World-wide study reveals new clinical insights into feline hypoadrenocorticism
New research has set out to describe the clinical findings, treatment response and outcome in a population of cats diagnosed with hypoadrenocorticism.
It has established that; hypercalcaemia was documented more frequently in cats with hypoadrenocorticism than previously documented; a form of hypoadrenocorticism exists without hyponatremia and hyperkalemia; testing for exocrine pancreatic insufficiency may be warranted in cats diagnosed with this condition; and cats with non-neoplastic (not cancer) associated hypoadrenocorticism that survive initial hospitalisation can have a favourable long-term prognosis.
The hypoadrenocorticism research was co-ordinated to present the largest case series on cats with this rare condition. It reports on forty-one cats with hypoadrenocorticism from 24 referral hospitals across 14 countries.
Feline hypoadrenocorticism is sparsely reported. Hypoadrenocorticism is caused by dysfunction of the cortex of the adrenal gland, resulting in insufficient production of cortisol (a glucocorticoid hormone), aldosterone (a mineralocorticoid hormone) or both. Aldosterone regulates the body’s water and salt balance, and cortisol has several functions including helping the body to manage stress, helping to control blood glucose (sugar) levels, reduction of inflammation and regulating metabolism.
Hypoadrenocorticism is primarily caused by an immune–mediated destruction of adrenal tissue; but other causes include neoplasia (cancer). Clinical signs of the disease can be vague and non-specific. Patients may present with lethargy, diarrhoea, vomiting, increased thirst, increased urination, and unplanned weight loss, as well as collapse.
Nearly all reports of feline hypoadrenocorticism comprise of cats with hyponatremia, defined as an abnormally low blood concentration of sodium, and hyperkalemia, which is defined as an abnormally high blood potassium level.
The feline hypoadrenocorticism research was a multi-centre retrospective observational study. Data for the whole cohort was assessed using descriptive statistics and the differences between cats with and without hyponatremia and hyperkalemia was evaluated.
Within the cohort, 36 cats had hyponatremia, hyperkalemia or both, and five cats did not. The results found the median age of cats was 5.7 years (range, 0.2 to 13.8). Twenty-three (56%) cats were male and 18 (44%) were female. In two (4.9%) cats, hypoadrenocorticism occurred secondary to lymphoma (a type of cancer).
Cats with hyponatremia, hyperkalemia or both were less likely to have a history of vomiting but more likely to be hypothermic (have a low body temperature), dehydrated and/or weak on examination than cats without HH. The frequency of hypercalcemia (increased blood calcium level) was 31.7%. Exocrine pancreatic insufficiency (the inability to properly digest food due to a lack or reduction of digestive enzymes made by the pancreas) was diagnosed in 4/7 cases where tested; all four cats had concurrent cobalamin (vitamin B12) deficiency.
Thirty-five (85.4%) cats survived to discharge. Median survival time (MST) for all-cause mortality was 2035 days (95% CI 294 – 4380 days); MST for disease-specific mortality was not reached.
Emma Roberts, Senior Internal Medicine Clinician at Bristol Vet Specialists, who led the study said:
“Feline hypoadrenocorticism is sparsely reported in the veterinary literature, with most reports limited to one or two cases. To date there have only been three single case reports of cats with hypoadrenocorticism not associated with hyponatremia, hyperkalemia or both.
Our world-wide study was warranted to enhance our understanding of this disease in cats. We are pleased that we now have the data both to describe the clinical findings of a large population of cats with this disease and to document their response to treatment and outcome and can share our findings with our colleagues in the veterinary profession.”
The Clinical findings, treatment and outcomes in cats with naturally occurring hypoadrenocorticism: 41 cases - led by Emma Roberts, Senior Internal Medicine Clinician at Bristol Vet Specialists - has been published in the Journal of Veterinary Internal Medicine. It was supported by the Small Animal Medicine Society (SAMSoc).
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