Autoimmune polyendocrine syndrome in a standard poodle with concurrent non‐endocrine immune‐mediated diseases

Hypothalamic-pituitary-adrenal axis recovery after intermediate-acting glucocorticoid treatment in client-owned dogs

BACKGROUND

In dogs, duration of hypothalamic-pituitary-adrenal (HPA) axis suppression after systemic glucocorticoid treatment is reported to vary from a few days to up to 7 weeks after glucocorticoid discontinuation. These data are derived mainly from experimental studies in healthy dogs and not from animals with spontaneous disease.

HYPOTHESIS AND OBJECTIVE

To determine the timeline for recovery of the HPA axis in a group of ill dogs treated with intermediate-acting glucocorticoids (IAGCs).

ANIMALS

Twenty client-owned dogs that received IAGC for at least 1 week.

METHODS

Single-center prospective observational study. An ACTH stimulation test, endogenous ACTH concentration, serum biochemistry profile, and urinalysis were performed at T0 (2-6 days after IAGC discontinuation) and then every 2 weeks (eg, T1, T2, T3) until HPA axis recovery was documented (post-ACTH cortisol concentration > 6 μg/dL).

RESULTS

The median time of HPA axis recovery was 3 days (range, 2-133 days). Eleven of 20 dogs showed recovery of the HPA axis at T0, 6/20 at T1, and 1 dog each at T2, T5, and T9. Dose and duration of treatment were not correlated with timing of HPA axis recovery. Activities of ALT and ALP were significantly correlated with the post-ACTH cortisol concentration (rs = -0.34, P = .03; rs = -0.31, P = .05). Endogenous ACTH concentration was significantly correlated with pre (r = 0.72; P < .0001) and post-ACTH cortisol concentrations (r = 0.35; P = .02). The timing of HPA axis recovery of the dogs undergoing an alternate-day tapering dose was not different compared to dogs that did not (3.5 vs 3 days, P = .89).

CONCLUSION AND CLINICAL IMPORTANCE

Most dogs experienced HPA axis recovery within a few days after IAGC discontinuation. However, 2/20 dogs required >8 weeks.

[Polyendocrine syndromes in dogs]

The autoimmune polyendocrine syndrome (APS) refers to a combination of autoimmune endocrine disorders. It is rarely described in dogs. The most common combinations are hypoadrenocorticism and hypothyroidism, followed by diabetes mellitus, and less often hypoparathyroidism and orchitis. The diagnosis of the APS is based on the diagnosis of each endocrinopathy, as is the therapy, which involves the substitution of deficient hormones. If a patient was previously stable under treatment and is showing further signs (e.g. polyuria, polydipsia, or weight loss), the development of additional endocrinopathies like hypoadrenocorticism or diabetes mellitus should be considered. The diagnosis of the initially diagnosed endocrinopathy should also be critically questioned. This article summarizes some cases of our own animal hospital and selected cases published in the available literature.

Histopathological evaluation of the adrenal glands in a cat with primary hypoadrenocorticism and multiple endocrine disease

Case summary

A 6-year-old male neutered domestic longhair cat was referred for investigation of weight loss, hyporexia, vomiting and diarrhoea. The cat was diagnosed with primary hypoadrenocorticism, exocrine pancreatic insufficiency, cobalamin deficiency and a chronic enteropathy, and started on therapeutic treatment. Diabetes mellitus developed 4.5 months later, and the cat was started on insulin therapy. The cat was euthanased 10 months following the diagnosis of hypoadrenocorticism due to the development of status epilepticus, which was not associated with glucose or electrolyte abnormalities. Histopathological assessment of the adrenal glands at post-mortem examination documented lymphoplasmacytic adrenalitis, with the lymphocytic population being predominant. Immunohistochemical staining classified the lymphocytic infiltrate as T-cell rich, supportive of the cat's hypoadrenocorticism being due to autoimmune disease.

Relevance and novel information

This case documents the novel use of immunohistochemical staining in combination with histopathology to further assess the adrenal glands in non-neoplastic-associated primary hypoadrenocorticism in a cat. This identified similar pathological changes to those previously described in dogs with autoimmune primary hypoadrenocorticism. Additionally, this is the first report of a cat with multiple endocrine disease that included primary hypoadrenocorticism and highlights that monitoring for the development of additional endocrine disease should be advised in these cases.