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Leucine for Pets: Benefits, Sources & Deficiency Symptoms

Among the 11 essential amino acids that dogs can’t produce on their own, leucine is one of the three branched-chain amino acids (BCAAs). This means that, like valine and isoleucine, its structure contains a side chain with a branch. The other eight essential amino acids have linear side chains.

Table of Contents

What is an essential amino acid?

Amino acids are the building blocks of proteins, and there are 20 of them that occur naturally. Of these 20, 11 are considered essential for dogs because they can’t produce them on their own and must get them from their diet. The BCAAs are three of the essential amino acids.

Essential vs non-essential amino acids for dogs:

There’s a difference between essential and non-essential amino acids for dogs. Essential amino acids are required for survival because dogs can’t produce them on their own, while non-essential amino acids are those that the body can produce.

While all 20 amino acids play important roles in a dog’s health, the 11 essential amino acids are particularly important because dogs can’t live without them.

What are the functions of amino acids in dogs?

Amino acids play a variety of roles in dogs, including:

– Building and repairing tissues

– Acting as hormones or neurotransmitters

– Regulating metabolism

– Boosting the immune system

What is leucine?

Leucine is an essential amino acid that plays a number of important roles in dogs. These include regulating blood sugar levels, healing wounds, and building and repairing muscle tissue.

Leucine was first isolated from cheese in 1819 by a French chemist, Proust (Wu 2013). Braconnot used acid hydrolysis to isolate leucine from skeletal muscle and wool in 1820, giving it its name. Its structure wasn’t discovered until 1891 when Schulze produced leucine from isovaleraldehyde. Leucine is a variant of isoleucine that was first discovered to be required for optimal growth in humans in 1935.

Leucine is formed in plants and microorganisms through the conversion of pyruvic acid but animals and humans do not biosynthesize leucine and must obtain it from their diet.

Sources of Leucine:

Leucine can be found in a variety of foods, including meat, poultry, fish, milk, cheese, nuts, and legumes. It is also available as a dietary supplement.

Some of the main sources of leucine added to dog food include high-protein animal products, dairy products, eggs, pulses and whole grains.

Some of the best sources of leucine for dogs include:

  • Beef
  • Chicken
  • Fish
  • Eggs
  • Nuts
  • Seeds
  • Dairy products

Leucine synthesis:

Leucine is carried around the body in blood and used to make new proteins or oxidized in tissues. It aids in the control of blood sugar levels, muscle protein synthesis, and growth of muscle and bone tissues. After eating a high-protein meal, leucine levels rise quickly in the blood before declining back to fasting levels.

Leucine is mostly converted to acetyl coenzyme-A (CoA) and enters the Krebs cycle to be used for energy. A small amount of leucine is used for gluconeogenesis, the creation of glucose from amino acids, and ketogenesis, the production of ketones from fatty acids.

Ananieva et al. (2016) found that leucine is utilized in many organs including the liver, skeletal muscle, adipose tissue, and gut. Other studies, including Neis et al. (2015) showed that gut bacteria affect the bioavailability of amino acids, including leucine

Uses of Leucine in dog’s body:

Energy metabolism:

Leucine can be metabolized into the ketone body acetate, which can be used for energy by the body, particularly during periods of fasting or when carbohydrate-containing foods are not available.

Leucine and lysine are the only two ketogenic amino acids that catabolize to acetyl-CoA, but not glucose (Brody 1999).

Leucine is exclusively ketogenic which means it can only be used for energy by the body and not for building new proteins.

What are the benefits of leucine for dogs?

Leucine is an important amino acid for dogs because it plays a role in muscle growth and recovery. It’s also involved in regulating blood sugar levels and boosting the immune system.

Cell growth: Leucine binds with receptors on the surface of cells and helps to stimulate cell growth and repair.

Muscle growth: Leucine is a key amino acid involved in muscle protein synthesis, which is the process that helps muscles grow. It also helps to preserve muscle mass during periods of stress or illness.

Recovery from exercise: Leucine plays a role in helping muscles recover from exercise by reducing muscle damage and promoting the growth of new muscle proteins.

Blood sugar regulation: Leucine helps to regulate blood sugar levels by stimulating the release of insulin, a hormone that helps to lower blood sugar levels.

Boosting the immune system: Leucine plays a role in immune system function by stimulating the production of white blood cells, which help to fight infection.

Too much Leucine – Leucine toxicity in dogs:

Wishart 2019: Insulin resistance and impaired metabolism of glucose

Wishart (2019) found that too much leucine can lead to hyperactivation of mTORC1. This can cause insulin resistance and impair glucose metabolism. This can be caused by your dog consuming a very high-protein diet(Melnik 2012)

Leucine and diabetes:

Diabetes is a chronic disease that is characterized by high levels of sugar in the blood.

Leucine has been shown (Pedroso et al. 2015) to help regulate food intake, metabolism, blood sugar levels and improve insulin sensitivity, making it a potential treatment for diabetes.

More studies are needed to determine its role in weight management – whether the reduced food intake is key in a dog’s weight reduction or if cell metabolism results in weight reduction.

It has been shown to help reduce fat and control glucose levels in dogs.

Other studies on Leucine supplementation:

A 2016 Study found that leucine supplementation in obese individuals – both animals and humans had adverse effects. High-fat diet combined with leucine supplements increased insulin resistance and increased oxidative stress.

Athletes often use leucine supplements to help with muscle growth and recovery. However, there is little evidence to support these claims. More research is needed in this area.

Leucine has also been shown to have potential benefits for cognitive function and brain health. However, more research is needed in this area as well.

Leucine supplement for dogs:

If your dog is not getting enough leucine in their diet, you may want to consider giving them a leucine supplement. Leucine supplements are available in powder or tablet form and can be found at most health food stores.

When is leucine supplementation necessary?

To increase muscle mass or prevent protein degradation in muscle wasting conditions such as;

  • Canine hip dysplasia
  • Osteoarthritis
  • Cancer
  • Cachexia
  • Anorexia

In these conditions, leucine helps to preserve muscle mass and can help to stimulate the growth of new muscle proteins.

To improve exercise performance or recovery:

Leucine has been shown to help reduce muscle damage and promote the growth of new muscle proteins, which can help improve exercise performance and recovery.

To regulate blood sugar levels:

Leucine has been shown to help regulate blood sugar levels by stimulating the release of insulin, a hormone that helps to lower blood sugar levels.

If your dog is diabetic, you should talk to your veterinarian before giving them a leucine supplement, as it may interact with their diabetes medication.

To boost the immune system:

Leucine has been shown to play a role in immune system function by stimulating the production of white blood cells, which help to fight infection.

The recommended dosage

The recommended dose of leucine for dogs is 1-2 grams per day.

AAFCO recommends feeding puppies diets with a higher amount of leucine compared to adult dogs. AAFCO’s minimum recommendation is 1.29% of puppies’ diets and 0.68% for adult and senior dogs on dry matter basis as shown in the table below;

You should talk to your veterinarian before giving your dog a leucine supplement, as they can help you determine the correct dose for your dog’s individual needs.

Leucine dosage for cats:

According to AAFCO’s minimum recommendation, you should feed your kitten a diet with a minimum of 1.28% leucine and 1.24% for adult and senior cats. As shown in the table below, cats require a relatively stable amount of leucine amino acid throughout their lifetime.

Leucine for senior pets:

To maintain healthy and strong muscle mass, older cats and dogs will find increased levels of leucine or BCAA diets. Leucine is an amino acid that is involved in muscle growth, repair, and recovery. It can also help to regulate blood sugar levels and boost the immune system.

As dogs and cats age, they may have a decreased ability to absorb and use leucine from their diet. This is why it’s important to feed your senior pet a diet with high levels of leucine.

If you are unsure about whether or not your senior pet needs a leucine supplement, talk to your veterinarian. They can help you determine the best diet for your pet’s individual needs.

Deficiency symptoms:

A leucine deficiency can cause muscle wasting and weakness. Deficiency symptoms may also include;

  • Fatigue
  • Weight loss
  • Loss of appetite
  • Muscle weakness

If you think your dog may be deficient in leucine, talk to your veterinarian. They can perform a blood test to check for deficiency and recommend the best course of treatment.

How is leucine deficiency diagnosed:

A leucine deficiency can be diagnosed with a blood test. Your veterinarian will take a sample of your dog’s blood and send it to a laboratory for analysis. The laboratory will measure the levels of leucine in your dog’s blood and determine if they are deficient.

How is leucine deficiency treated:

If your dog is deficient in leucine, your veterinarian will recommend a course of treatment. Treatment may include;

Dietary changes:

If your dog is not getting enough leucine in their diet, your veterinarian may recommend changing their food to a diet that is higher in leucine.

Leucine supplements:

If your dog is not able to get enough leucine from their diet, your veterinarian may recommend giving them a leucine supplement. Leucine supplements are available in powder or tablet form.

Your veterinarian will help you determine the correct dose of leucine for your dog based on their weight and individual needs.

Leucine crystals in dog urine:

Leucine crystals are yellow-brown discs with concentric rings that resemble a tree trunk. Leucine crystals are not common in sound urine. They’re found in acidic urine.

They’re generally a sign of severe liver failure. Abdominal swelling, vomiting, nausea, disorientation, and malaise are other possible symptoms.

Treatment entails providing the liver with the necessary nutrients and removing any obstructions to its functioning.

Other treatments may be needed depending on the situation. Read more about all types of dog urine crystals here.

FAQs on Leucine amino acid for pets:

Q: Is Leucine safe for dogs and cats?

A: Leucine is an amino acid that is essential for dogs and cats. It is safe for pets when given in the correct dose. National Research Council explained in its 2006 Report that leucine should be added as an essential ingredient that pet food manufacturers should add to pet food and list on the label. AAFCO followed the NRC’s recommendations and has set minimum amounts that your dog or cat should feed every day.

Read NRC’s Report on Nutrient Requirements of Dogs and Cats here

Q: What are BCAA amino acids?

A: BCAA amino acids are branched-chain amino acids. Leucine is a BCAA amino acid. Other BCAA amino acids include valine and isoleucine.

Q: What are the benefits of feeding my dog or cat a diet with high levels of leucine?

A: Some of the benefits of feeding your pet a diet with high levels of leucine include;

  • Muscle growth
  • Repair and recovery
  • Regulation of blood sugar levels
  • Boosting the immune system

Q: How much leucine should I feed my dog or cat?

A: The amount of leucine you should feed your pet will depend on their weight and individual needs. Your veterinarian can help you determine the correct dose of leucine for your pet.

Q: What are the side effects of leucine?

A: The side effects of leucine are rare but may include;

  • Upset stomach
  • Diarrhea
  • Vomiting

If you notice any of these side effects in your pet, stop giving them leucine and talk to your veterinarian.

Q: Where can I find leucine supplements for my dog or cat?

A: Leucine supplements are available from many pet stores and online retailers. You can also ask your veterinarian for a recommendation.

Q: What are the signs of leucine toxicity in dogs and cats?

A: The signs of leucine toxicity in pets are rare but may include;

  • Muscle weakness
  • Lethargy
  • Coma

If you notice any of these signs in your pet, stop giving them leucine and talk to your veterinarian right away.

Q: What is the difference between valine and leucine?

A: Valine is another branched-chain amino acid. It is similar to leucine but has a different chemical structure. Valine is not as effective as leucine in terms of muscle growth and repair.

Q: Can I give my dog or cat leucine if they are pregnant or nursing?

A: You should talk to your veterinarian before giving your pet leucine if they are pregnant or nursing.

Q: My dog ate chicken with leucine, will they be okay?

A: Most likely, yes. If your dog ate chicken with leucine, they will probably be fine. Leucine is an amino acid that is found in chicken and other meats. It is safe for dogs when consumed in small amounts. However, if your dog ate a large amount of chicken with leucine, they may experience some stomach upset. If this occurs, talk to your veterinarian.