In Part 5 of Mission RENAL, a series on Chronic Kidney Disease (CKD) in pets, Dr. JD Foster, small animal internal medicine and nephrology expert joins to discuss non-regenerative anemia in cats with chronic kidney disease and introduce Varenzin™-CA1, the first FDA conditionally approved oral treatment for this condition. They explain why anemia matters, how it affects quality of life, and how this innovative medication works differently from older therapies. Sponsored by Elanco, this guide empowers pet owners with Real Education for Navigating Advanced Longevity in dogs and cats with chronic kidney disease.
Please note: Varenzin-CA 1 (molidustat oral suspension) is indicated for the control of non-regenerative anemia associated with chronic kidney disease (CKD) in cats. Discussions within this podcast pertaining to treating anemia with Varenzin-CA1 are solely pertaining to the treatment of CKD-related non-regenerative anemia.
What Is Anemia in Cats with Chronic Kidney Disease?
Anemia means a reduced number of red blood cells, which are responsible for carrying oxygen throughout the body.
In cats with non-regenerative anemia associated with chronic kidney disease, the body is not producing enough new red blood cells to replace old ones.
Why Chronic Kidney Disease Causes Anemia
Healthy kidneys produce a hormone called erythropoietin, which signals the bone marrow to make new red blood cells. When kidney tissue is damaged and replaced by scar tissue, that hormone production decreases, especially in later stages of CKD.
- Stage 1 CKD: non-regenerative anemia is uncommon
- Stage 2 CKD: some cats may develop non-regenerative anemia
- Stage 3 CKD: most cats develop non-regenerative anemia
- Stage 4 CKD: non-regenerative anemia is expected
This makes non-regenerative anemia a predictable and common consequence of advancing kidney disease.
How Non-Regenerative Anemia Affects Quality of Life of Cats with Chronic Kidney Disease
One of the most compelling moments in the episode is Dr. Foster’s story of Brutus, a big cat with a big presence, whose personality faded as his non-regenerative anemia progressed, and returned once the non-regenerative anemia was treated.
Common Signs Cat Owners May Notice
- Low energy or “blah” behavior
- Decreased interest in food
- Less interaction with family
- Reduced play or mobility
- Overall loss of personality
Non-regenerative anemia doesn’t just affect energy, it reduces oxygen delivery to every organ, including the brain, liver, gastrointestinal tract, and kidneys themselves.
Why Treating Non-Regenerative Anemia Is More Than Symptom Control
A major myth addressed in this episode is that non-regenerative anemia is “just a side effect” of CKD and not worth treating.
Dr. Foster explains that non-regenerative anemia can actually worsen kidney disease progression. Research has shown that cats with more severe non-regenerative anemia may progress more quickly from earlier CKD stages to later ones.
This creates a vicious cycle:
- Kidney disease causes non-regenerative anemia
- Non-regenerative anemia reduces oxygen delivery
- Low oxygen stresses remaining kidney tissue
- Kidney disease progresses faster
Treating non-regenerative anemia helps break this cycle, making it a key pillar of CKD management, not an optional add-on.
Traditional Treatments for Non-Regenerative Anemia with Chronic Kidney Disease and Their Limitations
Before Varenzin-CA1, treatment options for non-regenerative anemia in cats with CKD were limited:
Blood Transfusions
- Used in crisis situations
- Temporary (red blood cells last only weeks)
- Not sustainable long-term
Injectable Synthetic Erythropoietin
- Human-derived hormone
- Can be effective
- Risk of immune reactions over time
- Requires injections
While these therapies are still used, they come with limitations that made earlier or proactive treatment challenging.
How Varenzin™-CA1 Works: An Innovative Approach to Anemia
Varenzin™-CA1 contains molidustat, which works very differently from older treatments.
In CKD, kidney damage is often patchy. Some nephrons (functional kidney units) still work well, but they receive too much oxygen because neighboring nephrons have failed. That excess oxygen falsely tells the kidney cells, “Everything is fine, no need to make erythropoietin.”
This message is delivered by a signal called hypoxia-inducible factor (HIF).
What Molidustat Does
- Blocks the HIF signal
- Prevents healthy kidney cells from being “fooled” by excess oxygen
- Allows remaining functional kidney tissue to resume erythropoietin production
- Stimulates the cat’s own red blood cell production
Instead of replacing the hormone, Varenzin™-CA1 restores the body’s ability to make it.
When Veterinarians Consider Starting Varenzin™-CA1
The approach to non-regenerative anemia treatment has shifted with the availability of Varenzin™-CA1.
- Normal hematocrit in cats: ~32-50%
- Treatment is often started when hematocrit drops below ~30%
- Earlier intervention is now favored, rather than waiting for severe non-regenerative anemia
Because Varenzin™-CA1 has shown a favorable safety profile, veterinarians are more proactive, aiming to treat non-regenerative anemia before clinical signs appear.
How Varenzin™-CA1 Is Given (From a Cat Owner’s Perspective)
One of the biggest advantages of Varenzin™-CA1 is ease of administration.
What Owners Can Expect
- Oral liquid medication
- Given once daily
- With or without food
- Highly palatable (tasty!)
The easy administration of this treatment improves compliance and reduces stress for cats and owners alike. Some cats even appear to enjoy the medication.
Varenzin™-CA1 Dosing Cycles and Monitoring Requirements
Because Varenzin™-CA1 is FDA conditionally approved, it follows a specific dosing protocol:
Dosing Structure
- Up to 4 weeks on medication
- Followed by at least 1 week off
- Treatment resumes based on bloodwork
Why the Break Matters
Without breaks, red blood cell counts could rise too high, which can cause complications. The structured cycle helps prevent overcorrection.
Monitoring Includes
- Red blood cell counts (hematocrit)
- Blood pressure monitoring
These checks are already standard in cats with CKD, making integration into care straightforward.
How Long For Improvement with Varenzin™-CA1?
Most cats respond predictably:
- After 1 cycle: improvement in hematocrit
- After 2 cycles: continued improvement expected
- Some cats normalize quickly; others need several cycles
If improvement is not seen after 3 weeks, veterinarians reassess for other causes of non-regenerative anemia, such as iron deficiency, inflammatory diseases, or blood loss. It is advised to treat the underlying condition before restarting treatment with Varenzin-CA1.
Individualized Care Makes the Difference
No two cats with CKD are the same. Successful management relies on:
- Ongoing lab monitoring
- Early detection of complications
- Open communication with your veterinarian
- Individualized treatment plans
Treating non-regenerative anemia is not about chasing numbers, it’s about helping cats feel like themselves again, preserving quality of life, and supporting long-term kidney health.
Specialists for Chronic Kidney Disease in Cats and Dogs
Many family veterinarians diagnose and manage CKD. If you need extra support, a veterinary internal medicine or nephrology service can help with:
- Complicated staging or rapid changes
- High blood pressure, significant protein in urine
- Anemia related to CKD in cats
- Dialysis or advanced therapies (case-by-case)
Thank You To Our Sponsor:
Sponsor Note:
This episode is supported by Elanco™, makers of Varenzin™-CA1. The discussion mentions a conditionally approved FDA treatment to control non-regenerative anemia associated with CKD in cats. Talk with your veterinarian to see what’s appropriate for your pet.
Varenzin™-CA1, Elanco and the diagonal bar logo are trademarks of Elanco or its affiliates.
Indication
Varenzin™-CA1 is indicated for the control of nonregenerative anemia associated with chronic kidney disease (CKD) in cats.
Important Safety Information
Varenzin™-CA1 is for oral use in cats only and prescribed only by licensed veterinarians. Keep this drug and used syringes out of reach of children. Wash hands immediately after use. In case of accidentally swallowing, call a doctor immediately. Women who are or may become pregnant should use the product with caution. Do not give to pregnant, nursing or breeding cats. Before using Varenzin™-CA1, talk to your veterinarian if your cat is allergic to molidustat, has a history of seizures or thromboembolic disease predisposition. Use with caution in cats younger than 1 year of age. Common side effects include vomiting and high blood pressure. Red blood cell proportion should be monitored. Click here for complete safety information.
PM-US-26-0018
