First, if she is not eating properly, this issue is much larger then a lack of stool. Where straining to pass feces could be related to a bit of constipation (though uncommon in the rabbit due to their great fiber filled diet), to see this combined with appetite decline is more worrying and more suggestive of an early stage gastric slowing and stasis. And this is one of the few true rabbit emergencies. So, if you think she is eating less +/- drinking less and isn't passing stool; then it would be prudent for her to be seen by her vet before this can progress any further.
Just to note, signs we often see with GI stasis include:
- Decreasing or sudden lack of appetite for food +/- water)
- Changes to fecal production (from soft stools, to strangely shaped fecal pellets to diarrhea or no fecal production at all)
- Off color/lethargy/ hiding
- No GI sounds or loud uncharacteristic grumbles/growl
In situations like these, we need to address both the stasis and any trigger for it. In this case, we'd want her vet to perform a full physical exam to pinpoint the trigger (ie dental disease, GI upset, respiratory disease, a blockage from non-edible items like those she may have eaten, etc). Depending on the vet's findings, they can address the underlying trigger and initiate treatment. To keep the guts moving and get them back on track, often these cases need pain relief, pro-motility drugs, +/- antibiotics. If her signs are severe, she may need to be hospitalized. Or if you are able to provide diligent supportive care at home, they may advise you on how to syringe feed her.
Typically, rabbits with appetite decline and GI slowing need to be hand or syringe fed (usually hourly) to continue nutrition input to meet their body's requirement and keep her guts moving to prevent/address stasis. To support her, it is worthing getting a vet to dispense a critical care feeds that you can syringe feed the bunny. A very good product for this is Oxbow’s Critical Care feed (LINK) or Supreme Recovery diet (LINK) and most vets will be able to provide this to you. This is a highly nutritious herbivore feed that can be easily made into a slurry for syringe feeding. And it is much easier to use then trying to create a balanced critical care diet at home. Just to note, as a short term option (since the fiber level wouldn't be high enough for long term use), you can syringe veggie baby food with her pelleted feed crushed into it.
Now be warned that if you do undertake syringe feeding her, then this can be a challenge (we all end up with rabbit food on us when we are syringe feeding rabbits). To administer it in as stress free means as possible, I would advise having a peek of this guide (HERE) since a video is worth at least a thousand words. If she is quite resistant to being fed, then do watch the end of the video for 'towel wrapping' her to keep her snug and secure while you are feeding her.
In regards ***** ***** and drinking, if either is compromised then her vet might give sterile fluids under her skin. Otherwise, you can try tempting her with pedialyte (fruity flavors are best tolerated) or diluted Gatorade (50% diluted with water). These will help replenish electrolytes and get some glucose into her system. If she isn't keen on it, you can give pedialyte via dropper of syringe. A typical dose for animals is 4.8mls per 100 grams of body weight per day (obviously divided over all day drinking). This is her maintenance rate and it is a good starting place for supporting her against dehydration.
Overall, a depressed appetite and no feces is a very serious situation for a rabbit and this shouldn't be ignored. I would advise that she should see her vet immediately. They will be able to treat her for this and advise you on how to administer critical care diet and nurse her through this situation. Overall, prompt treatment and supportive care are the best things we can do to get this under control and give Thumper best chance of recovery and getting back to herself.
If you don’t already have an rabbit vet, you can find one near you at http://www.aemv.org/vetlist.cfm or http://rabbit.org/vet-listings/
Please take care,