I did some reading and, apparently, this is either camplylobacter or some form of bacterial overgrowth in the intestine (possibly both). The links I've found have not been very precise in describing it, but have been very precise in suggesting what should be done. Here's a sample:
Trial & error found the treatment. DOG SHOW CRUD Non-specific diarrhea syndrome Progressive diarrhea. It's a BACTERIAL imbalance in the digestive tract. This is NOT a new form of Parvo. Parvo tests will show a LOW positive & subsequent tests will continue to show low positives, will be inconclusive, or will give erratic results. This disease is so similar to Parvo, that some dogs have tested in the low positive for Parvo. But they do not have Parvo, and it has been recommended that three Parvo tests are needed to exclude Parvo.
Mode of infection: widely varied, but mostly from contact with urine, feces, something brought in on shoes, etc. Symptoms usually start 12-48hrs after initial contact & spread to susceptible dogs rapidly (young or weaker dogs). It's everywhere! It's on your shoes, in the places where dogs sniff, urine on posts or ground, or trees, or feces, etc. Pups have a difficult time surviving, but if caught quickly enough (before anorexia), no one dies. Death occurs because of dehydration. Some dogs get better without treatment. This disease seems to move from the West to the East through the dog shows.
It is medically known as Campylobacteriosis, name of the organism causing this is Campylobacter Jejuni. This disease can be tested for specifically, so if you have an affected dog that appears to have Parvo, but in your mind know that, that could not be possible, have them tested for "Camby". It is important to note that this disease can be transferred between humans, dogs, cats and other livestock. Dogs are alert, hungry, and energetic, with normal feces.
It starts with fecal mucus sheath & continues to get progressively softer until it is watery & contains blood. It then becomes explosive. Vomiting may accompany & may or may not also contain blood. Feces have a sweet/flowery aroma along with a "slaughterhouse on a summer day" smell (similar to Parvo diarrhea but with a floral hint). Feces are *usually* mustard colored. Dogs dehydrate at an astounding rate. Dogs are also at risk of intusseption (sp?).
Do NOT automatically assume Parvo when you see this. Parvo treatments have killed the majority of Crud dogs. If you suspect Parvo, try the Cephalexin 1st, if it doesn't work, THEN assume Parvo. Do NOT use Amoxycillin. Keflex has worked in the past, but slowly & speed is the important thing here. Dogs should show improvement within hours of treatment. What is happening is that there is a bacterial growth in the digestive tract which throws it off balance. The body is trying to counteract this by removing the extra (or offending) bacteria. It seems to do this by trying to remove ALL body fluids as quickly as possible. Death is caused by massive dehydration. From the 1st signs of symptoms, death can be as short as 12 hrs, or as long as 7 days.
And here's where you can read what the Merck Veterinary Manual has to say about campylobacteriosis: http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/20700.htm
If you suspect your dog has parvo, but tests are negative for parvo, please talk to your vet about the possibility that you may be looking at a case of "dog show crud" or campylobacteriosis instead.