British Shorthair Blood Type B Edmonton: The Test Before Any Surgery

Cats have three blood types: A, B, and the rare AB. Unlike humans, cats produce strong naturally-occurring antibodies against the blood type they do not have. A Type B cat has anti-A antibodies in its bloodstream from birth, and a Type A cat has weaker anti-B antibodies. This is why a transfusion mismatch in cats is more dangerous than in humans: even a small volume of mismatched blood triggers an immediate antibody reaction.

The genetics are straightforward. Type A is dominant over Type B. A cat with one A allele and one b allele is phenotypically Type A but is a carrier and can produce Type B kittens. A cat with two b alleles is Type B. The UC Davis VGL DNA test detects the b allele directly, so it can identify carriers as well as Type B cats. The in-clinic card test detects the phenotype (whether the cat is functionally Type A or Type B) but cannot identify carriers.

The breed's history is the answer. Modern British Shorthair populations were rebuilt from a small founding group of cats in the post-WWII period, after near-extinction during the wars. Whatever genetic frequencies happened to exist in that small founding group got carried forward at high frequency through subsequent selective breeding. Type B happened to be over-represented in the founders, and the recessive b allele persists at elevated frequency in modern BSH bloodlines.

This is not unique to BSH. Other breeds with small founding populations show similar patterns. Devon Rex, Cornish Rex, and Turkish Van all carry 20 to 50 percent Type B prevalence for the same population-genetics reason. Other breeds (Burmese, Siamese, Oriental Shorthair, Russian Blue) come from populations where the b allele was rare, and they are nearly always Type A.

For an Edmonton adopter, the practical implication is simple: any BSH or BSH-mix cat should be blood-typed before its first anaesthesia, because the 20 to 45 percent prevalence is high enough that the test pays for itself many times over the cat's lifespan in avoided surgical risk.

1. Pre-anaesthesia (the most common situation)

Any BSH going under anaesthesia in Edmonton should be blood-typed first. Anaesthesia itself does not require blood, but complications during surgery sometimes do, and a Type B cat receiving Type A blood has a severe reaction within minutes. The test is fast, cheap, and one-time. Modern Edmonton clinics will type before major surgery in nearly all cases; for routine spay or neuter, ask the clinic to type your BSH as part of pre-surgical bloodwork. This is a reasonable, easy ask in 2026, and most veterinarians will agree without pushback.

2. Breeding (the BSH-specific risk)

Neonatal Isoerythrolysis (NI) is the most dangerous consequence of BSH blood type mismatches in breeding. When a Type B queen nurses kittens with Type A blood, the anti-A antibodies in her colostrum destroy the kittens' red blood cells in the first 24 to 48 hours. Affected kittens die rapidly, often within days. Prevention requires testing both breeding parents before pairing. Type B queens should be bred only to Type B toms, or kittens born to a Type B queen by a Type A tom must be hand-reared and prevented from nursing during the critical first 24 to 48 hours. Ethical Canadian BSH breeders blood-type both parents as part of standard pre-breeding screening.

3. Emergency transfusion

If your cat is in a car accident, has a sudden bleeding crisis, or needs a transfusion for any reason, the receiving Edmonton emergency clinic will type before transfusing. Having the result already on the medical record saves critical minutes. The emergency clinic will also crossmatch (a separate test that checks compatibility between specific donor and recipient blood samples) but starts with a typing result if available. Pre-existing blood type records are particularly valuable in true emergencies.

Two methods exist, with different costs, accuracy levels, and turnaround times. Discuss which fits your cat's situation with your Edmonton veterinarian.

For most pet BSH owners in Edmonton, the in-clinic card test at the first wellness exam is the practical choice. Cost is small, result is fast, and the typing goes on the medical record permanently. For ethical breeders, the UC Davis VGL DNA test is the standard of care because it identifies carriers (Type A cats with one b allele) that the card test would miss.

The process: your Edmonton vet draws a small blood sample (often part of pre-surgical bloodwork), runs the card test in the clinic or sends a swab to UC Davis VGL, and records the result on the medical chart. The result is permanent and never needs to be repeated.

• Blood type on record. If not yet typed, ask for the in-clinic card test as part of pre-surgical bloodwork. Cost is small, result takes 15 minutes.
• Pre-anaesthetic bloodwork. CBC and chemistry panel, particularly important in middle-aged or older BSH given the breed's elevated risks for HCM, kidney disease, and dental disease.
• HCM screening status. If your BSH has been echocardiogrammed and is HCM-negative, the anaesthesia plan is straightforward. If HCM-positive or unscreened, discuss cardiologist consultation with your Edmonton vet before non-emergency anaesthesia.
• Auscultation at the pre-op exam. Your vet listens to the heart. A new heart murmur warrants discussion about echocardiogram before non-emergency anaesthesia.
• Crossmatch availability. If your cat is at elevated transfusion risk (major surgery, very low body weight, history of bleeding), ask the clinic about their blood-product availability and crossmatching protocol.
• Pre-existing condition documentation. If your BSH has been diagnosed with HCM, kidney disease, dental disease, or any other condition, ensure the surgical team has the records.

These items are standard pre-anaesthesia diligence for any cat, with breed-specific emphasis on blood typing and HCM screening for BSH. Reputable Edmonton clinics will appreciate the questions because they signal an engaged owner who will follow post-op instructions carefully.

Neonatal Isoerythrolysis is one of the most heartbreaking outcomes in BSH breeding, and it is entirely preventable through blood typing of both parents. The mechanism:

1. A Type B queen has anti-A antibodies in her bloodstream from birth.
2. She mates with a Type A tom (or a carrier tom who throws Type A kittens) and conceives a mixed litter.
3. Kittens with Type A blood are healthy at birth.
4. Within the first 24 to 48 hours, the kittens nurse on colostrum, which is rich in maternal antibodies.
5. The anti-A antibodies in the queen's colostrum cross into the kittens' bloodstream and destroy their Type A red blood cells.
6. Affected kittens develop severe anaemia within 24 to 72 hours. Most die within the first week of life.

Prevention requires testing both breeding parents before pairing. Ethical BSH breeders blood-type queens and toms and plan pairings accordingly. Type B queens should be bred only to Type B toms. If a Type B queen must be bred to a Type A tom, kittens must be hand-reared (bottle-fed) and prevented from nursing for the critical first 24 to 48 hours, then allowed to nurse after the colostrum window closes.

For Edmonton adopters: this risk only affects breeding cats. A pet BSH that has been spayed or neutered will never produce or expose kittens to NI. The blood type information still matters for transfusion safety, but the NI risk specifically applies only to intact breeding cats.

If you are considering buying a BSH kitten from a Canadian breeder, blood typing of both parents is one of the verification standards that distinguishes an ethical breeder from a corner-cutter. Ask for:

• UC Davis VGL DNA blood type certificate for both the queen and the tom, dated, with their registered names on it.
• Documentation of the pairing decision. A Type B queen bred to a Type A tom should have a clear plan for hand-rearing kittens to prevent NI. A Type A queen bred to a Type B tom presents no NI risk but the kittens' types still matter for future surgical planning.
• PKD1 DNA test certificate for both parents (autosomal dominant, inherited from Persian outcrosses historically).
• Annual echocardiogram reports for both breeding parents (HCM screening).

Ethical breeders maintain these records and produce them on request. A breeder who claims their cats are tested but cannot provide the certificates with the parents' registered names is a red flag. The full breeder verification protocol lives in our dedicated Edmonton BSH adoption guide.