Thursday, March 31, 2011

Arthritis in cats

While I love my dog patients, cats are the nearest and dearest creature to my heart. Hence the obsession with bottle-raising kittens, I suppose. But I digress. Arthritis in cats is an interesting and complex subject that has only been recently garnering attention in the vet world. Mistakenly, for the longest time, it was thought that cats were physiologically extremely similar to dogs. In essence, cats were thought of as "little dogs." It has only been in the last 10ish years that this assumption has been challenged and recognized as completely wrong. Cats are NOT small dogs.

As a result of this thinking, as well as the fact that people are more likely to take their dog to the vet than their cat, there is a dirth of literature on the subject of cat diseases and illnesses. Arthritis is a great example of this. For dog arthritis, there is Rimadyl, Previcoxx, Deramaxx, and Metacam, all fairly safe for long-term use. There are dog supplements of glucosamine and chondroitin. The subject has been well-researched, and research is ongoing in every aspect of it.

On the other hand, there is only one NSAID approved for use in cats - Metacam. It is labeled only for one-time usage, unfortunately. Joint supplements are poorly researched, and not much is known on the topic. Cats are basically left out in the cold when it comes to to arthritis management.

This subject is near and dear to me because I have an old kitty with some of the gnarliest hips ever seen. Seriously, this is what I was told by my orthopedics professor. He actually said that my cat had the worst hips he'd ever seen. Unfortunately, once arthritis has set in, there is no cure for it. The disease is permanent and painful. No one really understands what causes it, other than old age with the contribution of obesity frequently noted. In dogs, there are many possible underlying causes: hip dysplasia, previous trauma, necrosis of the femoral head as a puppy, and the like. Cats just seem to get arthritis, for whatever reason.

The veterinary world is finally getting somewhat interested in this subject. As a vet student, I enrolled my cat in a study on a new NSAID (unnamed) developed specifically for cats. I'm not sure what the results of that study were (it was a controlled, double blinded, prospective trial), but it's encouraging that the research was being done!

In the meantime, these are the options that exist for kitties with arthritis. Most cats are treated with a combination of these medications and therapies:

Pain control
-Buprenex: this is a partial opioid liquid that can be given orally. Unfortunately, it needs to be given up to 3 times a day and is quite, quite expensive these days. It can be a good long-term solution when combined with other pain medications and life-style changes. It tends to make kitties extremely, extremely sweet (basically, because they're high).
-Gabapentin: this is an anti-convulsant that was also found to have good neuropathic pain control. It has recently been used in pets with a variety of different pain types. It is a liquid, fairly inexpensive, and seems to have good results. In some cats, it causes vomiting and sluggishness.
-Metacam: this is a non-steroidal anti-inflammatory medication. It is only approved for one-time use in cats due to the possibility of acute renal failure. Some veterinarians will use it chronically in cats due to intractable pain and an absence of other good options. Its use for this is controversial, due to the possibility of kidney damage.
-Tramadol: this is an opioid like drug that can control pain in cats. It is inexpensive, however some cats become intensely dysphoric on it - so it doesn't work for everyone.
-Amantadine: a drug similar to ketamine (called "Special K" on the street) that works on nMDA pain receptors. This is fairly new in the pain control arena, and again, there are no studies in cats yet. It is all experimental therapy. I have no experience with this drug personally.

Joint supplements
-Adequan: recently, veterinarians have started using the injectable form of glucosamine/chondroitin in cats. There are no studies evaluating it at this time, but anecdotally, it works. I use this in my old kitty. Subjectively, he seemed markedly improved with it.

Other, non-traditional therapies
-Acupuncture: this has recently made a big splash in arthritis treatment in cats. I have not personally tried it (yet), but many veterinarians swear by it for pain control.
-Cold laser therapy: another relatively new modality in the fight against kitty arthritis. I know practically nothing about it, but some practitioners are swearing by it for all manner of diseases including IVDD, trauma, and heart failure!

-In cats with severe hip arthritis, there exists the possibility of either doingva total hip replacement (running thousands of dollars per hip) or femoral head osteotomies - in which the head of the femur is removed, thus stopping the bone on bone contact that makes hip arthritis so painful.
-For front limb arthritis, there are no good surgical options.

-Fat kitties should undergo weight loss. This takes undue stress off of joints and helps with pain control.
-Dietary modification: Hill's has recently released a j/d diet specifically targeted at joint pain. It is supposed to reduce the need for NSAIDs (in dogs) by 25%. As an ER doctor, this isn't something I use much, but I have heard of very positive results with this diet.

This is the current state of feline arthritis treatment. It's a hodge-podge of different approaches, which is usually better than a single modality approach anyway. And now that veterinarians are realizing the need for better pain control in felines, perhaps the research will finally start to take off. In the meantime, if you have a kitty with arthritis, make sure your veterinarian is recommending multi-modality therapy - multiple pain medications, as well as possible acupuncture, laser therapy, joint supplementation, appropriate weight loss/management, and possibly dietary management.


Anonymous said...

Thanks for this very informative article about feline arthritis. When my manx cat had arthritis, I had alot of trouble finding good articles about arthritis in cats.... most covered arthritis in dogs. I would have been thrilled to find an article like this.

Best wishes to your kitty.

Nicki said...

How exciting to have an NSAID for cats. I'll be interested to hear more. I'm glad they finally have feline j/d although I have not gotten to use it yet. The canine version worked great for Oreo until he had to switch to k/d which also worked great.

Anonymous said...

I've seen a metacam "protocol" for cats that recommends very low oral doses every 3 days or so to control chronic pain. I cannot remember the dosage but it's technically quite sub-therapeutic, however there seems to be an appreciable effect for the cats.

The Homeless Parrot said...

Anon -interesting. I'll look into that information!