--- title: "Otitis in dogs: primary causes, perpetuating factors and why it keeps recurring" slug: otitis-in-dogs-primary-causes-perpetuating-factors-recurrence excerpt: "Canine otitis is rarely \"just a dirty ear\". When it recurs, there is almost always an untreated primary cause and ignored perpetuating factors. See how the PPSP model organizes clinical reasoning and reduces relapses." author: Milene Fozza category: Veterinary Technology published_at: "2026-07-29T10:32:00+00:00" reading_time: 5 canonical_url: "https://api.allears.vet/en/blog/otitis-in-dogs-primary-causes-perpetuating-factors-recurrence" locale: en --- # Otitis in dogs: primary causes, perpetuating factors and why it keeps recurring External otitis is one of the most frequent complaints in small animal practice — and also one of the most frustrating for the clinician, because it recurs. The owner comes back weeks later with the same reddened ear, the same odor, the same tilted head. The temptation is to repeat the ceruminolytic and topical antimicrobial and move on. But recurring otitis is almost never a topical treatment problem: it is an incomplete diagnostic reasoning problem. To organize that reasoning, it helps to revisit the **PPSP** model — **Primary, Predisposing, Perpetuating and Secondary** factors. Every real case of otitis is a combination of these four groups of factors, and treating only one of them is the recipe for relapse. ## Primary causes: what actually starts the otitis The primary cause is the condition that, on its own, is capable of initiating inflammation of the ear canal in a previously healthy ear. This is where recurrence lives: when the primary cause is not identified and controlled, any improvement is temporary. The main primary causes include: - **Allergic dermatitis** (atopy and adverse food reaction) — the most important. In many dogs with recurrent bilateral otitis, the ear is the first or only manifestation of an underlying allergic skin disease. - **Foreign bodies**, especially grass awns in dogs that spend time outdoors — typically unilateral and acute in onset. - **Ectoparasites**, such as *Otodectes cynotis*, more common in puppies. - **Keratinization disorders** and **endocrinopathies** (hypothyroidism). - **Autoimmune diseases** and neoplastic processes of the canal. The clinical question that changes everything is: *why did this ear become inflamed in the first place?* Without that answer, treatment is palliative. ## Predisposing factors: the favorable terrain Predisposing factors do not cause otitis on their own, but they increase risk by altering the canal microenvironment. They are factors that make the ear more vulnerable: - Pinna and canal conformation (pendulous ears, stenotic canals in brachycephalic breeds). - Excessive moisture (frequent baths, swimming). - Abundant hair in the canal and excess cerumen. - Aggressive cleaning or improper use of cotton swabs, which traumatize the epithelium. Recognizing them matters because some are manageable (bathing routine, drying) and others are anatomical and permanent — which changes the long-term control expectation communicated to the owner. ## Perpetuating factors: why the ear does not heal Here lies the most underestimated reason for recurrence. Perpetuating factors are changes that set in **after** the otitis began and that, on their own, maintain inflammation even when the primary cause is resolved. - **Secondary otitis media** — a canal that seems to respond to topical therapy but does not heal often hides bulla involvement. Without treating otitis media, the external otitis always comes back. - **Proliferative changes and fibrosis** of the canal, which narrow the lumen and hinder drainage and drug delivery. - **Canal mineralization** in chronic cases — at an advanced stage it can make medical control unfeasible and indicate a surgical approach. - **Bacterial biofilm**, which protects microorganisms from antimicrobial action. The central point: **perpetuating factors do not disappear on their own once the primary cause is controlled**. They require their own intervention — and ignoring them is the most common explanation for otitis "that won't respond". ## Secondary factors: what we usually treat first Secondary factors are the agents that take advantage of the altered environment — typically *Malassezia pachydermatis*, *Staphylococcus pseudintermedius* and, in chronic, severe cases, Gram-negative rods such as *Pseudomonas*. They are what cytology reveals and what topical therapy attacks. The classic mistake is treating **only** the secondary factors. They are a consequence, not a cause. Resolving the infection without addressing the primary cause and perpetuating factors only guarantees the dog will return to the clinic. ## Why clinical documentation is part of the treatment Recurrent otitis is, in practice, a disease managed over months. What separates successful control from an endless cycle of relapses is the ability to see the **complete history**: which ear was affected each time, what cytology showed, which primary cause was investigated, whether otitis media has already been considered. In the rush of daily practice, that history gets lost between incomplete records and partial memories. And it is precisely here that recording the anamnesis well stops being bureaucracy and becomes clinical practice.
Track otitis recurrences without rewriting the history
## Conclusion Recurring otitis is almost never a failure of the topical — it is a failure of mapping. The PPSP model forces the clinician to ask not only *which bacterium*, but *why this ear*, *what makes it vulnerable* and *what prevents healing*. Treating all four groups, and not just the secondary one visible on cytology, is what separates real control from temporary relief. And keeping the clinical history accessible and searchable is what makes that follow-up sustainable in routine practice.