In and of itself, a bout of diarrhea isn’t necessarily an immediate cause for concern in a puppy. The presence of blood in diarrhea, however, warrants a visit to the vet if only to rule out any serious issues. Dietary changes can cause your pup to have an upset stomach. This is a fairly common issue with feeding. The presence of absence of other symptoms will guide you in judging the severity of the situation.
Switching puppy food brands, graduating from puppy to adult food or even introducing some kibble into an otherwise soft diet may cause diarrhea in a puppy. Any change in diet could be a cause. In fact, your vet’s first question may be related to the whether you’ve changed your dog's nutrition recently. However, bloody diarrhea is rarely the result of a simple stomach upset caused by an unfamiliar brand of kibble.
The Wrong Food
Dog owners would be naive to assume that their dogs ate only what was in their bowls. A puppy who has got into the trash and consumed spoiled meat may find himself suffering from diarrhea as a consequence. Check for evidence that you dog hasn’t eaten anything he shouldn’t, if he has diarrhea. This will enable to you rule in or out the consumption of spoiled food as a possible cause. Trauma to the anus caused by your pup attempting to pass a sharp bone or other indigestible item can cause blood to appear in the diarrhea. But this is not technically bloody diarrhea, as the blood is coming from a wound rather than from inside the digestive system. If the blood is particularly bright red, this is a sign that it is fresh and hasn’t been mixed with the stool, suggesting your pup may have a rectal injury.
Causes for Concern
Blood in the diarrhea is an immediate cause for concern. Although the reason for the presence of blood may be benign -- for example, your dog may have suffered an anal fissure while straining to defecate -- it is important to rule out more serious issues, such as anal sac disease, tumors and rectal prolapse.
Stress, infection, anxiety and even gluttony can cause a pup to have diarrhea. Under common circumstances, the pup will pass loose, watery stools for a day or so before his immune system manages to tackle the issue. In some cases, for example if your dog has a parasite, the symptoms may persist, either intermittently or constantly, for weeks -- in which case you should make an appointment with the vet.
Lack of appetite, lethargy, dehydration and flatulence commonly accompany diarrhea. These are often caused by the diarrhea itself. If these are the only accompanying signs, there likely isn’t an immediate cause for concern. However, if your dog has a fever, is vomiting or is suffering from rapid weight loss, visit the vet.