Investigation and differential diagnosis of vomiting in the dog

Diagnosis of conditions leading to dogs vomiting

source: Clive Elwood
In Practice vol 25 no 7, July/August 2003
starts p374, 9 pages long

Some vomiting in dogs is normal. They are omnivorous, and sometimes need to get rid of indigestible objects that they have eaten. Bitches also vomit frequently when they are feeding pups.

The reasons for dogs vomiting are likely to vary according to age, breed and gender. Pups are likely to have eaten something that disagrees with them, or may have infections, or anatomical abnormalities. Some breeds, such as golden retrievers and boxers, tend to be especially sensitive to their diets. Large breeds are more prone to gastic dilation-volvulus, while rough collies and Belgian shepherds are prone to gastric neoplasia. Prostate problems in dogs and pyometra in bitches can also cause vomiting.

The length of time a dog has been vomiting can give some clues as to the cause. Dogs that suddenly start vomiting may, for example, have an infection, have eaten something they cannot digest, suffered poisoning, or have an acute abdominal problem, like pancreatitis. Dogs that have been vomiting over a longer period, and just intermittently may have inflammatory bowel disease, or chronic gastritis, or both. What the dogs produce when they vomit can also give clues. Dogs suffering from gastric irritation may vomit bile in the morning. Pyloric obstruction is linked to vomiting undigested meals. Intestinal obstruction is linked to vomiting watery matter. When a dog vomits dark blood, looking like coffee grounds, there could be intestinal inflammation, neoplasma, or benign ulcers, though fresh blood may just be linked to the action of vomiting.

Diarrhoea tends not to be associated with pure gastric, renal, splenic or hepatic disease. Signs of a dog being in pain may also give clues as to the cause. Dogs may react for example if they are touched, or show they are in pain by being restless, or taking up a posture as though they were praying. Their bellies may also be swollen. Less serious conditions tend not to affect dogs' appetites and the way they behave.

Dogs that stop vomiting when they are not allowed food may be suffering from an obstruction. Certain diseases, such as diabetes, kidney failure, and pyometra, are linked to drinking a lot of water.

Dogs that suddenly start vomiting and do not produce anything, and also have swollen bellies may be suffering from gastric dilation-volvulus, and need immediate attention.

Owners can be asked about whether any objects have gone missing in the house, or whether dogs might have eaten corn cobs or other objects at a social event. Another avenue of investigation is dogs' access to toxins, such as glycol, ethylene, or lead, and any medicines they might be taking. Rupture of internal organs, for example due to previous accidents in which dogs have been injured, can also lead to vomiting.

Diagnosis includes checking for signs of dehydration, such as sunken eyes, dry membranes, and skin tenting. The heart rate and temperature should also be assessed. A high temperature is linked to inflammation and infections. Physical examinations also include palpating the abdomen and rectal examinations. Blood tests, diagnostic imaging such as radiography and ultrasound, and endoscopy may be needed. Exploratory surgery is a further option, which should only be undertaken when non-surgical diseases have been excluded, and the dog has been stabilised. The article examines the different reasons why dogs vomit, and how to diagnose the cause, in further detail.