Cerebellar hypoplasia is a condition that affects the brains of dogs. Dogs with cerebellar hypoplasia are born this way. Although there is no cure for this disorder, many dogs who have cerebellar hypoplasia can go on to live a long, enjoyable, if not a little clumsy, life. 

Here’s everything you need to know about cerebellar hypoplasia in dogs, including causes, signs, diagnosis, and management. 

What is Cerebellar Hypoplasia?

Cerebellar hypoplasia in dogs is a condition where the cerebellum, the part of the brain that controls coordination, fails to fully develop. 

The cerebellum is responsible for:

• Maintaining a dog’s balance by detecting subtle shifts in balance and sending signals to the rest of the body to adjust and/or move to keep upright
• Coordinating muscles to work together so that the body moves smoothly and intentionally
• Coordinating eye movements
• Helping the body learn gross and fine motor skills

Symptoms of cerebellar hypoplasia in dogs are associated with movement, especially intentional movement. Cerebellar hypoplasia can range in severity from mild and barely noticeable to severe, causing tremors, difficulty walking, difficulty eating, and difficulty with pretty much everything other than sleeping.  

What Causes Cerebellar Hypoplasia in Dogs?

Cerebellar hypoplasia occurs when something negatively impacts the development of the cerebellum while a puppy is in utero (before birth, still inside the mother). Cerebellar hypoplasia can be caused by intrinsic factors due to genetic mutations, and is known to be an inherited disorder in Airedales, Chow Chows, Boston Terriers, and Bull Terrier breeds. 

Cerebellar hypoplasia in dogs can also be caused by extrinsic factors. Poor nutrition of the mother dog and infectious diseases, including (but not limited to) canine herpesvirus, canine distemper, fungal diseases, tick-borne diseases, and accidental migration of intestinal parasites into the brain have all been associated with cerebellar hypoplasia in dogs. Exposure to toxins and brain injury or trauma can also cause abnormal underdevelopment of the cerebellum. 

Symptoms of Cerebellar Hypoplasia in Dogs

Intention tremors are a classic sign of cerebellar hypoplasia. Dogs with intention tremors look totally normal until they focus and try to do something (like eating out of a bowl), at which point their head and neck will start to shake or bob back and forth. In puppies, intention tremors may look cute, but they indicate a problem with the cerebellum. 

Additional symptoms of cerebellar hypoplasia in dogs may include:

• General head bobbing
• High-stepping or overstepping when walking
• General clumsiness and unsteadiness on feet
• Poor judgment of distance and frequent falling
• Standing with legs wide to steady self
• Tremoring limbs that get worse when a dog is moving or eating, and get better or disappear entirely when the dog is asleep
• Different-sized pupils in the eyes (rare)
• Hyper-reflexion when reflexes are tested by a veterinarian 

Cerebellar hypoplasia affects puppies and adult dogs the same way. However, because cerebellar hypoplasia generally affects the way a dog walks and moves, symptoms are usually first noticed in puppies as they start to explore their world (around 6 weeks of age). 

Symptoms of cerebellar hypoplasia do not get worse over time, they stay the same, or in some puppies, get better as they adjust to their cerebellar challenges. 

Diagnosing Dogs with Cerebellar Hypoplasia

Cerebellar hypoplasia in puppies and dogs can usually be diagnosed by a veterinarian with a combination of oral history from you (your impressions of how your dog does at home), age and breed information, and physical exam findings. The more information you can give your veterinarian, the better. Details about your dog’s birth and/or mother are particularly helpful, as this condition develops in utero. 

Because symptoms can be mimicked by some metabolic or toxicological conditions (for example, tremors due to poisoning with strychnine, extremely low thyroid, or unregulated diabetic dogs), your veterinarian may recommend running some lab work, such as a complete blood count, blood chemistry, fecal exam, and/or a urinalysis, to rule out other conditions that could cause tremors. 

A diagnosis of cerebellar hypoplasia can be confirmed with an MRI study if so desired, but the signs of cerebellar hypoplasia are usually enough to diagnose the condition without additional imaging studies. 

Cost of Testing for Cerebellar Hypoplasia

• Physical exam and office visit fee ($40-$100, depending on whether you visit a family veterinarian or a board-certified veterinary neurologist)
• Lab work ($150-$300)
• MRI ($2,000-$4,000)

How to Treat Cerebellar Hypoplasia

There is no treatment or cure for cerebellar hypoplasia, but many dogs with this condition can lead a long and happy life. It is important to remember that you have a special needs pet that will need you to look out for him or her. 

Depending on the severity of your dog’s condition, you may need to restrict what your dog can and can’t do to help prevent accidents or injury. You may have to help your dog eat, or you may need to prevent your dog from climbing stairs or swimming to avoid injury. 

Dogs with cerebellar hypoplasia may not be good candidates for group activities, such as visits to the dog park. However, this decision needs to be made on an individual basis with the advice of your local veterinarian, who will be your best resource when it comes to your dog’s limitations.

How to Prevent Cerebellar Hypoplasia in Dogs

Since cerebellar hypoplasia happens in utero, the only way to help prevent it is to make sure pregnant dogs are healthy and safe. This includes: 

• Providing the pregnant dog with adequate nutrition by feeding a food labeled by AAFCO to be complete and balanced, and formulated for growth and lactation, which is usually labeled puppy food
• Checking with your veterinarian before giving any additional supplements to a pregnant dog
• Ensuring that all vaccinations are kept up-to-date and boosted BEFORE the dog gets pregnant 
• Providing adequate internal parasite control by administering a monthly broad-spectrum dewormer against heartworms and intestinal parasites that is labeled safe for use in pregnant or nursing dogs
• Providing adequate external parasite protection by giving a monthly flea and tick treatment that is labeled safe for use in pregnant or nursing dogs
• Preventing access to any household or backyard toxins
• Providing an enclosure to prevent trauma or injury

If you are bringing a puppy home from a breeder or shelter, ask whether there is any known history of cerebellar hypoplasia, especially if you are getting a breed that is at higher risk. Reputable breeders can provide documentation that their dogs are free of genetic disease. Keep in mind that shelter pets may have an unknown history.

Related Conditions

• Cerebellar abiotrophy
• Neuroaxonal dystrophy
• Cerebellar dysfunction as a result of canine herpesvirus