Weakness in Dogs

Key Takeaways

Weakness is a symptom where dogs move slowly, struggle to rise from rest, are reluctant to exercise, and sometimes have muscle shaking. 

• Weakness is associated with many diseases and conditions, which range in severity from mild to life-threatening emergencies

• Cases of weakness always warrant prompt veterinary attention

• Weakness is investigated using physical examination, laboratory testing, diagnostic imaging and muscle stimulation tests

• Treatment targets the underlying condition and typically includes different types of medication such as immunosuppressants, antibiotics, and anti-inflammatories

• Prognosis depends on the underlying condition identified

A Closer Look: What is Weakness in Dogs?

Weakness is a common symptom which can be a feature of many diseases. Mild, gradual onset of weakness is usually not urgent, however, severe, sudden onset weakness is a serious medical emergency.

Severity varies significantly. Progressive conditions such as degenerative myelopathy, a condition where the nerve fibers of the spine stop communicating effectively, initially present with mild weakness but progress to collapse within 6-12 months. 

Other conditions, such as hypothyroidism, result in mild weakness which does not progress over time.

Conditions such as traumatic injuries affecting the spinal cord or internal bleeding present with severe weakness or collapse, usually with a rapid onset. These conditions require emergency veterinary attention.

Possible Causes

Weakness in dogs is categorized by the type of condition causing the symptoms. Categories include:

Degenerative diseases such as degenerative myelopathy or lumbosacral stenosis

Developmental disorders such as fading puppy syndrome

Autoimmune conditions such as immune-mediated hemolytic anemia, steroid-responsive meningioarteritis, and myasthenia gravis

Infectious conditions such as kennel cough, bacterial or viral gastroenteritis, lungworm or heartworm

Inflammatory conditions such as inflammatory myopathy

Conditions with an unknown cause such as idiopathic protein-losing nephropathy

Metabolic disorders such as hypothyroidism, Addison’s disease, Cushing’s disease,  diabetes mellitus, and liver diseases.

Nutritional diseases such as vitamin B12 deficiency

Cancers of the liver, spleen, or lymph nodes

Poisoning such as ethylene glycol, chocolate, and carbon monoxide

Traumatic injuries such as internal bleeding, and spinal injury

Risk Factors

Weakness is sometimes seen alongside other symptoms that can indicate a more severe underlying condition. These include:

• Tremors • Uncoordinated gait (ataxia) • Paralysis • Lameness • Loss of appetite • Weight loss

• Pale gums • Labored breathing

Cases of weakness always warrant prompt veterinary attention

Testing and Diagnosis

Diagnosis of weakness in dogs involves investigation of the underlying condition and includes:

• Physical examination including neurological and orthopedic examination • Blood tests • Urinalysis

• Muscle biopsies • Diagnostic imaging

• Specific tests such as Tensilon test for myasthenia gravis, and stimulation tests for muscle or nerve disorders

Treatment options are specific to the underlying condition but may include:

• Immunosuppressants • Antibiotics • Antiinflammatories • Surgical intervention

Similar symptoms

Dogs that are unable to move normally due to conditions such as joint disease or spinal disc extrusion may appear weak, however typically the symptoms seen in these dogs are associated with pain rather than true weakness.

Associated Symptoms

Weakness is often seen alongside similar symptoms such as:

• Lethargy • Exercise intolerance • Uncoordinated movement (ataxia) • Loss of appetite

Clinical shock or anemia often present as weakness in dogs alongside pale gums and labored breathing.