What is soy protein?
Soy protein is sourced from soybeans and is sometimes used as a dietary supplement in pets. Soy contains many types of proteins, but isoflavones are a specific category of proteins found in soy that are used for their estrogenic effects. Isoflavones may also have antioxidant, anticancer, antimicrobial, and anti-inflammatory effects. In animals, soy protein has been used in weight management, metabolic disease management, cancer management (especially lymphoma), and hormone-related conditions such as prostatic hypertrophy and urinary incontinence.
The U.S. Food and Drug Administration (FDA) does not review non-drug health products (e.g., herbals, nutraceuticals, shampoos, and other supplements) for safety or effectiveness before they are sold to the public. Manufacturers of non-drug health products must ensure their products are safe and labeled accurately.
The FDA requires that these non-pharmaceuticals contain a disclaimer that says, “This product is not intended to diagnose, treat, cure or prevent any disease.” Health Canada licenses “veterinary health products” after reviewing safety, efficacy, and manufacturing information provided by the manufacturer. These products are not tested by Health Canada.
Your veterinarian is the best source of information about the safety of non-drug health products in pets. Just because a product is natural does not mean it is safe. All medicines and medicinal plants are potentially toxic if used inappropriately or given at high doses. Supplements can also have side effects, like pharmaceuticals. Few supplements and herbs have been subjected to rigorous scientific trials to determine their efficacy.
Although the information in this handout may be helpful, it also may be incomplete and may not represent the full range of effects the supplement could have on your pet.
How is soy protein given?
- Soy protein comes as an ingredient in pet food or in capsule, powder, or tablet forms.
- All forms are given orally (by mouth).
- Give with or without food. If vomiting occurs when given on an empty stomach, give future doses with food.
- Follow your veterinarian’s instructions on administering this supplement and give for the entire time prescribed by your veterinarian, even if your pet is feeling better.
What if I miss giving my pet the supplement?
If you miss a dose, give it as soon as you remember. However, if it is almost time for the next scheduled dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once or give extra doses.
Are there any potential side effects?
Soy protein may cause the following side effects:
- Vomiting
- Diarrhea
- Constipation
- Gas
Serious adverse reactions may occur. If any of the following signs develop, stop giving soy protein and contact your veterinarian immediately:
- An allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face
Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses, but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.
Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting supplement may take several weeks to show full effects and should stop working within 24 hours, although effects may last longer in pets with liver or kidney disease.
Are there any drug interactions I should be aware of?
The following medications should be used with caution when given with soy protein:
- Antidepressants such as monoamine oxidase inhibitors (MAOIs)
- Chemotherapeutics
- Hormone therapies
- Insulin
- Levothyroxine
- Warfarin
Vitamins, herbal therapies, and supplements have the potential to interact with each other, as well as with prescription and over the counter medications. Be sure to tell your veterinarian about any medications (including all vitamins, supplements, or herbal therapies) that your pet is taking.
Are there any risk factors for this supplement?
DO NOT USE soy protein in:
- Pets that are allergic to any component
- Pets that are pregnant or nursing
USE WITH CAUTION in:
- Pets with kidney disease
- Pets with liver disease
- Pets with thyroid problems
Is any monitoring needed with this supplement?
- Your veterinarian will let you know when and how they want to reassess your pet to ensure the supplement is working and not causing side effects.
- At home, monitor for any side effects such as those noted above. If any side effects occur, discontinue the supplement, and contact your veterinarian.
How do I store soy protein?
- Store the supplement according to the manufacturer’s directions.
- Protect from light, moisture, heat.
- Keep the container out of reach of children and pets.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the supplement, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet’s weight and symptoms. Report any adverse effects to the FDA or Health Canada.
