There is a large variation in the severity of signs associated with Vomiting (V) and Diarrhea (D). A dog that had a very small amount of diarrhea and vomited once, then it is possible the owner could provide symptomatic treatment at home for a few hours and if not better schedule an appointment. 

Specific treatments of vomiting are dependent on the cause. Here is the general approach to treating vomiting and diarrhea: 

• If your pet vomits once and/or has a small amount of diarrhea then eats normally with no further vomiting, has a normal bowel movement and is acting playful, then the problem may resolve on its own. 
• If you discover any predisposing cause such as exposure to trash, change in diet or plants your dog may be eating, always eliminate that cause. 
• If your dog vomits several times, has diarrhea and you bring your dog in (which is recommended), then you may try the following: 
  • Do not give any medications without consulting your veterinarian. Some medications can be toxic. – Dealing with both vomiting and diarrhea can be difficult. Often with Vomiting we hold food for 2 to 4 hours – with Diarrhea sometimes is it longer – even 24 hours. These are general guidelines trying to treat both conditions. If your dog is acting sick, lethargic or the vomiting and/or diarrhea continues – PLEASE schedule an appointment.  
  • Withhold food and water for four to six hours. Oftentimes, the stomach lining may be very irritated. Some dogs will want to eat and continue vomiting. Give the stomach “time to rest” for a few hours. 
  • If your pet has not vomited by the end of this time, offer small amounts of water (a few tablespoons at a time). Continue to offer small amounts of water ever 20 minutes or so until your pet is hydrated. Don’t allow your dog to over drink as this may lead to vomiting. 
  • If there has been no vomiting after the small increments of water are offered, then you may gradually offer a bland diet. – Small frequent feedings of a bland digestible diet such as Hill’s Prescription Diet i/d, Iams Recovery Diet, Provision EN or Waltham Low Fat, are usually recommended. You can make a homemade diet of boiled rice or potatoes (as the carbohydrate source) and lean cooked hamburger, skinless chicken or low-fat cottage cheese (as the protein source), Feed small amounts at a time. Don’t over feed as your dog may eat the entire bowl and vomit. Feed a meatball size portion and if there is no vomiting, offer a small amount more about 1 hour later. Give small amounts frequently – every 3 to 4 hours – for the first day. You can gradually increase the amount and decrease the frequency as your dog tolerates. 
  • Feed a bland diet for 2 days. – Return to regular dog food should be gradual over a period of one to two days. At first, mix in a little of your dog’s food into the bland diet. Feed that for one meal. Then feed a 50/50 mix for one meal. Then feed ¾ dog food and ¼ bland diet for a meal – then feed your dog’s regular food. 
  • Leash-walk your pet to allow observation of bowel movements, observe for normal urinations and note any additional vomiting that may otherwise occur without your knowledge. 

Recommendation: If your pet is lethargic and having both vomiting and diarrhea, the best thing to do is to have your dog evaluated. If there is any blood in the stool or vomit, your pet should be seen today.