Feline Hypersomatotropism – more common than we realise?

I'm going to be speaking with Dr. Chris Scudder about this comorbidity that might be a bit more common than we realize. So, to start with Vicky, I wondered if you'd introduce yourself and explain your role at International Cat Care because a lot of our veterinary audience will know you as Vicky Hall's feline behaviourist. But they won't necessarily know about the work that you've been doing with International Cat Care.

And then we realized that there was a way to do things that was more strategic and more efficient, use resources more efficiently, put cats front and centre of everything. This is no critique of the tens of thousands of people all over the world that are working in shelters. Their passion, their devotion, their hard work is absolutely extraordinary.

But when we started to look at how this model was developing, we realized we can support you with a way of working that will take what you're doing from good to even better with regards to your productivity. That traditional model of rescue reactive is painful. It's psychologically difficult. It leads to burnout. But this new way of working allows things to work in a more strategic, proactive way.

The great thing about that is that the cats benefit, but the people who are working in the sector benefit too. So we developed these ideas. Key players have contributed their incredible skills and understanding of the sector. So it's like all this wonderful knowledge, all coming together. So this was going on for years with me as a sort of consultant, working with various other people in the project.

And then in 2019, there was an opportunity for me to start the new phase of my career, to close my behaviour practice and actually become an employee for the first time in a few decades, and actually to work with International Cat Care. So I consider that to be a huge joy and privilege. So here I am, four and a half years later, an employee still.

And my title is Head of Unowned Cats, which means that I continue to develop the cat friendly homing model, develop training courses, coaching courses, the website content, resources, that kind of thing. And also expanding beyond the homing centre side of things and looking at cat population management in general.

And that's very much a sort of global thing, talking to people around the world who do this wonderfully and understanding what good and effective looks like and trying to pass on good practice information.

And it gives us the opportunity to take all our collective learning and go forward over the next three years with more people and more resources to spread the cat friendly homing internationally, to develop more courses, more training opportunities, both online and face to face, resources, events where we can involve people who maybe aren't aware of what we've been doing or even who we are as an organization in some countries. So this is really exciting for us.

It's like a massive acceleration of our work, as a result of this grant. Over the next three years, we're actually targeting the UK, Portugal, Greece, Cyprus, and Australia. This doesn't mean the other countries won't matter for the next three years, you know, all our resources are available to all countries.

But targeting five specific countries enables us to do that deep dive to find out what the issues are within the country, what the challenges are, and bring this all together to see if we can create this suite of resources and frameworks and training that will have the widest relevance possible. That's what we're trying to do. Cat friendly homing is not an algorithm. It's very much a way of thinking and a way of working that has these core principles as the foundations of everything.

This sector is full of people who are incredibly resourceful, devoted and passionate to their work. And we want to reach out to those people and get them excited about the idea of evolution. Because evolution, if you see it through the lens of change, it feels daunting. But if you see it through the lens that we experience it, where every time we learn something new, we get hugely excited about it. It's a lovely thing. We're always looking for ways of showing our love towards cats.

I think a really good way of showing our love is, for our own evolution, find out as much as we can so that we know we can meet their needs. What an exciting thing!

We have a bi monthly newsletter that has interviews, videos, articles, all sorts of things every couple of months for those people who really want to get a sense of what's happening across the world. And we encourage people to get in touch with us. My email is on the website. If there's something you need with regards to the care for unowned cats that's not on there, let me know and I will make a point of getting it on there if I can.

I wanted to ask you why we now use the term hyposomatotropism and not acromegaly in cats, perhaps the way we used to?

In cats, what we've learned over time is either cats do not have those demonstrable phenotypic changes, or we're just less akin to being able to identify them. So there was some data published in one study, which asked referring vets if they thought that the cat that they were testing had a suspicion for excessive growth hormone of which only a quarter of which had a suspicion. When the three quarters had the condition, but the phenotypic changes weren't there to alert the veterinarian.

Hyposomatotropism is describing the condition of excessive growth hormone. And maybe that is the more common presentation in terms of we're not phenotypically identifying it, but we are identifying the growth hormone change. So it might be a better descriptor. So that's why we're leaning more to using that nowadays, although I do fully appreciate it's definitely more of a mouthful.

And so if you have an increased IGF-1, then your confidence that that patient truly has excessive growth hormone is reasonably high. So again, its reliability is pretty good. When are we measuring IGF-1? I think that's going to in part be dependent on clinical suspicion.

So you can measure IGF-1 even before you start endogenous insulin, but then their IGF - will increase after they receive exogenous insulin and then they may breach that threshold of increased suspicion or underlying HST as the cause. So you can definitely test them before you even start exogenous insulin, the downside is you may miss a few. So if you are going to wait, then the time to wait at the moment seems to be about eight weeks will be a reliable time point to wait.

While I think it's entirely reasonable to see how patients do and to test those that are doing things slightly atypical with their diabetic response, if you only test those that have an atypical response to exogenous insulins, I do think you'll miss some. Not all of them are wacky diabetics to control and some of them seem to respond very beautifully to routine doses and strategies of diabetic management and insulins.

So if you've got an owner who's very unlikely to ever want additional treatments, then I think not investigating and just managing that diabetes, even if they're relatively routine and never knowing if they had underlying HST is acceptable. But if you've got an owner who may consider pursuing additional investigations, additional more targeted treatments, then I think even if you do have a relatively easy to control diabetic, I do think there is merit in testing those.

In the feline HST setting, then, pasireotide doesn't seem to be shrinking the pituitary. In terms of cabergoline, I'm not aware of any data looking into that. My understanding from human medicine is it doesn't do too much for growth hormone producing tumours. There are other types of pituitary tumours like prolactin producing tumours, which are responsive to cabergoline by reducing their pituitary size. I don't believe the same happens with the growth hormone producing tumours.

In cats, their pituitary is either unchanged or they continue to enlarge over time.

And if that owner wanted to go into the realms of learning about additional treatment options, I would discuss that with them. And that may include wanting to know the pituitary size. So, if they're extremely polyphagic, or they are ones with phenotypic suspicion, then you might want to do additional investigations to try and determine whether or not that IGF 1 truly represents HST or not.

If they didn't have those characteristics, it would be reasonable to retest at a later time point and see what that does over time, probably another 3 months. If they are borderline again, yyou might entertain the idea of considering pituitary imaging if the owners wanted to know if that cat had HST, because they might do something pituitary specific on the back of that information. That would be my general approach.

If you're looking for more free CPD from ISFM in March, we have two open access webinars. The first is from Purina on 'How to manage the CKD patient with comorbidities.' And the second is from IDEXX on 'Feline gunky-eyetis, when to swab and when to test.' We'll be back again next month with another episode. If you don't want to miss out, do make sure you've signed up to Chattering with ISFM on your preferred podcast platform.