Rabbits/Cecal dysbiosis and diet - older bunny
Hi Dr. Kremplels,
We have a holland lop who is just about to turn 12. He's a neutered house rabbit and we've had him since he was 8 wks old. Chuck has survived a lot, including E. cuniculi, bilateral cataracts since age 4, and an ear abscess that eventually required surgery to ablate the inner ear. But in spite of the fact that he's totally blind, half deaf, has a weak back leg, and mostly hops in circles, he's a pretty happy, cuddly guy. He does get metacam and gabapentin for arthritis/possible nerve pain and lactulose to help his liver.
His latest issue is that his vet says his calcium levels are too high, but the recommeded dietary restriction is wreaking havoc with his cecals. Chuck has always eaten lots of dark green leafy stuff like kale, chard, collards, broccoli, parsley, carrot tops, plus a tbsp or so of pellets daily and occasional treats of fruit. Now we're down to pretty much just timothy pellets, timothy hay, parsley, cilantro, and carrot tops and he's developed awful, smelly, squishy cecals. Even though he never lost his appetite, he started losing weight slowly when we cut out the cruciferous veggies, and we couldn't figure out what to do other than increase his pellets. His vet cautiously suggested adding more fruit to his diet very slowly to increase his calories, but it seemed to make things worse. What should we be feeding our little guy to get things back in balance? Is total dietary restriction the only way to keep his calcium levels in check or is there some way to give him back some of his favorite foods? We have a good vet that we found through the HRS site, and well definitely take Chuck in if we need to, but we both out of work right now so we'd love to know if there's anything we can try before we have to rack up more bills for a vet visit/labs/more meds. Thanks for any ideas you can offer!
Tselia and Brent
Dear Tselia and Brent,
When the vet says his calcium is "too high", what exactly is the level of calcium? Rabbits typically have considerably higher calcium levels than carnivores, and if the vet is more accustomed to the values seen in dogs and cats, you might be getting a false alarm. Also, blood calcium levels in rabbits can rise and fall dramatically, often depending on what bun has been eating, but not always. Problem is, you can't really get fasting blood values for a bunny, since food should never be completely withheld. (Might be time for a re-check after a diet of only timothy!)
Second, as weird as it sounds, we more commonly see rabbits with metabolic bone disease showing *low* blood calcium levels, since they are leaching it from the bones and rapidly excreting it via the kidneys. This is when you start to see kidney calcification and bladder stones.
I'd suggest an abdominal radiograph to see if Chuck has any renal calcification or signs of bladder sludge or stones. If not, then I'm not sure I'd worry too much about "high" calcium levels unless they are off the charts. There's an excellent overview of blood calcium homeostasis in rabbits here:
Here's a relevant excerpt from the above:
"Calcium metabolism is unique in the rabbit. Unlike other mammals, blood calcium levels fluctuate widely. Intestinal absorption of calcium is virtually complete, making serum calcium levels proportional to dietary calcium intake. Both ionized and total serum calcium concentrations are elevated in the rabbit compared with those in other species (ionized calcium, 3.4 + 0.26 mEq/L; total calcium, 12.92 + 1.0 mg/dL). In most mammals, hypercalcemia is abnormal and may lead to renal damage or soft tissue calcification. Rabbits seem to tolerate relative hypercalcemia, although in rare instances persistently elevated blood calcium levels can result in soft tissue calcification even in the rabbit."
That said, you can't really be sure that high-calcium greens and vegetables are the only culprit for high blood calcium levels in rabbits. It's a combination of things, including hormone changes with age.
Since Chuck has been off the greens, have his calcium levels been re-checked? If they haven't changed, then I'd say it's not the greens, and he might be able to go back to his former diet. He's not a spring chicken, and to deprive him of the things he loves at this age seems a little sad. Especially if the greens are not what's causing the problem. If there really is a problem.
Has the vet suggested a short course of subcutaneous fluid therapy to see if that might help? That could be something to ask about, too.
I hope this helps.