Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am very sorry to hear about your fellow's inability or unwillingness to rise. He may not want to eat and drink because he needs to eliminate and is having trouble getting up and getting into position to eliminate. As you can imagine if you had a full bladder you would not feel like eating or drinking.
Has he ever had radiographs of his spine or hips?
Any history of weakness or arthritis in the rear?
If you pinch his toes on his rear feet does he feel it?
I know this may be difficult given his size but if you support him standing by putting a towel under his abdomen and helping him up to a standing position, then flip his rear feet so the topside is down does he immediately right them?
It is important to find out whether he is too weak and painful to get up or whether he has truly lost the ability to do so.
What color are his gums and tongue? If they are white or very pale pink that can signify internal bleeding and that could make him too weak to rise. If his color is poor this is a true emergency.
Does his abdomen look bloated?
Is he holding his eliminations, or has he passed any urine or stool consciously since this began? Or has he has lost the ability to control his urine and stool (incontinence)? If he has loss of control he has some loss of neurologic function.
It is very possible given his breed mix that he is dysplastic. Sometimes it is simply too painful to get up. Symptoms can happen suddenly if a piece of the arthritic changes in his hip breaks off and is free in the joint.
But if he has a history of dragging his toes, and now cannot feel them normally, that can signify neurologic problems, such as an intervertebral disc(s) (cushions between the bony vertebrae) that are out of place or spinal arthritis putting pressure on the spinal cord or even a mass in or around the spinal cord.
Another possibility is a condition called FCE, fibrocatilagenous emboli, where a chunk of cartilage breaks off and lodges in the blood vessels that supply the spinal nerve roots. It is very painful initially as blood supply to tissue is blocked off. The pain only lasts a short time, less than a few hours to a day, but the weakness from the nerve damage it causes it can last for weeks or in rare cases is permanent.
Rotties and German Shepherds are prone to a disease process that affects the rear legs called lumbosacral stenosis (LSS).
It can have many of the same symptoms as a FCE as it causes neurologic symptoms too. It is caused by weak spinal ligaments that allow the bones in the spinal column to move and place pressure on the spinal cord or it can be due to inflammation of the ligaments inside the spinal cord canal causing pressure on the spinal cord leading to loss of function, just like a FCE.
FCE are initially painful but after that it's just a matter of regaining function.
LSS can be painful on and off until the spinal column is stabilized and the pressure is taken off the spinal cord permanently.
Another possibility if he seems not painful but has lost coordination and feeling in his rear legs is a condition called ascending myelopathy. This is a progressive degeneration of the spinal nerves that begins with incoordination of the rear legs then progresses to loss of urine and stool control (continence). This would be very unlikely with him if his symptoms came on very suddenly. Myelopathy is a slowly progressive disease process.
He really needs a veterinary examination as soon as possible. Radiographs to look for a collapsed disc space or arthritis of the spine and hip dysplasia would be helpful. We need to know what the problem is to treat it successfully.
If those look fine then an MRI of his spinal cord in the back of the body will be helpful.
Pain and inflammation in these conditions is controlled with nonsteroidal anti-inflammatories like Deramaxx or Rimadyl as well as Tramadol and/or Gabapentin.
You can use these with the omega 3's and glucosamines if arthritis or hip dysplasia is diagnosed. Long term nutraceuticals help improve cartilage and joint fluid health as well as reduce inflammation.
Nutraceuticals I recommend include a combination of a glucosamine/chondroitin product (examples are Dasuquin or Cosequin) and an omega 3 fatty acid (like 3V Caps or Derm Caps). I recommend an omega 3 fatty acid dose based upon the EPA portion (eicosapentanoic acid) of the supplement as if we do that the rest of the supplement will be properly balanced. Give him 20mg of EPA per pound of body weight per day. For example an 80 pound dog could take 1600mg of EPA per day. Omega 3's and glucosamine/chondroitins work synergistically and improve cartilage health and joint fluid quality and quantity as well as reducing inflammation. They can take several weeks to see full improvement but some dogs do very well with this combination. They are available over the counter.
Another option is a product called Duralactin. This is an anti-inflammatory product derived from milk proteins and it also has omega 3 fatty acids incorporated into it which can be very helpful. See this link for further information: http://www.duralactin.com/products_canine.html
There is no treatment for myelopathy, unfortunately. We can only definitively diagnose that condition after death because it requires a biopsy of spinal cord tissue. In many cases we rule out everything else and with a history of little to no pain and a gradual onset then we assume it is myelopathy. There is a blood test that looks for genetic markers for the disease. If you want to test him for the disease the available blood test available is pretty accurate. Here is a link to a website which will give you information about how to get him tested: http://www.offa.org/dnatesting/dm.html
If he is not responding to cortisone or nonsteroidals then I think that more diagnostic testing should be done. An MRI of his spinal cord will help diagnose intervertebral disc disease or lumbosacral stenosis. Those conditions can be treated surgically.
In the meantime try and keep your pup quiet if he does start to get up and move around again. With spinal instability the more they do, especially jarring activities like running and stairs, the faster the condition can progress.
At this point if he has not gotten up for more than 12 hours, and absolutely if it has been more than 24 hours, he should be seen by a veterinarian. There is little that you can do for him at home other than keep him quiet and clean.
Please let me know if you have any further questions.