Health & Nutrition
TICA Genetics Corner
One of the benefits of performing DNA testing on our cats is that we are able to identify and establish their genotype, or their genetic state, at various positions in the DNA that have been associated with certain diseases. The presence of a particular DNA combination at that site could tell us that the cat is at risk of developing a particular disease, or that it is a carrier for the mutation but won’t develop the disease, or that it is clear of the mutation all together. By knowing this information, we can make appropriate care choices for the tested cat.
Using the results of the tested cat in combination with the test results of potential mates, we can also proactively leverage DNA testing to help produce healthier kittens. We achieve this by avoiding tom x queen combinations that could produce kittens with an at risk genotype.
By knowing the parents’ genotype and the mode of inheritance of the particular disease in question, it is easy to determine the probability of any kitten born in a litter of being clear, carrier, or at risk for a recessive disease. Remember that recessive conditions require both parents to contribute the mutation to a kitten to produce an at risk state. In the case of dominant conditions, the only potential outcomes are clear and at risk because dominant diseases only require one copy of the mutation from either parent.
It can be helpful to depict the probability that a particular mating will produce kittens at risk of a particular mutation by graphing them on a Punnett Square. In this example, we have a hypothetical condition where N is the normal state, n is the mutated state, and only ‘n/n’ kittens will be affected because the mode of inheritance is recessive. Keep in mind that N/n kittens will not be affected but carry the mutation and can transmit it to future generations.
Each parent, depending on its genotype, will contribute either the ‘N’ or the ‘n’ form of the gene to a kitten. This in turn will result in that particular kitten’s own genotype of N/N, N/n, or n/n (clear, carrier, at risk respectively). Each of the four squares shown for each of the six possible matings in the Figure represents a 25% chance for producing a kitten with that genotype. Thus, the matings resulting in one, two or four red squares will on average produce litters containing 25%, 50% and 100% affected kittens, respectively.
For example, breeding an N/N tom to an N/n queen can only produce kittens that are N/N or N/n - none of the kittens would be susceptible to this theoretical recessive condition (2 green squares and 2 yellow squares). On the other hand, breeding an N/n tom to an n/n queen gives a 50% chance that a kitten will have the condition, since kittens can be either N/n or n/n (2 yellow squares and 2 red squares). All kittens from the mating of two n/n parents will be n/n and thus likely be susceptible to the condition (four red squares).
It is worth pointing out that a carrier can still be a part of a well-managed breeding program. A cat that is a carrier for a recessive mutation can be safely bred to a clear cat; the mating will produce a 50:50 ratio of clear and carrier kittens. By using a “test and replace” program, you can test the litter and keep a clear kitten to replace the carrier parent, thereby retaining the carrier parent’s good genes in your gene pool while successfully removing the known mutation from your breeding program.
Figure: Six potential matings and the potential genetic outcomes for a theoretical disease that has a recessive mode of inheritance. Green are clear, yellow are carrier, red are affected.
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Breakthrough Drug to Treat Heart Disease in Cats May Benefit Humans
According to research by a team of veterinarians at the University of California, Davis, School of Veterinary Medicine, a new drug intended to treat heart disease in cats may also hold potential in treating humans.
Affecting one in seven cats and one in 500 humans, hypertrophic cardiomyopathy (HCM) is the most common form of feline heart disease. The illness results in thickening of the ventricle walls and can lead to blood clots, congestive heart failure and sudden death. In humans, HCM is a frequent cause of abrupt cardiac death that can even strike seemingly healthy young athletes.
The novel drug, MYK-461, proved effective in altering feline heart function in a study of five cats with a naturally occurring form of inherited HCM. In all five, the drug eliminated left-ventricle obstruction. This means that the novel drug may help keep excessive growth of the heart’s walls at bay – without surgery or interventional procedures. A paper describing the work was published in the Dec. 14 Journal PLOS ONE.
As of now, the treatment only serves to address symptoms of HCM, not the causes or progression, though the scientists noted that the same drug had similar results when used on mice. The hope is that with improved heart function, cats with HCM may enjoy a longer lifespan and high quality of life during that time.
The study illustrates the value of companion animals as models of human disease in translational studies, conclude the authors, and may lead to a new treatment for HCM in both species. “There has been little to no progress in advancing the treatment of HCM in humans or animals for years,” said Associate Professor Joshua Stern, chief of the Cardiology Service at the UC Davis veterinary hospital. “This study brings new hope for cats and people.”
With this proof of concept that the drug is viable for use in cats, UC Davis hopes to lead a clinical trial in the near future. If conducted, the trial could determine if MYK-461 or a related compound has the potential to become the accepted protocol for care of cats with HCM. It also promises advances in HCM treatment for humans, making Stern’s research a great example of comparative medicine.
Potentially Poisonous Plants
If your cat has ingested any of part of the plants below, and you cannot get to your vet, call the Pet Poison Hotline 800 - 213 - 6680
Pet Poison Helpline is a 24-hour service available throughout North America and the Caribbean for pet owners and veterinary professionals who require assistance with treating a potentially poisoned pet. We have the ability to help every pet, with all types of poisonings, 24 hours a day. Our knowledge and expertise will put your mind at ease when dealing with a potential emergency.
In order to provide this critical service, please be advised that there is a $35 per incident fee, payable by credit card. This fee covers the initial consultation as well as all follow-up calls associated with the management of the case
Bird of Paradise
Cherry (seeds, wilting leaves, and pit)
Crown of Thorns
Fruit Salad Plant
Jack in the Pulpit
Lily of the Valley
Marigold (Marsh Marigold)
Oak Tree (buds and acorns)
Peach (wilting leaves and pits)
Potato (all green parts)
Snow on the Mountain
Star of Bethlehem
Swiss Cheese Plant
Tomato Plant (entire plant except ripe fruit)
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