Sizing a deep-chested dog

The geometry of deep-chested breeds

Deep-chested dogs possess anatomical proportions that differ significantly from square or barrel-chested breeds. Breeds such as Greyhounds, Whippets, Dobermans, and Dachshunds feature an exaggerated depth of sternum relative to their overall body mass and neck width. Their ribcages extend far downward behind the front legs, creating a steep incline towards a tucked abdomen.

This distinct build creates specific challenges when fitting a harness for deep chested dog profiles. Standard sizing algorithms often assume a predictable ratio between body weight, neck circumference, and chest girth. For a deep-chested breed, this ratio does not hold. A 30kg Doberman and a 30kg Labrador may share an identical overall weight, but their chest circumferences and chest depth differ dramatically.

When selecting equipment, understanding this skeletal geometry is essential. A harness must clear the armpits, seat securely against the sternum, and buckle around the widest part of the ribcage without slipping backward into the flank or riding up into the throat.

Why weight guidance misleads for deep chests

Weight is a measure of mass, not shape. Basing harness selection primarily on weight leads directly to sizing errors for deep-chested dogs. Manufacturers that publish weight guidelines base those figures on average breed proportions. A deep-chested dog will consistently exceed the average girth range for its weight category.

For example, a Dachshund may weigh 5kg. Based solely on weight, generic charts often assign this breed to an extra-small or small size. However, the dog's ribcage depth frequently requires a chest strap designed for a larger sizing category. Selecting a harness based on weight leaves the chest strap stretched to its absolute limit, restricting movement or failing to buckle entirely.

Furthermore, several major harness manufacturers do not publish weight guidance at all. Ruffwear, Blue-9, Rabbitgoo, and Puppia state sizing exclusively in terms of chest measurements. Only brands like Julius-K9, PetSafe, and Kurgo publish weight recommendations alongside girth ranges. Even then, weight serves solely as a tie-breaker when a dog falls between two sizes. To find the correct fit for any breed, you should use the sizing tool to match physical measurements directly against published girth ranges.

Measuring deep-chested dogs step by step

Accurate physical measurement is the only reliable foundation for fitting a harness for deep chested dog profiles. Take all measurements while the dog is standing square on a flat surface.

Follow these steps to obtain precise metrics:

• Find the widest point of the chest: Locate the deepest part of the ribcage, situated directly behind the front legs.
• Measure girth: Wrap a soft tape measure around this widest point. Keep the tape snug against the coat, but do not compress the skin. Note the measurement in centimetres.
• Check clearance behind the front legs: Ensure the measuring point sits roughly two to three fingers' width behind the armpit for medium and large dogs, or one to two fingers' width for smaller breeds like Dachshunds or Whippets. Harnesses that sit too close to the armpit cause painful chafing during motion.
• Measure neck circumference: Wrap the tape around the base of the neck where a collar naturally sits. For deep-chested breeds, this measurement is often surprisingly small compared to the chest girth.

If you already hold a size recommendation from one manufacturer and want to compare it across brands, consult the conversion chart before purchasing.

Harness sizing and chest girth comparisons

Because harness sizes are not standardised across the pet industry, a size label from one manufacturer does not correspond to the same label from another. A Medium in one brand may have a girth range that aligns with a Small or Large in another.

Below are the official chest girth measurements published by major manufacturers:

Ruffwear Harness

Ruffwear relies entirely on chest girth for sizing and publishes no weight guidelines:

• XXXS: 23-33cm
• XXS: 33-43cm
• XS: 43-56cm
• S: 56-69cm
• M: 69-81cm
• L: 81-91cm
• XL: 91-107cm

Blue-9 Balance Harness

Blue-9 utilizes a multi-point adjustment system and publishes girth measurements without weight guidance:

• XS: 34-45.5cm
• S: 44.5-64.5cm
• M: 53-81cm
• M/L: 61-90cm
• L: 73.5-110.5cm

PetSafe Easy Walk Harness

PetSafe provides eight distinct sizes to accommodate subtle differences in chest dimensions:

• Petite: 30.5-43.2cm
• Petite/Small: 33-45.7cm
• Small: 38.1-53.3cm
• Small/Medium: 48.3-66cm
• Medium: 55.9-81.3cm
• Medium/Large: 61-86.4cm
• Large: 68.6-101.6cm
• Extra Large: 81.3-124.5cm

Julius-K9 IDC Powerharness

Julius-K9 offers nine size options covering small to giant breeds:

• Baby 1: 29-36cm
• Baby 2: 33-45cm
• Mini-Mini: 40-53cm
• Mini: 49-67cm
• 0: 58-76cm
• 1: 63-85cm
• 2: 71-96cm
• 3: 82-115cm
• 4: 96-138cm

Kurgo Tru-Fit Smart Harness

Kurgo structures its range across five traditional size tiers:

• X-Small: 30-44cm
• Small: 41-56cm
• Medium: 46-71cm
• Large: 61-86cm
• X-Large: 71-112cm

Rabbitgoo ControlPro No-Pull Harness

Rabbitgoo provides five sizes governed strictly by girth:

• XS: 29.5-47cm
• S: 33-59.5cm
• M: 38-70.5cm
• L: 43-85cm
• XL: 53.5-96.5cm

Puppia RiteFit Harness

Puppia publishes girth measurements across four adjustable sizes:

• S: 33-48cm
• M: 38-56cm
• L: 50-75cm
• XL: 55-80cm

Selecting structural features for deep-chested dogs

Beyond raw girth measurements, the physical design of the harness determines whether it fits a deep chest securely. Deep-chested breeds require maximum adjustment independence between the neck loop and the girth strap.

Harnesses with fixed neck openings or rigid chest plates often fail on Greyhounds and Dobermans. If the neck opening is large enough to pass over the head and seat on the shoulders, it may sit too loose once fastened. Conversely, if the neck fits securely, the chest strap may fall short of reaching around the deep ribcage.

Look for Y-shaped harness designs featuring independent adjustment points on the neck, sternum, and ribcage straps. This design keeps the shoulder joints completely free while allowing the chest strap to fasten securely behind the broadest part of the sternum.

Frequently asked questions

Why does my deep-chested dog fall between harness sizes?

Deep-chested breeds frequently have narrow necks paired with disproportionately large ribcages. Weight-based sizing estimates average body proportions rather than extreme depth. When chest girth places your dog in a larger size than neck circumference suggests, always prioritize the chest measurement to ensure proper fastening and clear movement.

Should I size up if my dog's girth measurement is on the boundary?

Yes. If your dog's chest girth sits at the upper limit of a size range, select the larger size. Deep-chested dogs expand their lungs significantly during exercise. Sizing up ensures the harness straps do not restrict respiratory expansion or rub tightly behind the front legs.

Can I fit a deep-chested dog using weight guidance alone?

No. Weight guidance fails to account for chest volume or body shape. Two dogs weighing identical amounts can have chest girths that differ by ten centimetres or more. Manufacturers like Ruffwear and Blue-9 publish no weight guidance for this reason. Girth is the defining metric.

How do I stop a harness from chafing my dog's armpits?

Chafing occurs when the chest strap sits too close to the front legs. Measure the distance from the elbow to the start of the ribcage. Ensure the harness sternum strap is long enough to position the girth loop two to three fingers' width behind the armpit.