By Dr Daisy A. May MRCVS, BVSc, Veterinary Surgeon
Arthritis is perhaps the most common disease of cats in the UK and USA – period.
Did you know that around 90% of cats in their teens have arthritis? In fact, as many as 60% of cats over the age of six have arthritis in at least one joint.
In fact, the only other possible contender for the top spot would be dental disease (but of course, this is not the topic of today’s post).
In 2021, a novel injectable feline arthritis treatment became widely available: Solensia.
The purpose of this article is to ensure you – the pet owner – have all of the information you could possibly need to make an informed decision as to whether or not you want to consider Solensia as an option for treating your cat’s arthritis.
I wanted to write this blog post because realistically, there is not enough time in the consult room for your vet to deep-dive into the benefits, the research, the possible side effects, the alternatives etc…so of course you’re going to head home and Google it before committing (I would)…and frankly, I want to make sure you’re getting accurate, relevant information.
‘Cos I really like cats.
And I’m a vet, myself – so that helps.
What Is The Arthritis Injection For Cats?
Solensia is an injectable medication produced by the pharmaceutical company Zoetis. It is used to treat arthritis pain in cats, and is given by subcutaneous injection (injection under the skin) every 28 days. The active ingredient in Solensia (which is the trade name) is a drug called frunvetmab.
It’s a little complicated, but frunevetmab is basically a protein molecule that attaches to a protein inside your cat’s body called “nerve growth factor” (NGF). When frunevetmab binds to NGF, this helps prevent pain signals from being able to reach your cat’s brain…and if pain signals don’t reach the brain, then pain is not experienced.
Oh, and for those who are interested, frunevetmab is produced using genetically altered hamster ovary cells.
Initially, this sounds rather horrifying.
However – it certainly does not mean that hamsters are being farmed and their ovaries harvested to make Solensia!
Far from it. In fact, all of the cells used to produce frunevetmab today come from a single original, individual Chinese hamster. Day-to-day production of the drug doesn’t require hamster abuse.
How Effective Is Solensia?
My reason for believing this is that the vast majority of my clients who opt to treat their cat’s arthritis with Solensia absolutely rave about the benefits and the difference they’ve seen in their cats. Most of them come back for repeat injections every 4 weeks, which presumably they would not do, were it not working.
A scientific interpretation of the success of this drug is a little more complicated, though. Here’s what you need to know:
The most significant, pivotal trial conducted to assess Solensia’s effectiveness involved studying 275 arthritic but otherwise healthy cats. These cats were split into two groups: the first received Solensia (monthly for three months), and the second received a placebo.
The effectiveness of Solensia was then assessed using a pain scoring system, which the cat’s owners completed themselves. The system involved owners scoring their cat in terms of their physical activity level (including jumping, grooming, and ease of using the litter tray), sociability and quality of life.
The cats who received Solensia did improve significantly; 76% or so of these cats showed a reduction in pain score. However, 65% of cats receiving the placebo (ie, a “fake” injection, but owners didn’t know it was fake) also showed a reduction in pain score! This is likely because the owners of these cats believed that their cat was receiving an arthritis medication and so were kind of expecting and looking for improvements.
My take away from this? It does appear that Solensia works, but it’s difficult to know exactly how well it works, because the only means we have of establishing this is to ask the cat’s owners.
And (time and time again in clinical studies) when you give one group of pets an actual drug, and the other group a placebo, owners of the pets who receive a placebo will consistently report that their pet improved!
Why? They think their pet is taking medication, so they are expecting improvement. Sometimes, people see what they are expecting to see.
This makes it really difficult to decipher the true effectiveness of the medication, although having reviewed all of the research, Solensia working better than the placebo in every instance; and anecdotally, as a vet, I have absolutely seen Solensia change and dramatically improve the lives of elderly feline patients.
What Are The Other Benefits Of Solensia?
If your cat has kidney disease as well as arthritis (as is so commonly the case, for older cats), then the traditional first-line treatment for feline arthritis may not be the safest option for them and you should absolutely consider Solensia as an alternative.
This first line feline arthritis treatment is the non-steroidal anti-inflammatory class of medications, or “NSAIDs” for short. These drugs are great for arthritis, but may not be appropriate for cats whose kidneys are not functioning well.
Solensia is the safer option if your cat has kidney disease as well as arthritis. Evidence shows that Solensia will be very well tolerated by cats with IRIS stage 1 or stage 2 kidney disease; it is also believed to be well tolerated by cats with stage 3 or 4 kidney disease, although at present safety data to confirm this doesn’t seem to be available.
You should check with your vet if your not sure what IRIS stage of kidney disease your cat has.
A second massive benefit of Solensia treatment is that it does not require you – the pet owner – to administer oral medication (tablets, liquids, capsules etc) at home to your cat once or twice daily. As we all know, this can be difficult if not impossible, and it can certainly negatively affect your bond with your cat.
The couple of occasions when my own cat has needed to take medication for a week or two at home, I’ve had no choice but to stick it down his throat (because he will painstakingly eat around it, when it’s in his food).
By the end of a single week, he can hardly stand to be in the same room as me, and will stalk away in an offended manner even when I attempt to regain his trust with the aid of Dreamies.
So – when my own somewhat mentally unstable fluffball of a three-legged cat eventually becomes arthritic, unless there’s a reason he can’t have it, he’ll probably be getting Solensia…unless anything changes in terms of the evidence base for Solenia between now and then.
What Does The Feline Arthritis Injection Cost?
The short answer is, quite a lot, unfortunately.
Assuming you have a “standard” sized cat, between 2.5 – 7kg (5.5 – 15.5lb), your cat needs a single 1ml vial of Solensia as their monthly dose.
If you have a supersized kitty, for example a Maine Coon, who weighs more than 7kg/15.5lb, they are gonna need two 1ml vials as their monthly dose, instead.
My sources for the below are a combination of my own experience working as a vet in the UK, plus Reddit (don’t come for me)…but basically, a Solensia injection for a “one vial” cat is going to set you back around £130 / $160 (monthly), and double that for a “two vial” cat.
That’s a lot of money.
I discussed the following already in my recent blog post ‘How To Save Money On Vet’s Bills – Ten Ways To Save’, but there is a massive hack that you can use here to more than cut the cost in half, and it goes as follows:
1) Set the scene appropriately by explaining candidly to your vet that this medication is somewhat unaffordable.
2) Request a written prescription for Solensia. Most practices will charge anywhere from £12-20 ($15-25) as an admin fee for providing this. It is worth asking for a six-month prescription; many vets will be happy to provide this. A few may feel more comfortable (for whatever reason) providing you with a three month prescription…but it never hurts to ask.
The prescription is basically a piece of paper that enables you to purchase the prescription-only drug Solensia from an online pet pharmacy of your choosing; you’ll just need to take a clear photo of the prescription on your smartphone, and upload this at checkout.
3) Order your Solenia online from a trustworthy pharmacy (do your research, check ratings etc). At the time of writing (1 June 2023), the going rate for Solensia online is around £45 / $56 per vial.
FYI : it comes in packs of two. It’s not possible to purchase a single vial.
4) It will arrive cold-stored, in a refrigerated truck like a grocery delivery, so you need to make sure you’re at home when it arrives to grab it and stick it in the fridge. It’s got to stay cold stored, up until you’re ready to use it.
5) Now that the Solensia is sitting merrily in your fridge, you have two options:
a) Book monthly appointments with a veterinary nurse or vet tech at your regular clinic for them to administer the medication by injection under the skin (usually these appointments will be much cheaper than an actual vet consult; at some practices, they are even free!)
b) Ask your practice if the vet/nurse/tech can teach you to administer the injection yourself at home. I am frequently happy to do this where owners are keen, seem competent to handle injectables, and (importantly) are not going to faint at the sight of a needle. This option is especially great if you are already medically trained; for example, perhaps you’re a human nurse.
Where your vet is happy to allow you to administer the medication yourself at home, this quickly becomes the cheapest and most convenient option, as well as being the least stressful for your cat (since they don’t have to face the dreaded cat carrier and car journey to the vets to get their monthly Solensia injection).
Honestly, there aren’t many instances where I won’t teach a pet owner how to give Solensia themselves at home; my rationale for this is that I’ve taught 90-year old pensioners to give their cats twice daily insulin injections, so in reality nearly every pet owner is capable of administering a subcutaneous (under the skin) injection safely at home, with a little training and briefing.
Oh, just one thing to be aware of, though: it’s easier than you’d think to inject through a pinched-up tent of cat’s skin and out the other side, thereby effectively administering the Solensia onto the cat rather than into the cat.
\Whilst this isn’t going to cause harm, it’s a massive waste of money. If your vet makes this mistake, they aren’t going to charge you for round two, but if you slip up yourself at home, you’ve just wasted a small fortune.
What Are The Possible Side Effects Of Solensia?
Based on a review of the research currently available, Solensia appears to be a relatively safe choice for treating feline arthritis with relatively few known side effects and/or adverse effects.
Perhaps the most common side effect you might notice when your kitty starts Solensia is an upset tummy. But the link is not super clear:
In one study, vomiting was reported in 13.2% of cats treated with Solensia, and diarrhoea was reported in 6.6%.
However, vomiting and diarrhoea were also reported in some cats in the study’s control group (ie, a group of cats included in the study for comparison’s sake who did not receive Solensia), albeit to a lesser extent.
In another study, cats who received a placebo experienced just as much vomiting and diarrhoea as cats receiving Solensia!
So, whilst it’s certainly possible that Solensia can cause tummy upset, it’s difficult to know exactly how much of this is simply coincidence, because frankly puking (especially grass and furballs) and runny poops are so common in cats generally!
Loss of appetite and lethargy also appear to be possible (if uncommon) side effects of the Solensia injection.
Understandably, as with any injection some soreness and discomfort at the injection site may be experience for hours to a few days following injection. This side effect is reported in around 4% of patients who receive Solensia injection.
Finally, as with literally any medication, allergic or anaphylactic reactions may occur. These are extremely rare, with Solensia.
If a reaction does occur, it’s likely to happen within the first 30 minutes of receiving a new drug for the first time; so, if your cat is heading to the vet for their very first Solensia injection and you’re feeling nervous, you could always plan on hanging around in the waiting room for half an hour after the injection and monitoring him or her, just to be on the absolute safe side.
What Other Treatments Are Available For My Cat’s Arthritis?
In terms of medicinal treatments, a nutshell your options are:
…all of which I have discussed in greater detail in the following blog post:
In terms of non-medical treatments, laser therapy may be effective in some individuals and is worth looking into for those keen to find adjunctive treatments.
For obvious reasons, hydrotherapy is not an option for the vast, vast majority of cats!
Thanks for sticking around! Where would you like to head next?