Pets with Addison's Disease show a variety of vague symptoms that come and go. Many are weak and lethargic. They vomit and have diarrhea. Their hair falls out and they lose weight. Their heart beats more slowly than normal. Some dogs drink excessively and urinate excessively (PUPD).
Symptoms of Addison's Disease come and go. For example, a pet will vomit one day and be fine the next. Or, a pet will be lethargic for a week and be fine the next week.
Addison's disease in dogs and cats is an extremely difficult disease to diagnose because the symptoms resemble those of many other diseases. For example, excessive drinking and urinating commonly resembles diabetes. Anorexia, vomiting, and diarrhea resemble gastrointestinal diseases and parasitic infections. In addition, the symptoms come and go making it difficult to pinpoint what is happening.
To further complicate the difficulty of accurately diagnosing Addison's disease, about 5% of pets with Addison's disease will have other endocrine diseases at the same time. For example, a pet can have Addison's disease, hypothyroidism, and diabetes.
The most significant indicator of Addison's disease is having a low sodium level so that the ratio of sodium to potassium is below the normal 23:1. In addition, there may be changes in white blood cells with eosinophils decreasing (eosinopenia) and lymphocytes increasing (lymphocytosis). There may be changes in red blood cells, which decrease as a pet develops anemia. Blood tests may show decreased sugar levels (hypoglycemia) and high liver enzymes, such as alkaline phosphatase. Blood may show elevated urea and creatinine because these waste products, normally removed by the kidney, are not cleared.
Without a normal amount of sodium in the body, the blood pressure falls.
Without a normal amount of sodium in the body, the urine becomes very dilute. The pet drinks excessively and urinates excessively, but the blood pressure is so low that the blood reaching the kidney is not cleared and waste collects in the blood.
The heart looks smaller than normal because there is less blood than normal filling it.