Overview of Methionine for Dogs and Cats

 Methionine, an over-the-counter medication commonly known as M-Caps® or  Uracid® for humans, is used to prevent bladder stones and control urine odor for dogs and cats.

L-Methionine is a neutral, genetically coded amino acid that is not manufactured in the body. It is one of ten so-called “essential” amino acids that must be supplied in the diet.

Methionine is a principle supplier of sulfur to the body and helps prevent disorders of the hair, skin and nails.

It belongs to a group of compounds called lipotropics; chemicals that help the liver process fats (lipids). It lowers plasma cholesterol by increasing hepatic production of lecithin and reduces hepatic fat.

Methionine also protects the kidneys; is a natural chelating agent for heavy metals; regulates the formation of ammonia; and helps create ammonia-free urine.

Sulfate is produced as a byproduct of metabolism of methionine and the excretion of sulfate as sulfuric acid causes acidification of the urine.

Methionine is essential for absorption, transportation, and bioavailability of selenium and zinc in the body.

Recent studies show that deficiency of methionine may be associated with the development of age-related cataracts and that methionine supplementation may delay their development. Cysteine, carnitine, and taurine may rely on methionine for their synthesis.

Depending on the product, methionine may be available as a prescription drug or as an over-the-counter medication. However, it should not be administered to animals except under the supervision and guidance of a veterinarian.

Brand Names and Other Names for Methionine

This amino acid is registered for use in humans and certain animal species (dogs, cats, horses).

Human formulations: M-Caps® (Pal-Pak), Pedameth® (Pal-Pak), Uracid® (Wesley), and generic methionine.

Veterinary formulations: Ammonil® (Daniel/Jones Medical) 200 mg tablets, Methio-Tabs® (Vet-A-Mix) 200 and 500 mg tablets, Methio-Form® (Vet-A-Mix) 500 mg palatable, chewable tablet for cats, and generics.

Uses of Methionine for Dogs and Cats

Methionine may be used as follows:

As a urinary acidifier to prevention the development of struvite bladder stones

To reduce ammonia content of urine (to control urine odor)

Treatment of laminitis in horses

Precautions and Side Effects

Methionine should be given with food to avoid gastrointestinal disturbance that may otherwise result.

It should be used with caution in cats as, in this species, it may cause Heinz body anemia. Excessive methionine intake by cats leads to the production of a metabolite that causes undue oxidation of hemoglobin to methemoglobin and Heinz-body formation.

Methionine is contraindicated in renal failure and pancreatic disease. Patients with established hepatic insufficiency should not be given methionine, and methionine should be used with caution in all patients with liver disease. In advanced liver disease, methionine may increase clinical signs of hepatic encephalopathy by increasing the production of mercaptan-like compounds.

During treatment, it is recommended that urine pH, blood pH, and, in cats, a complete blood count (CBC) be monitored.

Drug Interactions

Methionine may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with methionine. Such interactions may include:

Methionine increases the urinary excretion of quinidine by acidifying the urine.

Urinary acidification decreases the effectiveness of aminoglycoside antibiotics in treating urinary tract infections, as these antibiotics work better in an alkaline environment.

How Methionine is Supplied

Methionine is available in human formulations that includes 200mg capsules (M-Caps), 500mg tablets (Uracid), and a 75mg/mL fruit flavored liquid (Pedameth). Veterinary preparations include 200 and 500 mg tablets.

Dosing Information of Methionine for Dogs and Cats

Medication should never be administered without first consulting your veterinarian.

The dosage prescribed may vary depending on the reason for prescribing.

The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse.

The recommended daily allowance has not been established.

In dogs, for urinary tract acidification, the usual dose is 0.2-1.0 gms orally every 8 hours.

In cats, for urinary tract acidification, the usual dose is 0.5 gms orally every once daily.