Despite the fact that cats suffer from arthritis at least as much as dogs, they have always been the losers when it comes to having a good range of treatments. Up to now we have been forced to rely almost entirely on meloxicam. Reasons for this might be:
- A poorer recognition of the signs of arthritis in cats and therefore lower demand
- The smaller market and financial benefit to drug companies (dogs visit the vet at least twice as much as cats)
- The difficulty in giving medications to cats
- The increased risk due to the prevalence of kidney disease
Now, in 2023 we are witnessing the appearance of a wholly new approach to treatment that might overcome many of these concerns.
These are exciting times, but we also need to be cautious and realistic. You’ll see in this article that it is by no means a silver bullet. However, with Solensia there is real hope for cats that we have a new and effective tool to improve their quality of life.
What is Solensia?
Solensia is a trade name for frunevetmab in Australia. It neutralises nerve growth factor (NGF), which has been shown to be involved in the perception of pain. As a monoclonal antibody, it has the potential to be highly specific to its target, and block it almost completely.
In Australia, Solensia has been registered for the alleviation of pain associated with osteoarthritis in cats.
How Well Does It Work & How Quickly?
In our clinic, we have seen some cats benefit greatly after starting Solensia, but what does the evidence say? The results of a single placebo-controlled study conducted by the parent company are shown here and referenced below.
There are three important things to note here:
- All arthritis treatments show a caregiver placebo effect, but for this particular product, it is especially large
- The difference between the two groups is statistically significant for Months 1 and 2, so we are confident that Solensia is helping at least some cats
- Unquestionably, there will be many others who receive insufficient benefit and require different arthritis remedies
My view is that the large placebo effect is a direct result of the difficulty we have in correctly identifying signs of pain in cats. However, it is also possible that it only brings benefit to a minority. Our own experience is that Solensia can be very effective in some cats, but hard to judge as well.
A further clue that anti-NGF treatments are helpful is in the clearer results we see for the canine equivalent, Beransa.
Based on laboratory studies, a positive response would be expected to appear at around day 6.
Solensia Dosage & How Often
Solensia is given by vets at a dose of 7 mg by subcutaneous injection for cats between 2.5kg and 7kg.. Above this, two vials are needed but I would suspect that most of these cats would benefit more from weight loss. If desired, the dose is repeated every month. It is generally recommended to try at least two doses before deciding whether it is effective enough.
NGF is important for foetal and juvenile development. Therefore, Solensia must not be used in breeding, pregnant or lactating cats, or those less than 12 months of age.
Human Health Risks
Similarly, pregnant women, women trying to conceive, and breastfeeding women should take extreme care to avoid accidental self injection or needle stick injuries. To be safe, it is best that they take no part in giving the injection or even holding their pet.
Just to be clear, a treated cat poses no risk to humans.
Solensia Side Effects
Up to 10% of cats given the injection showed signs of hypersensitivity such as skin itching, hair loss, and dermatitis. In some cases this could be severe enough to require stopping treatment. Otherwise, adverse effects appear rare.
Our prior experience with monoclonal antibodies like Cytopoint shows us that they are much safer than traditional drugs like anti-inflammatories. This is because as naturally occurring proteins, they require minimal metabolism or detoxification by the liver or kidneys.
It is therefore likely that Solensia can be used at normal doses in cats with kidney disease, unlike anti-inflammatories which become more dangerous. However, until there are studies of their use with liver or kidney disease, caution is still advisable in these cats.
Solensia appears safe when used in combination with other drugs, and at the time of vaccination. The only concern with using multiple treatments could be that if an adverse effect occurs, you may not be able to work out which one caused it.
How Much Does Solensia Cost?
The cost in 2023 for a single injection of Solensia is around $90. This is in the same region as the higher priced anti-inflammatory drugs.
Our experience so far is that for some cats, it maintains their quality of life when other choices fail. It can also be used when other treatments aren’t safe enough to use and for those cats that owners cannot easily medicate. In summary, we believe is worth a try if costs allow.
Anyone who has an arthritic cat knows that we still aren’t doing enough for them. The development of monoclonal antibodies brings us just one step closer, and just might give us more time to enjoy our lovely old cats.
Therefore, talk to your vet about whether it might be good for your cat.
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By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. Meet his team here.