Many people consider breeding their dog or cat, partly for the experience of doing this, sometimes in the belief that this is a good way to make easy money. While I applaud  people breeding good natured, healthy animals and feel the experience of seeing new life being born and develop is great, it is definitely not a way to earn easy money.  Breeding cats in a domestic household is usually not a conscious decision.
More commonly it is just a surprise that little Tiger is old enough to get pregnant. Cats tend to come ‘on heat’ (or ‘on call’) at about 5 or 6 months of age, sometimes slightly earlier. At this time their behaviour becomes extremely odd, with lots of vocalising, rolling around and holding their tail to the side. I have had clients certain that the cat has been severely injured when they see this behaviour. Unfortunately cats are ‘induced ovulators’, meaning they  stay on heat until they mate, and then they ovulate. So it is no surprise that they are very successful at getting pregnant:  their whole cycle is geared to making sure each mating will become a pregnancy.  
Breeding a dog usually takes more effort on the owner’s part. Dogs tend to cycle about every 6 months and it is only during the second week of their heat that they are fertile. However, this does correspond to the time when the females are willing to mate. Strangely enough, the males tend to be prepared to mate at all times. If trying to mate your bitch you can leave her at the male’s place for the week and hope that it Happens. Alternatively, an experienced breeder will often supervise the mating and will tend to plan 2 or 3 matings about 2 days apart.  Pregnancy in both cats and dogs lasts about 2 months (63 days is full term for both species).
When giving birth the first stage of labour lasts about 24 hours and this is when they nest, may be restless, pant, and sometimes get a clear vaginal discharge. Their temperature may drop at this time; it is a good idea to take your dogs temperature at an earlier time so as to be able to detect a drop from normal. The second stage of labour is when there are contractions. The first foetus is usually delivered within 1 hour in cats and 2 hours in dogs, with subsequent foetuses being delivered each 15 minutes to 2 hours.They are having problems if they have good, strong contractions for more than 30 – 60 minutes without production of a foetus; if foetal membranes are seen at the vulva for more than 15 minutes; or if there are weak contractions and no offspring after more than about 3 hours. The timings do vary but the rule of thumb is always seek advice if you are even slightly concerned.  
The mother will usually lick the baby as it is delivered and then eat the foetal membranes, crushing and chewing off the umbilical cord. If the mum does not seem to know to do this, then you should remove the membranes, tie off the cord about 1-2 cm from the pup with a piece of cotton and rub the baby to stimulate breathing. It is important that they suckle soon after birth; the mother produces colostrum for the first 48 hours after birth and the pups and kittens gets lots of antibodies at this time. These antibodies are extremely important in fighting infection in the early weeks of life while their immune system is still very undeveloped. 
If at any time shortly after giving birth or when the pups are still very young (ie the first 4 weeks after birth), your bitch develops a tremor, starts to pant or be wobbly on her legs; she may have a condition called eclampsia or “milk fever”, in which her blood calcium levels drop. This is an emergency and must be treated as soon as it is seen. Calcium is needed for muscle contraction, including the heart muscle, and a dog can die if not promptly given intravenous calcium. If this occurs in the middle of the night, you need to go to an emergency centre, as the situation cannot  wait until morning.  Having said all this,  having puppies or kittens is usually a wonderful experience. However, it is a commitment, especially if you are breeding a dog, so you should plan to be at home (ie not working) when she is due to have the pups so you can be on hand if there are problems.
Please discuss any concerns with us, we are always happy to talk about what is going on. There is obviously much more you will need to know than can be covered in a short article. From my viewpoint the most fun surgery we ever get to do is a caesarean – our nurses fight each other over who gets to take care of  the Puppies as they come out. 
Happy breeding, Rosalie