Notes on Animal Health, August 2024: Would You Clone Your Dog? Should You?

Because the lifespans of our domestic pets are so much shorter than ours, inevitably pet owners experience the heartbreak of their death. But what if you could give your pet immortality, well, a type of immortality? Science has now given us the ability to clone our pets, and in doing so we can keep them alive, at least genetically, forever. But should we?

Cloning refers to the creation of organisms, called clones, that are genetically identical. Identical twins, which occur in humans and other mammals when a fertilized egg splits into two embryos, are naturally occurring clones. In the laboratory, there are actually three different types of cloning: gene cloning, reproductive cloning, and therapeutic cloning. Gene cloning produces exact copies of genes or segments of DNA. Therapeutic cloning produces embryonic stem cells with the goal of creating new tissues to replace injured or diseased ones, and reproductive cloning produces copies of whole animals, such as our pets.

It is often claimed that the first artificially cloned mammal was created in 1996, when, after over 200 failed attempts, researchers in Scotland cloned a sheep they named Dolly. However, mammals, including sheep, had been previously cloned, but the starting materials were embryonic cells. What was unique about Dolly was that she was the first mammal cloned from the genetic material contained in a somatic cell, in other words a cell originating from the body, and not an embryonic cell. While every cell’s nucleus contains a complete set of genetic blueprints, embryonic cells are primed to divide and differentiate. In contrast, many of the genes in adult somatic cells are switched off and their capacity for replication is limited. In the technique used to create Dolly, called somatic cell nuclear transfer (SCNT), the genetic material in an egg cell, called an oocyte, was removed and replaced by the DNA contained in the nucleus of a cell taken from the mammary gland of the donor ewe. The newly reconstituted oocyte was then grown in vitro until it was ready to be implanted into the uterus of a surrogate, which eventually gave birth to Dolly, a clone of the genetic donor.

Following Dolly, many other mammals, including cats, were cloned, but the first dogs weren’t cloned until 2005, because dog oocytes proved to be very difficult to maintain and grow in vitro. Since those early days, cloning has come a long way with several thousand produced, and now it is commercially available for a number of species, including horses and rabbits. In fact, Argentine polo ponies may be the most cloned animal in the world. Sinogene, BioVenic, and Viagen are just a few of the companies offering cloning as a service. The price varies, but is generally in the range of $50,000 for a dog, a bit more for a horse, and a bit less for a cat.

Even if you have the financial resources that allow you to clone your beloved Fido, Fluffy, or Trigger for that matter, there are a few other issues you should consider. First, for reasons not entirely understood, clones tend to have more adverse health conditions than naturally conceived animals. For example, large offspring syndrome, which includes large size at birth, breathing difficulties, reluctance to suckle, sudden perinatal death, and increased prenatal loss, has been frequently reported in bovine and ovine cloned offspring. In addition, abnormal cardiovascular functions, such as pulmonary hypertension and right-sided heart failure in cloned calves and sheep, and left- and right-sided heart abnormalities in cloned piglets, have also been reported.

‍Results of some studies, but not all, also suggest that cloned animals tend to have shorter lifespans. Because pet owners generally only clone their dog or cat once, the number of clones from any particular animal is limited, and therefore, these issues have not been well studied in these species. One review, however, of 16 cloned working dogs in South Korea did report that the birth weight of the clones, when compared to their naturally bred counterparts, was slightly higher, but the clones demonstrated normal growth patterns. In addition, physical and neurological examinations of the clones were unremarkable, and serum and hematological values were within normal range. One positive finding of the review was that the clones were more successful in their training than dogs who were not clones. The authors noted that elite working dogs were chosen as DNA donors, and speculated that training aptitude may be very much in the genes.

A second consideration of cloning concerns the recipients that are used to produce the clones, as well as any excess or defective clones produced in the process. For example, in 2005, to create Snuppy, the first cloned dog, over 1,000 embryos were implanted into 123 recipients; not a particularly good success rate. Cloning methods, however, have since improved significantly. For example, when Snuppy was recloned in 2017, 94 embryos implanted into only 7 recipients produced 4 clones. Nevertheless, one does have to wonder about the quality of life for these recipients. How many times are they used for the process? Are they ever adopted or do they live their lives in a laboratory so they can produce cloned pets? And what is the fate of any excess clones or those that are born with genetic defects? One research group that has cloned over 1000 dogs indicated that they now only use their recipients once, but they did not indicate their final disposition. In addition, the puppies are delivered by cesarian section to minimize risk to the clones, a procedure required only occasionally in natural breeding. This same group also reported that the current survival rates for clones are quite high and their health and lifespan are excellent, but they did not provide any specific details.

Finally, pet owners should also understand that a clone may look and act very different from the original pet. Small changes can occur in the DNA during the cloning process and environmental factors, such as nutrition, stress, and disease, may alter which genes are turned on or off in the developing fetus, a process referred to as epigenetics.

People clone their pets for various reasons. A CEO of a mineral exploration company in Canada cloned his dog because she had the unique ability to detect sulfide scents which are often associated with mineral deposits. The two resulting cloned puppies appeared to share the unique detection ability of their donor, and the CEO was happy with his decision to clone his dog. For others cloning is a mechanism to cope with the loss of a beloved pet. A dog trainer in Texas had a special bond with her Ragdoll cat, and when it died suddenly at 5 years of age, she decided to clone it. But the clone turned out to have an entirely different personality, and although she loved it, she did not feel the same connection to it as she had to the original pet. There have not been any scientific studies exploring the satisfaction of people with their cloned pet. In general, the anecdotal reports indicate that while many are thrilled with the results some are disappointed, so it is not something one should undertake lightly.

Cloning of animals, including our pets, is no longer science fiction. If one has the financial resources, you can bestow a type of immortality on them. However, money aside, before you clone your pet, you should consider the ethical issues, such as the quality of life of the egg donors and recipients, and whether you can take care of more than one pet if multiple clones are produced. Finally, would your time and resources be better spent adopting from humane shelters, which in many places are now overflowing with unwanted pets? As with many advances in science the question is not can you, but should you?

– Cindy Cole, DVM, PhD, DACVCP




First Five
First Five is our curated list of articles, studies, and publications for the month

Gorillas and food as medicine
Recently, a team of researchers documented that western lowland gorillas (Gorilla gorilla gorilla) in Moukalaba-Doudou National Park frequently consumed a number of different plants that might have therapeutic value in the treatment of a number of conditions. The team identified four native plant species that are both consumed by gorillas and used in traditional medicine: the fromager tree (Ceiba pentandra), giant yellow mulberry (Myrianthus arboreus), African teak (Milicia excelsa) and fig trees (Ficus). Biodiverse regions, such as central Africa, are home to a huge reservoir of unexplored and potentially medicinal plants, zoopharmacognosy is one approach aimed at discovering new drugs.

Pet-people pen pals
A new study provides evidence that seriously ill children and teenagers can benefit by becoming pen pals with cats and dogs affected by cancer. With the consent of the patients and their parents, researches arranged a letter exchange between 16 young patients and the owners of pets experiencing cancer. Over a period of months, the two groups exchanged letters, many hand-written and including colorful drawings and photos. The letters enhanced the patients’ quality of life in ways similar to what has been seen with face-to-face animal therapy programs, including improved mood, distraction from their problems and overall decreased emotional distress. The researchers surmise that the letters allowed the patients to express themselves freely and without judgement. For example, “if a child wrote, ‘I’m scared about my upcoming MRI scan’, the dog may just reply, ‘Oh my gosh, I get it’.” The pet owners also reported an improvement in well being and feeling positive about their pet being able to help another human.

Crocheted kitten hats anyone?
In a new study scientists from the University of Montreal have recorded electrical activity in the brains of awake cats for the first time, thanks to specially crocheted wool caps that hold the electrodes in place. It is hoped that this capability will allow more accurate assessment of pain in cats, possibly leading to new treatments. Previously, cats had to be sedated to allow recordings of electroencephalograms (EEGs) which can be helpful in assessing the effects of analgesic treatments because they can show the brain’s responses to pain and to stimulation of the senses.

Of dogs and dingoes
A new study out of the Queensland University of Technology analyzed the DNA from ancient dingoes and the results suggest that Australia’s native wild dogs arrived in two waves of migration between 3000 and 8000 years ago. Although originally dingoes were thought to have been brought to Australia from south Asia by humans, new evidence suggests that they arrived in two waves across a land bridge between Australia and Papua New Guinea that eventually became submerged. The researchers examined 42 ancient dingo specimens, ultimately obtaining nine full genomes, including the oldest Australian genome ever sequenced for any species. They then compared the ancient DNA with samples from 11 modern dingoes, 6 New Guinea singing dogs and 372 domestic dogs, wolves and other canids. The analysis confirmed that the two main Australian populations of dingoes—one concentrated on the east coast and the other on the west—had already diverged at least 3000 years ago. The east coast dingoes are more closely related to New Guinea singing dogs than they are to the western dingoes, possibly indicating two distinct migrations of dingoes into Australia.

The secret to a fast horse is in the gut
The findings of a new study out of the University of Surrey in the UK suggest that a more diverse microbiome in the gut is associated with a lower risk of health issues and better athletic performance in horses. Researchers collected multiple fecal samples over the first year of life from 52 Thoroughbred foals born on 5 stud farms in 2018 and sequenced and recorded the bacterial populations. The researchers then followed the horses for 2 years and tracked their racing performances. They also kept records of the horses’ respiratory health and orthopedic and soft tissue injuries. The team found that greater bacterial diversity at 28 days of age was linked to better racing performances. Also foals with low bacterial diversity had an increased risk of musculoskeletal injuries later in life. Significantly, foals that had been treated with antibiotics in the first few weeks of life had significantly less bacterial diversity, less earnings, and developed respiratory diseases at higher rates than non-treated foals.

‍

‍