Addison’s Disease in Dogs  

How Dangerous is Addison’s Disease in Dogs? 

Addison’s disease in dogs is a serious condition that causes various symptoms and requires lifelong treatment. In the case of an Addisonian crisis, the disease can even be life-threatening. 

Causes: What Leads to the Condition? 

The causes of Addison’s disease in dogs (also known as hypoadrenocorticism or adrenal insufficiency) are diverse and not yet fully understood. Therefore, veterinarians group the causes into primary and secondary Addison’s disease. 

Primary Addison’s Disease: Originating from the Adrenal Glands 

The majority of affected dogs suffer from primary Addison’s disease. This results from the destruction of the adrenal gland tissue. Damage most often occurs in the adrenal cortex, where aldosterone and cortisol are produced.

The few functioning cells produce too few hormones, causing cortisol and aldosterone levels in the blood to drop. An electrolyte imbalance due to a lack of aldosterone is called typical Addison’s disease, while the absence of cortisol alone is called atypical Addison’s disease. 

Potential causes of gland tissue damage include: 

• Inheritance: Certain large breeds like Great Dane, Leonberger and Standard Poodle are more frequently affected by Addison’s disease 
• Autoimmune Diseases: The body produces immune cells that attack its own cells, causing damage to various organs, including the adrenal gland 
• Acquired: Conditions such as infections or tumours may damage the adrenal gland tissue
• Iatrogenic: Prolonged use of glucocorticoids (cortisone) in dogs or sudden discontinuation can inhibit the adrenal gland’s function. This form of Addison’s disease is therefore induced by the vet itself (iatrogenic) 
• Cushing’s Disease: Although Cushing’s disease refers to adrenal overactivity, it can unfortunately end in total adrenal gland failure, leading to Addison’s disease in dogs 

Secondary Addison’s Disease: Originating from the Pituitary Gland 

If there is a disorder of the pituitary gland (hypophysis) or the hypothalamus, an important part of the brain, it results in secondary Addison’s disease. The pituitary gland and hypothalamus are the main control centres for adrenal glands, regulating hormone activity through adrenocorticotropic hormone (ACTH) and corticotropin-releasing hormone (CRH).

A lack of ACTH or excessive CRH inhibits cortisol production. 

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Symptoms: What are the Main Symptoms? 

The symptoms of Addison’s disease in dogs vary depending on whether there is a deficiency in cortisol, aldosterone, or both. Aldosterone imbalance affects sodium and potassium levels, so dogs lacking both hormones typically suffer more severely. Symptoms of Addison’s disease in dogs include: 

• General symptoms: Weakness, poor overall condition, depressive behaviour 
• Gastrointestinal issues: Severe (possibly bloody) diarrhoea, vomiting, loss of appetite, weight loss 
• Increased drinking and urination (polydipsia and polyuria) 
• Muscle tremors leading to cramps 
• Addisonian crisis (shock-like state): heart failure, hypothermia, weakness, low blood pressure, life-threatening sudden potassium increase (hyperkalaemia) 

Diagnosis: How is Addison’s Disease Detected in Dogs? 

Addison’s disease is relatively rare in dogs and often presents nonspecific symptoms, making diagnosis challenging. If the vet suspects Addison’s disease, they will initiate various specific tests. 

Important parameters such as electrolyte imbalance can be identified through blood tests and blood pressure measurement. A decreased specific gravity of the urine further supports the suspicion. Narrow blood vessels or small adrenal glands seen in an ultrasound scan are additional significant indicators. 

The vet will perform an ACTH stimulation test for a confirmed diagnosis. An initial blood sample will measure the baseline cortisol level. Then, the vet will inject ACTH and after approx. an hour, take a second blood sample. In healthy dogs, cortisol levels rise after ACTH administration. If cortisol remains unchanged, Addison’s disease is very likely. 

Treatment: What are the Treatment Options? 

Treating Addison’s disease in dogs involves long-term therapy and managing an Addisonian crisis. 

For long-term therapy, glucocorticoids or mineralocorticoids are used, which your dog will typically have to take for life. Regular vet check-ups are required to normalise blood values and determine the right medication dosage. Once stabilised, semi-annual check-ups usually suffice. Long-term medication and regular exams can lead to significant expenses over time. 

An Addisonian crisis requires extensive treatment, often necessitating hospitalization. Treatment includes: 

• Infusions for fluid therapy to stabilise circulation 
• Administration of crystalloids (e.g., sodium) 
• Conducting an ACTH test 
• Multiple doses of glucocorticoids 
• Treating hyperkalaemia with calcium gluconate 

An Addisonian crisis is a life-threatening emergency requiring intensive veterinary care. 

Prognosis: What are the Chances of Recovery from Addison’s Disease in Dogs? 

The prognosis depends heavily on the cause and severity of Addison’s disease. When identified early, slow-progressing Addison’s disease can often be managed successfully with long-term therapy, leading to a long life.

However, an acute Addisonian crisis, incorrect or absent treatment is often life-threatening. Unfortunately, Addison’s disease in dogs is not curable. 

Prevention: How Can I Prevent Addison’s Disease in My Dog? 

While the disease itself cannot be prevented, early diagnosis of similar symptoms may avoid a life-threatening Addisonian crisis. If Addison’s disease is diagnosed, avoid stressful situations like long trips, sports, and dog shows.