Page 8 - Clinical Connections - Spring 2020

黑料社 RESEARCH STUDY VETERINARY SERVICES Cutting-edge treatment
Adrenalectomy for Pituitary-Dependent Cushing鈥檚
David Church, Deputy Principal and Acting Vice Principal (Clinical Affairs)
Hyperadrenocorticism (Cushing鈥檚 syndrome) is one of the most common endocrine diseases in dogs
attending first-opinion veterinary practices. An 黑料社 VetCompass studyv, based on data from 193,814 dogs attending 110 clinics, found an incidence of 0.28% in UK dogs.
Affected dogs鈥� 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鈥檚 syndrome.
Following on from the success of
the College鈥檚 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鈥檚 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鈥檚 syndrome.
While hypophysectomy is addressing the core of the problem 鈥� removing the offending functional endocrine pituitary tumour 鈥� the costs and risks associated with 鈥榖rain surgery鈥� 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鈥檚, that less than 15% thought the response with trilostane treatment was good and that over 90% of dogs with Cushing鈥檚 treated with trilostane in UK general practices were euthanised within 15 months of diagnosis because of 鈥減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 鈥渇ear of brain surgery鈥�, hypophysectomy is not for everybody either.
What can be done?
In 2020 is there another realistic option for managing pituitary-dependent Cushing鈥檚 syndrome?
The answer is a resoundingYES! Perhaps surprisingly the answer is based upon another surgical rather than medical option 鈥� bilateral adrenalectomy! In other words, ask our soft-tissue surgery team
to remove the source of the excess and
uncontrolled over-production of cortisol 鈥� 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鈥檚 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 鈥� pheochromocytoma, pituitary-dependent Cushing鈥檚 or Addison鈥檚 disease 鈥� which would you select?
I am sure the vast majority of you would select Addison鈥檚 disease. If that is the case, could I suggest that with the next pituitary- dependent Cushing鈥檚 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) 鈥楽urvival analysis of 219 dogs with hyperadrenocorticism attending primary care practice in England鈥�. 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), 鈥楨pidemiology of hyperadrenocorticism among 210,824 dogs attending primary-care veterinary practices in the UK from 2009 to 2014鈥�. J Small Anim Pract, 57: 365鈥�373.
For small animal referrals, please call:
01707 666399
Email:
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