A normal occurrence in both people and dogs, positional nystagmus refers to eyes are working in concert with the vestibular system, which is responsible for maintaining normal balance. In contrast, nystagmus in dogs is a condition that involves rapid and involuntary eye movements when a dog isn’t moving their head. The dog’s eyes may jerk back and forth repeatedly.
Seeing a dog with nystagmus can be alarming for anyone. Along with flickering eye movements, your dog may tilt their head to one side or lose their balance easily. If your dog is showing signs of nystagmus, make sure to contact your veterinarian right away. Read on to learn more about nystagmus in dogs including the signs, causes, and treatments.
What Is Nystagmus in Dogs?
Positional nystagmus is when a dog’s eyes move as they turn their head. This is a normal occurrence and helps your dog maintain their balance and know in which direction to move. “The movement should not continue when the head isn’t moving,” explains Dr. Terry Fossum, DVM, board-certified veterinary surgeon and host of The Cutting Edge Vet podcast. “Nystagmus in dogs refers to an involuntary and rhythmic movement of the eyes when the dog’s head is still.”
Typically, nystagmus tells you there is something wrong with the dog’s nervous system, specifically the vestibular system, that warrants immediate veterinary care. Nystagmus, along with disorientation and a loss of balance, may be signs of vestibular disease. Dogs might tilt their head to one side or have difficulty standing or walking.
There are several ways to categorize nystagmus in dogs based on the direction of the eye movement. For instance, nystagmus can be described as horizontal (side to side), vertical (up and down), or rotary (circular motion).
An alternative way to categorize nystagmus is according to how quickly the eyes move. Jerk nystagmus is the most common type. With this form, the eye moves in one direction slowly, then jerks back in the opposite direction rapidly. Another type is rotary nystagmus, which refers to “small, circular movements or oscillations of the eyeballs which may be fast or slow,” she says.
How Is Nystagmus Diagnosed?
In addition to abnormal eye movement, nystagmus may be accompanied by other symptoms, Dr. Fossum says. If your veterinarian suspects your dog has nystagmus, they’ll try to rule out other causes, such as an infection or tumor. Symptoms of nystagmus include:
- A loss of balance or coordination (ataxia)
- A head tilt
- Nausea or vomiting
- Walking in circles
- Drooling
- Rolling or leaning to one side
- Standing with their limbs spread apart to maintain balance
Depending on your dog’s symptoms, a veterinary examination may include a neurologic exam, routine blood work and urinalysis, blood pressure measurements, and skull X-rays. To investigate the possibility of an ear infection, the vet can take a sample from the ear canal for laboratory testing. That way, they can identify the type of debris or organism that’s causing the infection.
In addition, “the veterinarian may refer you to a neurologist, who may elect to sample your dog’s cerebrospinal fluid to try to determine an underlying cause,” she says. Other potential tests include a CT or MRI scan to determine if there are any lesions in the brain that could be causing nystagmus. Following a thorough examination, “if no underlying cause is identified, your veterinarian will likely label your dog as having idiopathic vestibular disease,” she adds. Idiopathic means the disease has an unknown cause.
What Causes Nystagmus?
“Nystagmus is most commonly seen in older dogs with vestibular disease,” Dr. Fossum says. Vestibular disease is also known as “old dog vestibular disease or canine idiopathic vestibular disease and refers to any abnormal function of the middle or inner ear that causes a sudden loss of balance and coordination.” Cocker Spaniels, Doberman Pinschers, and German Shepherds are among the breeds predisposed to nystagmus.
The vestibular system is responsible for maintaining normal balance, head position, and posture. It has components in the brain, as well as the inner and middle ear, which lies just beneath the eardrum. The inner ear consists of the vestibular system and the cochlea, which plays a critical role in a dog’s hearing. The cochlea “is involved in transforming sound waves into electrical impulses that are then sent to the brain,” she says.
Any disease affecting the middle ear or specifically targeting the inner ear has the potential to cause vestibular disease, she explains. For example, the ear can trap moisture and debris, leading to an overgrowth of yeast or bacteria and possibly an ear infection. Moreover, certain medications are associated with vestibular disease, so it’s important to provide a complete list of your dog’s medications to your vet.
Other causes of middle or inner ear disease are trauma, injury, granulomatous meningoencephalitis (i.e., an inflammatory disease of the central nervous system), viral infections such as canine distemper, seizures, congenital abnormalities, hypothyroidism in rare cases, and neoplasia of the inner or middle ear or brain, she says. Neoplasia refers to the abnormal growth of cells or tissues in the body, and the resulting growth is called a neoplasm or tumor, which can be benign or malignant.
Treatment and Prognosis for Nystagmus
Deciding on a course of treatment for nystagmus will depend on what’s causing vestibular disease and the severity of the dog’s symptoms, Dr. Fossum explains. For example, the veterinarian may prescribe an antihistamine, such as Benadryl or meclizine, to help with symptoms like dizziness, nausea, and motion sickness. An anti-anxiolytic can help treat anxiety in dogs. If your dog is vomiting or refusing food, the vet may recommend fluid therapy and enhanced nutrition, or they could put your dog on an antiemetic to ease nausea and vomiting. “In severe cases, hospitalization and fluid therapy may be indicated,” she adds. A vet may also prescribe systemic antibiotics if the cause is a bacterial infection, such as a middle or inner ear infection.
When providing at-home care to your dog, make sure they’re in a safe and comfortable environment, away from stairs or furniture to avoid falling or hurting themselves. Your dog may need help with eating, whether that involves hand-feeding your dog or giving them an appetite stimulant recommended by your vet.
With proper and timely care, “most dogs with mild to moderate symptoms will improve within 72 hours,” she says. “Although, in some dogs, a mild head tilt may take longer to resolve, and mild ataxia may be present long-term.” If brain lesions are the cause, nystagmus tends to respond more poorly than if it were caused by middle or inner ear disease.
In general, nystagmus in dogs isn’t preventable. However, keeping your dog’s ears clean may help deter bacterial and yeast infections that can cause middle and inner ear disease. “Be careful when cleaning your dog’s ears and avoid placing anything deep into the ear canal to avoid inadvertently rupturing your dog’s eardrum and causing middle or inner disease,” she says.
The signs of vestibular disease in dogs can seem very serious and concerning. However, “it is important to remember, in most cases, the disease is self-limiting,” she says. This means that the natural history of vestibular disease is to resolve on its own without treatment. Plus, “the majority of dogs recover completely within two to three weeks,” she adds.
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