Hi again Sue!
Thanks for your patience!
You have described to me a 14yr old male Boxer who is on a thyroid supplement and also on Rimadyl. He has had diarrhea for some time, and was treated with Metronidazole by your family veterinarian. Despite this, his diarrhea persists. He has lost weight.
There are a lot of different possibilities for what may be going on with your dog. The ones that I would be considering if he were on his way to see me are:
1. Small intestinal bacterial overgrowth (SIBO)
Dogs with this problem have frequent diarrhea and high folate levels on blood testing.
This is because folate is made by bacteria in the intestines, and is then absorbed into the blood stream. So, if SIBO is present for a long period of time serum folate concentration increases.
Unfortunately, only about 50% of dogs with SIBO have increased folate. Thus, if we do a blood test and find increased folate, we can be pretty sure that there is SIBO, but if the blood test is negative, the dog could still have SIBO. We also measure blood levels of cobalamin which will be decreased with SIBO as the bacteria bind this vitamin. So, these 2 blood tests together can be useful in diagnosis.
It is treatable with Tylosin (
http://www.petplace.com/drug-library/tylosin-tylan/page1.aspx )
Here is more about it:
http://www.vetmed.wsu.edu/courses_vm546/content_links/DfDx/Dog%20Case%203/small_intestinal_bacterial_overg.htm
http://www.petplace.com/dogs/chronic-diarrhea-in-dogs/page1.aspx
SIBO can be due to an underlying problem such as a food intolerance or exocrine pancreatic insufficiency, though that would be less likely in a dog of this age.
Here is more about them:
http://www.peteducation.com/article.cfm?c=2+1664&aid=143
http://www.sniksnak.com/doghealth/epi.html
2. He may have a Protein Losing Enteropathy (PLE).
The blood tests your vet did should help to support or deny this. If his albumin levels were low (OR if they have dropped substantially in the last few weeks/months), then this is something I would be considering more strongly. PLE is thought to have a genetic component and is often manageable using specific diets and medications. There are a number of different things that can cause PLE, from immune system problems to cancer. If your dog's ALBUMIN levels were normal, then this would be unlikely.
Here is more about it:
http://www.petplace.com/dogs/protein-losing-enteropathy-in-dogs-ple/page1.aspx
http://home.comcast.net/~lechaun1/kidneys.html
3. It is possible your Boxer simply has gastroenteritis from eating something he shouldn't have.
Table scraps, garbage or twigs and leaves could be the culprit! Gastroenteritis is an inflammation of the stomach and intestines and can be caused by a large number of things, including sudden dietary changes.
4. A bacterial infection.
Dogs can be affected by overgrowths of bacteria in the intestines. In an adult dog these might not be more than a nuisance. The 3 most common are Campylobacter, Salmonella and E.Coli. Here is a link with more information:
http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=2232
http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=598
5. Another possibility is Parasites. Here is a link to information about whipworms which are notoriously hard to identify by fecal analysis, and are not killed with pyrantel pamoate (standard dog dewormer):
http://www.VeterinaryPartner.com/Content.plx?P=A&A=1668
If your dog were coming to see me, I would do a complete physical exam, check a fecal sample for parasites, deworm him, and recommend a blood folate/cobalamin level. I would treat him with Tylosin if indicated.
In terms of what you can do at home, I would make the following suggestions:
1. Start a probiotic.
This is in order to get some "good bacteria" back into the system. An easy way to do this is by using a product called Culturelle. It comes as a capsule, and for a dog this size, if he were my patient, I would give him 1 capsule two or three times daily. It can be mixed in with some water and given by syringe into the mouth, or it can be sprinkled over a bit of rice. Here is more:
http://www.culturelle.com/
Another option would be FortiFlora which is available from your veterinarian. Here is more about it:
http://www.dogbuffs.com/?p=80 This has been shown in clinical studies to have positive effects on immune function.
2. I would also encourage your Boxer to drink as much as possible of clear fluids, since he may be becoming slightly dehydrated from all the diarrhea. So, water is fine, but also he can have pedialyte, Gatorade, apple juice diluted 50:50 with water, or chicken or beef broth diluted 50:50 with water. Give the fluids in small amounts frequently. For a dog this size that means about 1 cup an hour.
3. Start 2 tablespoons twice daily per 10lbs body weight of canned Pumpkin. Be sure to use plain canned pumpkin and NOT pie filler! For a 60lb dog, this would work out to 12 tablespoons or 3/4 cup TWICE a day. There should be improvement within 1-2 days. I usually suggest patients stay on this for 1 week, then gradually decrease.
If these things do not help over the course of the week, then I do think you are going to need to see your vet again. Things may be more evident now to your vet than they were previously. Something is going on with your dog! It sounds as though it is time to find out what.
I hope that helps you. If this has been helpful, please hit the green "Accept" button and leave feedback. I will still be here if you have further questions!
The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.
Fiona
I am a licensed veterinarian practicing in Ontario, and will always do my best to answer your questions. My on-line help, however, cannot take the place of a hands-on examination by a veterinarian.