That's fantastic that you are looking to go to a shelter, make sure you check out all the rehoming shelters in your area not just the RSPCA
MY purebred... a Groenendael dog 'Dante' gorgeous breed
as a breed they are prone to hip and elbow displaysia, progressive retinal atrophy and epilepsy. Getting them from a breeder who can give you all their RECENT health records and hip/eye/elbow scores that are all above the breed average will help you get an animal who has been bred for sound health.
Then the shelties, associated health problems are too numerous to list... haha and then i have two of them *sigh*
And then my mutt, 'Sadie', the rotti x retriever.
I personally disagree with the 'hybrid vigour' theory that you are 'watering down' health problems associated with purebreds. I feel that if you go and research a responsible breeder you will be getting yourself a good dog with a greater degree of certainty of what you will end up with. On the other hand, mutts are fabulous, can be amazingly healthy dogs and never have a problem with them. Or, you can end up with a mutt from two poorly bred purebred parents with health problems that only become amplified in the puppies. For example, Sadie is a rotti x retriever, two large breed dogs known for their high incidence of hip dysplasia. By getting a litter from two such parents you are not going to end up with puppies less prone to hip dysplasia, rather you run the risk of them having worse hips just as if you put a retriever to a retriever with bads hips, same applies to a german shepherd or rotti. So with Sadie i am constantly monitoring her for signs of bad hips and elbows, she is still young and not showing signs yet, and lucky because she is a runt and so only half the weight she should be, and therefore less likely to develope bad hips from excess weight even if she is prone to the disorder.
If you are going to get a mutt from a shelter, try and go for one that is obviously not a shepherd, rotti, retriever or spaniel cross as they are all known for their bad hips. I would definitely avoid breeds such as the bulldogs and sharpeis because of the skin folds, eye problems, soft palate obstructions, etc. Sharpeis are also very prone to bad ears because of their classic 'cauliflour ear' where the tissue is compacted and constricts the ear canal. This reduces the air flow in the ear and can lead to bad bacterial and yeast infections. I would suggest avoiding all brachicephalic breeds (your 'squished' faces like boxers, bulldogs, some cavs, etc.) as they all tend towards having breathing problems and the face is shorter but the exess soft palate interferes with swallowing and breathing.
Also avoid dolicocephalic breeds (long faces) such as your greyhounds, collies, borzois, salukis, afgahns, whippets, etc as they can get terribly teeth if you don't brush them often. This is because their teeth do not meet in the classic scissor bite of breeds that haven't been messed with so much such as your labradore (the mesocephalic head). teeth that meet in a good scissor bite such as labs tend to self clean while they eat and chew, other breeds dont have this and so rely on you to clean their teeth for them. On that note, i dont know if its been mentioned yet, but DO NOT feed your dogs bones that have been 'conveniently' cut in half longways by the butcher, request that they are left whole for you. but splitting the bone this leaves a solid edge for the dog to anchor its carnassial tooth (the massive bone crunching tooth) and CRACK, the dogs jaw is stronger than the tooth and thus the tooth cracks before the dog stops biting down. even my little shelties have done this (ive learnt all these lessons the hard way
) by leaving the bone whole the dog cant get a solid grip down the shaft of the bone and instead focusses on the soft cartilagenous material at the ends which is fabulous for cleaning (and nto breaking!) their teeth on.
i've gone on a rant here havent i? sigh.
so. research your breed, its easy to find all the potential health issues of your chosen shortlist of breeds by googling it. talk to breeders and find one that can show you all of their recent health records. you'll know when you have found a good one.
if you are going to go to the shelters make sure you assess the physical characteristics of the dogs you are interested in and be honest with yourself about how much work you are willing to put in in terms of maintaining dental health, future vet bills for health problems like hips and joint health, keeping skin problems under control and of course making sure you can handle the breeds required level of physical and mental stimulation. all very important things to consider. i havent even mentioned coat maintenance. ugh. im going to stop now
phil and (insert the other vet student here) who has been following this thread are certainly your/ best sources of knowldge here. i am only a vet nurse so take everything ive said with a grain of salt as there are mutlitudes of schools of thought on these topics.
do your research and good luck!