What Is Nystagmus in Dogs?
Nystagmus in dogs manifests as involuntary movement of the eyeballs, characterized by a back-and-forth or circular motion beyond the dog’s control.
Both dogs and humans experience physiological nystagmus during head movements. This physiological response aids in stabilizing the image the dog perceives while turning its head. It involves the coordination between the eyes and the dog’s vestibular system, which contributes to its sense of balance, understanding of body positioning, and perception of motion direction.
When a dog exhibits nystagmus without head movement, it indicates a malfunctioning vestibular system leading to abnormal (pathological) nystagmus. Pathological nystagmus can also occur due to positional changes, such as when the dog looks upward or lies on its side.
Types
The most common form observed in dogs is jerk nystagmus, characterized by slow movement in one direction followed by a rapid movement in the opposite direction.
Pendular nystagmus involves eye movements occurring at consistent speeds in both directions and is typically attributed to congenital conditions present at birth.
When the eyes move from side to side, it is referred to as horizontal nystagmus, while vertical nystagmus entails abnormal eye movement in an up-and-down direction.
Rotary nystagmus involves involuntary circular motion of the eyes. In rare instances, dogs may display disconjugate nystagmus, where each eye oscillates in a different direction, such as one eye moving horizontally while the other moves vertically.
Symptoms
Nystagmus in dogs typically presents alongside alterations in the pet’s balance or other neurological indicators. Symptoms may include:
- Involuntary and repetitive eye movements
- Head tilting
- Circular walking patterns
- Tumbling or rolling over
- Unsteady gait resembling drunkenness (ataxia)
- Asymmetrical pupil direction (strabismus) or uneven pupil size
- Reduced coordination or difficulty in discerning limb placement
- Decreased mental alertness
Causes
Nystagmus in dogs often arises due to pathological factors, commonly associated with damage to the middle/inner ear or the brain, crucial components of the vestibular system. Causes comprise:
- Infections of the inner or middle ear
- Surgical procedures or cleaning of the middle ear
- Congenital or hereditary anomalies
- Tumors affecting the middle or inner ear, as well as brain tumors
- Head injuries
- Strokes
- Inflammatory conditions of the brain like granulomatous meningoencephalitis (GME)
- Brain infections such as those caused by distemper virus or neosporosis
- Medications and toxins such as metronidazole, anesthetics, or marijuana
- Hypothyroidism, although rare
- Idiopathic peripheral vestibular disease, a common disorder in senior dogs, characterized by nystagmus, head tilt, and disorientation without a known cause.
Certain dog breeds may have a heightened risk of congenital nystagmus, including Doberman Pinschers, Cocker Spaniels, and German Shepherds, although nystagmus can occur in any breed. Abnormal nystagmus necessitates contacting a veterinarian. If a dog’s disorientation raises concerns about potential self-injury, urgent care veterinary services should be considered.
Diagnosis
Veterinarians diagnose nystagmus in dogs primarily through physical examination, although determining the exact cause solely through examination is not always possible.
Diagnostic procedures typically involve a neurological examination, which includes reflex testing and observation of the dog’s gait to pinpoint the affected part of the vestibular system. An examination of the ears is also essential; a torn or swollen eardrum may indicate a middle or inner ear infection.
In certain cases, veterinarians may suggest puncturing the eardrum (myringotomy) to obtain a sample for culture from the middle ear. This procedure requires anesthesia for the pet. If a middle or inner ear condition is suspected, a veterinarian may recommend a CT scan, usually performed at specialized clinics or veterinary hospitals under sedation or general anesthesia.
When concerns arise regarding brain involvement, veterinarians are more inclined to propose an MRI and analysis of the cerebrospinal fluid surrounding the brain. These procedures are typically conducted at specialty clinics or veterinary hospitals under general anesthesia. Pet owners should inform their veterinarians about recent ear cleanings, ear medications, any new medications the pet is taking, and potential exposure to marijuana.
Treatment
Treatment for nystagmus in dogs primarily targets addressing the underlying condition responsible for its manifestation, as nystagmus itself cannot be directly cured. When an underlying cause like an inner ear infection is identified, treatment focuses on resolving that condition, subsequently alleviating the nystagmus.
In instances where nystagmus arises without a discernible cause, as seen in idiopathic vestibular disease, treatment primarily involves providing supportive care. This may include environmental modifications to prevent self-injury and administering anti-nausea medications like maropitant citrate.
Dogs affected by brain disorders generally have a poorer prognosis compared to those with idiopathic vestibular disease or ear-related conditions. Treatment approaches vary considerably depending on the specific condition, such as a brain tumor or an infection.
Living and Management
Recovery and management of nystagmus in dogs vary depending on the underlying cause:
In cases where nystagmus is part of idiopathic vestibular disease, improvement typically occurs within one or two weeks. Nystagmus may naturally subside over several weeks, but if the underlying cause remains unresolved, symptoms may persist.
Due to altered balance with nystagmus, ensuring the safety of your pet is crucial to prevent accidental injuries. This involves keeping them away from stairs, porches, and other potential fall hazards, and considering confinement in a well-padded area. While placing them in a dark room might seem beneficial, it can exacerbate their balance issues by impairing their sense of orientation.
Conditions leading to nystagmus can recur, so one episode does not render your dog immune to additional episodes. Vigilance and appropriate management are necessary for ongoing care.
Prevention
Preventing nystagmus in dogs is challenging as most cases are not preventable. However, precautions should be taken during ear cleaning, as vigorous cleaning can potentially result in vestibular dysfunction and subsequent nystagmus.
Always consult your veterinarian before administering any ear medications, even if they have been used previously. Timely treatment of ear infections is crucial, as they can escalate to affect the middle or inner ear. It is important to address your dog’s ear infections promptly to prevent complications.
Nystagmus in Dogs FAQs
Is nystagmus in dogs painful?
Nystagmus in dogs itself isn’t painful, but the disorientation it causes can be distressing for them. Falls resulting from nystagmus may lead to injury, and underlying causes such as ear infections can cause discomfort.
What triggers dog nystagmus?
Dog nystagmus is typically triggered by dysfunction within the vestibular system. While often occurring without a known cause, conditions affecting the middle ear, inner ear, or brain can lead to nystagmus.
Does nystagmus in dogs affect their vision?
Most dogs with nystagmus retain their vision, but it may impact depth perception and visual clarity. In cases of congenital nystagmus or conditions affecting the dog, some with nystagmus may experience blindness, although nystagmus itself doesn’t cause blindness.