Notes regarding Cushing’s Clinical Presentations:

Nearly all Cushings dogs have SAP elevations and true PU/PD (USG < 1.025) and most are polyphagic.
Cushings dogs are > 6 years and usually > 9 years old, usually have poor skin coats, body scores > 3/5, and are usually sedentary animals.
Its important to remember that Cushings dogs usually look and play the part and other diseases cause false + stress related cortisol spikes. On rare occasion a Cushings dog will not follow the rules but this is truly an exception. Potential Cushings patient workups can be costly and frustrating if not definitive and, in my experience, the non definitive patient usually has something else going on that may be contributing to some of the clinical signs a cushings dog will have, especially SAP elevations or PU/PD. Based on this prelude of information I came up with the following algorithm in the spirit of diagnostic efficiency.
The following suggested protocol is based on current available literature on Cushings disease and extensive clinical- sonographic experience evaluation + Cushings and False + LDDST & ACTH stim. cases in order to maximize the efficiency of a Cushing’s workup in practice.

Screen first, workup second
1) UA: Repeatable (2-3 urine samples) Urine specific gravity & urine cortisol/creatinine ratio (UCCR): If repeatable

USG< 10.20 and + UCCR move to next step 2.
Note: UA is inexpensive and easy to obtain and if UA criteria is not met for Cushings then resources can be spent into

other more pertinent diagnostics or left on hold until the UA criteria is met in emerging Cushings cases.

2) Sonogram: Does the patient have concurrent disease clinically or sonographically as non-Cushings illness will influence the potential false + LDDST or even ACTH stim. The sonogram gives a global perspective of the internal health of the patient to be considered in the Cushings workup as an assessment of concurrent disease. Is there a concurrent neoplastic process, UTI pancreatitis, mucocele….? Are the adrenals enlarged (Cushings-PDH, stress, age related or breed variant), or atrophied (Iatrogenic Cushings or adrenal burnout), have asymmetric enlargement

( Adrenal tumor, hyperplasia, adenoma, age related variant), or is there vascular invasion (Invasive pheo with false + UA criteria or adenocarcinoma or phrenic thrombosis)? The sonogram answers these questions proactively.

3) LDDST (0.01 D-Sodium phosphate mg/kg IV) (Better screening test but plagued with false +) Use if there is potential early Cushings or if adrenal asymmetry present on sonogram suspecting tumor. Use LDDST in cats at a higher dose (0.1 mg/kg IV).

OR
4) ACTH stim. (Better confirming test but can have false +) Use if the patient “looks” Cushingoid or if bilateral adrenal

enlargement is present, or high normal width on sonogram, or if iatrogenic Cushings suspected (Cortisone tx in past). 5) If diabetic then run both LDDST & ACTH stim.

5) Run a serial blood pressure in a BP friendly non “white coat effect” atmosphere. Run at least 3 at different times over a few hours or when eating as the patient tends to be calm when eating or give Torbutrol when entering the facility.

6) Perform CT of the pituitary to identify macroadenoma expansion if any lethargy or dullness or other central clinical CNS signs are minimally present.

Suggested reading:

Behrend EN, Kooistra HS, Nelson R, et al. Diagnosis of Spontaneous Canine Hyperadrenocorticism: 2012 ACVIM Consensus Statement (Small Animal). J Vet Intern Med 2013;27:1292–1304 .