Certainly vomiting and diarrhoea are very common causes for a trip to the vet and a little like inappetance can be a sign of very many problems. At the top of the list is gastro-enteritis which in itself can be caused by a number of things, including many viruses and bacteria just like us.
My general advice for vomiting is the following. If it is a one off and the pet is otherwise well, just monitor and give them 12 hours without food and see what happens. Never deny water. If water is given and can’t be kept down, they should be seen. If the pet is quite lethargic or vomiting continues, take them immediately to the vet. For diarrhoea: If bright and well, give them 24 hrs, access to water at all times and a bland boiled chicken and rice diet in small feeds for 2-3 days. If the diarrhoea is resolving by the next day, keep this diet up for a few days. If diarrhoea is worsening or persisting beyond 24 hours, then bring your pet in.
Dogs in particular are what we call scavengers. They have evolved to live off all sorts of food including rotten material. Often if a dog eats a bad bacteria, they handle it quite well. Occasionally it may cause a mild transitory gastro-enteritis. Hence I’m happy to give them 12-24 hours to see what happens. If they’re not getting over it in this time, or if in fact they are quite lethargic, then they need to be seen.
The following is a brief list of the common causes of gastro-enteritis:
In order to diagnose which of the above is causing the problem we may need to consider tests such as x-rays, fecal pathology, blood tests, endoscopy or even ultra-sound. All of these diagnostics are available to us depending on our initial diagnosis and response to treatments.