Symptoms associated with internal parasites depend upon the location of parasite, the number of parasites, the age of the animal, and the overall health of the infected animal. Intestinal parasites are responsible for causing various digestive problems. These problems can range from an overall unhealthy condition to a severe bout of bloody diarrhea.
Intestinal parasites appear to be particularly bothersome when an animal has a pre-existing medical condition. The parasites can further weaken the animal's immune system, causing a decline in the animal's health. Animals suffering from immune deficiencies are more likely to exhibit pronounced symptoms from intestinal parasites than animals with healthy immune systems.
Young animals with undeveloped immune systems are particularly susceptible to intestinal parasites. These animals also exhibit the most pronounced clinical symptoms.
Recommendations for the Diagnosis, Treatment and Prevention of Parasite Infections.