Thursday, October 7, 2010

How To Know if Your Dog has an Ear Infection

Ear infections are difficult and painful for your dog. But how can you figure out if your dog has an ear infection, or something more serious? If you suspect your dog has an ear infection, contact VCA-VRA today.

Signs of an Ear Infection

About twice per week we are presented with a dog that has rather profound and acute signs of vestibular disease. These patients usually present a head tilt, often falling towards the side of the tilt, and occasionally vomiting. Early on, the dog will have a peculiar "typewriter-like" movement of the eyes which is called nystagmus. The eyes will move quickly in one direction then drift more slowly in the other direction and this eye movement will continue over and over again. Often, we get concerned pet owners that think these signs might be related to a brain tumor.
About 95% of the time these dogs have a triad of subtle signs which in combination are pathognomonic or absolutely diagnostic for ear disease extending beyond the ear drum. The reason that these cases are presented to us on a referral basis is because this group of clinical signs is rare in the most common form of ear infection. The many thousands of dogs that get an ear infection every year have an infection of their external ear which is technically designated as Otitis Externa. These dogs will typically shake their heads and paw at their ears and rub their ears on the ground. Often evidence of an infection is readily appreciated when one looks into the dog's ear canal unaided.

Issues Associated with Dog Ear Infections

The vestibular signs described above don't occur until the infection has spread past the ear drum which is the farthest medial (towards the midline) extent of the external ear canal.
Virtually all dogs whose infection has spread further and now have a more striking set of presenting signs has some if not all of the abnormalities caused by changes in all three of the nerves noted below: 

  1. 1)      Cranial Nerve VIII: Vestibular Disease - Head Tilt, Circling, Nystagmus  Vomiting, Falling towards the side of the tilt
  2. 2)      Cranial Nerve VII: Facial Palsy - Decreased movement of the face on the same side as the affected ear. The dog cannot blink his eye on that side and frequently his lip hangs down and won't move. Most of the time the whole ear moves much less on the affected side compared to the unaffected side.
  3. 3)      Cervical Sympathetic Palsy also called Horner's Syndrome (named after Johann Friedrich Horner, the Swiss ophthalmologist who first described the syndrome in 1869) - the pupil is smaller on the affected eye, the eye is sunken back slightly making the opening or orbital fissure smaller, this sign is enhanced because the eyelid droops somewhat.
This triad of signs is not only pathognomonic or diagnostic for ear disease but in virtually every case where middle or inner ear disease is suspected, all three of these nerves are affected. If one doesn't have all three nerves affected, then one should put disease processes, other than an ear infection, higher on the list of potential diagnoses.
What is important to note here is that although many conditions affecting the brain are life threatening, most ear infections are not. For many years we explained how the bony sac that is the middle ear or Tympanic Bulla in dogs is a good place for infection to sit and cause the clinical signs described. Certainly the middle and inner ear is virtually the only place in the skull where all three nerves are in proximity to one another. Repeated advanced studies have shown the middle ears to look perfectly normal in the face of rather severe clinical signs. Some dogs definitely have severe middle ear infections that are well documented with advanced studies, but this is usually the exception rather than the rule. This leaves us to wonder if the adjoining bone, the petrous temporal bone, might be the source of the infection and the area in which these three nerves are affected. At the current time the exact pathology has been elusive and we really can't say more than these dogs have ear disease. Fortunately, response to therapy is excellent.

Treatments for Canine Ear Infections

Topical medications alone are adequate to cure these cases about 95% of the time. We particularly like medications with Dimethyl Sulfoxide (DMSO) in them and have found most of them safe even when the tympanum (ear drum) is torn. Oral medications seem to be unnecessary.
If topical medication does not work, we recommend a thorough inspection of the ear canal and tympanum and bulla with endoscopy. This is often quite successful at removing much of the offensive material and increases the chance of a complete recovery. Unfortunately once the defenses have been breached and an ear infection has occurred, it is easier for the next infection to occur.
A very successful preventative approach that we use on dogs who's infection is under control consists of keeping the ears acidified so that infection is much less likely to take hold. White vinegar mixed with an equal portion of room-temperature water placed in both ears without pressure and then massaged 100 times keeps most infections away. This 50 percent vinegar solution should be used twice per week for good long-term infection prevention.

If you believe your dog has an ear infection and is in need of treatment, contact VCA-VRA today!