Almost forgot: have you changed brands of litter or types of litter boxes?
It is my understanding that some cats really have a problem with scented/perfumed litters and some are also put off by covered boxes, as these can concentrate odors and also can make the cat hunch over uncomfortably when he is trying to use the box.
Anyway, I found that handout. Here's what it says:
- house soiling
- separation anxiety
- iatrogenic causes of polydypsia/polyuria
- primary medical diseases, including but not limited to:
- inflammatory bowel disease
- renal failure
- cognitive dysfunction syndrome
- endocrine abnormalities
(sounds like you've already done this step)
- physical examination
- CBC, chemistry panel, urinalysis, fecal testing
- imaging study of the urinary tract
- further tests as indicated by the findings of the physical exam
(after ruling out a medical cause)
Two primary objectives must be met.
1) make inappropriate sites unavailable or unattractive, and
2) provide cat with its ideal or "ultimate" litter box(es).
1) Make inappropriate sites unavailable or unattractive for house soiling; this can be done in a variety of ways, including:
Restrict access to inappropriate sites: long-term confinement is not recommended since this may cause anxiety. Cats may use the litter box when confined, but this does not usually translate to continued long-term use once released, especially if other factors are not addressed.
Place the litter box over the inappropriate site.
Make sites unattractive by placing aversive material such as aluminum foil, double-sided tape, or a plastic runner with the protrusions pointing upward at the site.
Place a deterrent such as an ultrasonic device at inappropriate site.
When reliable box usage has been reestablished, gradual access to previously soiled sites may be allowed.
2) Offer a litter box cafeteria to determine cat's elimination preferences.
Offer several boxes with different configurations (box style, litter type, litter depth, etc.) at various sites to determine preferences; boxes with preferential usage are retained.
Consider using plastic boxes marketed for other uses as litter boxes; this will provide a greater range of sizes and shapes to select from.
Historical findings may help to direct cafeteria options.
Most cats prefer large, uncovered boxes with unscented, clumping litter; deep litter (3cm) is preferred over shallow litter (1cm), especially for defecation. Litter boxes should be easily accessible but not in heavy traffic flow areas.
Young kittens and geriatric cats may need boxes near their core area (where they spend the majority of their time).
Cats with mobility problems may require special box configurations such as low box sides that allow easy access.
In multiple cat homes, litter boxes should be distributed throughout the environment to allow all cats access. An understanding of the social dynamics between cats is usually essential to assure all cats have access to an appropriate toileting area.
The owner may need to remove soiled substrates from the environment to prevent return to those sites.
Cats appear to prefer clean boxes; clients should be instructed to perform:
- scoop once or twice daily to remove solid debris
- regularly (every 1-4 wks depending on size and number ox boxes) change and wash the litter box; all old litter dumped, box washed with liquid soap and water, box filled with new litter. Frequency of this change depends on box usage, litter type and cat.
- old plastic boxes may need to be replaced due to chronic discoloration perhaps associated with residual odor.
Consider trimming perirectal and interdigital hair of long-haired cats.
If trigger event can be established, make alterations to avoid that trigger in the future.
Some cats prefer one box for urine and a separate box for stool.
In general, drugs are not indicated for the treatment of house soiling. If extreme fear or anxiety is preventing the cat from using the box and a box cannot be placed in a "safe" area for the cat, then antianxiety medications may be considered; in some cases it may be appropriate to treat the aggressor.
If anxiety, fear, or strained inter-cat relations is preventing the cat from using the box, synthetic pheromone therapy in the form of a Feliwayฎ diffuser may be of benefit.
Contraindications / Precautions
Do not punish the cat if elimination is found outside the box.
House soiling is not done out of spite or revenge.
Any contributing underlying medical problems must be identified and treated.
Punishment is unlikely to resolve the problem and may worsen the problem.
In multicat households, there may be different individual preferences for elimination; multiple box types may need to be maintained.
If social factors are contributing, the inability or unwillingness to address them will hinder problem resolution.
It may take clients several weeks to complete the litter box cafeteria.
Client should be instructed to keep a log of house soiling.
Weekly or bimonthly contact is advised until the problem is resolved.
Prevention / Avoidance
Adequate litter box cleaning and maintenance should be stressed to all owners.
When additional cats are added to homes, the number of litter boxes should be increased; a standard rule is that the number of litter boxes should equal the number of cats plus an additional box.
Not sure if that gives you any new ideas, but I hope it helps.