Using in-clinic cortisol testing to detect endocrine diseases in dogs

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A decade ago, veterinary practices may have seen one or two cases of Cushing’s disease per year. Since then, the veterinary community has learned that low incidence was actually the result of low testing. Today, testing and awareness have improved. Veterinarians can see up to 10 cases annually and test for the condition weekly. With Cushing’s and other thyroid conditions such as Addison’s disease, clinical symptoms may be difficult to distinguish, and some testing methods can produce deceptively normal results. In-clinic, quantitative biomarker analyzers are often the best defense, providing quantitative results for rapid decision making and treatment.

Cushing’s Disease

There are two types of Cushing’s – pituitary tumor and adrenal tumor. A pituitary tumor sends too many signals, causing the adrenal gland to overproduce cortisol. An adrenal tumor inhibits the adrenal gland from receiving any signals and leads to an unstoppable surge of cortisol. In both, patients can exhibit polyuria, polydipsia, polyphasic, muscle weakness, panting, abdominal distention, hepatomegaly, alopecia and hypertension. Early detection and treatment are highly important to improve quality of life for the patient by improving polyuria and polydipsia and decreasing the chances of organ damage from secondary hypertension.

Cushing’s occurs more often in middle-aged or older dogs with no sex predilection and tends to occur equally on pure bred and mixed breed dogs. Some breeds such as: Bichon Frise, Miniature Schnauzer, and Lhasa Apso are predisposed.^1,2

Addison’s Disease

Conversely, Addison’s disease is the result of underproduction of cortisol. It is often seen in middle-aged dogs, more often seen in females than males, and several breeds including Standard Poodle, Labrador, West Highland Terrier, Great Dane, Bearded Collie, Pomeranian and American Cocker Spaniel are at increased risk.^3-7

Addison’s can be particularly difficult to diagnose as clinical signs may wax and wane, bloodwork can return normal and hospitalization can cause sudden stress-induced boosts in cortisol levels, giving a false impression that the patient is improving.⁸ If left untreated, a patient may go into an Addisonian crisis that may present with hypovolemic shock.

Diagnosing

In either scenario, when patients come in with symptoms, start by analyzing their history for a possible explanation. Run urinalysis and bloodwork, starting with CDC chemistry. Elevated results on the CDC stress leukogram indicate possibility of Addison’s and Cushing’s. That result would indicate you should first test for base cortisol levels, with additional testing recommended at four and eight hours to detect changes. Because it can deliver rapid results and accuracy due to the highly-sensitive immunofluorescent europium technology it utilizes, Bionote’s Vcheck V200 quantitative, in-clinic analyzer is an excellent option for saving time while distilling the best diagnosis from your analysis.

The Vcheck V200 in-clinic analyzer provides quantitative results in minutes. (Photo courtesy of Bionote)

Why In-Clinic?

Until recently the only testing option consisted of sending blood samples to a reference lab. Typically, for a rural practice, it could take 24-72 hours – at best – to receive the blood results. During winter months, samples may not have been sent out for weeks at a time due to inclement weather. In-clinic options for obtaining fast results – like the Vcheck V200 analyzer – give veterinarians, especially those in rural clinics, a new opportunity to run samples in-house at a lower analyzer and per-test costs along with faster turnaround. This allows treatment to start earlier and patients to recover from symptoms faster.

Cost is a big part of the decision for most clients. With inflation increases, clients appreciate options that allow veterinarians to work towards providing the same service and quality at the same cost as in the past, while providing the care they expect.

Running cortisol tests on a quantitative analyzer also allows a quick and cost-effective screening method to determine if additional testing is necessary. Many U.S. clinics opt to run ACTH stimulation tests for greater confidence in an Addison’s or Cushing’s diagnosis, but this testing can be cost prohibitive for many clients. Testing cortisol levels before running an ACTH or other similar tests justifies the added cost by focusing on potential causes instead of casting a wide, expensive net.

Trilostane is the only approved product in the U.S. for the treatment of Cushing’s. Before the option afforded by the Vcheck V200, veterinarians did not have a timely and cost-effective method for Trilostane monitoring and would often keep patients on a prescribed dose without confirmation of treatment success, or only modify the dose based on clinical signs. Measuring pre- and post-pill cortisol concentration levels on analyzers like the V200 can be done multiple times a day with quantitative results available in 20 minutes to either confirm or encourage readjustment of the treatment plan.

Better Care

Better care for dogs by increasing their comfort levels and longevity, are the goals. Newer technology and tools – including Bionote’s Vcheck V200 analyzer that provides quantitative results in-clinic, within minutes – should be considered during the mission to offer dogs a better life.

References

1. Schofield I, Brodbelt DC, Niessen SJM, et al: Frequency and risk factors for naturally occurring Cushing’s syndrome in dogs attending UK primary-care practice. J Small Anim Pract. 2021 Vol 63 (4) pp. 265-74.
2. Bellumori TP, Famula TR, Bannasch DL, et al: Prevalence of inherited disorders among mixed-breed and purebred dogs: 27,254 cases (1995-2010). J Am Vet Med Assoc. 2013 Vol 242 (11) pp. 1549-55.
3. Hughes AM, Nelson RW, Famula TR, et al: Clinical features and heritability of hypoadrenocorticism in Nova Scotia Duck Tolling Retrievers: 25 cases (1994-2006). J Am Vet Med Assoc. 2007 Vol 231 (3) pp. 407-12.
4. Gershony LC, Belanger JM, Hytönen MK, et al: Genetic characterization of Addison’s disease in Bearded Collies. BMC Genomics. 2020 Vol 21 (1) pp. 833.
5. Hauck C, Schmitz SS, Burgener IA, et al: Prevalence and characterization of hypoadrenocorticism in dogs with signs of chronic gastrointestinal disease: A multicenter study. J Vet Intern Med. 2020 Vol 34 (4) pp. 1399-1405.
6. Mooney ET, Hammond TN, Mahony TN, et al: Hypoadrenocorticism in a kindred of pomeranian dogs. Can Vet J. 2015 Vol 56 (1) pp. 44-47.
7. Hanson JM, Tengvall K, Bonnett BN, et al: Naturally occurring adrenocortical insufficiency- An epidemiological study based on a Swedish-insured dog population of 525,028 dogs. J Vet Intern Med. 2016 Vol 30 (1) pp. 76-84.
8. Hess RS: Hypoadrenocorticism. Textbook of Veterinary Internal Medicine, 8th ed. St. Louis, Saunders Elsevier 2017 pp. 1825-33.