HISTORY / CLINICAL SIGNS: 2 week Hx of inappetance with 14 lb (6.35kg) weight loss. Recent collapse at home.
PHYSICAL EXAM FINDINGS: BCS 4/9. QAR, dull mentation. T 100.8 ยฐF (38.2 ยฐC). P 110 bpm. RR 40 br/min. Lethargic, difficulty rising, hind limb ataxia with some CP deficits in left hind limb. Hematochezia. Moderate periodontal disease. Some cutaneous scabby lesions. Chronic torn right CCL with medial buttress. No other obvious abnormalities.
What is on your differential diagnosis list? What diagnostic tests would you order? Any other questions?
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DIFFERENTIALS for Hypoglycemia: Laboratory artifact. Insulinoma. Large neoplasm or paraneoplastic syndrome. Xylitol toxicity. Insulin overdose. Liver failure. Hypoadrenocorticism (Addison’s Disease). Pancreatic disease. Transient hypoglycemia in neonates, juveniles, hunting dogs. Cerebral injury or edema.
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DIAGNOSTIC TESTS & RESULTS:
- CBC: unremarkable (Is this to be expected in a dog so sick?)
- Chemistry: Hypoglycemia (BG 59mg/dL). Mild hypoalbuminemia. Mild hyperphosphatemia. Moderate hyponatremia. Moderate hyperkalemia. Mild AST elevation. Mild hypocholesterolemia. Low anion gap.
- Urinalysis: unremarkable
- SNAP 4Dx Plus Test: positive for Ehrlichia (no clinical signs or consistent labwork findings, so may just indicate past exposure)
Based on these preliminary findings, are there any other tests youโd like to run?
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- Insulin to glucose ratio: normal
- Baseline cortisol: <1ug/dL
- ACTH stimulation test: Cortisol remained low (<1ug/dL) 1 hour following cosyntropin injection.
- Abdominal ultrasound: Both adrenal glands are smaller than the normal reference range.
Based on this patientโs signalment, clinical signs, physical exam findings, and test results, what is your diagnosis, recommended treatment, and prognostic outlook?
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DIAGNOSIS: atypical Hypoadrenocorticism (Addisonโs Disease)
The lack of a stress leukogram (no neutrophilia or lymphopenia) in a very ill animal can be a tell-tale sign of Addison’s Disease, an endocrinopathy in which the adrenal glands fail to produce sufficient levels of glucocorticoids (cortisol, the major stress hormone) and mineralocorticoids (aldosterone, which balances the bodyโs fluid & electrolyte levels). This patient primarily has signs of a glucocorticoid deficiency rather than a mineralocorticoid deficiency (thus, an โatypicalโ case). (However, the low Na & high K is pointing to the development of an emerging aldosterone deficiency, too). Middle-aged dogs are most likely to acquire this #endocrine abnormality, and the Great Dane is one of the dog breeds predisposed.
The rear limb weakness and ataxia is suspected to be secondary to a metabolic neuropathy due to hypoglycemia (and perhaps somewhat due to the torn CCL); other neurologic differentials are to be explored if the patient does not improve.
TREATMENT: Initially managed with IV fluids (0.9% NaCl) + dextrose. Once a diagnosis was reached, the patient was out of crisis, and a physiologic dose of oral prednisone was started daily. (Mineralocorticoid supplementation is not yet indicated.)
PROGNOSIS: Overall, the prognosis for Addisonโs Disease is excellent with proper medication (though with giant breed dogs, meds can be cost-prohibitive). 50% of cases may eventually be weaned from treatment. However, during times of stress or if a dose of medication is skipped, the patient can decompensate and enter an Addisonian crisis.
Any other questions, comments, or suggestions?
You can learn more about canine hypoadrenocorticism (Addisonโs Disease) with The Meowing Vetโs comprehensive article for pet owners HERE.
Unless otherwise stated, these clinical cases are real-life cases that I have managed as a veterinarian in general small animal veterinary practice or else assisted with as a student in vet school. These cases are a great real-world learning tool for vet students and other veterinary professionals. They shall be used for learning purposes and collaboration of knowledge only. These cases are not intended to diagnose or treat any disease by pet owners. – Maranda Elswick, DVM
