Metabolic Acidosis in Cats: Causes, Symptoms, and Treatment

Kirsten McCarthy / Cats.com

Metabolic acidosis is a complex condition that can occur in cats of all ages. It’s essentially what happens when there is too much acid present in the body. The body constantly maintains a balance between acid and base (alkaline) and cats have many mechanisms responsible for doing this.

The kidneys and lungs play a key role in balancing acids and bases but sometimes they’re unable to maintain the balance. This may cause a build-up of acid in the blood, which then causes increased acid in the body. This can lead to many symptoms and consequences for our feline friends.

In this article we’ll discuss the common causes of metabolic acidosis in cats and most importantly the symptoms to watch out for and how it’s treated.

What Is Metabolic Acidosis in Cats?

One of the many causes of metabolic acidosis in cats includes ingestion of aspirin. yaya photos / Shutterstock.com

The level of acid and base in the body is mainly controlled by the kidneys and lungs. If there is dysfunction with these organs this can result in abnormal states such as acidosis (too much acid) or alkalosis (too much base).

Metabolic acidosis occurs when there’s too much acid in the body. This occurs when the blood pH is below 7.35 – making it acidic, as normal blood pH is 7.4.

This can occur due to a variety of mechanisms:

1. Increased Consumption of Bicarbonate (Base) by an Acid

If bicarbonate is being used up more than normal, it isn’t able to cope with the amount of acid in the body. This increased consumption of bicarbonate may occur in response to an acid in the body (endogenous) or one that enters from outside the body (exogenous).

Increased Acid in the Body (Endogenous)

In cases of acute metabolic acidosis, the body may produce large amounts of acid that uses up bicarbonate.

This happens in cases of diabetic cats when they enter a state of diabetic ketoacidosis (DKA). DKA occurs when there isn’t enough insulin in the body and they’re unable to use sugar for energy. Instead the body starts to break down fat cells which produce ketones. This leads to a build-up of ketoacids in the body, causing metabolic acidosis.

It also happens with lactic acid, causing a lactate acidosis. This occurs in response to dehydration through fluid loss, which causes reduced circulation around the body. This can result in lower amounts of oxygen circulating around the body and a build-up of lactate.

Ingesting Acid (Exogenous)

When acid is high in the body, it’s possible that this is because the cat has ingested large amounts of acidic material. Common examples causing this toxicity include ethylene glycol (antifreeze, deicer) and salicylates (aspirin).

Decreased Kidney Excretion of Acid

One of the functions of the kidneys is to excrete excess acids from the body to maintain a normal acid-base balance. However in cases of CKD, where kidney function is compromised, there is often a decrease in acid excretion. This can lead to a build-up of acid in the blood and increased consumption of bicarbonate.

2. Increased Loss of Bicarbonate or Gain of a Chloride-Containing Acid

When bicarbonate is lost, or if the body gains an acid that contains chloride, this is often referred to as hyperchloremic metabolic acidosis. The anion gap (the measure between the negatively charged and positively charged electrolytes in your blood) is usually normal.

Loss of Bicarbonate

Bicarbonates can be lost through the gastrointestinal tract in cases of diarrhea or vomiting. They can also be lost through the kidneys, resulting in a reduced amount of bicarbonate and an increase in acid.

Gain of Chloride-Containing Acid

This can occur due to distal renal tubular acidosis, which is essentially when the kidneys retain hydrogen and chloride, resulting in an acidosis. This can occur due to chronic kidney disease or an immune mediated disease. Some types of intravenous fluids can also have this effect.

Common Causes of Metabolic Acidosis in Cats

Acidosis can occur when there is increased acid in the body using up bicarbonate (base) or when bicarbonate is lost/reduced. Changes in acid and bicarbonate levels, will allow the acid-base balance to shift.

Metabolic acidosis in cats is usually associated with chronic kidney disease (CKD), also known as chronic renal failure. In fact, in one study, 52.6% of advanced CKD patients had metabolic acidosis.

Other common causes of metabolic acidosis in cats include:

• Diabetes mellitus
• Shock
• Ethylene glycol (antifreeze) toxicity
• Aspirin ingestion
• Ingestion of large amount of acidic food (uncommon)

Symptoms of Metabolic Acidosis in Cats

Cats with metabolic acidosis will often have rapid, deep breathing as one of their symptoms. Kirsten McCarthy / Cats.com

The symptoms of metabolic acidosis in cats can vary depending on the severity of the acidosis. In mild cases, you may not even notice any symptoms at all.

As metabolic acidosis is often associated with diabetic ketoacidosis or chronic kidney disease in cats, there may be other symptoms occurring from these diseases along with the metabolic acidosis symptoms, such as drinking a lot (polydipsia) and urinating more (polyuria).

Key symptoms of metabolic acidosis include:

• Rapid breathing (respiratory compensation)
• Depression
• Vomiting
• Diarrhea
• Confusion
• Seizures
• Coma
• Joint pain
• Abnormal heart rhythm

Long-term cases may also show:

• Weight loss
• Muscle loss (seen as a prominent, bony spine or weak limbs)
• Weakness
• Lethargy

Complications of Having Metabolic Acidosis

Metabolic acidosis, in acute or severe situations, can cause heart problems, a drop in blood pressure, severe shock, coma and eventually death. It’s a serious condition, especially in acute cases and should be treated promptly.

Diagnosis of Metabolic Acidosis in Cats

Now that we know the symptoms that metabolic acidosis can cause in cats and how serious it can become, we need to know how to treat it. But in order to treat it, your vet needs to diagnose it. Metabolic acidosis can be a tricky condition to diagnose in practice.

The ideal test for metabolic acidosis is testing arterial or venous blood gas analysis to check acid base parameters. This often requires sedation to perform and it will check blood pH, bicarbonate (HCO₃), total carbon dioxide (TCO₂), base excess of the extracellular fluid (BEecF), the anion gap and BUN:creatinine ratio. Although this is the ideal test, it isn’t widely available in general practice due to expense and practicalities. This means that diagnosing metabolic acidosis in general practice can be difficult.

Veterinarians often diagnose metabolic acidosis based on clinical signs and history (such as a history of kidney disease). The veterinarian will take a thorough history from you, including if your cat had access to toxins like ethylene glycol. They’ll examine your cat and check for signs of breathing difficulty or shock.

Routine blood work and urine testing is usually performed to check for underlying conditions like CKD, diabetes mellitus or hyperthyroidism. Your vet will also check electrolytes such as chloride (Cl), potassium (K⁺), calcium (Ca) and sodium (Na). Some vets may also use urine pH to diagnose metabolic acidosis, but this isn’t very reliable.

Treatments for Metabolic Acidosis in Cats

Treatment for metabolic acidosis in cats relies upon understanding the primary cause. Tyler Olsen / Shutterstock.com

Metabolic acidosis is a serious condition in the body, as high levels of acid in the blood can be detrimental. However metabolic acidosis can vary from mild to severe and not every case will be the same.

Recovery from metabolic acidosis usually depends on the underlying cause. In cases of acute toxicity or diabetic ketoacidosis, the recovery will depend on the severity of these cases and how quickly the underlying cause is treated.

In mild cases, there may be no symptoms noted and the acidosis may fix itself. The body will try to rectify any acid-base disturbance that occurs to restore the balance. More severe cases will require various treatment strategies.

1. Treat Underlying Cause and Provide Supportive Care

In many cases treating the underlying cause and giving intravenous fluids will usually resolve the metabolic acidosis. In these cases there will be no need for further treatment.

2. Medication

More severe cases may require medication to rectify the acidosis. This may include sodium bicarbonate or potassium citrate medication. Potassium citrate is particularly useful to use if there is a low potassium (hypokalemia) present.

Cat Care Tips

Cats with metabolic acidosis need specific diagnosis and treatment, but they also need lots of nursing care and monitoring at home. We have some cat care tips to help get your kitty back to optimum health.

Regular Veterinary Check-Ups

Cats with metabolic acidosis often have underlying health issues such as diabetes or CKD. These cats will need regular veterinary check-ups and in some cases, regular routine blood and urine testing to monitor their organ function. Always contact your vet if you’re concerned about your cat, even if you think it’s something small.

Close Monitoring at Home

Along with regular veterinary checks, close monitoring at home by owners is important. Cats that are unwell need lots of nursing and TLC at home. This will include monitoring symptoms and ensuring that they’re eating, drinking and toileting ok. You may need to improve accessibility to resources such as by having more water bowls and litter trays available.

Follow Recommended Diet and Medication

If your vet has prescribed medication or recommended a prescription diet (such as a renal diet for CKD), follow the instructions and stick to it. There’s a reason why your veterinarian has recommended these measures and not sticking to the plan may negatively impact your cat’s case. Contact your vet if you’re having difficulty getting your cat to eat the prescription food or medication. They may have some tips to help you or you can read our guide here on how to give pills.

Prevention of Metabolic Acidosis in Cats

Although not all cases of metabolic acidosis in cats can be prevented, there are some risk factors.

1. Diabetes Mellitus

Cats with severe diabetes, or that isn’t well controlled, may be at risk of diabetic ketoacidosis. If your cat has diabetes, be sure to stay on top of your cat’s medication and diet along with regular vet examinations. If you think your cat isn’t well controlled e.g. they may be urinating and drinking more than usual, contact your vet for advice.

2. Chronic Kidney Disease

CKD is a risk factor for metabolic acidosis and is more common in cats with advanced disease. It may not be possible to avoid this in these cases but feeding your cat a prescription renal diet and having regular veterinary checks will try to prevent this.

3. Toxicity

Ethylene glycol is an example of a toxicity causing metabolic acidosis. Reduce the chance of this by keeping anything potentially toxic or poisonous out of reach of your cats, ideally on high shelves in locked cupboards. Always clean up spillages thoroughly to prevent cats from licking it up. Contact your emergency vet immediately if you think your cat has eaten something toxic, early treatment may save their life.

4. Avoid Human Medications

Aspirin is a common human medication used to treat headaches and pain. Owners may think it’s harmless to give their cat a dose but at the wrong dose it can have severe consequences including that of metabolic acidosis. Avoid giving your cat any human medication (or pet medication!) unless advised to do by your veterinarian.

Always contact your vet if you’re concerned about your cat’s behavior or health. Cats like to hide their illnesses, so it’s important to get any new symptoms checked out.