The Howling (1981) and Howling IV: The Original Nightmare (1988) are both based on the same novel by Gary Brandner. Interestingly, Howling IV: The Original Nightmare (1988) actually represents the more faithful adaptation of the novel than The Howling (1981).
The budget was so low that the movie had to be made without sound. All the audio had to be dubbed in during post-production.
John Hough said in an interview in Fangoria that there wasn't a script when they went to go make the movie. The script was eventually written by Freddie Rowe and he would also receive notes and messages from him as well as additional pages. When Hough tried to ask for Rowe's phone number or an address so he could reach him, he was denied every time. He suspected Rowe was actually Clive Turner himself. Supposedly, because he and Turner never got along and that Turner kept trying to make power plays as he wanted to be the producer and director.
John Hough was thwarted by producer Clive Turner at every step who tried to alter the script while production was en route. After Hough turned in his version, Turner went out and shot tons of new scenes and edited the movie to the liking that he wanted and constantly fought Hough for.
Howling IV: The Original Nightmare (1988) is the only production in the 'Howling' series to have werewolves portrayed by dogs in any scenes.