Hyperadrenocorticism aka Cushing's Disease

Differentials: SLE, Hyperparathyroidism, Nephrogenic Diabetes, Hypoparathyroidism

Diagnostic Tests:

UCCR – Urine Cortisol/Creatinine ratio
a. Sensitive – can give false positive results
b. Normal results: rules out
Cushings
c. Incr results: requires LDDS test to confirm

2. ACTH Stimulation
a. Identifies 80-85% dogs w/ Cushings
b. Get exaggerated response to ACTH if dog has Cushings
i. Like UCCR: some dogs w/ severe, NON adrenal disease can also have an exaggerated response to ACTH
ii. 15-20% Cushings dogs have a normal response (& need LDDS)

3. TEST of CHOICE
LDDS – Low-dose dexamethasone suppression test
a. Give Dexamethasone
i. Normal dogs: suppress cortisol levels for 8 hrs
ii. Cushing dogs: No decrease in cortisol levels

i. DDX Pituitary Dependent Hyperadrenocorticism (PDH)
ii. TEST: HDDS – High-dose dexamethasone suppression

ii. Desmopressin Test - new, to differentiate pituitary from adrenal dependent

Treatment:

i. If an adrenal tumor is identified, surgical removal may be a viable option esp. that 80% of Cushing's is of pituitary type

ii. Lysodren (Mitotane) is a treatment for pituitary dependent Cushing's

iii. Trilostane - newer, more expensive but doesn't have the side effects of Mitotane.
References: Merck, Zuku Notes

 

Well,...
I concur fully with Irene Arboleda in regards Tentative Diagnosis and Tests etc . SLE can hardly be a Differential in this case though!!! Some people would consider it differential in nearly any canine skin disease :-)... but the most common signs of SLE are a non-erosive POLYARTHRITIS (an arthritis that affects several joints !),LAMENESS and PROTEINURIA! This patient is with hematology in normal range / SLE often comes with decreased platelet and white blood cell count too, immune mediated hemolytic anemia (IMHA)/. No mention of any lameness or any other signs ...
And I may add on Tumors and Hepatic Failure as differentials

 

tentative diagnosis: hyperadrenocorticism

other differentials:
-Nefrogenic/central diabetes insipidus
-psychigenic diabetes insipidus
-UTI
-Urolithiasis
- SLE-
-Paraneoplastic syndromes/or neoplasia
-Infectious (rickettsial and fungal)
Less likely:
-glomerular dz
- Hypothyroidism (not PU/PD)
-Hypoadrenocorticism (not PU/PD)

Further diagnostics in chronologic order:

-ACTH stem
-UCCR
-Low dose Dex
-High dose Dex
-AbdominaL RADS AND US
-URINE CULTURE( CONCURRENT UTI COMMON)

You would only proceed if not Cushing's

-Snap 4 DX
-UPCR
-Water deprivation test + ADH
- T4
-serology infectious dz
- Thoracic rads (look for neoplasia)
-Skin biopsies
ANA titers

RX Cushings:
-Mitotane or
-Trylostane

Adrenalectomy (for FAD)

Comments: Good case showing that not every cushioned dog has changes in bloodworm( hypercholesterolemia, low BUN, the infamous STRESS LEUKOGRAM, and elevated ALP. which are classical changes mentioned in many references and seen in many cases.

Daniel I partially agree with you. However I would still listed SLE not only because of skin issue but also because of the proteinuria.
A classic SLE will have lameness as clinical sign. As far as for WBC, may be increased or decreased, PLT may be decreased or normal. I would think in this case SLE is unlikely, but I wouldn't rule it out until you have rull out all other differentials. This case is a typical example that things just don't always read the book.

 

Just to add to final comments:
Daniel I think you could list hepatic failure

However I think this more even than SLE would be a very unlikely scenario:

Liver DZ with normal BUN, albumin, bilirubin, and liver enzymes, and no other changes in PLT, WBC, RBC showing some king inflammatory process going on (like an hepatitis)???

So that would be in the very bottom of list of differentials.

-Bile acids/liver panel could be performed to rull that out in any case.

 

1. Definitive diagnose: Hyperadrenocorticism /Cushing´s disease

2. Differential Diagnose:
-Hypothyrodism
-Alopecia X
-DM
-Hyperadrenocortism of food related

3. Tests:
First performe basic panel tests:
CBC: we would see a stress leukogram (neutrophilia, eosinophenia, lympophenia, and monocitosis)

Bioquemistry: elevated ALP (aprox. 90% of dogs will have elevations of this enzyme), hyperglucemia, and hypercholesterolemia

URI: proteinuria, low USG and cocci present (most dogs that have Hyperadrenocorticism also tend to have urinary trac infections)

If those tests make you suspect of hyperadrenocorticism then perform more advanced tests such as:

-ACTH supression test
-Low dexamethasone tests
-Urine cortisol/creatinine ratio

If those tests also have results suspecting of hyperadrenocortism then perform other tests that will definitively diagnose Hyperadrenocorticism:

-high dexamethasone test
-endogenous ACTH
-Abdominal ultrasound

*Treatement:
Pituitary dependant HAC: treat with trilostane (vetoryl) 1 mg/kg every 12 hours

If adrenocortical dependant HAC:
-Perform adrenalectomy or treat with Mitotane (Lysodranne) 40-50 mg/kg BID

 

hypothyroidism