Cat itching it's ear


One of the most common reasons pets go to the veterinarian is the dreaded ear infection. There are three type of ear infections: external canal (Otitis externa, OE), middle ear (Otitis media, OM), and the inner ear or brain (Otitis interna, OI). In this post, we’re mostly discussing OE and OM, which account for many ear infections.  


Signs of an Ear Infection

Ear infections can be quite painful for your pet, so you’ll most likely notice signs of discomfort. Some more specific signs that are typical of pets battling an ear infection include:  

  • Crusting or scabs in the ear 
  • Dark discharge 
  • Odor in the ear 
  • Redness or swelling in the ear canal 
  • Scratching at the infected ear 
  • Shaking or tilting their head 


Signs of Ear Infections in Pets


What Causes an Ear Infection?

Allergies can wreak havoc on our pets just like they can on humans. In fact, the most common primary cause for an external canal ear infection (OE) is allergies. The three common allergies are: infectious (fleas, ticks, mite, and lice), environmental (trees, grasses, pollens, weeds, house dust mites, and mold), or food (proteins like beef, chicken, and fish in cats). Infectious and environmental causes are more common than a pure food allergy, which is less than 10% of allergy patients.  

If allergies aren’t the culprit, your veterinarian will look for other potential causes for ear infections.  

  • In older patients, your veterinarian may evaluate your pet for endocrine disorders such as hypothyroidism.  
  • Your veterinarian may look for a foreign body in the ear canal if there are one-sided ear infections that happen acutely.  
  • Tumors can also be a cause of primary ear infections. In young patients, your veterinarian will most likely evaluate for benign growths like polyps or papillomas. In older patients, they may evaluate for malignant cancers like carcinomas.  
  • Rarer causes can include moist dermatitis from the ear staying wet, immune diseases, or topical reactions to medications.  

There can also be specific causes that are more likely for cats or dogs, or even certain breeds. Specific causes for cats could be Ceruminous Cystomatosis (blue ear cysts) or Proliferative Necrotizing Otitis Externa (PNOE). Canine-specific causes for brachycephalic dogs, more specifically Cavalier King Charles Spaniels, would be Primary Secretory Otitis Media (PSOM) or “glue ear” in the middle ear. 


Diagnosing External Ear Infections (OE)

When you come to the veterinarian with concerns about ear health, one of the first things that will happen is the care team will take a history. They’ll ask which signs your pet is displaying, how long your pet has been having signs, how quickly they started, which ears are affected, how old your pet was when signs started, and any other known allergy signs.  

The veterinarian will need to perform a thorough physical. A good physical exam can help tell if the issues look more like an infection, a foreign body, and/or a mass. Your veterinarian will look down both ear canals with an otoscope and see down to the ear drum (tympanic membrane). It is very important to know if the ear drums are intact or not. This affects the whole treatment and helps determine if it is an external issue or if there could be issues with the middle or inner ear.  

The veterinarian will need to know your pet is experiencing any neurologic side effects. This could include signs such as a head tilt, dizziness, rapid eye movement, third eyelid, sunken eye, droopy eyelid, small pupil, or more severe signs as facial paralysis. The presence of neurologic clinical signs like these make veterinarians more suspicious for issues with the middle or inner ear.  

The care team may also order additional tests such as a cytology of any debris or a mite preparation. Additional tests help determine if there are fungal, bacterial, or any infectious organisms. Each microbe or organism has a specific treatment, and dogs and cats may have different treatment plans.  


Dr. Schwartz examining a dog


Delaying the Exam 

If your pet is in too much pain or the ear canal is too swollen, the veterinarian may not be able to perform a thorough evaluation. In these cases, your veterinarian may send your pet home for a few days with an oral steroid. This will help decrease the inflammation and open the ear canal. For pets with known cardiology issues, the veterinarian may consult with a cardiologist to see if steroids can be used. Your veterinarian may also prescribe pain medications to make your pet feel more comfortable.  


Treating External Ear Infections (OE)

Sometimes, your pet only needs an ear cleaner to remove debris, inflammation, or rare/occasional organisms. Other times your pet may get a topical steroid in addition to the ear cleaner to remove inflammation or a few microorganisms.  

The medication may be in the form of a cream, ointment drops from a small bottle, or even a liquid. You can draw up liquid medications by a syringe and apply topically. This allows for more consistent application. Regardless of the form of the medication, treatment times can vary between as little as seven days to 30 days or more in a severe infection.  

In a few cases, an oral steroid may be used to open the ear canal. However, they are rarely used for external ear canal infections unless certain bacteria are present or there is an ulcerated ear canal or topical reaction.  


Diagnosing Middle Ear Infections (OM)

Your veterinarian may suspect an OM if there is a chronic infection or any neurologic signs. If an OM is suspected, patients will be referred to their closest veterinary dermatologist.  

To diagnose an OM, a patient goes under general anesthesia for imaging such as a CT or MRI, video-otoscopy (VO), which is an ear camera, and a myringotomy. For this procedure, a puncture into the middle ear is done by catheter or needle to sample the fluid for culture and flush any liquid/debris until it is clear. A patient will normally be on oral and systemic topical medications for one to three months following this procedure. Regular check-ups with your dermatologist will evaluate how the ear drum is healing and how your pet is responding to treatment. 

Your doctor will test the sample taken from the ear. An aerobic culture or fungal culture helps your dermatologist learn what is growing in the ear canal which helps direct treatment. There can be challenges with treatment in that there are microbes that are showing resistance to medicines (just like in human hospitals). There are also times where the bacteria and fungus create a biofilm around the area. A biofilm is a special film that makes it more difficult for medications to penetrate. Your pet may get other medications in this instance. 

Advanced imaging is also used for masses to see where they have invaded. Your veterinary dermatologist will use the VO machine to get better images of the mass and help biopsy or remove the mass with special tools or a laser.  


Protecting Your Pet’s Ears

Addressing ear infections is important. It helps keep your pet pain free and protects their health and hearing. If you suspect your pet is having chronic ear issues, reach out to your primary care veterinarian. You may also ask for a referral to a veterinary dermatologist or your nearest MedVet.