Fish oil capsules

Overview of Omega 3 Fatty Acids for OA

Omega 3s and Inflammation

Omega 3 Fatty acid supplementation can be a natural method of decreasing inflammation and pain associated with arthritis. Omega 3 supplementation has been shown in humans to maintain muscle mass, improve muscle strength and endurance, and enhance the effects of physical training.

Omega 3s can be provided through diets enriched with EPA and DHA, by giving natural sources (i.e. anchovies or sardines), or with fish oil supplements. The evidence for Omega 3 supplementation in dogs primarily comes from studies of therapeutic diets with high levels of supplementation, and results are generally positive.

These diets have been shown to improve weight-bearing, functional activity, and reduce the amount of NSAIDs needed. There is currently limited evidence with fish oil supplements, and no evidence with natural sources, so it is uncertain whether the same clinical results will be seen with fish/ fish oil supplements as with “joint” diets.

What are Omega 3s?

Omega 3s are one of several poly-unsaturated fatty acids (PUFAs) that have physiologic roles in the body. Omega 3 and Omega 6 are “essential” PUFAs that are required for numerous functions in mammals, but they must be consumed through the diet. Omega 7 and 9 PUFAs can be formed endogenously. The distinction of 3, 6, 7, and 9 are based on the location of the final double bond in the chemical structure.

Omega 3s include EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid), and Alpha Lipoic Acid (ALA). Omega 6 PUFAs include linoleic acid (LA) and arachidonic acid (AA); this is the same AA that we are familiar with in the mechanism of action of NSAIDs (LINK).

Metabolism of AA leads to the production of “inflammatory” eicosanoids (series 2 prostaglandins, PG, and thromboxanes and series 4 leukotrienes, LT), including prostaglandin E2 (PGE2). The metabolism of Omega 3 produces different forms of PGs and LTs that are less inflammatory (series 3 PG and series 5 LT).

Thus, increasing the amount of Omega 3s in the body leads to the replacement of AA in the cell membrane and decreased the production of inflammatory mediators. (Of note, Omega 6 is still an essential nutrient that must still be consumed, the goal of Omega 3 supplementation is to change the ratio of Omega 6 to 3. The ideal ratio is not fully known).

What is the best source of Omega 3s for dogs?

Dogs specifically need EPA and DHA to decrease inflammation associated with OA. The most potent source of EPA and DHA is fish oil. Dogs cannot metabolize ALA (flaxseed, linseed or canola oil) sufficiently to be helpful for treating OA.

Therefore, it is important that you recommend sources of EPA/DHA that can be effective. Omega 3s can be given in the form of fish or krill oil supplements, whole fish (anchovies, sardines), and prescription foods supplemented with fish oil.

Fish oil vs. Krill oil

Krill are tiny shrimp-like creatures and krill oil contains EPA and DHA, though less concentrated than fish oil. Purported benefits of krill oil over fish oil in humans includes potentially improved absorption as well as improved anti-oxidant properties due to the presence of astaxanthin. Astaxanthin is a powerful anti-oxidant and makes the fatty acids in krill oil more stable. When giving fish oil, it is important to be sure the product contains anti-oxidants (typically vitamin E) to protect the lipids from oxidation.

Studies have not been done in dogs comparing fish oil and krill oil, and a dose of krill oil has not been determined in dogs. There are studies in rats and humans that show krill oil is absorbed, but there are mixed results when comparing krill and fish oil. Some studies show that in humans, almost twice as much krill oil needs to be taken to get the same effects as fish oil.

Krill are sourced from the waters of Antarctica, where it is the primary food source for many animals. The krill fishing industry is rapidly growing and there is a legitimate concern for the impact that this will have on the Antarctic environment (as well as the world). There are some producers of krill oil products that claim to follow very high standards for fishing and environmental sustainability. However, some environmental protection groups have raised concerns that the krill fishing industry is causing a serious environmental threat. At this time, CARE is not recommending krill oil based on the environmental concerns and lack of clear evidence in dogs.

What is the recommended dose of Omega 3’s?

The recommended dose of fish oil is 75-100 mg/ kg total EPA/DHA. (The dose range reported for dogs is 50-220 mg/kg, but we typically recommend staying around 100 mg/kg)

The maximum daily dose is 310 x (BW in kg)0.75

For example, a 22.7 kg (50 lb) dog would need about 2,000 mg (2 grams) of fish oil per day. The maximum dose for a 50 lb dog would be 3,200 mg/ day.

Too much math? Here are charts for recommended dosages by bodyweight:

Omega 3 Dosing (for dogs under 50 lbs)

Body weight (lbs)Body weight (Kg)Recommended Daily Dose (100 mg/kg)Maximum Daily Dose
52.3230 mg574 mg
104.5450 mg965 mg
156.8680 mg1308 mg
209.1910 mg1623 mg
2511.41140 mg1919 mg
3013.61360 mg2200 mg
3515.91590 mg2469 mg
4018.21820 mg2730 mg
4520.52050 mg2982 mg
5022.72270 mg3227
Recommended and maximum daily doses of Omega 3s (50lbs and under)

Omega 3 Dosing (51-100 lbs)

Bodyweight (lbs)Bodyweight (Kg)Recommended Daily Dose (100 mg/kg)Maximum Daily Dose
50 lbs22.72270 mg3227 mg
55252500 mg3466 mg
6027.32730 mg3700 mg
6529.52950 mg3924 mg
7031.83180 mg4153 mg
7534.13410 mg4374 mg
8036.43640 mg4590 mg
8538.63860 mg4804 mg
90414100 mg5014 mg
9543.24320 mg5222 mg
10045.54550 mg5427 mg
Recommended and Maximum Daily Dosing (51-100 lbs)

Omega 3 Dosing (101-150 lbs)

Bodyweight (lbs)Bodyweight (Kg)Recommended Daily Dose (100 mg/kg)Maximum Daily Dose
100 lbs45.54550 mg5427 mg
10547.74770 mg5629 mg
110505000 mg5829 mg
11552.35230 mg6027 mg
12054.55450 mg6222 mg
12556.85680 mg6415 mg
13059.15910 mg6607 mg
13561.36130 mg6797 mg
14063.66360 mg6985 mg
14565.96590 mg7171 mg
15068.26820 mg7356 mg
Recommended and Maximum Daily Doses (101-150 lbs)

 

What is the best way to supplement Omega 3s?

Omega 3s can be administered either by fish oil supplements, natural sources or in prescription foods. Prescription foods will typically have the highest concentration of EPA/DHA, though it is often hard to decipher the amount being fed on the food label and the source of EPA/DHA is not always clear in terms of sourcing sustainability.

The benefits of prescription diets are that these foods have research to support their efficacy and they are the easiest/ most practical method of supplementation. However, there will be times that these diets are not the right choice for the individual dog or client. Fish oil capsules or liquid or natural sources (fish) can be used instead. There is limited research looking at using these sources of EPA/DHA for treating OA in dogs.

Natural sources:

  • Anchovies, 6 oz can, 3400 mg EPA/DHA
  • Sardines, 6 oz can, 2800  mg EPA/DHA (about 100 mg per small sardine)
  • Salmon, 6 oz, 2200 – 2800 mg EPA/DHA
    • NOTE: CARE does not recommend using salmon or salmon oil as a daily source of Omega 3s in dogs as it is not the most environmentally sustainable source

Common Products

Most products will list the amount of EPA, DHA and total Omega 3s. The total number will be larger than the sum of EPA and DHA due to “other” Omega 3s. The ideal dose should be the total of EPA + DHA, not necessarily the total Omega 3 content. However, since a dose range for Omega 3s exists, it is OK to determine the dose using the total Omega 3 content.

The Fish Oil product that CARE currently recommends is:

  • Nordic Naturals Omega-3 Pet
    • Liquid
      • 1 tsp (5 ml)
        • 782 mg EPA/ 460 mg DHA  1426 mg total Omega 3
        • Be sure to keep liquid fish oil refrigerated after opening—they can spoil quickly so be sure to use it by the indicated time on the label. Also, be sure to shake before using.
    • Soft gel cap
      • 1 capsule
        • 1000 mg

Things to keep in mind

You can use human versions of Nordic Naturals products but be sure to choose a product that does not include Vitamin D. Other flavorings, such as rosemary and lemon, may not be harmful but may be off-putting to dogs.

Use caution when buying fish oil products from pet stores. ConsumerLab.com has tested several pet products and found that the actual product only contained a fraction of what was listed on the label. Buyer beware when it comes to supplements!

Drug interactions: Aspirin– when combined, may cause blood thinning (decreased platelet function). Aspirin is NOT recommended for dogs.

Side effects: Diarrhea at higher doses (increase slowly to prevent); some concern with delayed wound healing at high doses. May not be advised with chemotherapy—consult the attending oncologist.

Other considerations:

  • Fish oils are highly prone to oxidation, so they need to be protected from light and need adequate levels of Vitamin E or other antioxidants to preserve them.
  • Flaxseed (and other Omega 3 fatty acids) are not readily converted to the active forms EPA & DHA in pets.
  • There is CONSIDERABLE variability in supplements in terms of the amount of EPA & DHA per capsule or ml of liquid in both human and pet products. Dosing is critical to achieving the desired effects.
  • DHA is more important in cats (specifically related to bladder & joint disease), and cognitive issues in both older dogs & puppies. It’s common to see DHA added to puppy foods to help to increase learning.
  • There are several prescription pet foods that contain high levels of Omega 3s and therefore you would not need to add further supplements.
  • It will take about 2 months for omega 3s to incorporate the lipid bilayer of cells, therefore, clinical results should not be expected before this time.

Prescription Dog Foods with high level Omega 3s:

Purina JM ® Dry

  • 287 mg EPA/cup; 445 mg DHA/cup = total 732/ cup

Purina JM® Canned

  • 410 mg EPA/can;  380 mg DHA/can = total 790/can

Science Diet Metabolic + Mobility®

Science Diet J/D ® Canned

  • 1,080 EPA/ can

Science Diet J/D ® Dry

  • 409 mg EPA/cup

Blue Buffalo W +M ® Dry

  • 552 mg EPA /cup; 552 mg DHA /cup = total 1104

 

References

Bauer JE. Responses of dogs to dietary omega-3 fatty acids. J Am Vet Med Assoc 2007;231:1657-1661.

Bauer JE. Therapeutic use of fish oils in companion animals. J Am Vet Med Assoc 2011;239:1441-1451.

Lenox CE. An overview of fatty acids in companion animal medicine. J Am Vet Med Assoc 2015;246:1198-1202.

Roush JK, Cross AR, Renberg WC, et al. Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis. J Am Vet Med Assoc 2010;236:67-73. 

Roush JK, Dodd CE, Fritsch DA, et al. Multicenter veterinary practice assessment of the effects of omega-3 fatty acids on osteoarthritis in dogs. J Am Vet Med Assoc 2010;236:59-66.

Fritsch DA, Allen TA, Dodd CE, et al. A multicenter study of the effect of dietary supplementation with fish oil omega-3 fatty acids on carprofen dosage in dogs with osteoarthritis. J Am Vet Med Assoc 2010;236:535-539.

Mazaki-Tovi M, Abood SK, Schenck PA. Effect of omega-3 polyunsaturated fatty acids and body condition on serum concentrations of adipokines in healthy dogs. Am J Vet Res 2012;73:1273-1281. 

Moreau M, Troncy E, del Castillo JRE, et al. Effects of feeding a high omega-3 fatty acids diet in dogs with naturally occurring osteoarthritis. J An Physiol An Nutrition 2013;97:830-837.

Lenox CE, Bauer JE. Potential adverse effects of omega-3 fatty acids in dogs and cats. J Vet Intern Med 2013;27:217-226.