Posted by Danish Aamir on


(Be Happy Pets)

Kidney disease in dogs and cats occurs when there is progressive damage to various structures of the kidney that remove and filter waste products from the body. This damage may involve the nephrons and/or the glomeruli. When these structures are destroyed, toxic by-products may build up in the pet's bloodstream, leading to clinical signs of kidney disease. Chronic kidney disease prevalence is 30% in cats and 10% in dogs.

Kidney disease often results in biochemical changes in the pet's body that lead to general symptoms of illness and malaise. Since the kidneys produce hormones and enzymes such as erythropoetin and renin, when the kidneys fail, the pet may develop anemia, high blood pressure, and electrolyte imbalances. Calcium imbalance in the pet's body and then bones may also result from kidney failure.

Kidney disease in pets can be due to a variety of factors ranging from toxin exposure (such as antifreeze), trauma, non-steroidal anti-inflammatory drugs (NSAIDs), infection (i.e. leptospirosis, Lyme disease), metabolic and immune-mediated causes. These immune-mediated causes may be secondary to chronic skin disease, intestinal disease, and hormonal problems of the adrenal glands and pancreas. Periodontal or dental disease may also cause secondary kidney damage. Genetic causes may also be involved. Cases where underlying causes of kidney disease are not identified are called idiopathic.

Pets at high risk of kidney disease

Kidney disease may occur in any age or breed of pet, but the incidence is increased in middle-age and senior pets. Polycystic kidney disease is an inherited form of kidney disease often occurring in younger pets, and may be seen in Abyssinian cats, Terriers, and Beagles. Siamese cats also seem to have a higher incidence of kidney disease.

Urolithiasis/cystic calculi in dogs & cats

Urolithiasis/cystic calculi are common in dogs and cats. Urine is a complex solution containing many organic and inorganic ions. More of these ions can remain in solution in urine than in water because of the complex interactions occur among the various organic and inorganic constituents in urine. For several possible reasons (e.g., diet, decreased water intake, altered urine pH, relative lack of inhibitors of crystallization), the solubility product of a particular crystal may be exceeded, crystals may form, and these crystals may aggregate and grow.

Table.1. Prevalence of different types of urinary crystals formed in dog and cat. 

Type of Crystals

Prevalence (%)






Calcium oxalate















Chemical composition of most common Urinary crystals


The composition of struvite stones is MgNH4PO4.6H20. Calcium phosphate (as carbonate apatite) often is present in small amounts (2-10%). The presence of three cations Ca+2, Mg+2,and NH4+ detected by earlier qualitative methods was responsible for the name "triple phosphate" previously used for these stones. Struvite stones are spherical, ellipsoidal, or tetrahedral in shape and may be present singly or in large numbers of varying sizes. In dogs and cats, the bladder is the most common site of struvite stone formation, although they may occur at any site in the urinary tract. In pets, urinary tract infection by urease-positive bacteria (especially Staphylococci and Proteus sp.) plays the most important role in struvite stone formation. Hydrolysis of urea by these urease-positive bacteria liberates ammonia and carbon dioxide, which increases the pH of the urine and the availability of ammonium and phosphate ions for struvite formation. The solubility of struvite is markedly reduced in alkaline urine due to removal of protons from phosphate ions. Struvite solubility is reduced in animals with persistently alkaline urine even in the absence of urinary tract infection. In dogs that form struvite stones in the absence of urinary tract infection, predisposing factors include a family history of struvite stones, a diet based on vegetable proteins, and distal renal tubular acidosis. Urinary tract infection usually is not present in cats with struvite stones.


These stones are composed of calcium oxalate monohydrate (whewellite) or calcium oxalate dihydrate (weddellite). Oxalate frequently is not detected by qualitative analysis, and quantitative analysis is necessary. Calcium oxalate calculi usually are white in color and very hard, they often have sharp edges and may be single or multiple in number. They are found most often in the bladder and urethra; their recurrence rate may be as high as 25-48%. Urinary tract infection, when it occurs, is thought to be a complicating rather than a predisposing factor to oxalate urolithiasis.

Altered calcium metabolism may also play a role in development of oxalate urolithiasis. Increased urinary excretion of calcium (hypercalciuria) can result from increased absorption of calcium from the intestinal tract ("absorptive" hypercalciuria), from increased urinary loss of calcium ("renal leak" hypercalciuria), or from increased release of calcium from bone ("resorptive" hypercalciuria). In "absorptive" as compared to "renal leak" hypercalciuria, urinary calcium excretion is higher after feeding than during fasting. Chronic acidosis may be associated with increased urinary excretion of calcium due to increased calcium release from bone. Long term feeding of an acidifying diet may contribute to this "resorptive" hypercalciuria.

Citrate forms a soluble complex with calcium and normally may be an inhibitor of calcium oxalate formation. Acidosis may be associated with decreased urinary citrate excretion and thus may predispose to calcium oxalate stone formation.


Urate stones in pets are composed of the monobasic ammonium salt of uric acid (ammonium acid urate) Calcium oxalate may be a secondary component of some urate stones, and urate stones found in dogs with portosystemic shunts often contain struvite in addition to urate. Urate stones may be found in dogs with portosystemic shunts due possibly to reduced conversion of ammonia to urea and uric acid to allantoin. A defect in uric acid metabolism in some Dalmatian dogs predisposes them to urate stone formation.

Picture.1. Types of uroliths, morphology, and risk factors.

Causes of kidney stones

There are several factosr, usually working in combination that lead to uroliths formation:

  • Mineral Crystals

Urine that is saturated with excess amount of certain minerals is prone to form cystic calculi. These minerals commonly include magnesium, phosphorous, calcium, and ammonia. Most stones consist of an organic matrix of protein surrounded by crystalline minerals.

Note: Diet can have a major impact here, and is one of the primary methods we use to treat and prevent uroliths.



  • Urine pH

As a general rule, dog and cats tend to have an acidic urine. Some uroliths have a tendency to form in acidic urine, while others tend to form in alkaline urine. The urine pH can be affected by diet, intrinsic factors (renal tubular acidosis), and external stressors (hyperventilation syndrome).

Table.2. Precipitation of different urinary crystals at urinary pH


Crystals formation in urine pH

Struvite, calcium carbonate, calcium phosphate, urate


Uric acid, cystine


calcium oxalate

No effect of pH


  • Bacteria

Some uroliths form due to the presence of bacteria in the urine, so control of these bacteria is important. Bacteria are diagnosed by culturing the urine during a sterile urinalysis, or by culturing the inside of a stone after surgical removal. Normal urine is sterile, so any bacteria cultured from the urine is abnormal. When bacteria are cultured a pet has a urinary tract infection (UTI) and needs antibiotics. Common bacteria in UTI’s include E. coli, Staphylococcus spp., and Proteus.

Culture sensitivity test and MIC test (Minimum Inhibitory Concentration) are used to know the effective and proper dose of the antibiotic.

  • Diseases

Liver shunt is an abnormality of blood flow to the liver. Blood that would normally flow through the liver now bypasses the liver. One of the many consequences of this disease, called Portosystemic shunts (PSS), is the formation of ammonium urate bladder stones.

  • Medications

Medications can predispose pets to develop cystic calculi. Sometimes they do this by increasing the calcium level in the urine. Medications that increase or decrease the pH of the urine can also set the stage for stone formation. Some medications can actually cause formation of stones when used for long periods of time. The following list includes some of these medications:

  • Lasix
  • Cortisone
  • Ascorbic Acid (Vitamin C), excessive AA is metabolised to oxalic acid 
  • Sulfa medications
  • Tetracycline’s

Predisposing causes of cystic calculi include pets that are not drinking enough or are not allowed to urinate frequently. Bacteria and stone forming chemicals stagnate in the urinary bladder and increase the chance of a stone formation. Mechanical flushing of the bladder in the form of normal and frequent urination will prevent this.


Fluffy cat food is a complete balanced formula for all life stages of cat. It is tested regularly in the best research facility to provide the pets an optimal health benefits and long life, avoiding any dietary health issues. Medically recommended interventions and supplements are used to make it safe and healthy for your beloved companions.

1) High Quality Protein Sources

Use of highly digestible animal source protein to meet the exact requirements of the pet is the key to have optimal kidney and liver function. Excessive and low quality protein inclusion in pet food can build up ammonia in the blood stream and ultimately causes kidney failure. We are using chicken and fish based high quality protein sources that fulfill your pet’s daily protein requirements.

2) Highly Balanced Minerals

Balanced mineral in the diet prevents the urolithiasis in the pets. We strictly balance all the minerals especially Calcium (Ca), Phosphorus (P), potassium (K), and Sodium (Na) that are critical in urolithiasis. 

3) Urinary pH modifiers to restrict the optimal urinary pH

Pets have a narrow range of urinary pH values that prevents urolithiasis. The ideal urine pH should be 6.3–6.6 in cats (Merck Veterinary Manual 11Th edition). Any decrease or increase in the urinary pH can predispose the stone formation in pets. We use different pH modifiers (Acidifiers) in the Fluffy cat food to maintain the narrow range of urinary pH in cats.

4) Use of Antioxidants to maintain organ health status 

Fluffy cat food is supplemented with antioxidants like Vit. E, and certain compounds called Carotene and lutein to help in normal kidney health status. 

5) Miscellaneous supplements to support the kidney 

  • Supplementation of B-vitamins to compensate urine losses of these water soluble vitamins.

   6) Food Safety measure to make it safe for pets and pet owners

After production every batch of Fluffy cat food is vigorously tested in ISO certified commercial laboratories (University Diagnostic Labs, UVAS, Lahore) to ensure that it is microbiologically safe to use. Strict checks on mycotoxins at production and supply chain levels to prevent nephrotoxicity in pets.