Close-up of Iletin vial-1923. Iletin from Eli Lilly. Beef R/Neutral in varying strengths--not highly purified, nor were there any suspension insulins at the time. Photo is likely ca. 1922-1923

Bovine means "derived from a cow." An example would be milk. Generally, grocery stores sell cow's (or bovine) milk, but some also sell milk derived from other species, such as goats.

The pancreases of cows are used to make bovine insulin. The pancreases of pigs also are used to make insulin; hence the term porcine and discussions here of porcine insulin.

Amino acid differences

Bovine insulin compared to Porcine, Human, and Feline versions[1]. Up to three amino acids differ. Canine and porcine are identical.

Bovine insulin is one amino acid different than a cat's own insulin; it is the closest match available[2]. Using the graphic, you can see where it differs, Position # 18 on the A insulin chain.

Feline insulin has Histidine in that position, while bovine, or that of the cow, has Asparagine in that position.

Iletin ad from 1950 medical journal. This is pure beef insulin in U40 (front) and likely U80 strengths. Regular/Neutral, NPH/Isophane and Protamine Zinc/PZI were available then; Lente, Semilente & Ultralente had yet to be marketed.

For dogs, there are 2 amino acid differences between their own insulin and bovine: positions A #8 and A #10. On the A insulin chain, dogs have Threonine at A #8-cows have Alanine; dogs have Isoleucine at A #10, while cows have Valine.

These insulins are natural and entirely or partly derived from bovine (cow) sources. This means that they are similar (at least in the bovine part) to feline natural insulin (differing in 1 amino acid).

Lilly's Iletin I insulins were a mixture of beef and pork; they were 85-90% bovine insulin.

The only blend of bovine/porcine insulin marketed presently by any pharmaceutical company is PZI Vet, whose manufacturer, IDEXX, purchased the Iletin I PZI formula from Eli Lilly. It is the basis for PZI Vet insulin, but produced in a U40 strength, as opposed to U100.

Many humans also prefer beef-based insulins, which are claimed by some to give a clearer warning of impending low blood sugar than the comparable human GE and analog insulins.

Some Feline Diabetes Message Board insulin data from 2001[3], showing use of Iletin I pure beef and beef/pork insulin in varying types.

1999 notice[4] of Lilly's discontinuation of Iletin I beef/pork insulins; pure beef was discontinued in 1995.

Bovine Insulins

Bovine Insulins

Short Acting


Hypurin Bovine Neutral
Hypurin Vet Neutral


Insuvet Neutral


Iletin I R
(No longer produced.)

Intermediate Acting


Hypurin Bovine Isophane


Iletin I NPH
(No longer produced.)


Hypurin Bovine Lente


Insuvet Lente


Iletin I Lente
(No longer produced.)

Long Acting


Hypurin Bovine Protamine Zinc
Hypurin Vet Protamine Zinc


Insuvet Protamine Zinc




Summit PZI
Other Compounded Pure Bovine/Beef PZI

Prescribing information

Prescribing information for Bovine Insulins[5]. This shows information for the insulins of CP Pharma; information can also be applied to:Hypurin Vet Neutral, Hypurin Vet Protamine Zinc, Insuvet Neutral, Insuvet Lente, Insuvet Protamine Zinc, and U100 BCP PZI.

See also porcine insulins.

Further Reading



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