Addison's Disease (Hypoadrenocorticism) in Cats

Key Takeaways

Addison’s disease (hypoadrenocorticism) is a condition which occurs as a result of a shortage of stress hormones produced by the adrenal cortex.  

• Symptoms of Addison’s are typically vague and nonspecific, such as intermittent vomiting and lethargy

Left untreated, there is a subtle loss of body condition, which may culminate in an ‘adrenal crisis’ where the cat collapses in shock, which is a medical emergency

• Most cases of Addison’s have an unknown cause, but it can be caused by abruptly stopping steroid medications

• Diagnostics include physical examination, urinalysis, diagnostic imaging, and bloodwork

• Treatment usually involves a combination of medications

• With early identification, the prognosis for Addison’s is favorable

• The condition is usually chronic, however a good quality of life can still be achieved with consistent management

A Closer Look: What is Addison's Disease in Cats?

Stress hormones called corticosteroids are secreted by the adrenal glands in the kidneys. Production of these steroids are controlled by the pituitary gland in the brain. Disruption to either of these systems can result in reduced production of these steroids. If this condition persists long term, it can lead to Addison’s disease. This condition is difficult to diagnose because the symptoms are intermittent and non-specific. Left untreated, it is progressive and culminates in adrenal crisis, which is a life-threatening emergency.

Risk Factors

Hypoadrenocorticism is a very rare disease in cats, but it is a serious concern because it often goes undiagnosed until the cat experiences a life-threatening adrenal crisis.  During such a crisis the cat may collapse suddenly and have difficulty breathing with physical weakness and pale gums. In such a scenario the cat requires emergency medical attention. A cat receiving steroid treatments for a different condition can develop iatrogenic Addison’s and similarly suffer an adrenal crisis if the medication is discontinued abruptly.  

If the condition culminates in an adrenal crisis, a sudden onset of these symptoms is expected: 

Collapse • Weakness • Pale gumsRapid breathing (tachypnea)Difficulty breathing

Adrenal crisis is a life-threatening medical emergency requiring immediate veterinary attention.

Possible Causes

Auto-immune destruction of the adrenal gland is suspected as a potential cause for Addison’s disease in cats, but in most cases the cause is unknown. 

Anything that damages the adrenal glands in the kidney or pituitary gland in the brain can also cause Addison’s, including cancer,  inflammation, infection, or injuries.

When a cat is receiving steroid treatments, their body slows down its natural steroid production in response. If the treatment is discontinued abruptly the cat’s body will find itself with a shortage of steroids, as it takes time for the body to begin producing them again. This subcategory of hypoadrenocorticism is called Iatrogenic Addison’s.

Main Symptoms

Early symptoms of Addison’s disease are often subtle and intermittent, manifesting in moments of stress- or often not at all. The symptoms imitate other medical conditions like an upset stomach and include: 

• Loss of appetite  • LethargyVomitingDiarrhea • Excessive thirst • Excessive urination • Weight loss

Testing and Diagnosis

Medical history, including any prior treatments or diagnoses, and a timeline of symptoms may help suggest a diagnosis of Addison’s.

Diagnostics tools include

• Physical examination • Diagnostic imaging • Urinalysis • Bloodwork

Steps to Recovery

When Addison’s is diagnosed before an adrenal crisis, hormone replacement consisting of oral medication and monthly injections is the course of treatment. Affected cats require regular visits to a vet for bloodwork and shots for the remainder of life.

During an adrenal crisis, diagnosis and treatment often overlap in an effort to save the animal’s life. Treatment includes fluid therapy to restore salt and sugar balance, and IV injections of steroids. Long-term treatment can begin once the cat is stabilized.

For Iatrogenic Addison’s, the previous steroidal treatment is resumed, and then tapered off over time. This allows the body time to gradually resume natural steroid production.

In most cases, Addison’s disease is a lifelong condition. If Addison’s is caught before the crisis stage (and it is the only underlying condition present) the prognosis is favorable. Prognosis for an adrenal crisis is guarded.

The prognosis for iatrogenic Addison’s is good when caught early, with no ongoing treatment required once the steroid medications are withdrawn more gradually.

Prevention

Most cases of hypoadrenocorticism are idiopathic, and without a known cause there is no known way to prevent the disease. Iatrogenic hypoadrenocorticism is prevented by gradually tapering off any steroid treatments per veterinary direction, rather than cutting it off sharply. This condition is not known to be contagious.

Is Addison's Common in Cats?

Addison’s is very rare in cats.

Typical Treatment

• Hormone replacement • Fluid therapy

• Re-starting steroid therapy followed by vet-directed down-titration of medication

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