Pork Lung

Pig slaughter leaves lungs that federal rules forbid saving as human food. AAFCO counts lungs as a meat by-product fit for animal feed, and researchers have tested drying them into protein for pet food.^1,2,3,11

1. 01 // Source Pig at slaughter Lungs come out with the other organs when federally inspected plants process pigs.
2. 02 // Process Barred from human food Federal meat rules say livestock lungs shall not be saved as human food, so they move to the inedible stream.
3. 03 // Process Cooked or dried Wet food plants grind and cook them. For treats, researchers have tested air frying, convection ovens and freeze drying.
4. 04 // Output Pork lung Fresh or frozen lung, about 80% water, arriving at a wet food plant to be ground into the recipe.

1. 01

   A use for banned offal

   US rules bar pork lungs from human food, yet AAFCO calls lungs safe and nutritious for other animals. A Brazilian study proposes dried pig lung as a protein source for pet food.^2,3,11

2. 02

   Lean protein plus iron

   Raw lung holds 14.1 g protein, 2.7 g fat and 18.9 mg iron per 100 g. It raises the protein in a wet food without adding much fat.¹

3. 03

   Organ meat by name

   AAFCO counts lungs as a meat by-product. Listing pork lung by name tells the buyer which organ went in, where a by-products line would not.²

How much No published source gives a typical inclusion rate, and no dog trial has fed pork lung as a test ingredient.

1. Brands say

   Pork lung is a lean, high-protein meat

   Evidence

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

   This is plain arithmetic. USDA lists raw lung at 14.1 g protein and 2.7 g fat per 100 g, about 69% protein and 13% fat on a dry basis. A Brazilian study measured 11.9% protein as fed, so lots vary.^1,11

2. Brands say

   Lung is rich in iron

   Evidence

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

   Raw lung carries 18.9 mg iron per 100 g, about 922 mg/kg dry. In beef lung, hotter drying lowered heme iron, the best-absorbed form; at 50°C about 40% of the iron stayed heme.^1,6,7

3. Critics say

   Lung protein is cheap connective tissue

   Outruns the evidence

   Evidence

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

   In hydrolysates made from beef lung, collagen and elastin were the dominant proteins, and collagen lacks tryptophan. Yet a beef lung protein powder scored 1.0 on the human amino acid score. No study has tested pork lung protein in dogs.^5,7,8

4. Brands say

   Lung is easy to digest for sensitive dogs

   Outruns the evidence

   Evidence

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

   The only digestibility work is test-tube research on beef lung dried at 50°C, judged for people. No dog trial has measured lung digestibility, and no trial has tested it in dogs with sensitive stomachs.⁷

5. Critics say

   Lungs are condemned meat, unsafe for dogs

   Outruns the evidence

   Evidence

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

   Lungs are barred from US human food, and a Pork Board-funded study found Salmonella and E. coli in them, with debris in half the airways. AAFCO calls lungs safe for animals, and canning heat kills those bacteria.^2,3,4