Boy, is that vet uneducated!
Might want to send that vet a copy of the paper in this post, see case 2, starting page 1092.
(2020) Updates in Feline Diabetes Mellitus and Hypersomatrotropism
A couple quotes from that paper "
A serum IGF-1 concentration of greater than 130 nmol/L (>1000 ng/mL) has a positive predictive value of 95%" and "
However, only a proportion of cats with HS-associated DM have noticeable acromegaly and its absence should not exclude the possibility of HS." This latter means, just because you have the tumour, doesn't mean there are clinical signs.
From the email you got
Being given exogenous insulin alone can increase IGF-1 values.
Oh contrare, starting exogenous insulin can reduce IGF-1 values, and if IGF-1 testing is done within 73 days of starting insulin, 1/3 of acros had false negatives.
A recent study showed acromegalic cats with confirmed acromegaly having IGF-1 concentrations ranging between 890-2001ng/mL The insulin dose is also not too crazy, as an example the last acromegalic cat I managed was on 20 units of insulin twice daily. We often see complicated diabetic cats who require 5+ units of insulin twice daily through our diabetes clinic. So things like chronic pancreatitis or inflammatory disorders can reduce their insulin sensitivity as well.
Where to start! That 890-2001 mg/mL is for measurements in the UK, the United States measure in nmol/L. And actual though it says 130 above in the quote from the paper, MSU suggests above 92. Just because 1 acrocat is on 20 units, does not mean all acros will be on 20 units (not that 17 and not budging is far away from that). I've seen untreated acros on as low as 4 units and up to 90+ units. Chronic pancreatitis and other inflammatory orders do cause insulin resistance, but how many of those cats they had on 5+ units were on low carb food, and more importantly, how many of them had their IGF-1 tested? And those inflammatory disorders do not make such a large difference in dose needed, maybe max 3 units. Dry food has a worse effect.
The article I pointed to also has some words about CT scans and even MRI's not being definitive. When I was at CSU (first time), they had a cat that had SRT whose tumour was so small it did not show on either CT or MRI.
Oral medications involve things like octreotide or pasireotide have been shown to be effective in some but not all cats.
Nope, there are studies showing that's not true either for octreotide. One study was done at CSU. Would love to see any papers they have referring to success in cats. Pasireotide pricing is literally out of this world. Oh, and the paper above mentions cabergoline as a possible treatment. Surgery is done at AMC in New York, the surgery was done many years ago in Los Angeles and very briefly Spokane, Washington - but they didn't have a great track record, don't think they are doing it anymore. You do want to have the surgery with someone who has a proven track record - it's a risky surgery. And well, there is always London England, Royal Veterinary Clinic who has done over 50 of these surgeries. That vet really has not looked at recent research at all. RVC authors are on most of the current articles, including the one I linked.
Done now, I could say more. You need to try elsewhere. The "consultant" was clearly trying to sell their inferior radiation therapy (not SRT) too. Or maybe you pass the paper onto your vet, with the hint that you think the UGA vet is a little out of date. If you like your vet, maybe they'll be willing to treat and work with you.
