Fish Extracts

Fish processing leaves heads, skin and trimmings after other products are prepared. One documented way to recover value from those leftovers uses enzymes to release soluble material, then separates and concentrates it.²

1. 01 // Source Fish leftovers A studied extract began with heads, tails, skin, fish slices and some whole fish.
2. 02 // Process Protein broken down An enzyme cut proteins in the minced fish into smaller pieces.
3. 03 // Process Oil separated Filtering removed remaining scales and bones; centrifuging separated oil from the protein-rich liquid.
4. 04 // Output Dried extract The protein-rich liquid was concentrated and spray dried for use in the studied dog food.

1. 01

   Adds fish flavor

   In one feeding test, dogs ate more of a food containing salmon protein hydrolysate than its comparison food. That gives makers a reason to use an extract for taste.¹

2. 02

   Uses processing leftovers

   Heads, skin and trimmings remain after fish are prepared for other products. Recovering an extract gives processors another product to sell from that material.²

3. 03

   Contributes some protein

   Condensed, defatted fish solubles contain concentrated protein. How much reaches the bowl depends on the recipe amount, which an ingredient list does not disclose.^5,6

How much Dog studies tested fish hydrolysates at 5% and 10% of complete diets. Neither figure tells us the typical inclusion rate for fish extracts, which recipes do not publish.^1,2

1. Brands say

   Fish extracts make food taste better

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In a 10-dog, 2-bowl test, dogs favored food with 10% salmon hydrolysate. A separate 12-dog crossover swapped fish hydrolysate and fish oil for shrimp hydrolysate and salmon oil, with other ingredients adjusted, and found no preference between the two complete diets, not between the extracts alone.^1,2

2. Brands say

   Fish extracts make this a high-protein food

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Crude protein ranged from 75.6 to 89.9% across 11 samples of condensed, defatted fish solubles. That measures an ingredient type, not its amount in a recipe. The label cannot show a meaningful protein boost.^5,6

3. Brands say

   Fish extracts improve skin and coat through omega-3s

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In a 12-dog crossover, a diet containing fish hydrolysate and separately swapped-in fish oil raised blood omega-3 measures without improving coat scores. The design cannot credit the extract alone for the blood change or a coat benefit.²

4. Owners say

   Fish extracts are safe for fish-allergic dogs

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In a 50-dog diet trial, 5 dogs reacted to a fish challenge yet tolerated the specially hydrolyzed diet. That result applies to that diet, not unspecified fish extracts. Fish reactions were also documented in cod challenges.^3,4

5. Critics say

   Fish extracts are just filler

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Dogs ate more of a diet with 10% salmon protein hydrolysate in a controlled comparison. Flavor is a measured job for that extract, although the test does not prove every fish extract works equally well.¹