These are firm, swollen masses on the inside of your dog's ear flap.

As to "draining the drain", the drainage tube can become clogged. We use a rigid tube and often send home a needle to insert in the middle of the tube to unclog it. Since cat ears stand up instead of hanging down like a dog's ear, gravity doesn't help so much in draining the fluid. That is why you would "milk" the ear to removed the fluid that is accumulating. It shouldn't take much pressure to milk all the fluid through the drain. If it takes much pressure the drain is blocked and you need to call your doctor. Start at the base of the ear and milk/squeeze gently toward the tube opening. I would probably do this two or three times daily.

a broken blood vessel inside your dog's earflap, filled with blood, clots and other fluid.

The simplest and cheapest treatment for a hematoma involves your vet's syringing out, or aspirating, the fluid in the hematoma. She might then inject a steroid into the ear and prescribe medication to combat infection. One week later, your vet repeats the process. If the second treatment doesn't work, the vet may advise surgically correcting the hematoma. In larger dogs with hematomas, one alternative is placing a drain in the ear flap. This allows the fluid to drain continuously for a week or more rather than fill again rapidly as often occurs with aspiration. The ear must be big enough to accommodate the drain and the dog willing to put up with it.

Causes and Treatments for Ear (Aural) Hematomas in Pets - Vetstreet

Because dogs' ear canals are L-shaped (Figure 1), fluid does not drain easily from canal openings . . Quote: "Bilateral myringotomy was performed and the bullae were flushed with sterile saline; large amounts of yellow tinged mucus were removed from both bulla and sent for cytology and bacteriology. The dog was treated post operatively with meloxicam and amoxiclav pending culture results. The owners were contacted one week after surgery and reported an improvement in the dog’s hearing. ... PSOM can cause deafness, neck pain and vestibular disease. It occurs predominantly in Cavalier King Charles Spaniels, and should be considered as a differential diagnosis along with syringomyelia, cervical disc disease and progressive hereditary deafness. ... Diagnosis of PSOM can be challenging. In one report an operating microscope was used to examine the tympanic membrane as it can be difficult to accurately assess opacity of the tympanic membrane or changes in pressure with an auroscope. In this case, MRI clearly revealed bilateral fluid accumulation in the bullae. When presenting signs include head and neck pain, this imaging modality is invaluable in differentiating PSOM from syringomyelia secondary to Chiari malformation. Treatment of PSOM is surgical; myringotomy with subsequent flushing of the bulla is the standard recommendation. In addition, steroids have reportedly been used in conjunction with lavage of the bullae. In some cases, repeated surgeries may be required as the underlying abnormality leads to a potential recurrence of signs."

Fluid in Outer Ear of My Dog - Organic Pet Digest

Material in the middle ear of dogs having magnetic resonance imaging for investigation of neurologic signs. Owen MC, Lamb CR, Targett MP. Vet. Radiology & Ultrasound, Mar 2004, 45(2):149-155. Quote: "The aim of this study was to determine the prevalence and potential significance of finding material in the middle ear of dogs having magnetic resonance (MR) imaging. Of 466 MR studies reviewed, an increased signal was identified in the tympanic bulla in 32 (7%) dogs. Cavalier King Charles spaniels, Cocker spaniels, Bulldogs, and Boxers were over-represented compared to the population of dogs having MR imaging. Five (16%) dogs had definite otitis media and one (3%) had a meningioma invading the middle ear. Of the remaining dogs, 13 (41%) had possible otitis media and 13 (41%) had neurologic conditions apparently unrelated to otitis media. The most common appearance of material in the middle ear was isointense in T1-weighted images and hyperintense in T2-weighted images. There was no apparent correlation between the signal characteristics of the material and the diagnosis. Enhanced signal after gadolinium administration was observed affecting the lining of the bulla in dogs with otitis media and in dogs with unrelated neurologic conditions. In dogs without clinical signs of otitis media, finding an increased signal in the middle ear during MR imaging may reflect subclinical otitis media or fluid accumulation unrelated to inflammation. Brachycephalic dogs may be predisposed to this condition."

Hematoma: Swollen Dog Ear Flap and How to Treat it | PetHelpful