantly expanded the treatment arsenal for veterinarians managing canine otitis externa, allowing for more targeted therapy based on the specific pathogens involved and the severity of infection.
