I was hoping to get a response back from you. I'm not sure if the dog had imaging done or not. If the doctor found the tumor than it is a good chance that might be affecting her adversely depending on where it was. Tumors can be in the rectal region which migh cause abnormal bleeding. However, rectal bleeding can be due to a large number of causes. Let me give you the various reasons.
Rectal bleeding can be a problem in the rectum or the colon. If it happens right after defecating, it may be an anal gland problem. Just bleeding from the rectum without clots may just be a problem in the rectal area such as rectal polyps. You can read about anal gland problems here:
You can read about rectal polyps here:
Parasites such as worms and protozoan infections such as coccidia and giardia can produce blood in the stool and blood from the rectum after bowel movements. Common dewormers are Panacur, which is a prescription product so you need to obtain it from your Vet and it works on roundworms and whipworms. Wormers labeled as Pyrantel Pamoate are the best over the counter medication for roundworms. Drontal plus is also a prescription product and is used for the treatment of Tapeworms, though dewormers with praziquantel work well against tapeworms. Revolution and Interceptor as well as other heartworm medications also control whipworms and roundworms. Another reason to keep your dog on Heartworm medication.
You can read about these here:
If there is straining to defecate, frequent small stools, mucus with the stools, blood coating the feces, signs of discomfort such as licking, turning suddenly or crying, then most likely the problem is in the rectal area. This would include rectal polyps or prolapse, parasites, colitis, colonic ulcers, hemorrhagic gastroenteritis (HGE) and even cancer. HGE is very serious and life threatening. You can read about it here:
You can read about the various cause of red blood in the stool here:
If this is a tumor it might press against the spine and lead to loss of mobility. However, boxers are prone to some issues of the discs anyway so it might be a disc issue affecting the rear legs. Ticks can also lead to paralyses as well which clears up with the removal of the tick. I do understand you can't afford surgery but maybe one of the following organizations can help you.
Veterinary Bill Assistance Programs:
1. The Big Hearts Fund: http://bigheartsfund.org/
2. Cats in Crisis: http://www.catsincrisis.org/
3. Diabetic Cats In Need: http://fdmb-cin.blogspot.com/
4. The Dog And Cat Cancer Fund: http://www.dccfund.org/
5. Frankie's Friends: http://www.frankiesfriends.com/
6. Handicapped Pets Foundation: http://hpets.org/
9. The Mosby Foundation: http://themosbyfoundation.org/
10. The Onyx and Breezy Foundation: http://www.onyxandbreezy.org/
11. Paws 4 A Cure: http://www.paws4acure.org/
12. The Pet Fund: http://thepetfund.com/
13. Pets-DC: http://www.petsdc.org/
14. Shakespeare Animal Fund: http://www.shakespeareanimalfund.org/
This site may have additional resources as well.
These vets may offer a free initial visit though you may have to pay for extra procedures and medications. See the next one for the coupons.
That might allow you a second opinion. Now they do make doggie wheelchairs for dogs who lose control of their back legs and they even include an area to catch fecal matter that might slip out. Many are sold secondhand on auction sites. You can see one here:
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.