Expert: Jessica - 1/22/2010

Question
QUESTION: Hi, one of my cats has been diagnosed with a luxating patella.  She is 12 years and 9 months, is a bit chunky (about 11 1/2 pounds).  I have been trying conservative treatment--pain management, cosequin, but ultimately, surgery is the only thing that will correct her problem.  She is limping consistently now, and has become more sedentary in the past 2 to 3 months.  My question is, at her age (she's healthy outside of the knee problem), is there any reason NOT to have corrective surgery for her?

Thanks!

ANSWER: Hi Todd.  I would have some pre-operative blood work run, of course, as I'm sure your vet will recommend.  But if all her blood cell counts are normal and her organ function is fine, then I don't feel there is a good reason for her not to undergo the surgery to correct the problem, since her knee is causing her so much trouble.  A couple years ago, I actually had my 11-year-old cat undergo a complete rear-leg amputation due to cancer.  Within 2 weeks, he was nearly back to himself entirely, and today, he runs, jumps and plays like always.  

It may be a good idea to start her on a weight loss regimen with the help of your vet to reduce stress on her joints if she's a little hefty for her frame.  Exercise is probably out of the question for now, but there are some good diets out there that encourage weight loss naturally, prescription or otherwise.  My own preference are those which have high concentrations of protein, such as grain-free diets or prescription diets like Hill's m/d or Purina DM.  These seem to work best for my cats, and they also appear to taste better.  If your cat has any indication of kidney failure, however, these will probably be out of the question.  

Best wishes to you both!

Jessica



---------- FOLLOW-UP ----------

QUESTION: Jessica,

Thanks so much for your prompt and detailed answer.  It's good to read that the recovery can be so quick.

Yes, my vet has already done the bloodwork and she's okay in that respect.. the surgery will be at the University of Pennsylvania Vet Center, so she's in great hands.  My follow up question:  You mentioned something about kidney failure--I don't want to give my cat anything that my cause that problem.  I'd rather have her a little fat.  How would I know if kidney failure is an issue?  She's been to the vet 4 times in the past 5 months, she is healthy aside from the knee.  Thanks again!

Todd

ANSWER: Aw, Moose is such a beauty!

Kidney failure is indicated by the elevation of certain enzymes in the blood and also by dilute urine.  Your vet will know if your cat has any degree of kidney failure if her blood urea nitrogen (BUN) and/or creatinine levels are elevated, and her urine is dilute.  Cats with more advanced kidney failure might also have low blood protein levels, such as albumin and globulins.  If none of these things are true, your cat's kidneys are functioning healthily, and kidney failure is not a concern.  Pre-operative bloodwork checks these levels (aside from urine concentration), so if the pre-op tests were normal, she is in the clear.

In the past, it was feared that a diet too high in protein might be related to kidney failure.  This has recently been debunked.  However, what we DO know to be true is that kidney failure that already exists is worsened by phosphorus in the diet.  Phosphorus is found in high concentrations in meat.  And as you know, to make a food high in protein, it generally must contain a lot of meat.  So while the protein itself does not worsen kidney failure, the phosphorus that tends to come along with it does.  The good news is that it's not a concern unless your cat is already suffering from kidney failure.  Because a cat's natural diet is a high-protein, low-carbohydrate one, this is what I prefer to feed.

All that said, if this is a recent photo of Moose, she doesn't look to me like weight is a significant issue to worry about.  She looks good and healthy!



---------- FOLLOW-UP ----------

QUESTION: Thanks again--I do have one last follow up.  In my online research on this issue, I have read that by not doing corrective surgery on a severe case such as this, the possibility for a worsening/debilitating condition exists.  As I mentioned, she has become more sedentary in the past couple of months and I would imagine this is not good for her general health.  What are the negatives by not putting her through the surgery.  Also, is this condition very painful for her?  She sure doesn't complain, but just watching her walk makes me wince.


Answer
The negative of not going ahead with a corrective surgery for a luxating patella is that when the kneecap slips in and out of place, it causes abnormal wear on the joint - arthritis.  While a luxating patella is reparable, arthritis is not, and it can be debilitating.  

In early stages, a luxating patella is not always considered a very painful condition, but more of a sporadically uncomfortable one.  However, when a cat begins limping regularly, it is widely accepted to be quite painful.  The resulting arthritis is unquestionably painful, and the pain medications you have been using can be helpful, but some cats even require stronger pain relievers, ones that may be habit-forming.

It’s rare for a cat to cry out in pain, but when we see them limping, or we see their activity become limited, we can be certain they are experiencing pain.  So I don’t think there’s any question that your cat is feeling discomfort on a regular basis.  I think going ahead with the surgery is a very good idea in her case.

I hope all goes well!