Case 2

A 13 year old, female spayed, mixed breed dog was presented to AcaseAweek Clinic with history of collapse, depression, lethargy and vomiting 3 times the night before presentation. The patient had been anorexic for the past 2 days and appeared healthy previously. The patient lives mostly inside and her owner reported no possibility of accidental ingestion of foreign body or chemicals. Her vaccination status is current and she is on heartworm preventative. She was treated for Ehrlichiosis with doxycycline two months back.

Physical Exam:
Remarkable weight loss and muscle atrophy.
T: 98
P: 88
R: 44
MM: pale pink
CRT> 2 sec

Cardiovascular: murmur, cardiac arrhythmia, pulse deficit.
Respiratory: lungs sound clear
Abdomen: distended, positive succession, moderately painful

CBC/Cytology:
PCV: 23% [37-55]
WBC: 28.9 x103/μL [6-16.9]
Mature Neutrophils: 26.3 x103/μL [3.3-12]
Band Neutrophils: 0.6 x103/μL
Lymphocytes: 0.3 x103/μL
NRBC: 0.9 x103/μL
Smear: Platelets: 1-4/hpf
RBC morph: marked polychromasia, moderate anisocytosis

Biochemistry:
ALKP: 267 U/L [23-212]
ALT: 164 U/L [10-100]
AMYL: 2490 U/L [500-1500]
BUN: 130 mg/dL [7-27]
CREA: 6.1 mg/dL [0.5-1.8]
PHOS: >16.1 mg/dL [2.5-6.8]
TBIL: 1.4 mg/dL [0-0.9]

Urinalysis:
Bilirubin: ++
SG: 1.013
Blood: +++
pH: 5.0
Protein: +

Abdominocentesis:10 mL fluid was withdrawn.
Abdominal Fluid Analysis/Cytology:
Color: red
Turbidity: 3+
Protein: 7.2 g/dL
PCV: 23%
Smear: many RBCs, neutrophils and macrophages, moderate lymphocytes, almost no platelets seen, few reactive mesothelial cells.

What will be your tentative and differential diagnosis?
What further diagnostic test(s) you will perform to confirm your diagnosis?
What will be your treatment plan(s)?


Solution to this case

Soluton for case 1

Click here to see the Case before Solution

Diagnosis: Tentative diagnosis is hyperadrenocorticism (cushing disease) based on the typical presenting signs. Click here to see image of the case from merck vet manual site.

DDx: Hypothyroidism, diabetes mellitus, renal diseases and other causes of PU/PD.

Diagnostic tests:

Low Dose Dexamethasone Suppression Test (LDDS):

Basal cortisol: 5.1 µg/dL

4-hour post test: 2.2 µg/dL

8-hour post test: 6.5 µg/dL [<1.0>

These values indicate the hyperadrenocorticism, but to differentiate the adrenal tumor from pituitary dependent hyperadrenocorticism (PDH) we need to perform HDDS test.

High Dose Dexamethasone Suppression Test (HDDS):

Basal cortisol: 4.8 µg/dL

8-hours post test: 0.8 µg/dL [<1.0>

(The ACTH stimulation test is a screening test for diagnosis of hyperadrenocorticism, but was not done in this case.)

Definitive diagnosis: Pituitary dependent hypheradrenocorticism.

Treatment:

Mitotane is a commonly used drug in hyperadrenocorticism. Ketoconazole can be used in dogs which are unable to tolerate mitotane at the required dose.

This patient was started on 60 mg of Trilostane (Vetoryl®) once daily and his status will be monitored with an ACTH stimulation test in 1-2 weeks time. If he has still not achieved a hypoadrenal response at this time or has achieved a response but is still exhibiting clinical signs, we can consider increasing his dose or increasing to a BID regime. After achieving therapeutic stability, the patient should have an ACTH stimulation test every 3-4 months to monitor cortisol response to therapy.

Trilostane tends to be better tolerated by dogs. Trilostane is a competitive inhibitor of 3-β-hydroxysteroid dehydrogenase. This enzyme mediates the conversion of pregnenolone to progesterone in the adrenal gland, with the net effect being inhibition of cortisol production.

With PDH treatment, it is important to achieve a hypoadrenal response but avoid the complete adrenal suppression to a point that glucocorticoids and mineralocorticoids are deficient. Specifically, mineralocorticoid deficieny and hypoaldosteronism have the deleterious effects of cardiac disturbances (due to hyperkalemia and hyponatremia), hypovolemia and hypotension.

See detailed information about the Cushing Disease