What is it?
Vomiting may best be described as the active expulsion of the dog's stomach contents. It's actually a normal function - dogs often eat nasty things, and by vomiting them up they can minimise the risk of serious poisoning. However, it is a very non-specific sign, and can be caused by a huge range of different conditions.
What causes it?
In dogs, the most common cause is "Dietary Indiscretion", also known as "Garbage Gut" - essentially, they ate something rotten and nasty! However, there are a huge range of other causes, depending on whether it is Acute Vomiting (sudden onset) or Chronic Vomiting (it's been going on for a while). The common causes of Acute Vomiting include infections (e.g. gut infections, such as Salmonella or Parvovirus; a response to a high fever; or Pyometra); high worm burdens; reactions to certain drugs (such as NSAID painkillers); poisons (e.g. chocolate); intestinal obstructions; metabolic disorders (e.g. liver disease); pancreatitis; or neurological problems (such as Vestibular Syndrome or travel sickness). Chronic Vomiting, on the other hand, is more likely to be due to more ongoing disease processes, such as kidney failure; SIBO (Small Intestinal Bacterial Overgrowth); IBD (inflammatory Bowel Disease); or tumours in the abdomen or intestinal wall.
What dogs are at risk?
Any dog can begin vomiting - it depends what the cause is! In general, in a young dog or one with a habit of eating stupid things (typically but definitely not exclusively Labradors), we'd be leaning towards Garbage Gut or a blockage; whereas in an older dog, kidney disease or tumours are a little more likely.
What are the symptoms?
True vomiting can be difficult to distinguish from regurgitation (where the contents of the oesophagus or gullet simply "flop" out) or even from coughing up a big lump of phlegm. However, vomit when produced has a characteristic acidic smell, and is usually stained yellow or greenish.
How is it diagnosed?
Determining the exact cause is really important - while Garbage Gut, for example, can be treated symptomatically, an intestinal obstruction needs urgent surgery. To determine the likely cause, the vets will carefully examine the dog's abdomen, and check their heart and circulatory function. Blood tests can be used to determine how dehydrated (and therefore in danger of complications such as shock) the dogs is, and whether their kidneys or liver are working properly; whereas X-rays and ultrasound scans are used to examine the intestines and internal organs for signs of blockage or malfunction. In some cases, an "exploratory laparotomy" or Ex-Lap is needed - surgery to open the abdomen and actually look to see what's going on.
How can it be treated or managed?
It depends, of course, on the cause. Simple "Dietary Indiscretion" can usually be managed by starving the dog for 24 hours, providing water little and often, and then reintroducing a bland diet (e.g. boiled chicken and rice, or a commercial intestinal diet). Sometimes, antivomiting drugs may also be appropriate. In other cases (such as Pyometra or kidney failure), the underlying disease must be treated; and in some conditions (like an intestinal obstruction), urgent surgery to remove the blockage is required.
Can it be prevented?
The simplest way to prevent vomiting is to prevent your dog from eating nasty rotten things they find in the garden, the dustbin, or out on a walk!