Treating Acromegaly consists of trying to treat the fundamental disease itself but also treating the effects of the conditions that result from Acromegaly.
Treating Acromegaly itself
There are three basic methods of treating Acromegaly itself:
• Surgery: removal of the tumour and pituitary gland or hypophysectomy.
• Radiation therapy – either traditional treatment or Stereotactic Radiation Therapy (SRT).
• Medical treatment using pituitary inhibitors. While unsuccessful when used for cats in the past, recent research is making huge advances on this subject.
Unfortunately, all treatment options are very expensive and all but traditional radiation therapy are only available in a handful of very few highly specialised vet hospitals at this time. Not all treatments are available in all regions of the world.
The barriers of cost and availability mean that for a number of people, treating the Acromegaly itself is simpy not possible. If that is the case, there are nonetheless many things that you can do to treat the effects of Acromegaly (see the next section) that will truly help your cat.
While Hypophysectomy is commonly used to treat Acromegaly in humans, it requires a highly specialised veterinarian surgeon and team, and this treatment has only been performed by a handful of hospitals.
A Hypophysectomy removes the tumour and the piturary gland. The operation is performed by going through the roof of the mouth.
In Europe, Hypophysectomy was first performed in the Netherlands at Utrecht University – the only country to perform this surgery on cats for a number of years. Today, it is also available at the RCV in London. In the US it can be performed in Washington State (it was previously available in California). It is also available in Japan and has very recently started to be performed in Australia, in Melbourne.
The advantage of the surgery is simply that is does absolutely remove the root cause – the tumour. So, the cat is “cured” of Acromegaly once the tumour is removed.
Most cats see their diabetes cured also, with a return to normal numbers and insulin no longer needed.
In addition, improvement to some organs damaged by acromegaly may be seen, especially concerning damage to the heart.
Your cat will however need on-going hormone replacement treatment following the surgery.
Costs are usualy less than those related to SRT – the actual surgery itself is less expensive than may be thought given the highly specialised team necessary. Costs increase because of the long hospital stay of 10-15 days after the surgery that is usually required and the costs regarding various tests around the surgery. The on-going for life hormone replacement costs also need to be taken into account. Advanced imagery (MRI/CT Scans) are necessary to pinpoint the position of the tumour and make certain it can be removed.
Radiation Therapy: Traditional and SRT
1) Traditional radiation therapy is the most widely spread treatment available for cats. The goal of radiation therapy is to reduce the production of GH to levels that are no longer significant and to reduce the size of the tumour itself.
In general, it is more successful in reducing the size of the tumour than in reducing the GH levels. Traditional radiation therapy is given over a series of treatments, requiring multiple hospitalisations (and use of anesthesia) over a number of weeks.
2) SRT uses imagery to delivery radiation to a very targeted area and so can pinpoint the tumour itself. As is the case for hypophysectomy, it is available in a very limited number of hospitals.
In the US, Colorado State University is a leader in the domain. Yonkers in New York is another. The Ontario Veterinary College at the University of Guelph offers SRT. Currently, SRT is not available in Europe.
Usually only one course of treatment , over a few days, is given.
SRT is far more precise than general radiation therapy as it does allow directing radition precisey to the tumour itself. The course of therapy is much shorter, and your cat does not have to be put under anethesia the number of times necessary for traditional radiation therapy. SRT is though, very expensive. MRI/CT Scan exams are also necessary before SRT treatment in order to pinpoint the exact position of the tumour, adding to the total cost.
A major disadvantage of radiation therapy – whether traditional or SRT – is that results can range from none at all to a full response, may take months to start showing – if they do at all – and may or may not be permanent. There is no way to know how an individual cat will react.
Medical treatment using pituitary inhibitors (specifically targeting somatostatin receptors) has been used successfully with humans – but cats have not reacted to the same. Recently published research (results published the same time this is written, in May 2015³) is showing a potential breakthrough for cats with the use of fast acting Pasereotide, a newer somatostatin analog that decreases the secretion of GH.
The results of the study are promising, with a decrease in IGF-1 and in the amount of insulin needed. A longer term study is underway.
Studies using long-lasting Paseriotide are also going on; however, this medication is not yet approved for veterinary or human use in many countries, if it was approved for human use in the EU in November 2014. The fast-acting Pasereotide is approved in more countries.
A study published in February 20174 concluded that: “Pasireotide LAR (long-lasting) is the first drug to show potential as a long-term management option for cats with HS” (Hypersomatotropism).
Signifor or Signifor LAR (long-lasting) are the brand names in Europe for Paseriotide. Authorisation for veterinary use of Signifor LAR is pending.
In general, blood glucose levels will often be similar before and after treatment: the amount of insulin needed to control the levels, though, is usually very much reduced, and some cats will even go into remission and no longer need insulin therapy.
It is very important that you are monitoring your cat’s blood glucose levels, that you do reduce your scale with the treatment, and continue to adjust as needed.
At the moment, the cost is higher and the results are less good than for surgery. It is a very promising advance in dealing with Feline Acromegaly though. Should the continued research confirm the initial findings, it will provide a treatment far more widely available than either hypophysectomy or SRT treatment. Hopefully continued research along this line will help cats more in the future!
If available and possible for you, Hypophysectomy is currently the best option: when successful (the entire tumour can be removed), it cures Acromegaly, and certain organs will even improve vs. the damage caused by the disease. Many cats will no longer need insulin, their diabetes will also be cured. Your cat will need to be on hormone replacement therapy for life, though.
Paseriotide, if a newer treatment, is probably the best second choice – again, if your vet is able to prescribe that. It does greatly reduce the GH and IGF-1 secretions, and will therefore very much slow and control the progression of the disease. In terms of the related diabetes, it should lead to very much reduced levels of or even no more insulin needed. It is however, very expensive today.
Of the two radiation possibilities, SRT is preferable to normal radiation, which has lower results and requires multiple sesssions of anethesia. SRT is far more targeted and precise, so has less side effects. The problem with both SRT and simple radiation therapy is that it can takes months to see if there is any improvement, and results can range from none at all to being very successful…. and may or may not be permanent.
Treating the effects of Acromegaly
The numerous side effects of Acromegaly do need specific help and treatment:
• Agressively increase insulin as needed and use a rapid insulin along with your normal longer acting insulin to help bring your cat’s blood glucose levels under control. Note: rapid insulin should only be used with the help and advice of your vet. The same Tight Regulation protocol used on Diabetic Cat International for non acromegalic works very well for cats with acromegaly and will help you control your cat’s BGs.
• Treat the pain: an Acro Cat is usually suffering from significant pain as a result of the uncontrolled growth of bone and tissue – you need to talk to your vet about appropriate analgesics to help. One commonly prescribed analgesic that does seem to help many Acro cats is Gabapentin.
• Treat the hunger that goes with Acromegaly – let your cat eat what it wants.
• Treat the heart problems with the medications indicated by your vet: ACE inhibitors such as Enalapril will usually be prescribed by your vet. Other medications that may be prescribed include Aspirin, Sprironolactone, Pimoban and Benazepril. Note: Aspirin is toxic for cats: it is VERY important to not give more than what your vet has prescribed.
• Treat eventual kidney problems as you would normally with kidney disease: ACE inhibitors (Benazepril – Forketor in Europe or Lotensin in the US ), fluid therapy (Sub-Q fluids), B-Complex vitamins, antacids, and phosphorous binders if needed. Important: remember that due to the heart conditions you need to be very careful about the amount of fluids you administer
Even if you are unable to have treatment for the Acromegaly itself done, being aware of the side effects and treating them if and as they do occur will help your cat both in terms of quality of life and in length of life. You can make more than a difference in helping your cat with the above!
There are advances concerning the treatment of Feline Acromegaly being made every day. It is now being understood that it is behind a significant number of Feline Diabetes cases. With that understanding, we can hope that more research on treatment will continue!
If you live in the UK (or Europe), one of the leading Acromegaly specialists in the world is Dr. Stijn Niessen, who also runs the RVC Diabetes Remission Clinic. It would be very worthwhile having your vet contact the clinic for more help and information on their on-going research into, and treatment of, Acromegaly. Dr. Niessen was involved with the latest research on Paseriotide and is also behind the introduction of Hypophysectomy in the UK. There are various research studies going on at different times at the RCV Feline Diabetes Remission Clinic and it is possible that your cat could enter one of those studies. The FD Remission Clinic can help provide your vet with information on the use of Paseriotide.
The Facebook page can be found here: Diabetes Remission Clinic
The main RCV site is here: Royal Veterinary College – Internal Medicine
Please do post on the DCI forum. One of the Senior Members here has had two Acro cats. She is a wealth of information on the subject and can help you!
And we can – and will – help you regulate the diabetes caused by Acromegaly with Tight Regulation on forum!
Additional Reading and Resources:
Last updated February 2017
¹ Berg, R.I., Nelson, R.W., Feldman, E.C. Kass, P.H, Pllard, R & Refsal, K.R. (2007): Serum insulin-like growth factor-I concentrations in cats with DM and acromegaly. Journal of Veterinary Internal Medicine 21, 892-898
² Niessen, S.J., Petrie, G. Guadiano, F., Khalid, M., Smyth, J.B., Mahoney, P. & Church, D.B. (2007a): Feline acromegaly: an underdiagnosed endocrinopathy? Journal of Veterinary Internal Medicine 21, 899-905
³Scudder, C.J., Gostelow, R., Forcada, Y., Schmid, H.A., Church, D. and Niessen, S.J.M. (2015), Pasireotide for the Medical Management of Feline Hypersomatotropism. Journal of Veterinary Internal Medicine. doi: 10.1111/jvim.12608
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