What is PKD and what does it mean to my cat?
PKD is Polycystic Kidney Disease, it is an inherited conditions in cats that causes multiple cysts or pockets of fluid to form in the kidneys. These cysts are present from birth. Initially the cysts are very small but grow over time and may eventually disrupt the kidney function and cause kidney failure.
The number of cysts vary between cats as well as the rate in which the cysts enlarge. In most cats, the cysts will enlarge slowly over time and in many cases the signs or symptoms of kidneys will not show up until the cats are older this typically happens after 6 years of age. This is not to say that younger cats will not develop kidney failure, and in other cats, kidney failure will not develop at all.
Some breeds have a higher rate for Polycystic Kidney Disease. PKD is the result of a single, autosomal dominant gene abnormality. Check to ensure your breeder is a PKD negative cattery. It only takes one parent affected with PKD for their offspring to inherit the abnormal gene and be affected.
How to test for PKD?
Originally, when the disease was first recognized, the only way to identify the cats affected by PKD was to perform an ultrasound scan of the kidneys. Now, with technology a gene test is available for PKD by performing a blood sample or a cheek swab.
What is the treatment for PKD?
There is no typical treatment for PKD, the disease causes signs to those seen in cats with chronic kidney disease. Special diets, and fluid as well as medications can help ease the symptoms of PKD in cats.
What does PKD Negative mean?
For a cat to be PKD Negative it would be tested for the disease which is typically done through a cheek swab. For a cattery to be PKD Negative, this means their cats are tested negative for PKD, all breeding cats would be negative.
UC Davis states Feline Polycystic kidney disease (PKD1) is an inheritable form of polycystic kidney disease commonly seen in Persians as well as other breeds and cats with specific breed ancestry. Affected cats develop cysts on their kidneys which often leads to renal failure at a later stage.
Phenotype: The presentation of PKD1 is similar to one of the most common causes of death for any cat, renal failure. Early onset, bilateral presentation (both kidneys), and multiple cysts are all traits of PKD1. The kidney cysts for PKD1 present early, often before 12 months of age. Renal failure, however, usually occurs at a later age.
Mode of Inheritance: Autosomal dominant
Alleles: N= Normal/Unaffected, P= Polycystic kidney disease (PKD1)
Breeds appropriate for testing: Persian, Persian crosses and Persian-derived breeds (includes British Longhair, British Shorthair, Burmilla, Domestic Shorthair, Exotic Longhair, Exotic Shorthair, Foldex, Highland Fold, Highland Straight, Himalayan, Maine Coon, Napoleon, Ragamuffin, Ragdoll, Scottish Fold, Scottish Straight, Selkirk Rex), Devon Rex, Siberian
- Cats with N/N genoytpe will not have this heritable form of polycystic kidney disease and cannot transmit this PKD1 variant to their offspring.
- Cats with N/P genotype will be affected by this heritable form of polycystic kidney disease, though severity of symptoms cannot be predicted. They will transmit this PKD1 variant to 50% of their offspring, and those offspring will inherit this polycystic kidney disease.
- Cats with P/P genotype are suspected to be lethal and therefore are unlikely to be born and/or survive.
Additional Details
Polycystic Kidney Disease (PKD) is a well documented abnormality in domestic cats. Cystic kidneys can sporadically occur in any population of cats. PKD is not a new disease and has been reported in the literature for over 30 years. The heritable form of PKD1 may not have initially occurred in Persians as a new mutation, but perhaps in random bred cats. Unfortunately, PKD1 does not have a strong clinical presentation. The presentation of PKD1 is similar to one of the most common causes of death for any cat, renal failure. Thus, PKD1 has gone unnoticed for many years and has spread throughout the Persian breed. Any breed that has used Persians in their foundation or propagation should have concerns for PKD1.
Early onset, bilateral presentation (both kidneys), and multiple cysts are all traits of the heritable form of the disease. The kidney cysts for PKD1 present early, often before 12 months of age. Renal failure, however, usually occurs at a later age. Thus, PKD1 is considered a late onset renal disease. In the fancy cat breeds, PKD1 is inherited as an autosomal dominant condition. This implies that only one copy of the altered version of the gene is required to produce PKD1. Generally, 50% of PKD1 positive cats' offspring will inherit PKD1. A positive cat could potentially be homozygous for PKD1 and all offspring produced would have PKD1. It is suspected that cats that are homozygous for PKD1 are not abundant and the homozygote form could be lethal in utero or severely affected at a very early age. Further research is required to determine the effects of the homozygous condition.