VetClassics CAS Options Extra Strength Immune & Antioxidant Support Chewable Tablets Dog & Cat Supplement, 120 count

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A powerful blend of four functional mushrooms: Maitake, Reishi, Shiitake, and Turkey Tail combined with antioxidants to provide extra strength immune support. Formulated to support and balance the immune system to promote overall health and well-being for pets, especially during times of stress.

Key Benefits
  • The immune system is the surveillance system of the body, when the immune system becomes weakened, it is essential to reestablish a healthy immune system balance quickly to maintain overall health.
  • Mushrooms contain polysaccharides, beta glucans, and triterpenoids that work synergistically to help support the immune system.
  • Antioxidants Coenzyme Q-10, Vitamin A, Vitamin C, Vitamin E and Milk Thistle help to scavenge free radicals that can cause cellular damage.
  • MADE IN THE USA and VETERINARIAN FORMULATED - All Vet Classics products are veterinarian formulated and manufactured in the USA in an FDA audited, cGMP compliant facility.
  • SATISFACTION GUARANTEED - All Vet Classics products come with a 100% satisfaction guarantee, if you are not satisfied for any reason you can get a full refund!

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  • Item Number
  • Weight
    15.68 ounces
  • Lifestage
    Adult, Puppy, Kitten, Senior
  • Breed Size
    Small Breeds, Medium Breeds, Large Breeds
  • Food Form
  • Product Form
    Chewable Tablet
  • Drug Type
Nutritional Info

Active Ingredients per 3 g Tablet: Reishi Mushroom 578 mg, Shiitake Mushroom 446 mg, Turkey Tail Mushroom 150 mg, Maitake Mushroom 95 mg, N-acetyl-L-cysteine 79 mg, Vitamin C (Calcium Ascorbate) 60 mg, Coenzyme Q-10 1 mg, Selenium 0.026 mg, Vitamin A 1,050 IU, Vitamin E (D-alpha Tocopheryl Acetate) 53 IU.

Feeding Instructions


Weight Daily Feeding (Tablets)
Under 25 lbs 1/2 Twice
26-50 lbs 1 Twice
51-100 lbs 2 Twice
Over 100 lbs 3 Twice


Weight Daily Feeding (Tablets)
Under 5 lbs 1/2
Over 5 lbs 1

Vet Classics CAS Options

CAS Options is recommended to provide extra strength immune and antioxidant support.  A unique blend of four functional mushrooms—reishi, shiitake, turkey tail, and maitake—work synergistically with milk thistle, vitamin A, vitamin, C, vitamin E, coenzyme Q-10, and selenium to help support and balance the immune system and promote overall health and wellness.

Product Grouping

Mushrooms are a Superfood!

Reishi, shiitake, maitake, and turkey tail mushrooms contain immuno-supportive compounds like polysaccharides, beta-glucans, triterpenoids, lentinans, and amino acids. These may help balance immune system cells such as macrophages, natural killer cells and helper T-cells, which work together to neutralize damaging cells while nourishing the development of healthy cells.

The Immune System

The immune system is the surveillance and defense system of the body.  A healthy immune system recognizes cellular change, targets damaged cells and eliminates them to help protect the body from invaders such as toxins, viruses, and bacteria. If the immune system is compromised, it is essential to reestablish a healthy immune balance quickly, to keep it working properly for overall health.

Dog Running

Immune and Antioxidant Support

CAS Options Extra Strength Immune & Antioxidant Support is veterinarian formulated and recommended for use in dogs and cats over the age of 12 weeks.  It is available in soft chews and chewable tablets.

About Vet Classics

Since 1994, Vet Classics has offered a high-quality integrative, complementary pet health supplement line developed by veterinarians and staff scientists for dogs, cats and horses. All products are manufactured in Temecula, CA USA, in fully compliant cGMP Standard facilities following the highest industry standard. Their products carry the NASC Quality Seal which provides a symbol of quality assurance for consumers.

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Rating: 4.6 of 5 stars 6 Reviews 6 Reviews 4.7 out of 5 Stars

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100% of reviewersrecommend this product

Rating: 4.6 of 5 stars 4.7 / 5

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6 Reviews

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  • 5 out of 5 stars

    Chewable mushrooms

    By Easy on Sep 27, 2021

    This is great. My 8 year old rescue lab has cancer. I used this product to boost her immune system. She loves them. Easy to chew before her meal. Her rescue sisters are jealous trying to eat these chewable tablets as well.

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  • 5 out of 5 stars

    These are great!

    By Penny on Oct 7, 2021

    Our Vet recommended them for our 3 dogs. They really do help support their overall health and also help keep their teeth and gums healthy. The dogs eat them like candy. Great product!

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  • 3 out of 5 stars

    very large for cats

    By Mowgli on Oct 7, 2021

    my cat had a very hard time eating this. I even cut in half and tried crushing it in his wet food.

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  • 5 out of 5 stars

    Great Product

    By Neta on Aug 26, 2021

    This product was exactly what I was looking for and a much lower than I had been paying.

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  • 5 out of 5 stars

    Keeping the "Zodiac Sign" Away for Nearly Three Years

    By PuppyGoddess on Mar 22, 2021

    My oldest girl just turned 12 yesterday (21 March 21). She had two nasty Mast Cell Tum0rs removed in August 2018. We immediately began seeing a holistic veterinarian to keep the "zodiac sign between Gemini & Leo" away. (We don't say the c-word so we don't jinx ourselves, we don't want that monster back in our lives). Our vet prescribed CAS Options and we have used it faithfully since then. Two tablets twice daily (with meals) for our Husky/GSD/Malamute/White Shepherd princess. I truly believe that this product has helped us keep her healthy and safe! I love that we can now get it from Chewy without an Rx. Thanks, Chewy, for helping us keep our babies safe & healthy!

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  • 5 out of 5 stars


    By Annie on Jun 14, 2021

    I am just about to go through my first container. My vet recommended this product. I am putting faith that it is doing it’s job.

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