If your dog has decided to chase your cats and they are getting stressed, you have a difficult task to deal with. Dogs are natural hunters and if they see a furry little thing running fast in front of them, it is nearly impossible to stop them.
However, there are a few things you can try, to get some control over the situation.
First of all, make sure your cat has somewhere to escape - be it outdoors, upstairs, behind a child gate, etc.
You can work really hard on teaching your dog to sit/down/stay in every possible situation, in every room of the house, with all kinds of distraction around him (children running, TV blaring, hubbie cooking a meat dish in the kitchen, the cat sitting on the sofa...). Start on an easy level and build him up to bigger and bigger distractions. You have come a long way when you can have someone playing with the cat in front of your dog, as you work with him on his stay. Please read our article on how to teach a dog to stay.
Your dog could be chasing your cat because he's not getting enough mental stimulation. I think training the dog in search is an ideal exercise. Search exercises are the easiest things you can do! It tires the dog completely both mentally and physically and you will get a happy and content friend that will be more attentive. It is also a joy to watch the dogs weave across a field, nose held high and tail wagging determinedly! We've got 2 articles on tips for activation (activation tips 1 and activation tips 2) and you could also read about balancing exercises.
If you leave you dog alone at home, every day, for more than 4-6 hours per day, I can guarantee you that it is part of your problem. Most dogs will sleep (and build up energy!) most of the time that you are gone. This is acually the root to a lot of behavioural problems, like tearing furniture to treads, scratching doors, eating everything in sight, intensive barking, etc. As a rule, a dog should not be left alone for more than 4-6 hours per day in total. Because they are pack animals they have an inherited need to be with their pack and especially their pack leaders (that's you). I know that it is very hard to meet that demand (trust me, I've been there!), but we all want what is best for our dogs, don't we? You might be able to find a dog sitter, dog day care or a dog walker on UKdogsitters.co.uk. If you can't find someone suitable there, maybe there is a kind pensioner in your street that could have the dogs in his/her home during your working hours? He/she wouldn't necessarily have to walk the dogs (he/she might not be strong enough to hold them), but could let the dogs "do their toilet" in the garden during the day. The most important thing is not the exercise, its the companionship.
Although the reason for your dog to chase your cat is most likely an inate behaviour, sometimes they do it for pain relief. If your dog is suffering pain or discomfort, he'll be rewarded for chasing the cat by the endorphins that starts pumping around his system. When faced with a major stressor, the body's biochemistry instantly hurtles into a ready mode that marshals all the possible resources necessary to either escape or do battle. Thus, the adrenal glands located on top of the kidneys provide an instant surge of adrenaline, the body's rocket fuel, quickening the heart rate and blood flow and providing every cell with extra oxygen. They also release cortisol or hydrocortisone, causing an increase in both amino acids and blood sugar. These will be needed if tissue repair must take place. Finally, the pituitary gland at the base of the brain releases a variety of hormones, endorphins among them, that act as natural painkillers. If your dog is in pain, solving the reason for his pain, might make him more relaxed around the cat.
There are a few products on the market that might help you calm your pets down. You can try the D.A.P (although I have recently had a couple of clients say their dogs/cats had an adverse reaction to this and actually got very tense and hyper when using the D.A.P.) or Bach Rescue Flower Remedies. You can also try aromatherapy for your pets.
.is one of the best things you can do. Just sit down and watch your dog. Indoors, outdoors, when the cats come in the room, when he/she meets another dog, when you get visitors, etc. You will soon learn to see the signs that your dog is displaying, for example, when he/she is about to get up to chase the cats - and you can cut in just before he/she is off. It takes some training, but once you have learned to "read" your dog, you will reap the rewards.