What is Otitis Media and Interna?
The ear is not just an instrument for hearing, it also helps your equine keep a sense of balance. The horse’s ear is divided into three parts; the outer, middle and inner ear. The visual part of the ear is called the outer ear and it consists of auricular cartilage, skin, hair, and the auditory canal. The outer ear is also called the pinna or the auricle, it helps collect sound waves. The middle ear includes the eardrum, the eustachian tube, and the three smallest bones in the horse’s body: the malleus, incus, and stapes.
The middle ear helps to transmit sound waves from the outer ear into the inner ear. The inner ear consists of auditory nerves, the cochlea, a bony labyrinth, and the vestibular system which helps maintain a sense of equilibrium (balance). The cochlea in the inner ear helps convert sound waves into nerve impulses, which are then transmitted to the brain.
Inner ear infections can spread to the horse’s brain and lead to meningitis and swelling of the brain. Untreated otitis media and interna in horses can also result in:
- The eardrum rupturing
- Hearing loss
- Neurological issues, such as facial paralysis.
- The fusion and fracture of the tympanohyoid joint. When the tympanohyoid joint fractures, it can cause a hematoma, which can be fatal to the horse
Equine otitis media and interna are the inflammation of the middle ear and inner ear structures. Otitis media and interna are not common problems in horses but once the infection spreads from the middle ear to the internal area, serious consequences can develop.
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Symptoms of Otitis Media and Interna in Horses
Symptoms may include:
- Head tilt
- Ear droop
- Nasal discharge
- Decreased tears
- Ear paresis
- Corneal ulceration
- Inability to blink
- Facial paralysis
- Hearing loss
Causes of Otitis Media and Interna in Horses
Otitis media and interna may be caused by:
- Bacterial infection
- Bottle feeding
- Fungal infection
- Drug reaction
- Food allergies
- Guttural pouch infection
Diagnosis of Otitis Media and Interna in Horses
The veterinarian will want to go over the medical history of your horse. He may ask to see vaccination, dental and deworming records. Let the veterinarian know if your horse is on any current supplementation or medication. The veterinarian will then perform a full physical exam including taking the patient’s temperature, palpating lymph nodes, checking the color of the gums and noting the overall look of the condition of the horse. The veterinarian may want to perform an endoscopic examination, which will check the ear structures.
The horse will need to be sedated for the procedure; if the veterinarian chooses to use an otoscope to examine the ear, the horse will need to have general anesthesia. Further diagnostic tests may include head x-rays, computed tomography of the skull and a culture of the middle ear fluid. A complete blood count will help determine if the patient has a bacterial infection. When allergies are a consideration, the veterinarian may suggest a skin-prick test and/or an IgE blood test.
Treatment of Otitis Media and Interna in Horses
Treatment of otitis media and interna in horses is usually involves the administration of pain medication, nonsteroidal anti-inflammatory drugs, and oral antibiotics. The patient may also be prescribed medicated ear drops. Horses that are experiencing neurological issues may need to be hospitalized for observation and treatment. In some severe cases of otitis media and interna, the veterinarian may refer you to an equine surgeon. The equine surgeon may need to perform a total ear canal ablation or bulla (middle ear) osteotomy.
Recovery of Otitis Media and Interna in Horses
Patients that are treated in the early stages of otitis media and interna have a very good recovery prognosis. It is important to follow the veterinarian’s treatment plan. Follow up visits will be needed to monitor the horse’s progress. Sometimes infections do not respond well to a particular antibiotic. In a case such as this, the veterinarian may need to change your horse’s medication. A complete blood count will need to be retaken to ensure the infection is responding well to the prescribed medication.
If your horse had surgery, he will be kept in the hospital for a minimum of 24 hours. The intravenous therapy will continue overnight, in order to provide fluids and medication to the patient. Once your horse is released, the equine veterinarian will provide you with post-operative instructions. The incision must be kept dry and clean. The horse will be restricted in regards to exercise for 4-6 weeks. Sutures or staples will need to be removed by the veterinarian.