In 1993 dogs were reclassified genetically as a subspecies of the grey wolf. They now fall under Canis Lupus. So technically wolf dogs are not even hybrids anymore. Depending on which science circle you're in, but they are not plants so...
http://www2.fiu.edu/~milesk/Genetics.htm
"A wolfdog is a cross between a gray wolf and a dog--what some refer to as a wolf hybrid. The term "hybrid", however, is used differently in the various scientific disciplines. For example, in horticulture, hybrids are formed by humans as crosses of different 'types' of plants; the term is used equally for crosses both among and within species. Conversely, in evolutionary biology, the term "hybrid" is used almost exclusively to describe offspring arising from a naturally-occurring cross between two separate and genetically distinct species.
(“The domestic dog is an extremely close relative of the gray wolf, differing from it by at most 0.2% of mtDNA sequence....
In comparison, the gray wolf differs from its closest wild relative, the coyote, by about 4% of mitochondrial DNA sequence.&rdquo![]()
So one might recognize the potential for confusion arising from the use of the word "hybrid" when applied to a wolf/dog cross. It is more appropriate to refer to these animals as wolfdogs.
In 1993, the Smithsonian Institution and the American Society of Mammalogists reclassified the dog from its separate species designation of Canis familiaris to Canis lupus familiaris. So, now, the Timber wolf (Canis lupus nubilus), the Mackenzie or Tundra wolf (Canis lupus occidentalis), the dog (Canis lupus familiaris ), etc., fall under the genetic umbrella of the gray wolf: Canis lupus."