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Cats with chronic kidney disease can now live longer and better than ever before.
“It’s been a very exciting time in the last decade where we’ve really improved our skills in diagnosing and identifying chronic kidney disease,” said Dr. Shelly L. Vaden, professor of internal medicine at North Carolina State University College of Veterinary Medicine. “We have made many improvements in medical management as well.”
Dr. Vaden spoke last August during the New Therapeutic Approaches to Chronic Care symposium at the AVMA Virtual Convention 2020. Another congress presentation focused on RenalTech, a new tool from Antech Diagnostics that uses artificial intelligence to predict which cats will be in the next two years develop chronic kidney disease.
During a Morris Animal Foundation webinar in October 2020, Dr. Jessica Quimby, associate professor of internal medicine for small animals at Ohio State University’s College of Veterinary Medicine, on trying to gain a deeper understanding of CKD in cats while improving practice aspects of treatment.
A mosaic of treatment
Dr. Vaden said that around 2 to 20% of all cats and 30% of cats over 10 years of age have chronic kidney disease. With recent advances in diagnostics and medical management, veterinarians can now treat some cats for extended periods of time.
“When we look at this and talk about treating some of these cats for three years or more, we really need to be very thoughtful and use an evidence-based approach to our treatment and diagnosis,” she said.
Chronic kidney disease is usually diagnosed by imaging or by finding persistent azotemia or an increase in serum-symmetrical dimethylarginine concentration. The next step is the staging according to the system of the International Renal Interest Society.
RenalTech, a new predictive diagnostic tool from Antech Diagnostics based on artificial intelligence, predicted that Billy (above right), a neutered 12 year old male cat, would develop chronic kidney disease in the next two years, and said Amber (above) ahead left), a neutered 7 year old cat, would not do that. (Photos courtesy of Antech Diagnostics)
Sophie was 19 years old before she died of chronic kidney disease. It belonged to Dr. Jessica Quimby, an associate professor of internal medicine for small animals at Ohio State University College of Veterinary Medicine who studies CKD in cats. (Courtesy Dr. Quimby)
The IRIS stages from 1 to 4 are based on serum creatinine and SDMA concentrations, the latter recently added. The staging system also provides staging based on the severity of proteinuria and high blood pressure.
“Staging becomes important because it is a way of communicating where we are diagnostic, where we are therapeutic, where the animal is in terms of expected progression and symptoms,” said Dr. Vaden.
For a stage 1 or early stage 2 cat, it is important to identify and treat any underlying primary kidney disease if the veterinarian is able to identify a treatable disease. In a late stage 2 or 3 cat, Dr. Vaden with evaluating and managing factors associated with progression. For a stage 4 cat, Dr. Vaden explained the many complications of chronic kidney disease.
“When I look at chronic kidney disease management, I see it as a mosaic,” said Dr. Vaden. “Instead of finding one size fits all, I try to identify what problems are there and then address them. And some of these problems are interrelated. So again, try to look at these as a mosaic and see what we need to address, what we can address to make an animal feel better. “
Dr. Vaden made recommendations to control aspects of diet, proteinuria, hypertension, anemia, metabolic acidosis, secondary renal mineral disorders, hypokalemia, and gastrointestinal symptoms (see sidebar).
Risk factors, predictive diagnostics
A JAVMA scientific article dated February 1, 2014 examined the risk factors associated with developing chronic kidney disease in cats studied in primary care veterinary clinics. The retrospective case-control study looked at feline patients who were examined at Banfield Pet Hospitals in 2010.
The abstract states: “Risk factors for CKD in cats included thin body disease, previous periodontal disease or bladder infection, anesthesia or documented dehydration in the previous year, a neutered man (versus a neutered woman), and living in parts of the United States other than that Northeast. The likelihood of CKD decreased with increasing body weight in undehydrated cats, short haired cats and a previous diagnosis of diabetes mellitus and increased if vomiting, polyuria or polydipsia, appetite or energy loss or bad breath were present at the time of diagnosis or inclusion of the control group, but not when these signs were reported 6 to 12 months earlier. The mean weight loss over the previous 6 to 12 months was 10.8% and 2.1% in cats with and without CRF. “
Dr. Jennifer Ogeer, Vice President Medical Affairs and Commercial Marketing at Antech, spoke at the AVMA Virtual Convention 2020 on the topic of “Using Artificial Intelligence to Eliminate the Surprise of Chronic Kidney Disease”.
In October 2019, Antech announced RenalTech, a predictive diagnostic tool for chronic kidney disease in cats based on machine learning. This is a type of artificial intelligence that uses algorithms to identify patterns in data. Antech and Banfield are owned by Mars PetCare, and RenalTech was developed based on data from feline patients studied at Banfield Pet Hospitals for 20 years.
Details on a version of the model using four measurements – creatinine concentration, blood urea nitrogen concentration, urine specific gravity, and age – were published in the November / December 2019 issue of the Journal of Veterinary Internal Medicine. The model was able to predict CKD in cats two years prior to clinical diagnosis. Dr. Ogeer said comorbidities that were identified as significantly associated with an increased likelihood of CKD compared to no CKD were hyperthyroidism, diabetes mellitus, hepatopathy, and being underweight.
RenalTech uses additional parameters – white blood cell count, urine protein concentration and urine pH. Dr. Ogeer said the tool predicts whether a cat will develop CKD with greater than 95% accuracy over the next two years. After the tool made about 300,000 predictions for cats in the United States and Canada, Antech found that the median age for cats predicted to have CKD within two years was 15 years, while the median age for cats with one CKD was predicted within two years, 9 years was years.
In order to make a prediction for a single cat, RenalTech requires measurements from two visits within 24 months and more than 60 days apart. All parameters are available from a full blood cell count, a chemistry profile and a full urinalysis.
“RenalTech provides actionable information that veterinarians can use to create targeted, personalized care plans for their feline patients,” said Dr. Ogeer.
Study illness, support cats
The October 2020 Morris Animal Foundation webinar provided an overview of what pet owners need to know about chronic kidney disease in cats. Dr. Quimby commented on future directions.
“While it’s a very common disease, there is actually a lot about the pathophysiology or disease process that we don’t really understand for cats,” she said.
Researchers are trying to learn more about the disease process in cats, including the reasons why it starts in the first place. Dr. Quimby has examined the aging kidney and how it leads to malfunction.
Another thing that Dr. Quimby’s focus is diet: choosing the best diet for cats with CRF and making sure the cats actually eat the food. She and her colleagues study aspects of nutrition and the microbiome of the intestine.
On the clinical side, Dr. Quimby, how important it is to make cats with CRF feel better. She said, “If we can’t fix kidney disease, we want to be able to support it as best we can”.
Dr. Quimby said appetite stimulants have been one of the most influential developments in treating CKD in cats. After working in a cat-only practice for a few years, the practice began using mirtazapine as an appetite stimulator for cats with CRF. Dr. Quimby led research into better use of mirtazapine and discovered information that helped develop transdermal delivery.
Veterinarians are also now freer or more encouraged to use anti-nausea medication. Dr. Quimby said that some practitioners do not believe that anti-nausea medication is necessary for kidney disease, but she noted that toxins build up in the blood and cats make them feel very sick.
A major hurdle is getting the cat to the vet. Many people recently have focused on developing cat-friendly practices, implementing stress-free handling, and thinking about things from the cat’s perspective.
For example, it has become popular to give cats gabapentin to relieve the stress of visiting the vet. Cats with CRF need a reduced dose, which Dr. Quimby and colleagues are currently investigating. Dr. Quimby said gabapentin has been very helpful during the last few years of her own cat with CKD.
