I often field questions from bloodhound owners about many diseases or conditions affecting their dog and what it means for their dog and for it's offspring. Often I hear incorrect interpretations of what a condition is and whether or not it is inherited or acquired and whether or not it should matter.
I want to try to define and classify some conditions that affect bloodhounds and the importance of these in your dog or it's offspring. Just a few definitions first: Inherited refers to a a trait that is linked to a gene and is passed on from one generation to another. A trait can be dominant, recessive or polygenic. Dominant means that if the sire or dam has the trait then all of the offspring will have the trait. A recessive trait requires at least two genes for the trait to show up. A dog may carry the gene, but you won't see it unless he/she carries both recessive genes. A polygenic trait means that it takes multiple genes for a trait to be expressed, not just a simple recessive gene.
Congenital means that a dog is born with a trait that is not necessarily an inherited trait. Congenital traits can be caused by any number of "problems" during pregnancy (infection, poor positioning in the uterus, toxins or unknown causes).
Acquired means that the trait developed during the life of the dog due to aging changes, infection, trauma, excess growth rate, nutrition, etc.
What type of traits should you be concerned about? For your own dog, any type of trait is concern; for his/her offspring, any inherited trait should be of concern. Also if offspring have an inherited trait (even if parents don't), or if siblings, cousins or other relatives show an inherited trait, you should be concerned. A dominant trait is easy to figure out. If you don't like a certain trait that is dominant, simply don't breed affected dogs with a dominant trait, for all offspring will also have that trait.
A recessive trait is a little more difficult than a dominant trait to weed out. Such a trait may be carried from generation to generation and not show up until two bloodhounds carrying the same recessive gene are bred--and suddenly you see the trait show up. Carefully evaluate litter mates, previous litters, previous generations, etc. (this shows the importance of keeping track of all puppies). Try to determine the source of the gene and be very careful to whom you breed your dog or bitch again. Figure 1 will hopefully show how this can happen.
Let me give you an example of how you may go about reasoning through a breeding consideration. Aortic stenosis shows up in a puppy bred form bitch X who was bred to Dog Y. Aortic stenosis is inherited and is of polygenic nature. To stop transmission of the genes absolutely, neither X or Y should be bred to each other again nor to any other bloodhound. Also all litter mates likely carry at least one of the genes and should not be bred. This is difficult ot do and may not be practical. A suitable option would be to do an echocardiogram on X and Y and all offspring (up to one year old, you cannot absolutely screen out aortic stenosis at two to six months of age), and breed X and Y again only to echocardiogram normal bloodhounds.
I hope some of this information has been useful and can help you make
a more educated decision. The more we know about a problem in our
hounds, the better we can be at preserving their health and the health
of future generations of bloodhounds.
a=recessive gene A=dominant gene
Bitch X (genes aA) is normal
Up to 25% of the offspring can show the trait; keep in mind that maybe only one will or none; it all depends on how the genes get shuffled and which sperm and eggs survive
|Bo dy System Involved||Trait||Inherited||Congenital||Acquired|
|Blood||Clotting disorders, dyschrasias (i.e. Hemophilia)||yes (autosomal gene)|
|Cardiac||Aortic stenosis||yes (2 genes, 1 autosomal, 1 dominate)|
|Pulmonic stenosis||yes (unknown mode)|
|Cardiomyopathy||yes =/-, hypothyroidism|
|Persistent ductus arteriosis||yes (polygenic)|
|Eyes||Cherry eye||yes =/-||yes|
|Cataracts||yes||yes (geriatric onset)|
|Entropion/Ectropion||yes dominate gene|
|KCS (dry eye)||yes|
|Persistent papillary membrane||yes|
|Inflammatory bowl disease||yes|
|Megaesophagus||yes linked with hypothyroidism||yes||yes|
|Umbilical or inguinal hernias||yes|
|Musculosketal||Degenerative joint disease||yes|
|Elbow dysplasia||yes recessive||yes|
|Hip dysplasia||yes .25 -5%||yes|
|Lumbo sacral instability||yes =/-||yes|
|Atlanto/occiputal instability||yes +/-excessive growth rate|
|OCD (osteochondrosis)||yes +/-excessive growth rate|
|Panosteitis||yes +/- excessive growth rate|
|Neurological||Degenerative disc disease||yes|
|Demodex (juvenile, generalized)||yes|