It is not always that easy to tell if your dog is sick or getting sick. There are a number of things to watch out for that should raise red flags, however, so keep these in mind and you will know when a trip to the vets clinic is in order.
For younger dogs changes in eating or drinking habits are good indicators of problems. If your dog seems excessively thirsty and starts drinking more than is normal, she could be developing a disease like diabetes, or it could be an indication that a change in medication is warranted. If your dog stops eating for a period of time or starts wanting a lot more food and raids the garbage can or the table, then something is probably out of order.
Vomiting is another indicator. Some vomiting in dogs is not a problem, but if this continues for a couple of days or if you see indications of blood coming up, you should take the animal to the vet.
Checking your dogs gum colour can also help you determine if your dog is suffering from any illness. Normal gums should be a shade of pink. Abnormal gums, which are white, grey, blue or yellow in colour, can be indicative of internal bleeding, anemia or a disruption of normal blood flow, which prevents proper oxygenation of a dogs blood or may result in a loss of red blood cells.
A dogs coat should be full and shiny. If the sheen has gone out of the dogs coat or especially if you see splotches of missing hair, then something is amiss. It could be a problem with parasites like fleas or ticks, or there could be disease of some sort.
Observation of your dogs stools from time to time is also a good idea. A dogs stools should be firm and moist. If your pet has diarrhea for a period of time or has hard, dry stools and strains a lot when having a bowel movement, then it is time to visit the vet.
General lethargy is another indicator, although it can be a subtle one. If you dog does not want to play or go for a walk, for example, then something is probably wrong. If this condition continues for more than a couple of days, it would be wise to see your vet.
A good rule of thumb is to keep a close eye on your dog and look for any sort of changes. If those changes persist for a while then there is probably a reason, and it is also probably a good idea to have the dog seen by a vet.