1. Introduction of Cortisol

Cortisol, often referred to as the ‘stress hormone’, is a vital hormone produced by the adrenal glands in pets. It plays a crucial role in regulating various physiological processes, including metabolism, immune response, and stress management. In times of stress, cortisol levels rise to help the body cope with the situation by increasing energy production and suppressing non-essential functions such as digestion and immune response. However, chronic stress or imbalances in cortisol levels can lead to health issues in pets, including immune system suppression, weight gain, and behavioral changes.

2. Clinical Application of Cortisol

In veterinary medicine, cortisol testing is particularly useful in diagnosing conditions such as Cushing’s syndrome (hyperadrenocorticism) or Addison’s disease (hypoadrenocorticism), where cortisol levels are either excessively high or insufficient, respectively. Additionally, cortisol monitoring can aid in assessing the effectiveness of treatment regimens and guiding therapeutic decisions.

3. Cushing’s Syndrome

• Introduction

Cushing’s syndrome, also known as hyperadrenocorticism, is a hormonal disorder commonly observed in pets, characterized by excessive production of cortisol, a steroid hormone, by the adrenal glands. This condition can result from various underlying causes, including adrenal tumors or prolonged administration of corticosteroid medications.

• Common Clinical Symptoms

The clinical symptoms of Cushing’s Syndrome in pets are diverse and reflective of the systemic effects of excess cortisol production. They include increased thirst and urination (polydipsia and polyuria), heightened appetite leading to weight gain and increased abdominal girth, along with skin problems such as thinning, hair loss, itchiness, infections, and inflammation. Pets may also experience muscle weakness and decreased exercise ability. Additionally, there is a heightened susceptibility to urinary tract infections, urinary incontinence, hematuria, and other bacterial infections.

Furthermore, pets with Cushing’s Syndrome may be prone to fractures or joint pain due to weakened bones. Blood tests may reveal elevated levels of certain markers such as ALP (alkaline phosphatase) and BUN (blood urea nitrogen), alongside characteristic changes observed in a low-dose dexamethasone test.

Attention: The corresponding symptoms of Cushing’s syndrome appear, and hypothyroidism should be ruled out first before diagnosis. (T4 and TSH tests can be performed to rule out hypothyroidism)

4. Addison’s Disease

• Introduction

Addison’s disease, also known as hypoadrenocorticism, is a rare but potentially life-threatening endocrine disorder affecting pets, particularly dogs. This condition arises due to insufficient production of adrenal hormones, primarily cortisol and aldosterone, by the adrenal glands.

• Common Clinical Symptoms

Clinical symptoms of Addison’s disease in pets encompass lethargy, weakness, loss of appetite, weight loss, gastrointestinal disturbances such as vomiting and diarrhea, increased thirst and urination (polydipsia and polyuria), dehydration, hypotension (low blood pressure), shaking or tremors, hypoglycemia (low blood sugar), hyperpigmentation of the skin and mucous membranes, and in severe cases, collapse or shock. These symptoms can vary in severity and may come and go intermittently.

Attention: If your pet shows corresponding symptoms, it is recommended to undergo a cortisol test.

4. Dignostic Procedures of Cortisol

• Evaluation of the First Cortisol Test

• Diagnosis of Cushing’s Syndrome

If the first cortisol assessment result is 55-166nmol/L, regular physical examinations are recommended if asymptomatic.

If the first cortisol assessment is greater than 55 nmol/L, Cushing’s syndrome is suspected, and a low-dose dexamethasone stimulation test is required to confirm the diagnosis. Inject 0.01mg/kg dexamethasone intravenously, conduct the second cortisol test 4 hours later, and conduct the third cortisol value test 8 hours later. The interpretation results are as follows.

(Recommendation: fast 6-8 hours before the first cortisol test and 8 hours during the test. You can drink water to avoid mood swings)

• Diagnosis of Addison’s Disease

If the pet’s first cortisol assessment is less than 55 nmol/L, it is suspected to have Addison’s disease, and an ACTH stimulation test is required to confirm the diagnosis. Inject ACTH2.2IU/kg intramuscularly, with a maximum of no more than 40IU. After 2 hours, a cortisol concentration test is performed. The interpretation results are as follows.

In Conclusion

• Cortisol testing focuses on endocrine alopecia, skin pigmentation abnormalities in dogs and cats, physical examination of aging dogs and cats, early screening and early interventional treatment to prevent later risks.
• Cortisol testing is an essential part of diagnosing Cushing’s syndrome and Addison’s disease.
• With regular cortisol testing, doctors can adjust treatment plans to better control cortisol levels and improve symptoms and your pet’s overall health.

Healvet Cortisol Rapid Quantitative Test

Quantitative detection of Cortisol content in dog or cat serum or plasma based on fluorescence immunochromatography technology.

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