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Recessive Pituitary Dwarfism Genes
The two genotypes shown are; Normal (AA) and Carrier (Aa) and produce on average approximately the following distribution of offspring. The affected (aa) are discounted at present as most dwarf dogs are infertile but not all, some males have been found to have active sperm but no
research has yet been done to test whether or not the sperm are in fact viable.
The difference with this particular gene is that unlike most other recessive genes the affected dogs actually eliminate themselves from the gene pool. To date no dwarf dog matings of affected x affected have been reported, it is assumed that all dwarf dogs are infertile, but as stated above this is not entirely true however the risk is assumed to be negligible, progeny are highly unlikely, nature however does at times tend to surprise us when we least expect it.
As already stated no confirmed reports have so far been made of dogs being born to dwarf x dwarf parents however some reports have been made of dwarf females carrying a litter sired by a normal dog resulting in the death of both dam and litter mid term but these reports have not been officially confirmed. There are a number of reasons why affected's are unlikely to breed aside from stature considerations, typically a female dwarf will go into heat for a protracted length of time, very much longer than a normal dog but will not ovulate but this is discussed a little later in the paper.