Has your cat been diagnosed with polycystic kidney disease? You are not alone. Polycystic kidney disease (PKD) affects up to 6% of all cats. Many cats with PKD will live long, happy lives despite having cysts in their kidneys. Unfortunately, some cats develop more or larger cysts than other PKD cats, and this can lead to chronic renal disease and kidney failure. It's best to identify and treat this feline disease as soon as possible.
What is Polycystic Kidney Disease?
Polycystic kidney disease (PKD) is an inherited disorder that can lead to feline kidney failure. PKD causes small fluid-filled cysts to form in both of your cat's kidneys. These cysts can be seen by ultrasound in kittens, years before they will cause any symptoms of illness in your cat.
As these cysts grow in number and size, they will start to enlarge the kidneys. Some cats with polycystic kidney disease have bosselated (lumpy) kidneys and enlarged abdomens. As uncomfortable as this may sound, your cat will not be in pain unless the cysts become infected.
Although cats with PKD have had this disease since birth, it typically won't disrupt your cat's kidney function until later in life, around age 7. It is most common in Persian cats, and 40% or more of Persians suffer from this renal disorder.
Polycystic Kidney Disease Complications
The role of the kidneys, in humans and cats, is to filter the blood and remove the body's waste products. Although the cysts themselves do not hurt or kill your cat, they can damage the function of these vital organs.
As your cat's cysts keeping growing and multiplying, they will displace normal kidney tissue. Without enough healthy tissue in your cat's kidneys, your cat will no longer be able to eliminate bloodstream toxins efficiently. By overwhelming the kidneys, PKD can lead to chronic kidney disease, which is the true threat to your cat's health.
Another possible complication of polycystic kidney disease is that the cysts could become infected. If your cat has been diagnosed with PKD, it is important to monitor your cat for signs of a bacterial infection. Kidney infections can quickly lead to sepsis, which is deadly without proper antibacterial treatment.
Polycystic Kidney Disease Treatment
Unfortunately, polycystic kidney disease is a slowly progressive and irreversible disease. Although you cannot remove or prevent your cat's cysts from growing, your veterinarian may aspirate some of the fluid buildup in large cysts with a needle.
The typical treatment for cats with polycystic kidney disease is to focus on keeping your cat's kidneys healthy and functioning as long as possible. Treatments are not specific to PKD, but are the same used to combat all types of kidney diseases:
- Increased water intake through wet food, extra water bowls and/or subcutaneous fluid injections
- Specialty diets low in phosphorus or sodium
- Supplements containing potassium and/or calcium
- Calcitriol to slow the progression of kidney disease and other medications to control the symptoms or infections Kidney transplant
With early diagnosis and proper treatment by a veterinarian, your PKD cat could still live a long and healthy life.
Does My Cat Have Polycystic Kidney Disease?
Unless your cat is Persian or a related breed, your veterinarian probably will not screen your cat for PKD unless your cat begins experiencing signs of general kidney disease. Renal failure is the leading cause of death in adult cats, so you should be familiar the symptoms of kidney disease. These include:
- Frequent urination
- Increased water consumption
- Anorexia (refusal to eat) or weight loss
- Lethargy or depression
Additionally, your cat might have any of the following symptoms:
- Vomiting or diarrhea
- Loss of movement or balance
- High blood pressure
Cats typically do not have symptoms until their kidneys have lost 60% or more of their function. If your cat suffers from a combination of the above symptoms, your veterinarian will run blood and urine tests to determine if your cat's kidneys are not functioning properly.
In order to determine the cause or your cat's kidney problems, your veterinarian might screen your cat for PKD. There are two ways to test your cat for PKD:
- Ultrasound: A popular test for PKD is to examine your cat's kidneys with ultrasound. However, unless your cat is a Persian or other high-risk genetic carrier, your veterinarian will not test your cat for PKD until AFTER your cat's kidneys have been damaged.
- Genetic test: A newer approach is to test your cat's DNA for the gene mutations that cause this disease. If you catch PKD while your cat is young, then you will be prepared to treat your cat's symptoms before they decrease your cat's quality of life.
via GIPHY by Mythicbells Persians
The Genetics of Polycystic Kidney Disease
If your cat suffers from polycystic kidney disease, then she most likely inherited this condition through DNA from one of her kitty parents. Most cases of PKD can be traced to a single mutation in a gene called PKD1 – this is true for both humans and cats. The genetic instructions for building healthy kidneys will determine whether your cat will have PKD.
Every cat gets two copies of most genes – one from each parent. However, it only takes one bad copy of PKD1 to cause your cat to develop cysts. The term for this type of inheritance is “autosomal dominant." DNA tests are available to screen Persians for the PKD1 mutation. Unfortunately, this will only indicate if your cat will develop cysts, not whether your cat will develop complications from PKD.
If your cat has the PKD1 gene mutation, then each of its kittens has a 50% chance that they also will inherit the bad PKD gene. Inheritance is why Persians have such high rates of PKD. Just by chance, some of the earliest ancestors of the Persian breed carried this mutation. Now, around 40% of all Persian cats have this disease. If you have a Persian cat, it is recommended to test it for PKD before deciding to breed it.
The Future of Polycystic Kidney Disease Treatment
We can currently use a DNA test to determine if your cat has polycystic kidney disease. Our scientists are still working to identify the genes that determine how rapidly this disease will progress. Many genes work together to keep your cat's kidneys functioning properly, and with your cat's help, we can identify these genes.
By understanding genetics, we can develop specific drugs to help prevent this disease from progressing. Gene-specific drugs will have fewer side effects and could one day potentially reverse this disease. In the future, genetic tests can be used to help you determine whether your cat will have a harmless or life-threatening case of PKD, and which interventions will be most successful at helping your cat live a long and healthy life.
If your cat suffers from polycystic kidney disease, he could help future cats with this disease by having his DNA sequenced and tested today. Basepaws offers a “cat scientist" discount price for cats suffering from this disease, to help scientists speed the identification and treatment of this disease. Contact us for more info. Please spread the word!