Thank you for the much more complete overview.
Here are my concerns:
1) Just because blood work is fine and xrays did not reveal anything abnormal, she has to have some, as of yet unidentified, disease condition. Some diseases hide well, especially those confined to the GI tract. It is not uncommon for the tests she had so far to be normal, but the real cause of the problem not yet found. I DO NOT agree with her vet in that she is not appearing healthy to me and if the diarrhea and anorexia/hyporexia is not resolved, she will be in danger. What needs to be established as well is does it appear she is dealing with a large bowel problem or a small bowel problem or both. I suspect her problem is more large bowel, referred to as colitis
, since it sounds like she is still feeling pretty well. There is often some crossover between the two and some unlucky dogs will have disease that crosses over both large and small intestine. It becomes more critical to ascertain if we are to the point of discussing biopsy of the intestine, only so we make sure we biopsy the correct area of the gut.
2) To review the blood work, I suspect a basic CBC and chemistry panel was run. Again, not uncommon for all to be normal here. There are specific GI tests (not usually part of a basic panel) that need to be requested. These are more sensitive to identify GI issues and focus on diseases of the pancreas and small intestine. These tests are usually grouped into a GI panel and include the following: TLI (to rule out pancreatic insufficiency
), SPEC-cPL (to rule out pancreatitis
), cobalamine and folate (to rule out small intestinal malabsorbtion diseases).
3) As far as stools, to be complete, a stool sample should be tested for Giardia
(preferably with the ELISA test in a lab). One would expect the other dogs would be showing some signs too, but not always the case. Also depending on what whipworm dewormer was given, that can be used to treat Giardia, but the treatment has to be continued for a longer time period than for treating whipworms. A fecal sample should also be evaluated for fecal bacteria, especially clostridium
4) As far as the tick panel, I am not convinced the doxycycline is needed and may be contributing to the decreased appetite. I am also not aware of any tick-borne diseases leading to these type of signs. Even if it were an "early" infection from a tick bite, such that it wouldn't be showing up on the test yet (not likely), we would not expect there to be any signs of disease yet either. A tick panal could be re-run in a few weeks, but I do not believe they are involved.
As far as the prednisone, it is true that some dogs do eat more when on steroids, but there are better and more effective appetitie stimulants that can be offered. Mirtazapine is one that works very well for many dogs. Steroids are also often used as part of the treatment for colitis or inflammatory bowel disease. This is best prescribed however only after confirmation that these conditions exist, which is best done with a biopsy of the intestine. If steroids are used for their anti-inflammatory properties in the gut, they need to be given at an appropriate dose to be effective and that often is initially fairly high. I believe that more of the effort needs to be placed on finding the cause of the diarrhea and getting that resolved, than to look for a food that she will eat or try to stimulate her appetite. I think when her bowel is better, her appetite will improve. There is nothing wrong with hand feeding as you have been for the short term, but the main focus needs to be the stools and why they are not improving.
Ultrasound may help to add information to the case, but even if a thickened bowel is identified, it will not tell you why it is thickened. If the above tests do not turn up any answers, I would strongly consider an intestinal biopsy to get the answer. In a dog this young, food allergy is a very strong possibility, but a food trial is not going to be too effective if she won't eat. If the biopsy would turn out to be suggestive of an allergy, immunosuppressive doses of steroid along with GI support medications like Vit B12 and probiotics can be helpful to calm the inflammation to the point that her appetite may return some and a limited ingredient diet could then be introduced. Metronidazole often works well here (I am not convinced that it decreased her appetite) or the drug called cerenia which both act to decrease inflammation in the gut and often allow for a decreased dose of steroid to control the signs. Cerenia is labelled as an anti-vomiting medication but has multiple uses.
Hopefully, this gives you some things to explore and discuss with the vet. It sounds as if perhaps a second opinion may be needed, preferably with an internal medicine specialist if there is one nearby. Please let me know if you have any further questions or concerns that I can address.