Anne E. Katherman, DVM, DACVIM (Neurology)
When your pet is stumbling and staggering around, almost as though drunk, the condition is called ataxia. It is an inability to make normal, coordinated, voluntary movements but is not caused by muscle weakness, involuntary spasms, or too little strength to move. Generally speaking, ataxia is a symptom caused by some type of central nervous system problem in which the brain cannot correctly tell the body what to do.
Ataxia affects a pet's ability to coordinate their head, legs, and body. Perhaps the pet cannot place their foot appropriately while walking, resulting in the pet knuckling their feet and dragging their toes on the ground. Since the pet does not realize where their feet are, they cannot just flip the feet over to walk normally. Dragging knuckles on the ground can damage the tops of their feet. Some pets with ataxia do not knuckle their toes, but their foot placement is exaggerated.
Ataxia needs to be differentiated from lameness or weakness due to musculoskeletal disease or generalized illness.
Three types of ataxia can be seen in dogs and cats, depending on whether the inner ear, brain, and/or spine is involved:
- Cerebellar (brain)
- Proprioceptive (brain or spine)
- Vestibular (inner ear)
The cerebellum is the part of the brain that coordinates voluntary movement, allowing your pet to reach toward the water bowl or you to move your arm appropriately when you want to pick something up. Common causes of cerebellar ataxia in pets are congenital defects and inflammatory diseases. Other causes include degenerative neurological diseases, brain tumors, and strokes.
The pet's head and torso sway and stagger (see video) and their feet step up high and wide in an exaggerated walk as though they are about to go up steps even though they're not. They may have head tremors.
Click on Image below to Play Video
Video courtesy of Dr. Leslie A. Jones
Proprioception is an awareness of where your body is positioned in space, strengthening coordination. It tells us how much force to use when pushing or pulling. Proprioception is how your pet knows without looking if their tail or foot is up or down, and you know if you are standing up straight or slanted. Proprioceptive ataxia is caused by a problem in the cerebral cortex of the brain or the spine. Common causes include brain tumors, infectious diseases of the brain or spinal cord, traumatic brain injuries, injured disks, and strokes.
The pet's unsteady body is seen swaying, knuckling, feet crossing over, and with a wide-based stance. You would see an inability to get the limbs into their normal positions. This form can affect one or more limbs and the torso.
Vestibular ataxia is caused by a problem in the vestibular system in the inner ear or within the balance center in the brain, both of which contribute to balance. The vestibular system helps your pet stay upright when walking forward and lets you walk or run on uneven ground without falling. The vestibular systems signal to the brain to let the eyes and extremities know what they are supposed to do. Here, the ataxia is characterized by leaning and falling to one side or, less commonly, both sides. It affects the head, trunk and limbs. It's often the easiest form of ataxia to recognize and often is worse if the animal is removed from contact with the ground.
Pets with vestibular ataxia may have a head tilt, walk like they are going in a circle rather than straight ahead, and may have odd back-and-forth eye movements called nystagmus. Drooling, leaning, rolling, and falling are common. Nausea or vomiting may occur as a result of dizziness.
Image Courtesy of Dr. Wendy Brooks
Your veterinarian will start by taking a detailed history of what has been happening to identify likely causes and will do a neurological examination (neuro exam) to determine where the problem is located. A neuro exam is quite simple and has two objectives: (1) Confirm that the pet has a neurological condition, and (2) see where the problem is located. A neuro exam may sound like you need to see a specialist, but you do not as the exam does not require special knowledge or expensive equipment. Your veterinarian will watch your pet walk, move, check reflexes, see what happens when they lift your pet's leg, and other tests to see what your pet's physical reaction is. The neuro exam checks on:
- Mentation (level and quality of consciousness)
- Posture of head, limbs, and body
- Gait (how the pet walks)
- Postural reactions (incoordination)
- Spinal reflexes (normal, diminished, or increased)
- Cranial nerves (e.g., vision, eye movements, facial sensation, etc.)
- Palpation of the spine to look for swelling or atrophy
- Nociception (ability to sense pain)
A neuro exam will suggest the location of the problem but cannot by itself determine which disease your pet has. The history you provide is the most important information in determining which diseases are likely causes of abnormal signs.
Treatment depends on what is happening with your pet. Your veterinarian needs to figure out where the problem is located, and which diseases are most likely, to determine which tests and treatments to recommend. Hospitalization with some medication to help the pet's specific signs, such as vomiting, and some IV fluids may be of most use, especially early in the game. Good nursing both at the clinic and at home can be helpful.
The prognosis for pets with ataxia depends on where the lesions are located and what the specific disease is that is causing the abnormal signs. Some diseases are benign, and recovery only requires time and supportive care. Other diseases are serious and may be difficult to resolve.