The adrenal glands are important organs in the body of small animals, which disruptions
associated with their performance due to lack of timely detection in most cases, result in
irreparable damage or death of the animal. The tissue structure of these glands is unique
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The adrenal glands are important organs in the body of small animals, which disruptions
associated with their performance due to lack of timely detection in most cases, result in
irreparable damage or death of the animal. The tissue structure of these glands is unique and the
cortical and internal parts of these glands are responsible for secreting important hormones in the
animal's body. In general, important functional diseases among adrenal gland diseases in small
animals can be classified into two categories. The first category is the diseases caused by excessive
proliferation and excessive growth of the adrenal gland, called hyperadrenocorticism, or cushing's
syndrome/disease, and other diseases caused by low activity of adrenal glands that are known as
Hypoadrenocorticism or Addison's syndrome/disease. Hyperadrenocorticism is primarily a disease
of old dogs and ferrets, but it also occurs rarely in cats. Polyuria and polydipsia, lethargy, pot-belly
and alopecia, are among the most frequent clinical signs. A stress leukogram (leukocytosis, mature
neutrophilia, lymphopenia, eosinopenia, and monocytosis), increased alkaline phosphatase (ALP)
and urine specific gravity <1.020 are good indicators of suspicion to Cushing’s disease. Increased
urine cortisol: creatinine ratio (UCCR) in a dog that has classical signs and lab data of Cushing’s is
very suggestive of hyperadrenocorticism. If the history, clinical signs, and routine laboratory data
are suggestive for hyperadrenocorticism then the diagnosis at this stage is a two-step process: first
rule in or rule out hyperadrenocorticism with screening tests [Low Dose Dexamethasome
Suppression Test (LDDST) and ACTH stimulation test] and then try to differentiate pituitary and
adrenal dependent hyperadrenocorticism with confirmatory tests [blood ACTH concentration and
High Dose Dexamethasome Suppression Test (HDDST)]. Addison’s disease usually occurs in young
to middle aged (3–6 years) dogs. Lethargy, weakness, vomiting, diarrhea, abdominal pain,
anorexia, bradycardia, microcardia, decreased blood pressure, polyuria and polydipsia are the
most constant clinical signs of the disease. Laboratory findings including azotemia, decreased
urine specific gravity, absence of a stress leukogram and especially a Na: K ratio <23:1 are the key
abnormalities to indicate primary hypoadrenocortisim. In such cases, blood cortisol concentration
and ACTH stimulation test could be used for diagnosis of Addison’s disease. To differentiate
pituitary and adrenal dependent hypoadrenocorticism, the concentration of blood ACTH should be
measured.
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