14 Vet Info-H • May–Aug 2023 • Vol 11 • No. 3 Feline polycystic kidney disease (PKD) is hereditary, in which there is progressive development of fluid-filled cysts in the kidneys and, sometimes, in other organs such as the pancreas and the liver.1 Feline PKD is highly prevalent among Persian cats, with a worldwide incidence in the breed being 38%, making it the most prominently inherited feline disease in Persian cats. It is also observed in other cat breeds such as Exotic Shorthair, Himalayan Shorthair, British Shorthair, American Shorthair, Burmilla, Ragdoll, Maine Coon, Neva Masquerade, and Chartreux.2-7 Feline Polycystic Kidney Disease Vet's Concern Feline PKD occurs due to a single autosomal dominant gene abnormality, which means that every cat with the abnormal gene is at a risk of PKD. The disease is inheritable—cats with the PKD gene, even those with only a few small cysts or those with no clinical signs, will still pass the genetic defect to their kittens, even if mated with an unaffected, healthy cat.7 Primarily, there is noticeable cyst formation in the kidneys, and the cyst grows progressively but at a slow pace. It concurrently causes deterioration of kidney tissue and a gradual decrease in kidney functions, ultimately leading to irreversible kidney failure. Symptoms Feline PKD is characterized by the presence of cysts in the renal parenchyma in variable sizes and numbers. The cysts are inherent from birth and are formed in the cells of the renal tubules. Most of them are observed in the cortex or in the corticomedullary area. These cysts increase in number and size proportionally with age, which explains that many cats remain subclinical for several years.8-12 ultrasound evaluation of the kidneys. Special radiographic dye studies may also be used in certain situations.15 • Relevant clinical findings include renal manifestations, along with extrarenal manifestations, where liver involvement is the most common. Hepatic cysts are an extrarenal manifestation in some cases. In a study, the cooccurrence of hepatic and renal cysts with PKD was found to be 12.6%.16,12 • Laboratory findings are not very distinct in feline PKD. They mainly indicate renal failure (ie, azotemia, hyperphosphatemia, non-regenerative anemia, and proteinuria). However, clinical stages are highly variable, as depicted in a recent study where several young cats presented with azotemia with a remarkably high creatinine concentration, compared with geriatric cats with less significant values.17,11,12 • Ultrasound is a reliable imaging method for diagnosing and monitoring PKD. Multiple genetic tests have also been developed to determine the presence of the mutation responsible, thus offering breeders, owners, and clinicians the ability to easily detect PKD at an early stage.5,9,18-20 The clinical signs of PKD are not distinctively characteristic; PKD manifests as chronic renal failure. The average age at manifestation of clinical signs is 7 years; however, signs can appear anywhere between 3 and 10 years. The generally observed clinical signs, based on the history, are apathy, anorexia, weight loss, bad appearance of the coat, polyuria and polydipsia, as well as gastrointestinal disorders. Clinical examination shows general dehydration and pale mucous membranes. On palpation, an increased volume and irregular structure of the kidneys are observed.8,13,14 Causes Feline PKD occurs due to a mutated gene called PKD1 (polycystic 1, transient receptor potential channel interacting). However, the exact reasons of what causes this gene mutation in the first place are unknown. Diagnosis • Feline PKD is diagnosed based on the breed, medical history, clinical signs, blood and urine tests, genetic testing, and
RkJQdWJsaXNoZXIy MjAwNDg=