Vomiting or diarrhea, lack of appetite or decreased activity, changes in urination, and coughing are all warning signs of illness in dogs, according to WebMD. Stiffness, lameness and difficulty rising are other warning signs.
Occasional vomiting in dogs is common, notes WebMD. However, a pet vomits that several times during the course of one day, experiences a reduction in appetite, or acts lethargic requires evaluation by a veterinarian. Blood in the vomit or vomit that looks like coffee grounds can indicate that the dog swallowed a foreign object, such as a bone, tinsel or a fish hook, which can irritate the stomach and cause intestinal trouble or blockages. Vomiting and diarrhea can also indicate gastrointestinal illness or parasitic infection with whipworms, roundworms or hookworms.
Decreased activity and lack of appetite may be due to fever, stress or pain, advises WebMD. A pet that goes for more than 24 hours without eating needs to see a veterinarian to rule out any issues. Decreased activity may also be due to heart disease.
Changes in urination may also signal trouble, notes WebMD. Increased urination usually accompanies increased thirst, which sometimes indicates liver or kidney disease or problems with the adrenal glands. Too little urination may occur as a result of bladder stones or urinary tract problems.
Dogs that are stiff, lame or unable to bear weight on one leg or that have trouble rising up on all fours may suffer from ruptured ligaments, hip dysplasia, disc disease or arthritis of the spine or hip, reports WebMD. Lyme disease can also cause arthritis and related stiffness in dogs.