It was the spring of 2007.

I was looking forward to a litter from my Tortie CPC, Donegals Irish Step Dancer (Stepper).

She had been bred to my Himalayan Flame point male, CH Donegal's Irish Creme (Irish).

Since Stepper was a colorpoint carrier and Irish was a Himalayan, statistically I was expecting a litter where half the kittens would be pointed, while the other half would be solid or particolor CPCs.

Although I have been breeding cats for more than a decade, nothing had prepared me for what I did get . . . because right from the birth, I knew there was something very different about one of the kittens . . .

During the delivery, when a white head emerged from the birth canal, I thought, "Yea, a Himmy," because I wanted Himmies. As the queen continued delivering,  I saw the black spot on the back of the kitten's head — not something found on a Himalayan at birth.

With astonishment I looked at this strange-colored newborn and asked myself, "What are you?"

It would be some months before I had even an inkling of an answer to that question.

Growing Up The photo on the right is Possum at 8 days of age. The face appears to be all white and it extended in a streak over the back of its neck.
With its mottled body color and white face, the strange appearing kitten looked more like a opossum than a cat . . . and that's what I began calling it — Possum.
Possum's body was mostly a mingling of red and black — the typical coat pattern of a tortoiseshell Persian.
The most obvious change as Possum developed was the face and eye color. By seven weeks of age (photo at right), Possum's white face was showing faint red coloring, the typical beginnings of a flame point Himalayan's red mask. At the same time, the kitten's eye color developed from the blue of a newborn to the copper eye color of a non-pointed Persian.
By 6 months of age (photo right), Possum's coat continued to be a strange mixture of colors . . . The body was the typical blend of red and black of a tortoiseshell Persian, while the face was clearly the face of a flame point Himalayan including a mask. Although the kitten's face was that of a Himalayan, its eyes were copper, not blue. It was all very strange indeed.

She's a He!

Since "she" looked mostly like a tortie, for the first four months of the kitten's life, I just assumed Possum was a girl — and that her strange coloring was some sort of an aberration of a CPC tortie.

I asked several breeders, a CFA representative, and a judge what they thought "her" color was from my photos and I received a variety of answers . . . smoke tortie and white . . . calico . . . brown patched tabby and white. There were a lot of different opinions.

It was at that time that Royal Canin Pet Foods sent members of their breeder club a booklet written for breeders. There was a chapter on unusual color patterns, more specifically on male tortoiseshells and calicos written by Lorraine Shelton. As soon as I read the chapter I realized that I had never checked Possum's sex. I had assumed because of the tortoiseshell pattern that she had to be a female. That's when I discovered two testicles and a penis!

Possum's Color and Sex — and the Contradictions

Now officially a "male", Possum's colors included variations of "white", black, and red, appearing to resemble his flame point sire in the face and his tortie dam along the body, except where the "pale" of the Himalayan body color mingled with the tortie pattern. It all just didn't make sense. Possum's color was a mass of genetic contradictions:

• Possum has the coloring of a flame point Himalayan on his head — a dominant color.
• What appears to be smokey blue on the body is actually the "white" of the Himalayan body color intermingled with the Tortoiseshell black, giving it a dilute appearance.
• He has the coloring of a black and red tortoiseshell on his body, a sex-linked color, meaning he must have two of the female X chromosomes.
• He has male genitals, meaning he has at least one Y chromosome.
• Although Possum has pointed coloring on his head, his eye color is copper, not the blue eye color expected of a Himalayan.

Photo by Vicki Longoria, Blue Bayou Feline Photography

Genetic Anomalies:

I began researching to see if I could discover what might being going on with the genetics of my unusually colored kitty. I discovered that there are three genetic conditions that usually account for unexpected coat colorations in male cats:

• Klinefelter's Syndrome: A male cat's genes are XY. A female cat is XX. Klinefelter's Syndrome is a genetic condition where the male cat has an extra X chromosome (XXY). This condition is what produces male tortoiseshells and calicos cats. They are usually sterile.
• Mosaicism: A mosaic or mosaicism denotes the presence of two or more populations of cells with different genotypes — all in one individual who has developed from a single fertilized egg. In some of these cats only some of their cells have an extra X chromosome, but other cells have the normal XY genotype. If the cells of the reproductive system have the normal XY genotype, these cats will be fertile.
• Chimerism: A chimera is an animal that has two (or more) groups of genetically distinct cells that originated from different zygotes. Chimeras are formed when two fertilized eggs or embryos fuse together very early in the development process and grow as one individual. Each population of cells keeps its own characteristics and the resulting animal becomes a mixture of sometimes contradictory "parts". When the cells that are different are ones that determine coat color, the difference becomes visually obvious.

What Is Possum?

Once I discovered Possum was a male, I realized my boy was a genetic anomaly. I emailed Lorraine Shelton, well-known feline geneticist, to ask her if my cat might fit into one of the three categories for the unusual male color patterns. Lorraine correctly identified Possum's Chimerism from his candid photos and asked for permission to use them in her international talks since he was the best marked chimera she had ever seen.

She also told me that Possum, if fertile, would breed as a flame point since he had the male genitalia from his flame point sire. She also told me that chimeras typically breed according to the facial color as the cells in the face are similar in type to the cells found in the genitals.

Understanding Chimerism Think of a chimera as two jigsaw puzzles with all the same shaped pieces but of two different pictures. A single puzzle can be made out of a combination of pieces from both puzzles. The completed puzzle would have parts of each different picture. In the same way, a chimera is made up of two different sets of DNA from two different zygotes that merged into a single embryo.

Genetic Testing

Since I have been doing all my cattery's genetic testing at UC Davis, it was logical that I get in touch with Dr. Leslie Lyons to see if she would do a genetic work up on Possum. When a swab of his cheek was DNA tested, it was determined that he had the genetic makeup of a Himalayan. As his mouth is part of his face and his face looks most like a Himalayan (is phenotypically expressed), this was not unexpected. The UC Davis coat color test for him, again from typical cheek swabs, showed that he carried dilute but had not inherited the chocolate gene carried by his sire.

Next, samples of blood and hair from various parts of his coat were tested to gather more genetic information regarding the "fraternal tortoiseshell twin" part of him. Dr. Gus Cothran at Texas A&M, a researcher currently doing CFA genetic testing and the scientist who spearheaded the Persian HCM study that my cattery became involved with in 2009, verified Possum's Chimerism. In fact, the DNA testing confirmed that Possum was BOTH a chimera AND a male with an extra X chromosome (XXY), so he is actually the result of TWO genetic anomalies.

My vet performed an ultrasound on Possum to see if he had a uterus in addition to his male reproductive system. The answer was no.

Photo by Vicki Longoria, Blue Bayou Feline Photography

Registration

I registered Possum with the CFA as an AOV male and named him Donegal's Tail of Two Kitties. I thought this name best represented his unique genetic condition. Of course, since he was not an accepted color of Persian, he could never earn any titles, but I did show him in exhibition several times so that judges and other exhibitors could see and handle such an unusual cat. Possum is as sweet as he is unique, and he took to his celebrity status in the show hall with gusto.

Looking For One More Answer

That left just one important question left to be answered — was Possum fertile? At a year old, Possum was showing typical male-type cat behavior, suggesting he was producing the male hormone, testosterone.

I took a urine sample in to be checked for sperm since some of the ejaculate spills over into the urine. Possum did have a few sperm present, but they were immotile. This could be due to the time lag between collection of the sample and the microscopic examination — or it could be the actual morphology of the sperm. His sample also contained two-headed sperm and some sperm with crooked tails. So the plot thickens!

Papa Possum

There is a theory that chimeras might produce offspring with enhanced immunity. The hypothesis theorizes that when DNA is present in an animal that is different from its own DNA, it might confer a higher immune function in both the animal and in its offspring. I decided to breed Possum to see if he would produce kittens with enhanced immunity. He was bred to two different girls.

Possum's "ladies", Hoosier and Jewel

First Litter:

Possum was bred to Hoosier, a tortie point female, and produced five kittens:

• One seal point male
• Two flame point males (one developed dry FIP and was euthanized at 13 months of age)
• Two flame point females

Second Litter:

Possum was bred to Jewel, a lilac and white bicolor CPC, and produced seven kittens:

• One blue point male
• One blue male
• Two black and white males (one developed wet FIP and died at 4 months of age)
• One blue and white male
• One dominant calico female
• One dilute calico female (developed wet FIP and died at 5 months of age)

It was my hope that Possum's chimerism would confer a stronger immune system to his offspring. In fact, it proved to be quite the opposite. Three out of the 12 kittens he produced developed FIP. That's a 25% incidence of FIP, significantly higher than the expected average rate of 5% for catteries in general and much higher than the 3% rate at Donegal over my 17 years of breeding.

On the other hand, as Lorraine Shelton predicted, Possum did breed like a flame point Himalayan, confirmed when he produced two flame point female kittens, a color that requires both a red gene and a pointed gene from both parents.

I decided Possum should be neutered.

Possum Is Neutered

When my veterinarian neutered Possum, it was very routine. Despite his unusual genetics, all his anatomy was as would be expected with any male cat.

Before neutering . . .

As Possum recovers from surgery, he bids farewell to his famous testicles . .

Possum's Professional Photos

Possum's beautiful professional photos are by Vicki Longoria of Blue Bayou Feline Photography. They were taken at one year of age. You can see what he looked like as he approached adulthood . . .

Photo by Vicki Longoria, Blue Bayou Feline Photography

Photo by Vicki Longoria, Blue Bayou Feline Photography

With Thanks

I'd like to express my thanks to the many people helping me determine and document the genetics that have produced such a unique kitten as Possum, especially:

• Lorraine Shelton, Featherland
• Dr. Leslie Lyons, UC Davis
• Gus Cothran, DVM, researcher for the Persian HCM study, Texas A&M University Research Center
• Rosemarie Williams, DVM, The Sound Cat Veterinary Hospital
• Vicki Longoria of Blue Bayou Feline Photography

The Red, White & Blue Maine Coon Another famous chimera was Solkatz Pretty Boy Floid, a male Maine Coon born in 1996 in Bremerton, Washington, USA. He displayed both dominant and dilute colors, appearing to have areas of red tabby, blue and white patches in his coat. He was fertile and sired many litters, over 30 kittens, always breeding and producing as if he were a red tabby and white boy.

About The Author: Jeanne O'Donnell of Donegal Himalayans in North Carolina began breeding in 1996 with the clear objective of producing CFA show quality Himalayans in chocolate and lilac. She also wanted to breed sweet and beautiful pets and show cats in a vast array of colors. The latter was inevitable because of the look and disposition of the cats she introduced into her breeding program. The former is still poetry in progress. Her cattery name, Donegal, is named for the county where Jeanne's husband’s ancestors lived in Ireland, the land of every shade of green and nestled historic castles. In 2008, Jeanne discovered that her foundation male, Ronan, had HCM. Jeanne became deeply involved with submitting DNA on all of her cats and kittens and  Ronan's diseased heart for a landmark Persian HCM study. In the summer of 2013 she began a massive fund drive and calls this ongoing effort Project Ronan's Big Heart after the cat who was determined to be the origin of the HCM in her breeding program. If you wish to be part of the fight against this devastating heart disease, go to https://support.winnfelinefoundation.org/ Jeanne O'Donnell's autobiography A Child Left Behind was published in 2006 by Tate Publishing Company. A couple of years later she became a member of the Cat Writers' Association, winning a Certificate of Excellence award for the article that was published on PKD and HCM in Cat Tracks, the magazine for the Atlantic Himalayan Club (worldwide organization for Himalayan breeders). An updated version of this article was just published in the August, 2013 issue of The Cat Fanciers' Association magazine called Cat Talk. Jeanne O'Donnell has begun a series of humorous cat books, two of which are completed. They are written in feline vernacular and feature candid photos of her cats which assist in telling the stories. The third one will focus on a  geeky cat with a strange appearance called Possum. The title, of course, is A Tail of Two Kitties.