An overview of fatty acids in companion animal medicine

Lenox, C. E. (2015). An overview of fatty acids in companion animal medicine. Journal of the American Veterinary Medical Association, 246(11), 1189–1197. https://doi.org/10.2460/javma.246.11.1189

What This Review Covers

This article, authored by Catherine Lenox, DVM and published in the Journal of the American Veterinary Medical Association (Vet Med Today: Timely Topics in Nutrition), synthesizes research on fatty acids in companion animals. It provides an overview of fatty-acid biology, identifies which fatty acids are essential, describes deficiency risks, reviews dietary sources, and examines how supplementation practices differ across products.

Essential Fatty Acids for Dogs

Certain fatty acids must be obtained through diet.

• Dogs require both linoleic acid (LA, an omega-6) and α-linolenic acid (ALA, an omega-3).
• Dogs can synthesize arachidonic acid (AA) from linoleic acid, but cats cannot and must obtain AA directly.
• DHA is described as conditionally essential for puppies because it supports nervous-system and retinal development.

Low ALA Conversion Efficiency (<10%)

One of the most notable points in the review is how inefficient dogs are at turning plant-based omega-3s into the long-chain forms that support health.

• Shared pathways: The same desaturase and elongase enzymes that convert linoleic acid into arachidonic acid also convert α-linolenic acid into EPA and DHA. Because these fatty acids share enzymes, an excess of dietary omega-6 can further limit omega-3 conversion.
• Conversion limits in dogs: The review explains that while ALA can theoretically be converted to EPA and DHA, this process is inefficient in dogs, with studies showing less than 10% conversion. In cats, the conversion is described as virtually nonexistent.
• Human comparison: For context, humans convert ALA at similarly poor rates—less than 6% to EPA and less than 0.1% to DHA—highlighting why relying on plant oils alone is insufficient.
• Clinical implications: Because EPA and DHA are the omega-3s most closely tied to anti-inflammatory effects, the review concludes that it is often prudent to provide preformed EPA and DHA from fish oil or algae oil to achieve levels that are nutritionally or clinically effective.

Omega Deficiency Risk for Pets

Fatty-acid deficiencies are rare in dogs fed complete commercial diets but may occur in certain situations.

• Risks increase with poorly balanced homemade diets or ultra-low-fat feeding, especially those relying on tallow, coconut oil, or olive oil.
• Reported signs of deficiency include poor coat quality, scaly skin, easy bruising, reproductive abnormalities, slowed growth, and neurologic changes.

Special Functions of Long-Chain PUFAs

Beyond preventing deficiency, the review describes unique roles for long-chain omega-3 and omega-6 fatty acids.

• They influence membrane fluidity and stability, which affects cellular function.
• Neural tissues, particularly myelin, concentrate long-chain omega-3s.
• DHA plays a role in retinal, neurologic, and auditory development, underscoring its importance in puppies.
• EPA and AA are precursors for eicosanoids (prostaglandins, leukotrienes, thromboxanes), which regulate inflammation and other processes.

Sources and Product Differences

The review highlights the importance of source quality in supplying fatty acids.

• Plants provide LA and ALA, while marine algae and fish oils supply preformed EPA and DHA.
• “Not all fish oils are equivalent”: composition varies widely depending on fish species and diet.
• Some products dilute EPA/DHA with additional omega-6, reducing their effectiveness.
• Certain supplements also include vitamins A and D, which may be unsafe in excess.

Omega Dosing and Safety Considerations

Lenox notes that dosing guidance for omega-3s remains inconsistent.

• Doses can be expressed per kg of body weight, per kcal of diet, or as a percentage of dietary fat—making comparisons difficult.
• Using an n-6:n-3 ratio can be misleading if the “n-3” fraction is mostly ALA rather than EPA/DHA.
• While omega-3 supplements are widely used, they are regulated as dietary supplements, not drugs—manufacturers are responsible for safety but are not required to prove efficacy before marketing.
• Potential adverse effects include impacts on coagulation and risks associated with rancidity if products oxidize.

Clinical Application

The review emphasizes that long-chain omega-3s have applications beyond basic nutrition.

• EPA and DHA help modulate inflammation through their influence on eicosanoid pathways.
• Veterinarians often use them in practice to support skin and coat health, and to help manage chronic conditions such as arthritis.