Pet Loss - Religious or Spiritual

Souls of Animals by Gary Kowalski, Stillpoint Publishing, ISBN 1883478219 (1998)
From the publisher:
Kowalski offers vignettes from the lives of creatures that illustrate the qualities he considers spiritual: playfulness, capacity for love, altruism, and awareness of death.

Maltese Crossing: Love, Loss, and Lessons of Compassion by Dr. P. D. Sargent, Golden Reflections Publications,
ISBN 0972002200 (2002)
Maltese Crossing is a short book, at first full of humor poking fun of the human world, but as fate changes, full of thoughtful reflection as the dog brings wisdom to the human, giving her a more fulfilling and deeply meaningful life. When the dog leaves for another celestial assignment, the human grieves deeply, mourning the loss that seems insurmountable.

Dogs Have Souls Too by George and Emily Watson, PMD Publishing, ISBN 0967487501 (2001)
If you have ever agonized over the decision to euthanize a pet friend, wondered whether animals have souls or worried that there might not be an afterlife for them, the uplifting story of this remarkable dog will ease your mind. By sharing their experiences, the authors provide comfort and reassurance to readers: The spirit of Miss Sarah most assuredly DOES live on. For more information or to order visit www.dogshavesouls.com.

Spirit Dogs: Heroes in Heaven by Susan Kelleher, Owl of Athene Press, ISBN 0965049515 (1998)
An illustrated short story about the narrator and her dog, Ivan, who make a trip to dog heaven after being in a car accident. The narrator is greeted by all the dogs she's owned during her life. One collie, who saved her life when she was a child, explains how a dog's ultimate goal is to serve humans in an exceptional way or to save a human life. He tells her that all dogs evolve to this point and that Ivan is almost there. He also explains that a dog's love for its owner is always available to that person, even after the dog has died. Ivan remains in heaven, and the narrator must return to Earth.