Thanks for the detailed info. I’ll look into potential causes for chronic bile vomiting and GI symptoms in a young Labrador that haven’t responded to dietary trials, allergy treatment, or acid reducers—especially with intermittent skin issues, mucus in stool, and a history of GI inflammation. I’ll also explore whether endoscopy (scoping) is the next logical step and what it might uncover.

I’ll let you know what I find as soon as I can.

Chronic Vomiting in a Young Labrador: Possible Causes and Diagnostic Plan #

Case Overview #

A 16-month-old Labrador Retriever presents with chronic intermittent vomiting (mostly yellow bile or saliva) that often occurs late at night or early morning, especially if the dog goes more than 4–5 hours without food. This issue began around 6 months of age. Extensive management has been attempted, including multiple small meals, late-night feedings, strict elimination of treats, hydrolyzed diets (Purina HA, Elemental), and courses of medications (e.g. omeprazole/Prilosec for acid suppression and corticosteroids for inflammation). Despite these interventions, the vomiting persists a few times per week. Diagnostic tests so far have been largely unremarkable: parasite screens (fecals) are negative, Cushing’s disease has been ruled out, lab work is normal, and an abdominal ultrasound only showed nonspecific gastrointestinal (GI) inflammation (e.g. mild thickening of the GI tract). The dog’s stools are now well-formed (no chronic diarrhea) but tend to be pale light brown/yellow-gray with occasional mucus. The dog remains in good overall condition (normal weight, active, no lethargy) and has intermittent itchy skin managed with allergy shots (with unclear efficacy).

Given the refractory vomiting and evidence of GI inflammation, less common or overlooked causes must be considered. Below we explore potential differential diagnoses – including motility disorders, structural abnormalities, inflammatory/immune conditions, and other systemic causes – and how endoscopic evaluation with biopsy (“scoping”) can help confirm or rule out these possibilities.

Potential Causes of Chronic Vomiting and GI Inflammation #

Bilious Vomiting Syndrome (BVS) – Bile Reflux Gastritis #

Bilious vomiting syndrome is a common cause of chronic early-morning vomiting of bile in otherwise healthy dogs (Bilious vomiting syndrome — Elwood vet) (Bilious Vomiting Syndrome in Dogs: Causes, Symptoms, and Treatment). It occurs when bile from the duodenum refluxes into an empty stomach overnight, irritating the gastric lining and triggering vomiting (Bilious vomiting syndrome — Elwood vet). This condition (sometimes called “bile reflux gastritis”) typically causes yellow, bile-stained vomit in the late night or early morning hours, often after a prolonged fast (Bilious vomiting syndrome — Elwood vet). Affected dogs are usually normal the rest of the day, with normal appetite and energy (Bilious vomiting syndrome — Elwood vet) (Bilious vomiting syndrome — Elwood vet). In this case, the timing (middle of the night) and bile content of the vomit strongly suggest BVS as a contributor.

Management of BVS involves reducing the duration of fasting (e.g. offering a late-night meal or snack) to keep some food in the stomach and buffer the bile (Bilious Vomiting Syndrome in Dogs: Causes, Symptoms, and Treatment). This was attempted (overnight feedings), which improved stool consistency but did not fully stop the vomiting – indicating either severe BVS or an additional problem. It’s important to note that gastric acid reducers (e.g. omeprazole) alone often do not resolve BVS because the primary issue is abnormal motility/reflux of bile, not excessive acid (Bilious Vomiting Syndrome in Dogs: Causes, Symptoms, and Treatment). If frequent feedings aren’t sufficient, pro-motility medication (prokinetics) at bedtime can be tried to improve gastric emptying and prevent bile from pooling in the stomach (Bilious Vomiting Syndrome in Dogs: Causes, Symptoms, and Treatment) (Bilious Vomiting Syndrome in Dogs: Causes, Symptoms, and Treatment). (For example, veterinarians may use metoclopramide or cisapride at night to move contents along.) In our dog’s case, a bedtime prokinetic could be considered if not yet tried. If the vomiting continues despite these measures, it suggests that something more complex than simple BVS is at play (Bilious Vomiting Syndrome in Dogs: Causes, Symptoms, and Treatment) (Bilious Vomiting Syndrome in Dogs: Causes, Symptoms, and Treatment), warranting further diagnostics.

Gastric Motility Disorders (Gastroparesis or Dysmotility) #

Beyond BVS, other GI motility disorders could cause chronic vomiting. Delayed gastric emptying (gastroparesis) is one example – if the stomach isn’t contracting properly, food and fluids may sit and cause nausea/vomiting after several hours. Dogs with gastric hypomotility often vomit food or bile many hours after eating, and may have bloating or discomfort. In general, gastric motility disturbances are under-recognized in veterinary medicine (Diagnosis and management of GI motility disorders). They can be primary (idiopathic) or secondary to other issues (e.g. inflammation, electrolyte imbalances, or systemic disease). For instance, chronic gastritis or inflammatory bowel disease (IBD) can disrupt normal motility (Diagnosis and management of GI motility disorders). Certain metabolic disorders like hypoadrenocorticism (Addison’s disease) can also reduce GI motility and mimic primary GI disease (Diagnosis and management of GI motility disorders).

If gastroparesis is present, one clue might be the presence of retained food in the stomach despite fasting. (In healthy dogs, no significant food remains ~8-10 hours after a meal (Diagnosis and management of GI motility disorders).) In practice, diagnosing motility disorders often involves ruling out other causes and sometimes performing specialized tests (contrast radiographs or gastric emptying studies). Treatment focuses on prokinetic drugs (as mentioned above) and treating any underlying cause. In our patient, if endoscopy or imaging finds food in the stomach when it should be empty, or if no other lesions are identified, a functional motility disorder would be a strong consideration.

Pyloric Stenosis or Outflow Obstruction #

A structural narrowing of the pylorus (the outflow tract of the stomach) can lead to chronic vomiting. Pyloric stenosis may be congenital (especially in brachycephalic breeds like Boxers, Bulldogs, Boston Terriers) or acquired later in life (seen more in small breed dogs such as Shih Tzus, Lhasa Apsos) (Congenital and Inherited Disorders of the Digestive System of Dogs - Dog Owners - Merck Veterinary Manual) (Narrowing of Pyloric Canal in Dogs | PetMD). While Labradors are not a classic breed for this condition, it’s not impossible. In pyloric stenosis (also called chronic hypertrophic pyloric gastropathy), the pyloric muscle or mucosa is thickened, partially blocking food passage from stomach to duodenum (Congenital and Inherited Disorders of the Digestive System of Dogs - Dog Owners - Merck Veterinary Manual). Affected dogs often have chronic, intermittent vomiting that occurs several hours after eating (once food has had time to accumulate) (Narrowing of Pyloric Canal in Dogs | PetMD). The vomitus may contain undigested or partially digested food (if the obstruction is significant) and bile may be present if only liquid passes through (Narrowing of Pyloric Canal in Dogs | PetMD). Owners often report that medical therapy (diet changes, anti-vomiting medications) does not fully control the vomiting (Narrowing of Pyloric Canal in Dogs | PetMD). Weight loss and poor appetite can occur in severe cases due to poor gastric emptying (Narrowing of Pyloric Canal in Dogs | PetMD) (not observed in our dog, but our management with small frequent meals might mask weight loss).

Diagnosis of pyloric outflow obstruction can be achieved via imaging (ultrasound may show a thickened pylorus or a distended stomach) or endoscopy (the endoscope may have difficulty passing into the duodenum, and a narrowed pyloric canal or hypertrophied tissue might be seen). In some cases, contrast X-rays (barium studies) or fluoroscopy are used to confirm delayed gastric emptying. Endoscopy with biopsy can also rule out a pyloric or duodenal mass lesion (such as a polyp or tumor) that could mimic pyloric stenosis. If pyloric stenosis is confirmed, surgical correction (pyloroplasty) is often needed to relieve the obstruction (Congenital and Inherited Disorders of the Digestive System of Dogs - Dog Owners - Merck Veterinary Manual), as dietary management alone is usually insufficient (Congenital and Inherited Disorders of the Digestive System of Dogs - Dog Owners - Merck Veterinary Manual).

Comment: In our dog’s workup, the ultrasound was interpreted as “general GI inflammation” – it’s worth reviewing whether the pyloric region was specifically examined. If not, or if uncertainty remains, an endoscopic exam can directly visualize this area. If the scope finds a tight pylorus or irregular tissue, biopsies can be taken to distinguish benign muscular hypertrophy from infiltrative disease (like pyloric inflammation or neoplasia).

Inflammatory Bowel Disease (Chronic Enteropathy) #

Inflammatory Bowel Disease (IBD) is a broad category of chronic gastrointestinal disorders characterized by inflammation of the GI lining, often due to an abnormal immune response. In dogs, IBD can involve the stomach and/or intestines and commonly causes chronic vomiting, diarrhea, or both. There are subtypes based on the predominant inflammatory cells (e.g. lymphocytic-plasmacytic IBD is most common, while eosinophilic gastroenteritis is a special subtype discussed below). IBD typically results from a complex interplay of genetics, diet, gut microbiota, and immune triggers. Many cases have no single identifiable cause (hence termed idiopathic).

Clinical features: IBD can occur in young or middle-aged dogs and may cause chronic intermittent vomiting, chronic diarrhea, weight loss, and/or poor appetite. In some dogs, vomiting is the primary sign (especially if the stomach is chiefly affected – sometimes called chronic gastritis). It’s notable that our patient’s vomiting started at a young age (~6 months) – IBD is not unheard of in young dogs, though it’s more common from 2–6 years. The lack of response to diet change and steroids in this case is puzzling, since many IBD cases show improvement with those therapies. However, some dogs have refractory IBD that requires more aggressive or targeted treatment (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). It’s also possible that a true diagnosis of IBD was never confirmed – meaning we might be treating “blind” without knowing if inflammation is present or what type.

Diagnosis: Definitive diagnosis of IBD requires a biopsy of the GI tract to identify the inflammatory cell infiltrates (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). Endoscopy is extremely useful here: a scope can visually examine the esophagus, stomach, and upper small intestine for signs of inflammation (e.g. redness, swelling, irregular mucosa) and obtain biopsy samples from multiple sites. A pathologist will then examine the tissue and report the type and severity of inflammation; IBD is diagnosed when abnormally high numbers of immune cells are found in the GI lining (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). This differentiates IBD from other issues like infection or cancer. It’s important that biopsies are obtained before long-term immunosuppressive treatment, because steroids can mask the histological signs of IBD (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). In our scenario, a trial of steroids was given empirically – if it was a short course or ineffective, it hopefully did not alter the disease much; doing biopsies now is still worthwhile.

Treatment: If IBD is confirmed, treatment typically involves dietary management, immunosuppressive drugs, and sometimes antibiotics or probiotics (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). Diet trials with novel or hydrolyzed protein (like the hydrolyzed diets already tried) are a cornerstone – though our dog didn’t improve on these, which might indicate a non-food-responsive disease. Immunosuppressants like prednisone, budesonide, or even stronger drugs (azathioprine, cyclosporine) can be used to control inflammation (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). The fact that a steroid trial did not resolve symptoms might mean either the wrong dose/duration was used, or that the condition is a steroid-resistant enteropathy. In such cases, obtaining that biopsy diagnosis is crucial; if it’s truly IBD, other medications (e.g. cyclosporine or chlorambucil) can be attempted (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). If the biopsy instead reveals a different problem (for example, a specific infection or even an early lymphoma), treatment would change accordingly.

IBD vs. other causes: Notably, if the dog does not respond to diet or steroids, one must consider alternative diagnoses (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). The current situation (minimal response to standard IBD therapies) indeed raises suspicion that something else (or something additional) is going on (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). Endoscopic biopsy will help determine if this is truly IBD or if we’ve been dealing with an entirely different pathology disguised as IBD.

Eosinophilic Gastroenteritis (Eosinophilic IBD) #

Eosinophilic gastroenteritis (EGE) is a form of inflammatory bowel disease where eosinophils (a type of white blood cell often associated with allergies and parasites) infiltrate the GI tract. This condition is considered relatively rare and is often seen in younger dogs (typically <5 years old) (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD) – more consistent with our 16-month-old dog. Certain breeds (German Shepherds, Rottweilers, Soft-coated Wheaten Terriers, Shar Peis) may be predisposed (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD), but any breed can be affected.

Symptoms: Eosinophilic gastroenteritis can cause chronic vomiting, diarrhea, loss of appetite, and sometimes weight loss (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD). It may present very much like “garden-variety” IBD, and indeed some classify it as a type of IBD. The concurrent “allergy-like” skin symptoms in our dog (itchiness) raise the question of an underlying allergic/hypersensitivity component – EGE could conceptually tie together GI signs and allergic tendencies (eosinophils are involved in allergic reactions). However, the dog’s skin issues could also be unrelated atopic dermatitis.

Causes: Known triggers or associations include food allergies, parasites, or drug reactions, as well as idiopathic immune dysfunction (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD). Interestingly, systemic mast cell disease and hypereosinophilic syndrome can also cause eosinophilic infiltration of the GI tract (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD) (more on mast cells later). Often, no definitive cause is found, and it’s labeled idiopathic EGE (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD).

Diagnosis: Like other IBD forms, diagnosing EGE requires biopsies. Endoscopy with biopsy can confirm eosinophils infiltrating the stomach/intestine (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD). It’s also important to rule out parasites as a cause of eosinophilia – typically veterinarians will do multiple fecal exams and may even treat empirically with broad-spectrum dewormers (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD). (Our patient had negative parasite tests and presumably deworming; we’ll revisit parasites separately below.) Bloodwork in EGE might show an eosinophil count elevation, but not always. Notably, our dog’s bloodwork hasn’t been mentioned as remarkable (no high eosinophils), but eosinophil count can be normal even with tissue eosinophilic infiltration.

Treatment: EGE is usually managed similarly to other IBD – diet change and immunosuppressive medications (corticosteroids are often effective in reducing eosinophilic inflammation). Many dogs with EGE respond well to a combination of diet and steroid therapy (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD). The fact that our dog did not respond to steroids may argue against a classic eosinophilic IBD… or it might mean the EGE is particularly severe or requires a longer course/higher dose. If EGE is confirmed, treatments like high-dose prednisone or alternative immunosuppressants could be tried. Also, identifying and eliminating any underlying cause (e.g. a food allergen or parasite) is crucial.

In summary, eosinophilic gastroenteritis remains a top differential for a young dog with chronic vomiting and systemic allergic traits. Only a biopsy can distinguish EGE from other types of IBD or other diseases.

Food Allergy or Intolerance (Food-Responsive Enteropathy) #

Dietary intolerance or food allergy in dogs can cause chronic vomiting and/or diarrhea, often accompanied by itching or skin problems (a true food allergy may manifest with both GI and dermatologic signs). In young dogs, a food-responsive enteropathy is a common cause of chronic GI upset – such dogs improve when a offending ingredient is removed from the diet. A classic approach is a strict elimination diet trial with a novel protein or hydrolyzed formula for 8–12 weeks (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ).

In our case, the dog has already been through extensive diet trials (hydrolyzed protein diets, even an elemental formula of free amino acids). These diets are designed to eliminate allergenic proteins, so if food allergy were the sole issue, one would expect significant improvement during the trial (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). The lack of improvement argues that this is not purely a food allergy. That said, we should confirm that the diet trials were done long enough and with total compliance (no treats or other foods) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ) – even a small dietary indiscretion can confound the results. The question indicates treat elimination and multiple diets, so it sounds like the owners were thorough. Therefore, a food-responsive chronic enteropathy is less likely here.

It’s worth noting that many dogs with IBD have some food sensitivity component and still require a specialized diet as part of management (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). Our patient’s current diet (Purina HA or Elemental) is already very restricted, so at least we know the diet isn’t making things worse. Unless the owners reintroduce a novel whole-food diet (for example a home-cooked novel protein) and see a change, it’s reasonable to say true food allergy has been ruled out.

Parasitic Causes (e.g. Physaloptera – Stomach Worm) #

It’s crucial not to overlook parasitic causes of chronic vomiting. One in particular, Physaloptera spp. (stomach worms), is notoriously sneaky. Physaloptera is a stomach-dwelling nematode that attaches to the gastric lining and causes gastritis, often leading to chronic intermittent vomiting (Companion Animal Parasite Council | Physaloptera spp.). Dogs acquire this parasite by ingesting intermediate hosts (beetles, crickets, etc.) or paratenic hosts (like rodents) that carry the larvae (Companion Animal Parasite Council | Physaloptera spp.) (Companion Animal Parasite Council | Physaloptera spp.). Outdoor dogs with access to eating bugs or small prey are at risk – which certainly could include an active young Lab in Texas.

Critically, Physaloptera infections are hard to diagnose via routine fecal exams. The worms are few in number (often only 1–3 worms in the stomach) (Companion Animal Parasite Council | Physaloptera spp.) (Companion Animal Parasite Council | Physaloptera spp.) and they shed eggs intermittently. The eggs also do not float well in standard fecal flotation solutions, so they are easily missed (Companion Animal Parasite Council | Physaloptera spp.). This means a dog can have a negative fecal test and still be infected (false negatives are common) (Companion Animal Parasite Council | Physaloptera spp.). Veterinarians aware of this often perform multiple fecal tests, use specialized techniques, or more often just treat empirically with a dewormer (e.g. fenbendazole) in cases of unexplained vomiting (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). It’s not stated whether our dog received an empirical deworming; if not, it should be considered.

(Companion Animal Parasite Council | Physaloptera spp.) Endoscopic view of a dog's stomach heavily infested with Physaloptera worms. Even a few of these worms can cause chronic gastritis and vomiting (Companion Animal Parasite Council | Physaloptera spp.). Eggs are rarely seen on fecal exams, so infections are often diagnosed only by visualization or trial deworming.

Physaloptera signs can include vomit that sometimes contains worms or blood (from gastric irritation), but often the only sign is periodic vomiting of bile or food. Severe infestations may cause weight loss or anemia, but mild cases show only vomiting (Companion Animal Parasite Council | Physaloptera spp.). Our patient isn’t losing weight and isn’t anemic (presumably), which fits a mild occult infection if one exists.

Diagnosis & treatment: The most direct way to diagnose Physaloptera is by endoscopy, where the small worms can sometimes be seen attached to the stomach lining and removed with forceps (Companion Animal Parasite Council | Physaloptera spp.). The embedded image above shows what an infestation might look like on scope. Short of endoscopy, a strategic trial of a broad-spectrum anthelmintic (e.g. a course of fenbendazole or pyrantel) can be both diagnostic and therapeutic. If the vomiting improves after deworming, it suggests a parasitic cause even if worms were never seen. Given all common tests have been “negative,” treating for a possible hidden parasite is often recommended by specialists (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ).

Aside from Physaloptera, other parasites (like Giardia or Helicobacter – though Helicobacter is a bacteria, not a parasite) can contribute to vomiting, but they are less likely in this scenario. Giardia usually causes diarrhea; Helicobacter organisms are often found in dogs’ stomachs (sometimes causing gastritis, sometimes harmless). An endoscopy could identify Helicobacter colonization (spiral bacteria on biopsy) and then a combination of antibiotics could be tried if significant, but current evidence is mixed on whether Helicobacter causes chronic vomiting in dogs or is just an incidental finding. In any event, parasitic or infectious causes should be ruled out or treated before labeling a case “idiopathic” – and endoscopy with biopsies will help by checking for any such agents in the stomach and intestine.

Mast Cell Tumors (Histamine Excess and GI Ulcers) #

Mast cell tumor (MCT) involvement is another “outside-the-box” consideration for chronic vomiting. Mast cell tumors are a type of cancer often found in the skin of dogs, but they can have profound systemic effects. Mast cells contain histamine, and when they degranulate (either due to the tumor itself or sporadically), they can release massive amounts of histamine into the bloodstream. Histamine in turn stimulates the stomach’s parietal cells to secrete acid. The result is hyperacidity and ulceration in the GI tract (Gastric ulcer disease in dogs and cats (Proceedings) - DVM360) (Gastrointestinal Ulcers in Small Animals - Digestive System - Merck Veterinary Manual). In other words, a dog with a mast cell tumor can develop chronic gastritis or stomach ulcers due to histamine, leading to vomiting (often with blood or coffee-ground material if ulcers bleed) and loss of appetite. This is considered a paraneoplastic syndrome of mast cell tumors (Gastrointestinal Ulcers in Small Animals - Digestive System - Merck Veterinary Manual). In some cases, even without obvious skin tumors, a systemic mastocytosis (widespread mast cell proliferation) could cause similar issues, though that is very rare.

Does this Lab have a mast cell tumor? We aren’t told of any skin lumps or masses; typically owners or vets notice those. Itchy skin in this dog was attributed to allergies, but one might consider if any of those “allergy” lesions could actually have been small mast cell tumors (mast cell tumors can sometimes be red, itchy lumps). It’s a bit of a stretch, yet worth checking the skin carefully. A buffy coat smear (microscopic exam of blood for mast cells) can sometimes hint at systemic mast cell disease if mast cells are circulating inappropriately.

Diagnostics: If a mast cell tumor is found on the skin, that could tie the GI signs together. Abdominal ultrasound could also look for any internal mast cell tumor (e.g. in the liver or spleen) if systemic mastocytosis is suspected. Endoscopy might reveal gastric ulcers or erosions if histamine has been causing damage. While ulcers themselves can be from many causes, finding one would prompt a search for mast cell tumors (and other causes like NSAID use, liver disease, etc.). Biopsies during endoscopy could, in theory, even find mast cells infiltrating the GI mucosa abnormally, but typically mast cell tumors in the GI tract present as discrete masses or widespread ulcerative gastritis.

Treatment: If mast cell tumor is confirmed, treating the tumor (surgery to remove a skin MCT, plus possible chemotherapy if aggressive) is primary. Meanwhile, supportive treatment with proton-pump inhibitors or H2-blockers (to reduce acid) and gastroprotectants (sucralfate to coat ulcers) can help manage the GI ulceration (Gastric ulcer disease in dogs and cats (Proceedings) - DVM360). In our case, omeprazole was given, which is good for ulcer management, but without addressing a histamine source it may not be enough. If no mast cell tumor is found, this differential can be set aside. But it’s an important one to mention because it’s often overlooked unless a skin tumor is obvious – any dog with unexplained gastric ulcers or refractory vomiting should have a mast cell tumor in the rule-out list (Gastric ulcer disease in dogs and cats (Proceedings) - DVM360).

Other Immune-Mediated or Autoimmune GI Diseases #

Apart from idiopathic IBD, there are a few other immune-related GI disorders that could be considered. These are rare, but since our search is for elusive causes, they merit a brief mention:

• Lymphocytic-plasmacytic gastritis: This is essentially IBD focused on the stomach (sometimes just called chronic atrophic gastritis). Certain breeds (e.g. Lundehunds, which often get gastrointestinal lymphangiectasia) can have immune-mediated gastritis. It would be diagnosed on biopsy similarly to IBD. Treatment is the same (diet, immunosuppressants).

• Autoimmune gastritis: In people, autoimmune destruction of stomach lining (like pernicious anemia from anti-parietal cell antibodies) is known; in dogs this is not well characterized, but one could speculate an immune attack on gastric glands could cause chronic vomiting. Again, biopsy would show characteristic changes (e.g. lymphocytes targeting glands). There’s no specific test for “autoimmune GI” in dogs beyond histopathology.

• Breed-specific enteropathies: Some breeds have unique GI immune diseases – for example, gluten-sensitive enteropathy in Irish Setters (an immune reaction to gluten) (Congenital and Inherited Disorders of the Digestive System of Dogs - Dog Owners - Merck Veterinary Manual), or immunoproliferative enteropathy in Basenjis, or histiocytic ulcerative colitis in Boxers (though that one causes diarrhea, not vomiting). Our dog is a Labrador, which doesn’t have a known breed-specific GI disease, but it’s worth noting in general. A gluten sensitivity could cause inflammation; the current hydrolyzed diets may contain starches but usually no intact glutens, and Purina HA is actually not gluten-free (it has cornstarch, but corn has no gluten; hydrolyzed soy protein is the protein source, which shouldn’t trigger gluten intolerance). If suspicion were high, a switch to a grain-free or specifically gluten-free diet trial could be tried, but this is low yield given everything else.

• Hypereosinophilic syndrome (HES): This is an extremely rare condition where eosinophils proliferate in multiple organs without obvious cause. It can affect GI (causing vomiting/diarrhea) and skin (causing lesions) among others (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD). If our dog had persistently high eosinophils in blood and issues in various systems, HES could be a differential. However, the lab work didn’t indicate eosinophilia, making HES unlikely.

In summary, these “autoimmune” GI diseases would generally be detected by biopsy as forms of IBD or similar, showing immune cell infiltrates or characteristic damage. The treatment is immunosuppression and supportive care, much like IBD. So, practically speaking, when we proceed with an endoscopic biopsy, we will be checking for any evidence of these immune-mediated patterns. If present, we adjust therapy to a more aggressive immune-suppressive approach accordingly.

Other Systemic or Miscellaneous Causes #

Finally, we should acknowledge other systemic disorders that can present with chronic vomiting and might be overlooked:

• Hypoadrenocorticism (Addison’s Disease): Addison’s disease is an endocrine disorder (adrenal insufficiency) that can cause waxing and waning GI signs. Dogs with Addison’s often have episodes of vomiting, diarrhea, loss of appetite, and lethargy that come and go, sometimes triggered by stress (Hypoadrenocorticism (Addison's Disease) - VetSpecialists.com). Importantly, Addison’s can be hard to recognize because early or “atypical” cases may have normal routine lab work and no electrolyte abnormalities (Everything you need to know about Addison’s disease in dogs - Vetster) (Everything you need to know about Addison’s disease in dogs - Vetster). It’s known as the “great pretender” and can mimic gastrointestinal disease (Hypoadrenocorticism (Addison's Disease) - VetSpecialists.com). In our case, the dog is young (Addison’s often strikes young adult dogs) and has GI issues without a clear cause – this raises Addison’s as a differential. The question notes an ACTH stimulation test for Cushing’s was negative; however, testing for Addison’s is a different test (ACTH stim measuring cortisol). Unless that was specifically done, Addison’s isn’t ruled out. The prior steroid therapy could also complicate testing (steroids can interfere with cortisol measurements). If Addison’s has not been definitively excluded, an ACTH stimulation test is recommended. Given the dog’s normal energy and lack of obvious Addisonian crises, this is a long shot, but worth thorough consideration because the treatment (cortisol +/- aldosterone replacement) would be entirely different.

• Chronic Pancreatitis: Low-grade, chronic pancreatitis in dogs can cause intermittent vomiting and nausea, sometimes without dramatic lab changes. Ultrasound might miss subtle pancreatitis. However, at 16 months old it’s less common, and one would expect some abdominal pain or elevated pancreatic enzymes at some point. The solid stool and normal appetite between episodes also argue against significant pancreatitis. A pancreatic lipase test (cPLI) could be checked if not done, but this seems less likely here.

• Exocrine Pancreatic Insufficiency (EPI): This usually causes voluminous diarrhea and weight loss rather than vomiting. It’s rare in Labs (more common in German Shepherds) and typically would have shown weight loss by now if present. Given our dog’s weight is stable and stool, though pale, is formed (not fatty diarrhea), EPI is not high on the list. A TLI blood test could confirm or rule it out easily if needed.

• Hepatobiliary disease: Liver or gallbladder disease can cause vomiting (e.g. a bile duct obstruction, or liver inflammation). The ultrasound presumably evaluated the liver and gallbladder and found no specific issues. Normal lab values (likely including liver enzymes and bilirubin) also make significant liver disease unlikely. The pale stool color at times might hint at reduced bile flow, but if that were true, the dog would likely be ill (jaundiced or losing weight) after months of this. So this is probably not the case.

• Gastrointestinal ulceration (non-steroidal or other causes): Chronic gastric ulcers can cause intermittent vomiting (often with blood or “coffee grounds” in vomit, which hasn’t been described here). Causes of ulcers include NSAID use (not indicated here), stress, mast cell tumors (as above), or certain infections. If ulcers were present, the omeprazole should have helped reduce symptoms (and steroid use would typically worsen an ulcer). So a primary ulcer without an underlying cause is less likely. Endoscopy can directly check for ulcerations and allow treatment (sucralfate, longer PPIs) if needed.

• Neoplasia (other than mast cell): While extremely uncommon in such a young dog, a GI lymphoma or other tumor could theoretically cause these signs. Lymphoma in the GI tract can cause vomiting with or without thickening noted on ultrasound (sometimes it can look just like IBD on ultrasound). Biopsies are required to tell lymphoma apart from IBD (ACVIM consensus statement guidelines on diagnosing and ...). If the endoscopic biopsies show any suspicious cells, additional tests (immunohistochemistry or PCR for antigen receptor rearrangement) can differentiate cancer from benign IBD. Another rare tumor in the stomach is a gastrinoma (Zollinger-Ellison syndrome), which secretes gastrin hormone and causes extreme acid production and ulcers (Gastrointestinal Ulcers in Small Animals - Digestive System - Merck Veterinary Manual). This is exceedingly rare in dogs, but it’s a distant differential if we found severe ulceration; blood tests for gastrin levels can diagnose it. Overall, neoplastic causes in a 16-month dog are low on the list, but endoscopy will help ensure we’re not missing an early malignancy.

With all these differentials in mind, we can see that endoscopic evaluation with biopsy is a critical next step. It offers a chance to confirm many of the diagnoses above or rule them out, guiding us to the correct treatment.

Role of Endoscopy (Scoping) and Biopsy in Diagnosis #

Endoscopy with gastrointestinal biopsy is minimally invasive and highly informative for chronic vomiting cases that don’t respond to initial therapy. Here’s how an endoscopic exam could help our particular case:

• Direct Visualization: The endoscope will allow the veterinarian to visually inspect the esophagus, stomach, and upper small intestine (duodenum). They will look for inflammation (redness, erosions), ulcers, abnormal mucus or bile presence, masses or polyps, or any parasites. For example, seeing a pool of bile in the stomach when the dog has been fasted suggests duodenal bile reflux. Visualizing a mass or thickened tissue at the pylorus could indicate pyloric stenosis or a tumor. Finding linear foreign material or hairballs is unlikely but possible. If Physaloptera worms are present, the vet might actually see one or more worms attached to the stomach wall, which would immediately give a diagnosis (and they can attempt to remove them via the scope) (Companion Animal Parasite Council | Physaloptera spp.) (Companion Animal Parasite Council | Physaloptera spp.).

• Biopsy Samples: No matter what the gross appearance is, small biopsy instruments will be passed through the scope to take mucosal biopsies of the stomach and duodenum (and possibly the esophagus if indicated). These tiny tissue samples are then examined by a pathologist. Histopathology can reveal conditions such as:

  • Inflammatory Bowel Disease: Identified by infiltrates of lymphocytes, plasma cells, eosinophils, etc. in the tissue (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). The pathologist can quantify the inflammation and sometimes note features like lymphangiectasia or fibrosis.
  • Eosinophilic gastroenteritis: Confirmed by high eosinophil counts in the biopsies, beyond what a normal sample would have (Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | PetMD).
  • Helicobacter infection: The bacteria can sometimes be seen in stomach biopsies (Warthin-Starry stain) if present; if heavy colonization is noted along with inflammation, the vet may treat for it.
  • Lymphoma or other neoplasia: Biopsy can show abnormal lymphoid cells or other cancer cells. Distinguishing lymphoma from severe IBD can be challenging, but special stains or molecular tests can be done on the biopsies to confirm cancer (ACVIM consensus statement guidelines on diagnosing and ...).
  • Mast cell infiltration: If mast cells are diffusely infiltrating the GI mucosa, a biopsy could show an unusually high number of mast cells. (Normally there are some mast cells in GI tissue, but markedly increased numbers would be a red flag.)
  • Granulomas or infectious organisms: Uncommon, but biopsy could reveal granulomatous inflammation that might indicate fungal infection (like histoplasmosis) or atypical infections. These are rare and usually there would be other systemic signs, but it’s part of the comprehensive check.

• Confirming Pyloric Stenosis: While endoscopy can’t measure muscle thickness directly, the endoscopist can evaluate the pyloric opening. If the scope cannot easily pass into the duodenum due to a stricture, that is a strong indication of pyloric stenosis. They may see a narrowed lumen or protruding tissue. Biopsies of the pyloric antrum could show chronic hypertrophic gastropathy changes or rule out a pyloric tumor. In some cases, though, imaging or surgical exploration is needed to definitively diagnose pyloric stenosis. Endoscopy is a great first step because if it’s normal, you may avoid unnecessary surgery; if it’s abnormal, it guides the need for surgical intervention.

• Upper vs Lower GI: Note that endoscopy (gastroscopy) will sample the upper GI. If chronic diarrhea or weight loss were major issues, we’d also consider colonoscopy for lower GI biopsies. In our case, diarrhea is not prominent, so upper GI scoping is the priority. If upper endoscopy is inconclusive and suspicion remains for IBD affecting primarily the intestines, then either a colonoscopy or exploratory surgery for full-thickness biopsies might be the next step (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ). Full-thickness biopsies (surgical) can sometimes yield better diagnostic information for small intestine disease (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ) (Inflammatory Bowel Disease in Dogs | VCA Animal Hospitals ), but that is more invasive and usually done if endoscopy is nondiagnostic or cannot reach the affected area.

• Therapeutic Potential: In addition to diagnosis, endoscopy can provide some therapy. For instance, if a foreign object is found, it can often be removed with the scope. If Physaloptera worms are seen, they can be physically removed. If severe pyloric stenosis due to a mucosal fold is present, sometimes a balloon dilation can be attempted endoscopically (though surgery is often still needed). These are situational, but worth noting.

In summary, endoscopy + biopsy is likely the most informative next diagnostic step for this dog. It can confirm conditions like IBD/EGE, identify hidden parasites, reveal structural problems like pyloric stenosis or ulcers, and even help discover unexpected issues (e.g. a subtle mass). By ruling in a specific diagnosis, we can tailor the treatment (be it surgical correction, targeted deworming, specific immunosuppressants, etc.). If the endoscopy and biopsies turn out largely normal, that itself is informative: it would make functional disorders (like idiopathic motility disorder or psychosomatic vomiting) more likely, and we would then focus on medical management for motility and symptomatic relief.

Below is a summary table of the potential causes we’ve discussed, along with their typical clinical features, how they are diagnosed, and their treatments:

Summary Table: Differentials for Chronic Vomiting in a Young Dog #

Table: Key differentials for chronic vomiting in a young dog, with their hallmarks, how to diagnose them, and how they are treated. Many of these conditions can co-exist or exacerbate one another (for example, IBD can cause motility issues; a food allergy can lead to IBD; etc.), so a thorough workup is necessary.

Conclusion and Next Steps #

For this 16-month Lab, the journey has been challenging. Common causes of chronic vomiting (dietary indiscretion, simple food allergy, giardia, etc.) have been ruled out or addressed without success. The next step is a comprehensive investigation for these less common causes. An upper GI endoscopy with biopsies will be particularly valuable to check for inflammatory diseases (IBD or eosinophilic gastritis), detect any hidden parasites or ulcers, and assess the pyloric structure. Concurrently, it would be wise to perform an ACTH stimulation test for Addison’s (ensuring any steroid given in the past has cleared) to definitively exclude hypoadrenocorticism as a contributor. If endoscopy is normal and Addison’s is negative, a gastric emptying study or trial of prokinetic therapy could be pursued to evaluate motility.

By systematically ruling in or out the above differentials, we move closer to relieving the dog’s vomiting. For instance, if biopsies confirm IBD, targeted immunosuppressive therapy (perhaps a different steroid or a combination therapy) can be instituted with careful monitoring of response. If eosinophils are dominant, we might revisit allergen exposure or consider stronger anti-inflammatory doses. If a structural issue like pyloric stenosis is found, surgical correction could be curative. And if a parasite is discovered, a deworming regimen will spare the dog further GI irritation.

In summary, chronic vomiting in a young dog often requires thinking beyond the obvious. Conditions like bilious vomiting syndrome or mild IBD can masquerade as “simple” vomiting for months, and rarer issues like Physaloptera infection or atypical Addison’s can be easily overlooked. A combination of advanced diagnostics (endoscopy, specialized blood tests) and clinical intuition is needed to uncover the root cause. With a confirmed diagnosis, a tailored treatment plan can greatly improve the dog’s quality of life and finally put an end to those nightly bouts of vomiting that have troubled her since puppyhood.