Page 8 - Clinical Connections - Spring 2020

RVC RESEARCH STUDY VETERINARY SERVICES Cutting-edge treatment
Adrenalectomy for Pituitary-Dependent Cushing新月直播檚
David Church, Deputy Principal and Acting Vice Principal (Clinical Affairs)
Hyperadrenocorticism (Cushing新月直播檚 syndrome) is one of the most common endocrine diseases in dogs
attending first-opinion veterinary practices. An RVC VetCompass studyv, based on data from 193,814 dogs attending 110 clinics, found an incidence of 0.28% in UK dogs.
Affected dogs新月直播� adrenal glands produce too much cortisol due to either a pituitary tumour (pituitary-dependent hyperadrenocorticism) or a tumour in the adrenal gland itself. Pituitary-dependent hyperadrenocorticism (PDH) is much more common than the latter.
Although the underlying cause of PDH in dogs is typically an adrenocorticotropic hormone (ACTH) producing tumour of the pituitary gland, treatment options for PDH have traditionally focused on the management of the resulting corticosteroid excess, using medications such as trilostane.
Therapy for PDH targeting the pituitary tumour itself involves either surgical excision of the pituitary gland and associated tumour (hypophysectomy) or radiation therapy. Unfortunately, although radiation therapy has been shown to reduce the size of the pituitary mass, it has been well documented that it does not reliably
or effectively reduce excessive ACTH secretion and thus is not really a suitable treatment option for pituitary-dependent Cushing新月直播檚 syndrome.
Following on from the success of
the College新月直播檚 feline hypophysectomy programme for the management of feline hypersomatotrophism, our neurosurgical hypophysectomy specialists, headed up
by Joe Fenn, have been adapting their techniques to manage pituitary-dependent Cushing新月直播檚 syndrome via hypophysectomy. An increasing number of dogs have undergone this treatment and almost without fail have shown a pleasing return to normality with effectively complete resolution of the clinical signs referable to Cushing新月直播檚 syndrome.
While hypophysectomy is addressing the core of the problem 新月直播� removing the offending functional endocrine pituitary tumour 新月直播� the costs and risks associated with 新月直播榖rain surgery新月直播� are not for everyone. Another VetCompass study2 showed that over 80% of owners were not satisfied
8 Spring 2020
with medical management of their dog with pituitary-dependent Cushing新月直播檚, that less than 15% thought the response with trilostane treatment was good and that over 90% of dogs with Cushing新月直播檚 treated with trilostane in UK general practices were euthanised within 15 months of diagnosis because of 新月直播減oor responses to treatment".
Clearly medical management with trilostane is not working for a substantial proportion of people and because of costs, risks and general 新月直播渇ear of brain surgery新月直播�, hypophysectomy is not for everybody either.
What can be done?
In 2020 is there another realistic option for managing pituitary-dependent Cushing新月直播檚 syndrome?
The answer is a resoundingYES! Perhaps surprisingly the answer is based upon another surgical rather than medical option 新月直播� bilateral adrenalectomy! In other words, ask our soft-tissue surgery team
to remove the source of the excess and
uncontrolled over-production of cortisol 新月直播� the same principle that underpins the use of trilostane, but just using a surgical rather than a medical approach to achieve the desired outcome.
Our soft-tissue surgical team here at the QMHA have considerable experience in carrying out bilateral adrenalectomies to manage pituitary dependent Cushing新月直播檚 syndrome and then managing the patients as Addisonians.
In terms of surgical and peri-operative complications, bilateral adrenalectomies
are no more problematic than any other flank celiotomy. Patients are managed as
we would any Addisonian with appropriate doses of cortisone (yes not prednisolone) and non-manufacturer-recommended doses of DOCP.
I wonder if I might ask you all a
simple question? If your own dog had
to have an adrenal endocrinopathy 新月直播� pheochromocytoma, pituitary-dependent Cushing新月直播檚 or Addison新月直播檚 disease 新月直播� which would you select?
I am sure the vast majority of you would select Addison新月直播檚 disease. If that is the case, could I suggest that with the next pituitary- dependent Cushing新月直播檚 dog you see, could you at least consider managing it with bilateral adrenalectomy and saving yourself and the owner a lot of expense and heartbreak.
References
1. Schofield, I., Brodbelt, DC., Wilson, ARL., Niessen, S., Church, D., O'Neill, D. (2019) 新月直播楽urvival analysis of 219 dogs with hyperadrenocorticism attending primary care practice in England新月直播�. Veterinary Record
2. O'Neill, D. G., Scudder, C., Faire, J. M., Church, D.
B., McGreevy, P. D., Thomson, P. C. and Brodbelt, D.
C. (2016), 新月直播楨pidemiology of hyperadrenocorticism among 210,824 dogs attending primary-care veterinary practices in the UK from 2009 to 2014新月直播�. J Small Anim Pract, 57: 365新月直播�373.
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