Breed-specific vertebral heart size (VHS) and vertebral left atrial size (VLAS) reference intervals differ substantially from the generic canine reference of 9.7 ± 0.5 vertebrae (v), and applying generic values to these breeds risks both over- and under-diagnosis of cardiomegaly.
In dogs, the following breed-specific intervals are established. For sighthounds as a group, the overall VHS reference interval is 9.0–11.2v and VLAS is 1.7–2.6v, with breed-level breakdowns as follows: Rhodesian Ridgebacks 9.3–11.5v VHS and 1.8–2.4v VLAS; Borzois 8.8–10.9v VHS and 1.7–2.3v VLAS; Afghan Hounds 9.0–11.5v VHS and 1.8–2.5v VLAS; Salukis 9.4–11.8v VHS and 1.6–2.6v VLAS; and Basenjis 9.0–11.6v VHS and 1.7–2.5v VLAS.American Journa…
Small breed dogs with elevated upper VHS limits require particular attention to avoid missing cardiomegaly. Boston Terriers have the widest VHS range of any breed in the sources, at 9.7–13.0v VHS and 1.6–2.7v VLAS. Pugs measure 9.7–12.0v VHS and 1.7–2.7v VLAS. Pomeranians measure 9.5–12.0v VHS and 1.7–2.6v VLAS. Yorkshire Terriers measure 9.0–11.4v VHS and 1.7–2.4v VLAS.American Journa…
Three additional small breeds have breed-specific intervals that exceed the generic upper limit. Jack Russell Terriers: 9.7–11.8v VHS and 1.8–2.6v VLAS. Miniature Pinschers: 9.6–12.2v VHS and 1.7–2.4v VLAS. Brussels Griffons: 9.3–11.9v VHS and 1.7–2.4v VLAS.American Journa…
Four herding and sporting breeds cluster near the generic range but have validated breed-specific intervals. Shetland Sheepdogs: 9.2–11.5v VHS and 1.7–2.4v VLAS. Cairn Terriers: 9.3–11.2v VHS and 1.6–2.4v VLAS. Italian Greyhounds: 9.1–11.5v VHS and 1.6–2.3v VLAS. English Springer Spaniels: 9.1–11.5v VHS and 1.7–2.4v VLAS.American Journa…
Four additional breeds have recently validated intervals. Miniature Australian Shepherds: 9.4–11.5v VHS and 1.7–2.5v VLAS. American Eskimo Dogs: 9.5–11.5v VHS and 1.7–2.4v VLAS. Tibetan Terriers: 9.2–11.4v VHS and 1.7–2.3v VLAS. Border Terriers: 9.3–11.6v VHS and 1.7–2.3v VLAS.American Journa…
Cavalier King Charles Spaniels (CKCS), a breed predisposed to myxomatous mitral valve disease (MMVD), have a mean VHS of 10.08 ± 0.56v (95% range 9.87–10.29v), mean VLAS of 1.79 ± 0.3v (95% range 1.68–1.9v), and mean modified VLAS of 2.23 ± 0.44v (95% range 2.06–2.39v). The radiographic left atrial dimension mean is 1.2 ± 0.34v (95% range 1.07–1.33v). The ACVIM MMVD consensus statement recommends using breed-specific radiographic values when available.Veterinary Radi…
Dachshunds have a median VHS above the generic reference, with sex-based differences. Females have a higher VHS than males on both right lateral (10.8v vs. 9.99v) and left lateral (10.56v vs. 9.74v) views. Right lateral VHS is significantly larger than left lateral in this breed (median 10.3v vs. 10.1v).Journal of the…
Norwich Terriers have a mean VHS of 10.6 ± 0.6v, significantly above the generic 9.7 ± 0.5v. Body condition score ≥6 is associated with a significantly higher VHS in this breed, and this variable should be factored into interpretation.Veterinary Radi…
Brittany Spaniels have a mean VHS of 10.6 ± 0.2v in normal dogs, compared to 11.9 ± 1.1v in dogs with MMVD. A threshold of 11.1v yields sensitivity of 90%, specificity of 72%, positive predictive value of 53%, and negative predictive value of 96% for cardiomegaly in this breed.Veterinary Scie…
Chihuahuas have a mean VHS of 10.0 ± 0.6v (95% range 8.9–11.0v) and mean VLAS of 1.8 ± 0.2v (95% range 1.3–2.1v). Both VHS and VLAS are unaffected by sex, body weight, coat length, or body condition score in healthy Chihuahuas.Veterinary Radi…
Maltese dogs have a mean VHS of 9.53 ± 0.46v and a median VLAS of 2.0v (IQR 1.8–2.1v).Veterinary Radi…
Miniature Schnauzers have published breed-specific VHS and VLAS reference intervals, though the source provides the upper VLAS value of 2.40v without reporting the full interval range in the available excerpt.American Journa…
In cats, healthy kittens aged 6–16 weeks have a median VHS of 9.5v (95% reference interval 8.0–10.9v), which is higher than previously reported values for adult cats. The median cardiac thoracic ratio is 67.2% (95% reference interval 54.4–79.8%).Journal of Feli…
In rats (Rattus norvegicus), VHS reference intervals differ by radiographic projection. Right lateral: mean 7.7v, reference interval 7.0–8.5v. Ventrodorsal: mean 7.5v, reference interval 6.6–8.6v. Dorsoventral: mean 7.9v, reference interval 6.9–9.0v. Males have higher VHS values than females across all projections.Veterinary Radi…
| Breed / Species | VHS Reference Interval | VLAS Reference Interval | Key Caveat |
|---|---|---|---|
| Generic canine | 9.7 ± 0.5v | — | Insufficient for breeds below |
| Rhodesian Ridgeback | 9.3–11.5v | 1.8–2.4v | Sighthound group American Journa… |
| Borzoi | 8.8–10.9v | 1.7–2.3v | Lowest upper VHS of sighthounds American Journa… |
| Afghan Hound | 9.0–11.5v | 1.8–2.5v | American Journa… |
| Saluki | 9.4–11.8v | 1.6–2.6v | American Journa… |
| Basenji | 9.0–11.6v | 1.7–2.5v | American Journa… |
| Boston Terrier | 9.7–13.0v | 1.6–2.7v | Highest upper VHS limit in sources American Journa… |
| Pug | 9.7–12.0v | 1.7–2.7v | American Journa… |
| Pomeranian | 9.5–12.0v | 1.7–2.6v | American Journa… |
| Yorkshire Terrier | 9.0–11.4v | 1.7–2.4v | American Journa… |
| Jack Russell Terrier | 9.7–11.8v | 1.8–2.6v | American Journa… |
| Miniature Pinscher | 9.6–12.2v | 1.7–2.4v | American Journa… |
| Brussels Griffon | 9.3–11.9v | 1.7–2.4v | American Journa… |
| Shetland Sheepdog | 9.2–11.5v | 1.7–2.4v | American Journa… |
| Cairn Terrier | 9.3–11.2v | 1.6–2.4v | American Journa… |
| Italian Greyhound | 9.1–11.5v | 1.6–2.3v | American Journa… |
| English Springer Spaniel | 9.1–11.5v | 1.7–2.4v | American Journa… |
| Miniature Australian Shepherd | 9.4–11.5v | 1.7–2.5v | American Journa… |
| American Eskimo Dog | 9.5–11.5v | 1.7–2.4v | American Journa… |
| Tibetan Terrier | 9.2–11.4v | 1.7–2.3v | American Journa… |
| Border Terrier | 9.3–11.6v | 1.7–2.3v | American Journa… |
| Cavalier King Charles Spaniel | Mean 10.08 ± 0.56v | Mean 1.79 ± 0.3v | MMVD predisposition; ACVIM recommends breed-specific values Veterinary Radi… |
| Dachshund | Median 10.3v RL / 10.1v LL | — | Sex difference; females > males Journal of the… |
| Norwich Terrier | Mean 10.6 ± 0.6v | — | BCS ≥6 elevates VHS Veterinary Radi… |
| Brittany Spaniel | Mean 10.6 ± 0.2v (normal) | — | Cardiomegaly threshold 11.1v: Sn 90%, Sp 72% Veterinary Scie… |
| Chihuahua | Mean 10.0 ± 0.6v | Mean 1.8 ± 0.2v | Veterinary Radi… |
| Maltese | Mean 9.53 ± 0.46v | Median 2.0v (IQR 1.8–2.1v) | Veterinary Radi… |
| Kitten (6–16 wk) | Median 9.5v (RI 8.0–10.9v) | — | Higher than adult cat values Journal of Feli… |
| Rat | RL 7.0–8.5v; VD 6.6–8.6v; DV 6.9–9.0v | — | Males > females Veterinary Radi… |
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