When should I call the vet

This is a hard question to answer and I will preclude my response with saying that "if you are worried, then call the vet immediately"

However, sometimes your pet may be"slightly off"  not quite 100% and it can be hard to know if you should act immediately.  Learning to observe your animal's normal behaviour is very important and gives you the ability to distinguish between normal and abnormal behaviour.  For example if your dog normally has soft faeces after eating a raw bone then you may not take him to the vet if the diarrhea normally resolves by itself within a day or two. However, if your dog develops diarrhea after eating a bone and this is not normal, then you might seek veterinary advice much sooner.  This is just an example of how understanding your dog's normal behaviour can be a big benefit.

Some scenarios for you.

My dog is drinking lots more water than normal.  But this is good, isnt it?

No.  An increase in water consumption by a dog or a cat may be a sign of a serious disease. Increased water intake may be normal, ie. hot days, a switch from wet food to dry food.  However, it could also indicate-: diabetes, renal disease, liver disease, pyometron or many other conditions. 

If your pet is drinking more water, go to your vet immediately.

I never speyed my dog when she was young.  She is 10 years old now, so she cannot get pregnant can she?

Wrong! Female dogs do not go through menapause.  They can breed for life.  Remaining "entire" also can lead to serious health issues and complications.  Infection in the uterus (pyometron) is a life threatening disease.  (See an example of a pyometron in the surgical section of this website.)  Please see your vet for a full check up to make sure your dog is well enough for surgery.  Your veterinarian will discuss all of the advantages as well as the risks with you.

I have heard that my cat can catch AIDS.  Could I catch it from my cat?

No.  The feline AIDS virus is not transmissible to humans.  However, it does act in a very similar way to the human disease.  It is eventually fatal in cats due to other complications.  Luckily we can now vaccinate our cats against this killer.  Please speak to your veterianrian for more information.