Clinical Reasoning in Veterinary Practice. Группа авторов

usually involves routine clinical pathology and dynamic or function tests +/− imaging to localise the organ affected, for example, liver, kidney, pancreas and adrenals.

      The location of the problem for patients who are regurgitating is almost always the oesophagus (occasionally the pharynx), whether the cause is primary or secondary GI. Thus, regurgitation is a clinical sign where location is considered first, and then the question is asked, Is this a primary or secondary GI lesion?

       Define the lesion

      Primary GI diseases causing vomiting

      Once the lesion has been located within the GI tract, it must now be identified. Biopsy may be appropriate or the type of lesion may be evident by visual inspection (e.g. foreign body).

      In the GI tract, as elsewhere, neoplasia and inflammation often look grossly identical, and biopsies should always be taken even if the GI tract looks grossly normal.

       Diseases of the stomach

       GastritisDietary indiscretionDrug induced, for example, non‐steroidal anti‐inflammatory drugs (NSAIDs)Immune‐mediated inflammatory diseaseInfection, for example, Helicobacter pyloriRarely clinically significant

       Gastric foreign bodies

       Gastric ulceration (see section below discussing haematemesis)

       Gastric neoplasia

       Disorders of the pylorusPylorospasmPyloric obstructionCongenital pyloric stenosisChronic hypertrophic gastropathy

       Abnormal gastric motility

       Intestinal disease

      Those intestinal diseases for which vomiting is a predominate clinical feature include the following:

       Infectious enteritis, for example, parvovirus, corona virus (diarrhoea will usually also be present)

       Dietary indiscretion (diarrhoea often present)

       Intestinal obstruction – foreign body and intussusception

       Inflammatory bowel disease especially in cats (dogs tend to more commonly present with diarrhoea as the major clinical sign).

      The closer the obstruction is to the pylorus, the more frequent and severe the vomiting.

      Secondary GI diseases causing vomiting

      A large number of secondary GI disorders can cause vomiting. However, most of these can be eliminated with relatively few tests – at least in dogs. Cats are more problematic, especially in the diagnosis of pancreatic and hepatic disease. In Table 3.1, the most important secondary GI disorders are listed with tests that are useful in their diagnosis.

Table 3.1 Secondary gastrointestinal causes of vomiting in cats and dogs.

Disorder	Clinical pathology that may be useful
Pancreatitis	Pancreatic lipase immunoreactivity (PLI), amylase (not in cats), lipase (not in cats), white blood cell (WBC) count, ALP, presence of lipaemic serum
Hepatic disease	ALT, ALP, GGT, bile acids, bilirubin, albumin, urea, glucose
Renal disease	Urea, creatinine, phosphate, SDMA, urine specific gravity (SG)
Hypoadrenocorticism	Na+,K+, urea, cortisol, calcium, glucose
Diabetic ketoacidosis	Blood and urine glucose, ketones
Toxaemia due to infection	WBC count
Hypercalcaemia	Serum Ca2+ (total and ionised)
Hypokalaemia/ hyperkalaemia	Serum K+
CNS disease	Cerebrospinal fluid (CSF) analysis (possibly)
Dirofilariasis (cats)	Heartworm antigen tests (often negative), eosinophil count
Lead toxicity	Blood lead and/or urinary delta‐aminolevulinic acid (δ‐ALA)
Hyperthyroidism (cats)	Thyroxine (T4)

You should consult other textbooks to read about specific details of primary and secondary GI diseases causing vomiting and regurgitation.

       Haematemesis

      Persistent vomiting of fresh blood or vomiting of digested blood (coffee grounds) can be of significant clinical concern. The cause may be primary GI disease or secondary GI disease. Contrary to popular belief, most patients that are vomiting do not have gastric ulceration and do not need to be treated with an anti‐ulcer drug. However, there may be a role for use of drugs that suppress gastric acid secretion (preferably proton‐pump inhibitors) to prevent secondary oesophagitis.

      Haematemesis may be the only sign of gastric bleeding, but concurrent melaena is common (see Chapter 12).

      Primary GI causes of haematemesis include:

       NeoplasiaLymphoma, adenocarcinoma, leiomyoma and leiomyosarcoma

       Gastric foreign body

       Severe inflammatory disease.

      Secondary GI causes of haematemesis include:

       Coagulopathy

       Secondary GI diseases causing gastric ulcerationNSAIDsHepatic diseaseHypoadrenocorticismGastrinomaMast cell tumour (non‐GI location)TraumaRenal failureSystemic inflammationFor example, pancreatitis, sepsisExtreme exerciseFor example, sled dog racing.

      Causes of regurgitation

Table 3.2 Oesphageal disorders causing regurgitation.

Megaoesophagus	Congenital
	Acquired – primary GIAcquired – secondary GI	IdiopathicPolymyositisMyasthenia gravisPolyneuritisHypothyroidismHypoadrenocorticismNeoplastic neuromyopathyLead toxicityTick paralysis (Ioxodes holycyclus)
External compression	Persistent right aortic arch
	Mediastinal lymphoma
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