Hello David, I'm Dr. Deb
I recently came online and see that your question about Lily hasn't been answered. I'm so sorry that you've had to wait for a response,but if you still need assistance, I'd like to help if I can.
Cats often use urination and defecation as a means of communication with other cats (if more than one is present in the household) or psychological stress can also trigger inappropriate elimination as well. However, when a cat is using the litter to urinate but not using it to defecated, then in my experience, the reason most often traces back to the litter box and/or litter itself. Although having said that, when an older cats starts to defecate outside the box, there could be other possible explanations which I'll cover below. 10 isn't that old but then, again, it's not young either so some aging changes may be responsible for this behavior.
Much research has been done on the topic of litterbox preferences and the following is a summary of this research as well as other problems which might trigger inappropriate defecation. Some of these things that I've listed may not be appropriate for your situation, but I've included them to be complete.
1. Some cats like a very clean box; when it becomes dirtier than they prefer, they'll poop elsewhere. So, the box should be scooped at least daily or twice daily and the entire box cleaned weekly with soap and water; avoid harsh smelling chemicals.
2. The number of boxes and size is important: The rule of thumb is one box/cat plus one box. A litter box length should be at least one and a half times the length of the cat (not including the tail) so they have adequate space to maneuver and cover excrement.
3. Cats prefer clumping litter.
4. Cats prefer unscented litter.
5. Cats don't like hoods on their boxes because they retain odors.
6. There is something about the texture of the litter that they don't like, for what ever reason. This is known as Litter Aversion and is a fairly common problem. One way to know if this might be the issue is if there is minimal digging or disturbance of the litter that's in the box. Digging is a natural instinct to cover waste material, especially feces. If they don't like the texture of the litter, they don't want to touch it with their feet. If you've used the same litter for some time, though, then this is less likely to be a factor.
7. They associated pain with the box when they had a bowel movement in the box and don't want to repeat the experience so avoid using it.
8. Most cats don't like their boxes to be located where there's a of noise or foot traffic; they prefer privacy. Again, probably not an issue in this case if the box is located where it's always been.
9. Use of enzymatic cleaners to degrade the fecal material rather than just cover up the odor (the cats can still detect it) are preferred. If Lily defecates in one particular area more frequently, she may think that it's ok to do so.
As to other possible explanations when this behavior develops in older cats, the following are possible:
1. She could be suffering from early dementia or Alzheimer's, similar to this condition in humans. One of the first signs of this condition is a loss of house-breaking...these cats basically "forget" that they're supposed to use the litterbox, become a little confused and defecate outside of the box.
There are limited treatment options but ones to consider include the following.
a) Feliway diffusers or a spray which are natural pheromones which can sometimes instill a sense of calm and reduce anxiety. These products are available on the internet or at most pet stores
b) NuCat Senior supplement which has anti-oxidants which may help.
c) Fish oil such as Welactin (which is a liquid that can be drizzled on the food) also has anti-oxidant properties.
d) Cognitive supplements such as Neutricks, SAMe (Novifit) and Senilife may be useful.
2. Older cats with arthritis often find it difficult to "assume the position" in a litterbox or the sides may be too high for them to comfortably enter the box.
Providing a different kind of box such as a plastic container which you would roll under your bed may be helpful...or any sort of plastic container with lower sides.
Treatment options for arthritis in cats is also limited but the following are ones to consider.
a) Cosequin for Cats which is a joint supplement and available on the internet.
b) . Occasional use of anti-inflammatory drugs such as Onisor which is licensed for use in cats but can only be given for three days in a row.
There is a drug called Metacam which has been used safely in the UK for some time now.
c) Adequan which is basically a stronger supplement but is an injection and needs to be given by your vet.
d) Fish oil supplements as I mentioned above.
e) Pain medication such as Buprenex can be very useful and could be given every day or only on the days that she needs it.
f) NuCat Senior supplement mentioned above.
3. Cats with hypertension can behave in some odd and unusual ways. This condition is rarely primary but usually secondary to other diseases such as Diabetes, kidney issues or Hyperthyroid disease. Although it's not always the easiest thing to do in a cat (adequately measuring their blood pressure since they tend to become so stressed at vet's office), it can be done and medication can be prescribed if elevated.
4. And, I hate to even mention it but when older cats start to behave unexpectedly, a brain mass would have to be included on the list, unfortunately. Usually these cats are showing other symptoms, though, so it's not likely if this is her only problem.
While drugs can be quite successful in changing inappropriate urination behavior, they aren't as effective at changing inappropriate defecation. The underlying cause for this behavior needs to be found and addressed, if possible....although it's sometimes a challenge to do so.
I hope this helps and provides various options to consider in trying to address this behavior. Again, my apologies for the delayed reply. Deb