It is obvious and scientifically confirmed, gray wolf and domestic dog can randomly cross resulting with a hybrid as a consequence of pairing each other different - however infertile (capable of interbreeding), matched by sufficient parental compatibility - species/subspecies individuals, succeeding with a birth of viable offspring.
Notice: It does not concern cross-breed by definition - a process where individuals from different breeds of the same (sub)species are mated with each other (vide domestic dog planned mating result of purebred parents, i.e. Scandinavian sled dogs - Eurohound or Greysther).
- unintentionally -> in wildlife
Not habituated to human presence (like wolves) and not socialised to be a human companion (unlike dogs).
Wild male gray wolf - being for example, a yearling/biennial (intending to establish its own pack) or a satellite away from its pack (i.e. after it being broken up) - can mate with encountered free-ranging female dog during wolf mating season. A fruit of that reproduction process is an offspring, assuredly abandoned by mother - after weaning as per domestic dog nature. Merely 4% of hybrid-cubs are able to survive scavenging as dump dogs, if not nursed by their half-related wolf pack where they lose competition with pure wolf pups anyway.
If fostered by a human, a hybrid-youngster remains instinctively wary of people (not habituated to human presence in its primary sensitive developmental period), behaviorally unstable (a lack of socialisation in its secondary sensitive developmental period), flighty-aggressive in defence (because of its instability towards unknown situations to face up and human wariness by instinctive avoidance). It seems to be tame or half-tame animal, driven by flexible emotions.
Habituated to human presence (unlike wolves) and not socialised to be a human companion (unlike dogs).
- intentionally -> by human intervention
Habituated to human presence (unlike wolves) and socialised to be a human companion (like dogs).
Most “first generation” animals are generally less suited as a good pet by most people’s standards and expectations. These “poorer pet-quality” animals often do not “work out,” for such hybrids generally exceed the ability of most people to socialize, contain, and generally provide a safe home. The same can be said of hybrids whose pedigrees indicate a wolf-content somewhere above 50% wolf. This is of course assuming that the pedigree is accurate and does not misrepresent the wolf-content - stands in Wolf Park site's section dedicated to wolf-dog hybrids. Such hybrids are a random collection of traits - inherited from parents, passed by generations, diverging not only litters between one another but also individuals within the litter. Every representative is able to inherit wild wolf traits deviating from standard dog behavior - complete (or almost complete - excluding the 'eating') predatory sequence, strengthened prey drive, resource guarding, territorial behavior, aggression in defence, different - than dog's - way to interpret received signals (vide eye contact); whereas protectiveness (being a misunderstanding in case of wolf nature part) and pack attachment (supposed to be redirected to human family) would be mostly recognized wanted ones.
More or less considered wolf-dogs should be properly handled by profesional trainer/owner and monitored by behaviorist.
Czechoslovakian wolfdog is one of two officially bred hybrids - scheduled breed generation started by mating of selected purebred (German shepherd) male domestic dog and precise Eurasian wolf female representative in captive. Pure dog breeding offered guarantee of imaginable effect - by its bloodline pedigree (genealogical tree) ensuring breed standard exterior repeatability (visual aspect) and character predictability (behavioral aspect).
The experiment took place in former Czechoslovakia (1955) concluding with the first litter being born (1958) as the selected breeding beginning (pairings of male dog/female wolf and male wolf/female dog in captive were both similarly successful).
To be exact, the principal goal of the experiment was not a new dog breed or hybrid creation but the verification of how to improve healthiness, endurance and stamina of working dogs without a loss of their dog type-specific predispositions. Researched wolf-dog hybrids worked helping border guards, supervised by the military in collaboration with Czechoslovak Academy of Sciences. As a result, primal wolf-dog breed standard was created (1966) by cynologist and breeder Karel Hartl, officially recognised as a national breed (1982), then internationally recognised by FCI (1989).
Interestingly, Czechslovakian wolfdog - together with Saarlooswolfhond - was classified by FCI as the pastoral dog - most probably assuming its being genetically relative to a shepherd dog (half-blood). That breed does not inherit a herding instinct. Its working trials are dedicated to individuals aspiring to work as protection dogs.
- half-wolfish -> mostly visually
Czechslovakian wolfdog appearance visually resembles gray wolf - mostly silver-grey coat color with a light mask, amber slanted eyes. The rest of breed standard is strictly defined.
After their direct wolf ancestors, it was inherited like it stands in their character description - independence, increased reactivity to environmental stimuli, suspiciousness towards unfamiliar persons. Czechoslovakian wolfdog remains attached to his handler/owner, even if not blindly obedient. It doesn't look at its handler/owner, rather paying attention to surroundings, finding it unnatural to bark.
- half-doglike -> mostly behaviorally
As per the breeding principles, Czechoslovakian Wolfdogs were selectively bred paying special attention to field orientation, sensibility, vigilance and stamina surpassing dog's one.
As the FCI Working Group representatives they can be trained specifically in scentwork/tracking, IPO (incl. obedience and protection training) or multiple sled dog racings.
According to their pioneer Karel Hartl, statistic CzW after 100km non-stop running regenerates its stamina 50% faster than a German shepherd after running half of that distance.
BEHAVIOUR / TEMPERAMENT : Lively, very active, capable of endurance, docile with quick reactions. Fearless and courageous. Suspicious. Shows tremendous loyalty towards his master. Resistant to weather conditions. Versatile in his uses.
Every Czechoslovakian wolfdog which I met, behaved independently, not reactively.. and most of all wolfish. The first adult one which I met - during our wait for dogtrekking championships results - suddenly grabbed my dog treat training pouch with its muzzle (not paying attention to my own dog nearby) and didn't want to let it go until his owner distracted him. It did it peacefully, confidently and without any aggressive emotions, just like a curious hand-rared gray wolf.
Besides, gray wolf species (subspecies Canis lupus lupus Eurasian wolf - unintentionally, Canis lupus occidentalis Northwestern wolf - intentionally), Canis familiaris domestic dog can occasionally hybridise with the rest of genus Canis like - Canis latrans coyotes (so-called coydog), Canis aureus golden jackals, Canis simensis Ethiopian wolf or Canis dingo Australian dingo. Gray wolf species itself seems to be more distinctive. DNA analyses of genome samples collected from multiple places of the USA area suggest that natively North American red wolf - in pair with eastern wolf - would be a hybrid of gray wolf-coyote emerged after Southeast gray wolf extermination and converting forests to agriculture. Gray wolf-coyote hybrids (so-called coywolf) - occasionally reported in the wild - were intentionally given a birth in captive through artificial insemination, then researched and monitored under laboratory and field conditions. Wolf-jackal hybrid - although reported - has been not confirmed scientifically.
Opposite to North America territory, possibility of mating between free-ranging dogs and wild Eurasian wolves for hundred years, has left a genetic mark on gray wolf DNA. International study - supervised by the University of Lincoln (United Kingdom), the Italian National Institute for Environmental Protection and Research, and the University of California (US) - proved that approximately 60% Eurasian gray wolf genome carried small blocks of the DNA of domestic dogs which result suggests that wolf-dog hybridisation has been geographically widespread in Europe and Asia and has been occurring for centuries.
Local wolf populations remain genetically distinct from dogs and their global human-associated - by coexistence (stray/feral dogs) and cooperation (working dogs, companion dogs) - population, pointing on distinctiveness not diminished by hybridity of wolf gene pool. The legal status of intentional wolf-dog hybrids stays still uncertain and unregulated.
From Wolves to Dogs, and Back: Genetic Composition of the Czechoslovakian Wolfdog (2015), research by collective work.
"wolfdog's wolfish soul", article by Urszula Charytonik, Dog & Sport, Polish magazine (4/2017)
Z Peronówki Polish CzW kennel
 Eurohound - intentional crossbred of pointer and Alaskan Husky (crossbred of Alaskan Malamute and Siberian Husky). Greysther - intentional crossbred of Greyhound and German Shorthaired Pointer (Vorstehhund, Vorsther).
 According to Ray Coppinger, "What Is a Dog?" (2016)
 Second one is Saarloos wolfdog - breed created experimentally by dog breeder Leendert Saarloos, by mating a German shepherd and Siberian wolf female (1932), basing on inbreed, then interpolating wolf bloodline. Recognised by FCI (1975). Excluded from working trials.
 FCI (Fédération Cynologique Internationale), Eng. World Canine Organization means the largest federation of kennel clubs - dog breeders organised groups united by countries, among the rest of separated like AKC (American Kennel Club) or KC (The Kennel Club) in United Kingdom (associated with Crufts - international canine event, dog show). AKC currently links to the FCI for breed standards.
 FCI Group 1 : Sheepdogs and Cattledogs
 FCI dog herding instinct trial
 Citation after FCI Czechoslovakian wolfdog breed standard.
 Coyotes and golden jackals coexist as indirectly competitive predators in gray wolf habitats. Australia doesn't have a native wolf population; wild dingo is Canis apex predator on the continent.
 Whole-genome sequence analysis shows that two endemic species of North American wolf are admixtures of the coyote and gray wolf (2016), research by collective work.
 Production of Hybrids between Western Gray Wolves and Western Coyotes (2014), research by collective work (David L. Mech as the leading author).
 Widespread, long‐term admixture between grey wolves and domestic dogs across Eurasia and its implications for the conservation status of hybrids (2018), study by collective work (Małgorzata Pilot as the leading author).