Have you ever wondered where veterinarians get blood for an animal having surgery or needing a transfusion? The answer is chilling. California’s animal blood supply has a dark side…one that’s only now beginning to change.
Until January 1, 2022, veterinarians in our state could only acquire the blood products —blood and its components, like plasma and red cells— they needed for procedures from private donors at their own facilities or from closed–colony blood banks. These colonies were intended to ensure a safe and steady supply of canine blood products. But behind that logic was a deeply inhumane practice: hundreds of large dogs — often retired greyhounds — were kept in cages for the sole purpose of being bled every three weeks.
Supporters of this system argued that keeping these dogs confined was a small price to pay for the greater good — saving the lives of other dogs who might need transfusions. But animal welfare advocates, including Valley Humane Society, saw things differently.
Not only was the practice unethical, it was riddled with complications, secrecy, and monopolistic control. For decades, California law allowed only two for–profit entities to operate these blood banks, both licensed by the California Department of Food and Agriculture (CDFA). Inspections occasionally revealed violations and penalties, but the details were often hidden from public view because closed–colony facilities were exempt from public records disclosure. In 2024, the Los Angeles Times reported that inspection reports and regulatory records for these facilities were “long sealed” from scrutiny. (latimes.com)
Supporters of closed colonies maintain that isolating donor dogs reduces exposure to external parasites like fleas, ticks, and infectious diseases. Yet research and lived experience in shelter medicine tell a different story: prolonged confinement often leads to chronic stress, depression, and weakened immune function. In reality, dogs who live enriched, home-based lives are typically healthier—both physically and emotionally—than those kept in isolation.
California law also prohibited the sale of voluntarily donated blood. Even UC Davis, which ran a successful community-based donor program supplying blood to its patients, was barred from sharing blood with other veterinarians. Clinics in need couldn’t even purchase blood products from out of state. When a dog required a rare blood product not available through the closed colonies, veterinarians sometimes resorted to using human blood products — driving up costs for pet owners and limiting availability for emergency cases.
Blood typing & transfusion risk
Do dogs have blood types?
Yes — dogs have several blood group systems, the most significant being DEA 1 (Dog Erythrocyte Antigen 1). Unlike in humans, dogs generally do not have preexisting antibodies against other DEA types before their first transfusion, so a properly matched or even reasonably compatible first transfusion is often tolerated.
However, that first transfusion can sensitize a dog’s immune system. If the same dog later receives incompatible blood, its body may recognize those donor red blood cells as foreign and mount a strong immune response — sometimes leading to severe or life–threatening hemolytic transfusion reactions. That’s why veterinarians now routinely blood type and crossmatch dogs before any second or subsequent transfusion.
What about cats?
There are no closed colonies for cats in California. Veterinarians who need feline blood typically rely on private or in-clinic donors, often cats owned by staff members or clients. Because cats naturally have antibodies against other blood types, it’s considered best practice to blood type every cat before a transfusion to avoid dangerous reactions, though most cats are type A.
What does blood banking look like now?
The laws governing animal blood banking began to change with Assembly Bill 1282, authored by Assemblymember Richard Bloom and signed into law in 2021. The bill, known as the California Pet Blood Bank Modernization Act, began the process of phasing out closed–colony blood banks and creating a regulated network of voluntary, community–based donor programs.
Since AB 1282 took effect, a few community blood banks have opened, and one closed colony has shut its doors— but we are still far short of the supply needed to replace closed colonies. The law requires community sources to consistently match or exceed the annual production of the old system before the remaining closed–colony facility can be shut down.
At Valley Humane Society, we’re committed to helping end this inhumane system. We were proud to help advocate for AB 1282, and hope to open a voluntary community blood bank within the next five years. Together with other shelters, rescues, and veterinary partners, we can ensure that California never again relies on dogs held in captivity solely for their blood.
What you can do
- Ask your veterinarian if they participate in community blood programs or accept blood from privately-owned pets.
- If you have a large, healthy dog, consider registering them as a donor when a clinic near you becomes available.
Note: Donors are not paid — California prohibits payment to prevent unethical practices like pet theft — but participating dogs often receive free health screenings and flea prevention as part of donor safety protocols.
Get involved today. Let’s show them compassion runs in our veins!