Chronic Kidney Disease (CKD) or Chronic Renal Failure (CRF) in Dogs & Cats

Chronic kidney disease (CKD) or chronic renal failure (CRF) in cats and dogs is a progressive and irreversible condition where they lose their ability to effectively filter waste. As opposed to acute kidney injury which is still reversible. It is, unfortunately, one of the most common ailments ageing pets can have, and it can be emotionally challenging to pet owners. 

Although this condition is irreversible, understanding the condition allows us to manage it more effectively to improve our cats and dogs’ quality of life, minimise symptoms and slow down the progression of the disease. 

What is Chronic Kidney Disease in Dogs and Cats?

Chronic kidney disease in dogs and cats refer to the structural and functional impairment of the kidneys in these animals. The definition of “chronic” means that the disease has been ongoing for a longer period as compared to “acute”. In CKD, the kidney damage has existed for at least 1-3 months. 

The kidneys are responsible for a number of systemic functions, including excretion of metabolic wastes, acid-base balance, blood pressure, and endocrine functions ^[1]. Impaired or loss of function of one or both of the kidneys will consequently affect your pet’s health. 

What are the symptoms of Chronic Kidney Disease in Dogs and Cats?

The kidneys are important in maintaining water and electrolyte balance in the body, early signs of CKD in dogs and cats may appear as excessive thirst and urination. Furthermore, since the kidneys also play important roles in regulating different functions of the body, other symptoms may also appear. Common signs and symptoms of CKD in dogs and cats include:

• Excessive thirst
• Excessive urination
• Weight loss
• Loss of appetite
• Vomiting and diarrhoea
• Depression
• Lethargy
• Anaemia (appears as pale gums)
• Bad breath

It’s important to note that chronic kidney disease in our pets is progressive and long-lasting, and significant kidney damage may already be present by the time symptoms manifest. Early detection and treatment are crucial to help slow the progression of the disease.

When should I take my dog or cat to the vet?

As a general rule of thumb, pet owners are advised to take their pet to the vet if you experience changes in your pet’s behaviour, appetite, or physical condition lasting more than 24 to 48 hours. The symptoms mentioned above would be a good guideline of what to look out for. 

Early detection is key, so it is recommended to have regular vet check-ups scheduled annually for younger pets and biannually for older or at-risk pets to catch any health issues before they become severe. 

What causes Chronic Kidney Disease in Dogs and Cats?

Chronic kidney disease in dogs and cats is considered to be a progressive disease. It is thought that an initiating injury to the one or both kidneys causes nephron loss or damage, which slowly progresses and causes the deterioration of the kidneys ^[2]. Examples of primary kidney diseases that can lead to CKD include:

• Bacterial pyelonephritis – Bacterial pyelonephritis is a bacterial infection of the kidneys of dogs and cats. A urinary tract infection which ascended from the bladder to the kidneys can cause bacterial pyelonephritis.
  
• Viral, bacterial or fungal infections – Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) in cats, leptospirosis (dogs), rickettsial infections from tick fever (dogs) can cause kidney issues which may lead to kidney damage.
  
• Nephrolithiasis (kidney stones) and ureterolithiasis (ureteral stones) – Formations of kidney and ureter stones can damage the kidneys as they cause physical obstruction to urine formation or flow.
  
• Acute kidney injuries – Acute kidney injury (AKI) in dogs and cats refers to sudden renal damage or injury. Among the things that can cause AKI include the ingestion of toxins for example, lilies for cats, grapes/raisins (dogs) and heavy metals. Certain medications and chemotherapy drugs can also cause AKI. AKI is still reversible if it is caught early, and treatment is done. AKI can progress on to CRF if undetected or undertreated.

• Cancers – Lymphoma is a cancer which is more common in cats and dogs. The cancer cells arise from lymphocytes which are a type of white blood cell and spread via the bloodstream to the organs like the kidneys, gastrointestinal tract and spleen. 

• Immune-mediated disease – Immune-mediated diseases can cause glomerulonephritis, a condition where immune complexes are trapped in the glomeruli, the network of vessels in the kidneys that make up the filtration system. This leads to damage of the glomeruli.
  
• Genetic/inherited disorders – Several genetic diseases that are associated with CKD in small animals include:

• Polycystic kidney disease – an inherited condition more common in cats than in dogs. Persians and Persian-related cat breeds are the most common ones affected. The disease is characterised by formation of cysts, which are fluid-filled pockets, in the kidneys. These cysts may grow and replace the normal kidney structure, leading to CRF.
  
• Amyloidosis – An inherited disease caused by the accumulation of abnormal amyloid proteins in the organs of the body, including the kidneys, liver and heart. This condition is rare and typically affects specific breeds (e.g. Abyssinian cats and Shar Pei dogs). 
  
• Renal dysplasia or renal malformation – A rare congenital condition characterised by poor development of the kidneys before birth. It can affect one or both of the kidneys, animals with both kidneys affected typically die shortly after birth. 

What are the risk factors for Chronic Kidney Disease in Dogs and Cats?

CKD can affect any pet, but certain factors can increase the risk of renal issues and CKD in dogs and cats, the International Renal Interest Society (IRIS) reported the following as risk factors of CKD in dogs and cats:

• Age – CKD is more common in older pets, more than 10% of dogs and 30% of cats aged 15 years are diagnosed with CKD¹. CKD in younger pets are typically associated with inherited renal diseases.
  
• Breed – Studies have suggested that certain breeds of dogs and cats are more at risk of developing CKD, these include Shar Pei, Bull Terrier, English Cocker Spaniel, Cavalier King Charles Spaniel, West Highland White Terrier and Boxers in dogs, and Persian, Abyssinian, Siamese, Ragdoll, Burmese, Russian Blue and Maine Coon in cats.
  
• Diet – Certain diets are also implicated to increase the risk of CKD, particularly low potassium or high phosphorus with high protein diets.
  
• Acute kidney injury – Acute injuries from primary or secondary kidney diseases can progress into CKD.
  
• Comorbidities – Comorbidities such as hypercalcaemia, periodontal diseases, kidney stones, cystitis, and hypertension may increase the risk of CKD in dogs and cats.
  
• Medications – Use of certain medications has been reported to be associated with the development of CKD, these medications include non-steroidal anti-inflammatory drugs (NSAIDs), aminoglycosides, sulfonamides, amphotericin and chemotherapeutic agents.

How is Chronic Kidney Disease in Dogs and Cats diagnosed?

Your vet may suspect CKD in your pet from their symptoms and clinical examination. They will also perform several tests to diagnose CKD.

• Physical examination – This will involve checking for signs of dehydration, palpation to assess the size or regularity of the kidneys. CKD in dogs and cats may cause the kidneys to be small and irregular, or enlarged in cases of cancers, inflammation or obstruction.
  
• Urinalysis – Urine samples from your pet will be taken to assess renal function by measuring the concentration of the urine. Urine can also be tested for the presence of protein, blood, and pathogens in your pet’s urine.
  
• Blood tests – Blood tests to measure the levels of blood urea nitrogen (BUN), serum creatinine, serum phosphate and symmetric dimethylarginine (SDMA) levels. 

• X-rays/radiographs – X-rays can be beneficial in visualising the kidney size and to detect the presence of kidney stones and ureteral stones.
  
• Ultrasound – Ultrasound imaging can also help the vet assess the condition of the kidney and urinary tract.

Stages of CKD in dogs and cats

The stages of CKD in dogs and cats can provide information on the extent of kidney damage. The IRIS has classified CKD stages as follows:

• Staging based on serum creatinine and SDMA levels:
  

Stage	Serum creatinine levels (mg/dl)SDMA levels (µg/dl)
	Dogs	Cats
1(Nonazotemic)	<1.4<18	<1.6<18
2(Mild renal azotemia)	1.4 - 2.818 - 35	1.6 - 2.818 - 25
3(Moderate renal azotemia)	2.9 - 5.036 - 54	2.9 - 5.026 - 38
4(Severe renal azotemia)	>5.0>54	>5.0>38

• Substaging based on proteinuria:
  

Substage	Urine protein to creatinine ratio (UP/C)
	Dogs	Cats
Non-proteinuric	<0.2	<0.2
Borderline proteinuric	0.2 - 0.5	0.2 - 0.4
Proteinuric	>0.5	>0.4

• Substaging based on blood pressure:

Blood pressure substage	Systolic blood pressure in dogs and cats (mmHg)	Risk of future target organ damage
Normotensive	<140	Minimal
Prehypertensive	140 - 159	Low
Hypertensive	160 - 179	Moderate
Severely hypertensive	>=180	High

These staging methods can be used as a guide on deciding the most ideal treatment approach for your pet. During your consultation, your pet’s test results will be reviewed and explained in detail. Your vet will provide guidance on the next steps for you and your pet, along with a personalised treatment plan tailored to their needs. 

How is Chronic Kidney Disease in Dogs and Cats treated?

Although CKD is irreversible, steps can be taken to slow down further loss of renal function. CKD is treated by managing symptoms and correcting the imbalance in metabolic and systemic functions. Treatments for CKD in dogs and cats are tailored to individual pets and include the following:

• Fluid therapy – Intravenous fluid therapy is commonly done to treat dehydration, this can only be done in a clinic or hospital. Subcutaneous administration of fluids can be done in pets who are unable to maintain proper hydration levels by oral intake alone. This can be done on an outpatient basis. 

• Dietary management – One of the most important aspects of CKD management in your pet is dietary management. Your veterinarian may recommend a prescription diet which contains less protein, phosphorus and sodium that is easier on the kidneys. Your pet will need to be on this diet for the rest of its life. Additionally, you should ensure fresh water is always available for your pet to ensure proper hydration.

• Phosphate binders – Phosphate binders are used to reduce the serum levels of phosphorus which are not expelled due to impaired kidney function. 

• Potassium supplements – Low potassium levels, also known as hypokalaemia, is common in dogs and cats with CKD. Other than impaired kidney function, acid-base imbalance and gastrointestinal complications also contribute to hypokalaemia⁶. To manage this, your vet may recommend potassium supplements for your pet.
  
• Management of proteinuria – Proteinuria which is protein in the urine is associated with a poorer prognosis. Angiotensin receptor blockers or ACE inhibitors are typically used to treat proteinuria in your pet. The use of ACE inhibitors may also contribute to hyperkalaemia, hence the use of the medication should only be done as per your vet’s instruction.

• Hypertension – Systemic hypertension is a common complication of CKD and it can lead to further progression of CKD as well as damage to other organs such as the brain, heart and eyes. Anti-hypertensive medications will be needed to manage this.
  
• Management of anaemia – Damage to the kidneys also affects the ability to produce the hormone erythropoietin which is the main hormone involved in red blood cell production. Erythropoietin injections or even blood transfusion may be needed if anaemia is severe. 

Treatment and management of CKD in dogs and cats are done for the rest of your pet’s life. It is important to continue monitoring your pet’s health and attend regular check-ups to ensure that they are responding well to the treatment.

Summary

Early detection and diagnosis of kidney injuries or kidney diseases can potentially mitigate the progression of CKD. Management of CKD is done for the rest of your pet’s life, hence why early detection and management can provide a better prognosis for your dog or cat.If you notice signs and symptoms of CKD in your pet, a prompt visit to your vet is important. 

Our team at Dr Paws Vet Care understands the challenges that come with CKD, and is dedicated to providing compassionate, long-term care tailored to your pet’s needs. We are committed to supporting you every step of the way to ensure your furry friend has the best quality of life possible. Schedule a consultation with us today for a comprehensive diagnosis and personalised treatment for your pet. 

Frequently Asked Questions

References

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2. Brown CA, Elliott J, Schmiedt CW, Brown SA. Chronic Kidney Disease in Aged Cats: Clinical Features, Morphology, and Proposed Pathogeneses. Vet Pathol. 2016 Mar;53(2):309-26. doi: 10.1177/0300985815622975. Epub 2016 Feb 11. PMID: 26869151.
3. DiBartola SP, Buffington CA, Chew DJ, McLoughlin MA, Sparks RA. Development of chronic renal disease in cats fed a commercial diet. J Am Vet Med Assoc. 1993 Mar 1;202(5):744-51. PMID: 8454506.
4. Silva MLE, Silva GEB, Borin-Crivellenti S, Alvarenga AWO, Aldrovani M, Braz LADN, Aoki C, Santana AE, Pennacchi CS, Crivellenti LZ. Renal Abnormalities Caused by Canine Distemper Virus Infection in Terminal Patients. Front Vet Sci. 2022 Mar 8;9:822525. doi: 10.3389/fvets.2022.822525. PMID: 35350433; PMCID: PMC8957885.
5. Segev G, Cortellini S, Foster JD, Francey T, Langston C, Londoño L, Schweighauser A, Jepson RE. International Renal Interest Society best practice consensus guidelines for the diagnosis and management of acute kidney injury in cats and dogs. Vet J. 2024 Jun;305:106068. doi: 10.1016/j.tvjl.2024.106068. Epub 2024 Feb 6. PMID: 38325516.
6. Parker VJ. Nutritional Management for Dogs and Cats with Chronic Kidney Disease. Vet Clin North Am Small Anim Pract. 2021 May;51(3):685-710. doi: 10.1016/j.cvsm.2021.01.007. Erratum in: Vet Clin North Am Small Anim Pract. 2021 Sep;51(5):ix. doi: 10.1016/j.cvsm.2021.07.014. PMID: 33773648.