English Greyhound

In a peer-reviewed measurement (Hudson et al., Journal of Anatomy) the Greyhound’s top speed is about 17 metres per second — roughly 61 km/h. That is the number we are prepared to put our name to.

Now compare it with what the standard itself asserts. The FCI historical note says the Greyhound reaches “over 45 miles per hour” — about 72 km/h, that is, roughly seven miles per hour more than the measured value. The figure from the standard’s note has spread across hundreds of sites and until recently stood on this page as well; we have replaced it with the result of the measurement and left both versions side by side, so that the reader can see where the divergence comes from.

The difference is not an academic one. 61 km/h is the speed at which a dog covers a hundred metres in about six seconds. No person, no lead and no fence of the “he’ll never clear that” variety has time to react to a start that begins with a glance. It is from this figure that the breed’s central management rule follows, discussed below in the section on training.

The FCI and Kennel Club standards describe the Greyhound as a dog of “remarkable stamina and endurance”. Peer-reviewed physiology describes it as a sprinter capable of one powerful and very short burst. That is a direct contradiction, and it is the most important thing to know about the breed.

Let us go through the evidence on the physiology side — there are three pieces of it, from different decades and different laboratories.

• Muscle composition. Guy and Snow (1981) showed that in the Greyhound’s skeletal muscle practically 100% of the fibres have high ATPase activity — these are “fast” fibres, built for power rather than for prolonged work. At the same time the activity of 3-hydroxyacyl-CoA dehydrogenase, the enzyme needed to oxidise fat, is reduced in them. In plain words: the fuel that stayers run on is fuel the Greyhound metabolises poorly.
• What happens over 800 metres. Dobson (1988) measured that after a distance of 800 m the lactate content in the Greyhound’s muscle rises 6–7 times over, while intramuscular pH falls to 6.40. This is a state of deep anaerobic acidification — precisely what makes carrying on impossible.
• What happens over 100 metres. Pellegrino (2018) showed that even a hundred metres raise blood lactate from 1.70 to 9.08 mmol/l. A distance most dogs would not even notice is already metabolically expensive for a Greyhound.

The practical conclusion for the owner is paradoxical and rather pleasant: the Greyhound is not a dog you have to run with for hours. Two short walks a day, plus the chance to open up a few times a week on fully fenced ground, cover its exercise needs. Trying to make it a partner for long runs works against its own physiology: it will give you the burst, and then spend a long time recovering.

The heart: constitution, not training

Schoning (1995) examined 230 Greyhounds post mortem and obtained a heart-mass to body-mass ratio of 1.3% in bitches and 1.2% in dogs. The key detail in that work is not the numbers themselves but the fact that the ratio did not depend on whether the animal had raced. The Greyhound’s large heart, in other words, is a constitutional feature of the breed and not a consequence of training.

For the owner this has an entirely practical consequence: a Greyhound’s heart can look enlarged on a radiograph and be perfectly normal all the same. If your veterinary surgeon is seeing your dog for the first time and has no experience of the breed, it is worth mentioning this particularity before an investigation of the “enlarged heart” gets under way.

Newcomers to the dog world often confuse the similar-looking breeds of the sighthound group. The Greyhound is the golden mean for size, but it has close relatives too. If, for instance, you are looking for a dog like a Greyhound but smaller, the Whippet deserves your attention. It is effectively a scaled-down copy, ideally suited to a town flat. And if even the Whippet seems too big, there is the Italian Greyhound — the smallest of the sighthounds, weighing under 5 kg yet keeping all the grace of its larger kin.

The comparison with the Whippet is worth a line of its own. It is almost the same body plan scaled down — and yet, on the evidence of a large study of lifespan (McMillan et al., 2024), the Whippet’s median lifespan is 13.4 years against 11.5 in the Greyhound. Two sighthounds of near-identical construction live differently, and the reason for that difference does not lie in the construction.

At the other end of the spectrum stands the stately Deerhound. Unlike the smooth-coated Greyhound, the Deerhound carries a rough coat and was bred to hunt deer in the rugged conditions of Scotland. The Greyhound is a sprinter of the plains. We shall come back to the Deerhound below: it is in that breed that the genetic cause was found for the post-operative bleeding so often ascribed to the Greyhound as well.

This is the most practical section on the page. A healthy Greyhound consistently falls outside the all-breed reference intervals on several parameters at once — and a veterinary surgeon who does not know that begins treating a healthy dog.

Below are the breed reference intervals published by IDEXX (2025) on a sample of 220 dogs and constructed to CLSI methodology. An important caveat: these limits are given for IDEXX’s own methods. In another laboratory, with other analysers and reagents, the limits may differ, so the table is a reason to talk to your vet, not grounds for a conclusion of your own.

Read that table again through the eyes of a clinician seeing a Greyhound for the first time. A high haematocrit, reduced platelets, reduced white cells, a raised creatinine and a low T4 are, by all-breed limits, the picture of several diagnoses at once. In the Greyhound this is normal.

Creatinine: muscle, not kidney

A raised creatinine in the Greyhound is a consequence of large muscle mass, not of renal failure. Direct evidence came from Drost and co-authors (2006): the glomerular filtration rate in the Greyhound proved to be higher than in dogs of other breeds — 3.0 against 2.5 ml/min/kg. The kidneys are not worse; they simply work harder. Urine specific gravity helps to tell “breed normal” from “a genuine problem”: if the kidneys concentrate urine normally, a high creatinine is not in itself a diagnosis.

The thyroid: do not rush to hypothyroidism

Gaughan and Bruyette (2001) showed that Greyhounds have reliably lower basal T4 and lower free T4, while TSH does not differ from other breeds. That is the key to the diagnosis: a low T4 in a Greyhound does not by itself mean hypothyroidism. The diagnosis has to rest on three things together — a low T4, a raised TSH and the clinical picture.

How widespread this is was shown by the work of Shiel (2007): in 91.3% of young untrained Greyhounds total T4 was below the all-breed norm. The sample of untrained dogs is the point here — it demonstrates that this is a property of the breed and not a consequence of racing work.

Why Greyhounds are asked to be blood donors

Two reasons. The first is the high haematocrit from the table above. The second is blood groups: only 13% of Greyhounds are DEA 1.1 positive, and that makes the breed a convenient source of blood for the banks.

And here is a common confusion worth untangling. “Universal donor” and “DEA 1.1 negative” are not synonyms: universality is not settled by a single antigen, and among Greyhounds the proportion of genuinely universal donors is about 57%. So “my Greyhound is DEA 1.1 negative” does not yet mean “suitable for anyone”: typing is decided by the laboratory, not by the breed on the pedigree.

This is the information worth giving your veterinary surgeon before the start of any procedure involving an anaesthetic — a dental included. Court (1999) formulated a practical rule that has entered veterinary practice since: thiobarbiturates are not used in Greyhounds. Propofol, ketamine combined with diazepam, and methohexital are named among the acceptable options.

The mechanism is enzymes, not “too little fat”

The most popular explanation — “the Greyhound has little fat, so the drug has nowhere to redistribute to” — does not survive checking. There are two arguments against it from the studies themselves: oxybarbiturates of similar lipophilicity produce no breed difference, and induction of the liver enzymes accelerates recovery. Both facts point to metabolism, not to distribution in the tissues.

The molecular answer came from two papers. Martinez and co-authors (Scientific Reports 10:69, 2020) pointed to the enzyme CYP2B11, and a paper from 2024 (PLoS ONE 19:e0297191) to POR (cytochrome P450 reductase). So the matter comes down to particular liver enzymes and to variants of the genes that encode them.

A counter-intuitive detail: “it is the racers who are at risk” is a simplification

You would think peculiarities of metabolism ought to concentrate in the racing lines. The data say otherwise, and in two directions at once. The CYP2B11-H3 variant occurs in 18% of racing against 59% of show dogs. The POR-H3 variant runs the other way: 35% in racing against 10% in show dogs. Two genes affecting the same system are distributed between the lines in opposite directions. So the simple rule “be careful with the racers” does not work: care is needed with the breed, regardless of whether the individual dog ran on a track or walked the show rings.

What not to say to your vet

The formula “Greyhounds metabolise drugs slowly” has become a convenient shorthand — and it is too broad. KuKanich and co-authors (2012) tested several drugs and showed that phenytoin, theophylline and diazepam behave within the usual limits in Greyhounds. The metabolic particularity of this breed is substrate-specific: it concerns particular drugs, not the whole of pharmacology. The right sentence for the consulting room runs roughly like this: “this is a Greyhound; the breed has described particularities in thiobarbiturate metabolism and reference intervals of its own for blood work”.

A checklist for the veterinary appointment

Gather everything breed-specific from this page into one short list and you get exactly what is worth going through with the clinician before the procedure rather than after it:

• Anaesthesia: do not use thiobarbiturates; propofol, ketamine with diazepam and methohexital are named among the acceptable options (Court, 1999).
• Blood work: the breed has reference intervals of its own — high haematocrit, reduced platelets and white cells, raised creatinine, low total T4. The IDEXX table above will serve as a printout for the practice.
• Kidneys: interpret a high creatinine together with urine specific gravity — in the Greyhound the glomerular filtration rate is higher, not lower (Drost, 2006).
• Thyroid: a low T4 without a raised TSH and without clinical signs is not hypothyroidism (Gaughan & Bruyette, 2001).
• After surgery: plan a check on the second day — late bleeding begins 36–48 hours in, and the pre-operative coagulation screen does not predict it.
• Heart: an “enlarged heart” on a radiograph in this breed calls for an interpretation of its own (Schoning, 1995).

The Greyhound’s most dangerous breed particularity is not the operation itself but the second day after it. Lara-García and co-authors (2008) described late post-operative bleeding in 26% of Greyhounds after castration, beginning 36–48 hours after the intervention. For comparison, in other breeds the same figure in their observations came to 0–2%.

The practical conclusion sounds mundane, but it is the one that saves dogs: the critical watch is not on the day of surgery but on the second day. Bruising, swelling around the wound, lethargy, pale mucous membranes a day and a half after discharge — that is a reason to telephone the practice, not to wait until morning.

What can be done about it

Marín and co-authors (2012) ran a randomised controlled trial on 100 dogs. In the placebo group bleeding occurred in 30%, in the aminocaproic acid (EACA) group in 10%, and the difference was statistically significant (p = 0.012). This is one of the cleanest pieces of evidence in breed-specific veterinary medicine.

Dosages we deliberately do not give: in the accessible sources the recommended doses diverge sevenfold, and the choice between them belongs to the surgeon who operates, not to a page about a breed. That is our editorial decision, not a doubt about the drug itself.

The subject is not closed, though. A retrospective study from 2024 on tranexamic acid (TXA) showed no effect — so the question of which antifibrinolytic, and for whom, remains a matter of discussion rather than a ready-made protocol.

Why the standard tests show nothing

The most insidious feature of this condition: prothrombin time and APTT in such dogs are normal. The pre-operative coagulation screen looks clean — and gives warning of nothing at all. The finding that does correlate with the bleeding is a reduced antiplasmin level, that is, accelerated dissolution of a clot that has already formed.

Molecular confirmation of this mechanism does exist: Court and co-authors (2023) found a causal variant in the SERPINF2 gene. One important caveat is usually lost in the retelling: that finding was made in Scottish Deerhounds, not in Greyhounds. Carrying the mechanism across to the Greyhound remains a reasoned assumption rather than a proven fact, and we mark that plainly.

Most Greyhounds come into families not from breeders but through the rehoming of former sporting dogs: they finish their racing careers at 2–4 years old and then live another decade as affectionate house dogs. That makes the breed one of the few in which an adult, already formed dog can be taken on with equanimity — the sighthound character is stable, and there will be no surprises of adolescence.

Former athletes have adaptation quirks of their own. They are used to a strict routine and to the company of other dogs, so the first days in the quiet of a flat can leave them at a loss. Usually the dog “thaws” within a few weeks: it learns to play, discovers toys and gets its own soft bed for the first time in its life. Many rehoming centres test such dogs in advance for compatibility with cats and children — that settles the prospective owner’s main question, so it is worth asking about the result of the test directly.

The veterinary side is worth preparing for separately. A former racing dog often arrives with dental calculus — see the section on periodontal disease — and almost always has spaying or castration ahead of it. Both procedures have rules of their own for a Greyhound: the anaesthetic protocol and the check on the second day. The most useful thing you can do in the first week is to find a practice that has already heard about the breed’s particularities, and to take along a printout of the breed reference intervals.

How to read racing statistics

Greyhound racing is a sharp subject, and the public argument around it is easy to get lost in. It helps to grasp the main thing: the sides mostly disagree not about the data themselves but about the denominator and the boundary of the count. Injury rates “per race” and “per dog per season” are two different numbers describing the same reality, and they are not interchangeable. In the same way, “left the register” and “died” in regulators’ reporting are two different populations, not parts of one whole. When you meet a striking figure, the first question to put to it is not “true or false” but “divided by what, and what exactly was counted”.

Let us gather together everything taken apart above. The portrait of the owner who will do well with this breed is composed not of character traits but of domestic conditions.

The Greyhound will suit you if

• You live in a flat and value quiet. This is the rare case of a tall dog that really is comfortable indoors: it hardly barks and sleeps for most of the day.
• You have access to a fully fenced area. Not a “quiet park”, not a “field where there is nobody about”, but a fence. This requirement is not up for discussion, and it follows from the figure of 17 metres per second.
• You are prepared to brush the dog’s teeth every day. Given 39% periodontal disease, that is not a wish but the breed’s core care procedure.
• You are content with an adult dog of settled character. Most Greyhounds come into a home through rehoming after a racing career.
• You are ready to act as “interpreter” between your dog and the vet — at least until the first appointment at a practice that knows the breed.

It is worth looking for another breed if

• You want a partner for long runs. The Greyhound’s physiology is built for a burst, not for distance: a hundred metres already raise blood lactate several times over.
• There is a cat or small livestock in the house. This is not an automatic “no” — many rehoming centres test dogs for exactly this compatibility — but taking a Greyhound into a home with a cat sight unseen is unwise.
• You are looking for a guard. The breed has neither a guarding instinct nor any leaning towards territorial behaviour; the watchdog score in the breed card above is the lowest for a reason.
• You are not prepared to dress your dog. A fine coat without undercoat and little subcutaneous fat make clothing in cold weather not an accessory but part of the care routine.
• You want a dog for competitive obedience. Sighthounds were selected over centuries for independence of decision, and a reliable recall in an open field is out of their reach in principle.

A set of striking claims circulates about this breed, copied from one text into the next. Being striking is a signal of risk, not grounds for trust, so we have checked each of them and taken the commonest off the page. Here they are, together with what is known instead.

• “The dog spends 75% of the gallop in the air.” A pretty figure that travels from site to site. That number is no longer on this page: we give only figures for which we can name a measurement. What has genuinely been measured about Greyhound movement is the +65% limb loading in the turn (see the section on aerodynamics).
• “A 270-degree field of view” and “it can see for a kilometre”. A dog’s field of view is in general about 240–250°, and visual acuity about 20/75 on the human scale — that is, noticeably poorer than a person’s. The Greyhound’s strength lies not in distance and not in the angle of view but in its response to movement: it launches at a moving object faster than it can make the object out.
• “The only breed mentioned in the Bible.” The claim leans on the English translation of 1611 (the Book of Proverbs, 30:29–31). It is an artefact of that particular translation: modern renderings of the same passage give “cockerel”, not “greyhound”.
• “The racing muzzle is for telling dogs apart in the photo finish.” The regulator’s rules name a single reason — the prevention of bites at the finish.
• “A Greyhound has less than 1% fat.” The figure comes from a measurement of dissectible fat — the fat that can be separated out by dissection. That is not the same as body fat percentage: a substantial part of the fat is distributed within the tissues and is not counted that way. The correct wording, without a number: the Greyhound has very little subcutaneous fat — hence both its sensitivity to cold and the definition of its muscles.
• “Cnut’s law forbade commoners to keep sighthounds.” The document is recognised as a twelfth-century forgery (see the section on history).
• “The Greyhound comes from Ancient Egypt.” The FCI standard does say so in its historical note, but sighthound genetics point to the independent emergence of this type of dog in several regions.

One stock claim, by contrast, did survive the checking, and with a number attached: the Greyhound really does have more red cells than the average dog. The haematocrit of 52–68.4% from the table of breed references is that same fact, only measured. It is that, and not the legend, which stands behind Greyhounds being asked so often to give blood.