What Is Neuroaxonal Dystrophy (NAD) in Dogs?
Neuroaxonal Dystrophy (NAD) in dogs is a hereditary disorder affecting their nervous system. It can manifest at birth or later in life. The nervous system facilitates communication between the brain and body parts, enabling movement, cognition, and vital functions like breathing.
Nerve cells consist of the cell body, dendrites, and axon. The cell body serves as the control center, dendrites receive signals, and axons transmit nerve impulses. NAD involves severe axonal swelling, forming spheroids throughout the nervous system. These alterations disrupt signal transmission between cells, leading to neurological issues.
Although NAD is rare in dogs, when neurological symptoms arise, conditions like granulomatous meningoencephalitis (GME) or distemper are more common. Veterinarians will conduct tests to exclude other ailments before confirming NAD.
While NAD is progressive, it typically doesn’t pose an immediate threat upon detection. However, if symptoms like paralysis, sudden blindness, or difficulty walking emerge, emergency veterinary care is imperative. If concerned about NAD symptoms, contacting a veterinarian promptly for evaluation is crucial.
Symptoms
Symptoms of Neuroaxonal Dystrophy (NAD) in dogs typically start mildly but progress, eventually leading to paralysis and blindness. The pace of symptom development varies. For puppies diagnosed with NAD, symptoms tend to escalate rapidly over weeks or months. Conversely, young adult dogs may experience a slower progression lasting over a year.
Common signs include:
- Paw scuffing or dragging
- Weakness in hind limbs, causing difficulty in standing or jumping
- Drunken gait (ataxia) and lack of coordination
- High-stepping gait
- Tremors
- Deafness
- Rigid extension of limbs
- Paralysis
- Nystagmus (involuntary eye movement)
- Blindness
Causes
Neuroaxonal Dystrophy (NAD) in dogs stems from a gene mutation, exhibiting an autosomal recessive pattern. This means that for a puppy to develop the disease, it must inherit the mutated gene from both parents. In certain breeds, the precise genetic trigger remains unidentified.
Dogs inheriting one mutated gene become carriers without displaying NAD symptoms. However, if these carriers breed with another carrier, they risk passing the disease to their offspring. Genetic testing is strongly advised for dogs intended for breeding to identify potential inherited conditions.
Symptoms of NAD may manifest within a few months in some breeds. However, in instances like Rottweilers, onset may occur when the dog is over a year old. The progression of NAD varies, with cases in younger dogs rapidly deteriorating over weeks to months, while older dogs may experience a slower decline lasting months to years.
Despite known instances in specific breeds, NAD remains rare. Breeds associated with NAD include Jack Russell Terriers, Chihuahuas, German Shepherds, Papillons, Dachshunds, Rottweilers, Giant Schnauzers, Border Collies, Boxers, and Spanish Water Dogs.
Diagnosis
Neuroaxonal Dystrophy (NAD) is an exceptionally rare condition in dogs. Initially, veterinarians will likely eliminate other potential conditions before considering NAD testing, often conducted at specialized clinics.
Recommended diagnostic procedures may involve:
- Urinalysis
- Blood tests
- Magnetic resonance imaging (MRI) of the brain and spinal cord
- Computed tomography (CT) of the brain and spinal cord
- Analysis of cerebrospinal fluid (CSF) for signs of inflammation or infection
- Infectious disease screening, particularly for distemper virus
For breeds predisposed to NAD, veterinarians may suggest genetic testing if available. Typically, these tests require either a blood sample or a cheek swab for analysis.
Treatment
Neuroaxonal Dystrophy (NAD) in dogs unfortunately lacks a cure. While some veterinarians may prescribe anti-inflammatory drugs such as carprofen or steroids like prednisone to alleviate inflammation, muscle relaxants like methocarbamol might be considered for pets experiencing rigidity or muscle spasms.
Regrettably, there’s no established medical treatment proven to consistently ameliorate NAD symptoms. Therefore, the primary approach to managing NAD revolves around ensuring the pet’s comfort within the home environment.
Living and Management
As there is no cure for Neuroaxonal Dystrophy (NAD) in dogs, management primarily focuses on providing supportive care and adapting the home environment to ensure the pet’s safety.
Given the challenges with mobility, such as difficulty in walking, running, and jumping, consider placing non-slip mats on hard floors to prevent slipping. Additionally, using ramps to assist your dog with accessing furniture or car rides can be beneficial. Since vision may be impaired, maintaining consistent furniture arrangements in the home can help your dog navigate safely.
Unfortunately, dogs do not recover from NAD. Puppies diagnosed with NAD typically experience a decline over several weeks to months and are often euthanized to prevent further suffering. While dogs diagnosed as young adults may exhibit a slower progression, eventual neurological decline often necessitates humane euthanasia.
Prevention
Preventing Neuroaxonal Dystrophy (NAD) in dogs is challenging since it’s a genetic condition. Pet parents cannot actively prevent NAD in their pets. However, adult dogs over two years old without symptoms are highly unlikely to develop NAD.
To minimize the risk of acquiring a dog with NAD, pet parents can opt to adopt mixed breed dogs from shelters or dogs from reputable breeders. For those considering adoption from a breeder, particularly if the breed has a test available for NAD, inquire whether the breeder has tested the dog’s parents for the NAD genetic mutation. If the breeder hasn’t conducted NAD testing, it’s advisable to discuss the possibility of testing the parents or the prospective pet before bringing them home.