The large variation in body type, conformation and size in our canine patients makes it necessary for us to treat each dog as an individual when assessing outcome measurements such as passive range of motion, as measured with goniometry.
Significant variations from the norm occur among dogs of different body types, breeds and sizes. Understanding these variations can help us to evaluate the normal or pathological state of our patients more accurately.
Let’s discuss the literature and variations in measurements found in different breeds and types of dogs.
Passive range of motion and joint function
Joint function or health is commonly measured with the use of goniometry, measuring the angle of flexion and extension of individual joints. We can use goniometric measurements in a few ways to assess the health and function of a joint.
Identifying a restriction or laxity in a joint is usually the first observation we make when using goniometry in our patients. When we can compare the joint of one limb to the parallel joint on the opposite limb, we can compare the dog to itself, but this requires a healthy opposite limb and joint. If a healthy joint is not available to compare to, we compare the angles we measure to what the literature has shown us to be normal ranges for a specific joint. The challenge with this approach is that there are significant differences between the ‘normal’ of different breeds, sizes and types of dogs.
Our clinical skills will also assist us here, as we will be able to identify abnormal end ranges by feel, instead of only by the measurement taken.
Measuring the progression of disease or rehabilitation is the other essential use for goniometry. In this way we are again comparing the dog to itself, and measuring the efficacy of our interventions; for example, we may want to decrease range of motion in a patient with joint laxity, by strengthening the musculoskeletal units responsible for flexing the joint. Goniometry allows us to compare flexion and extension values in the patient over time.
Reliable readings
Goniometry has been shown to have excellent inter-tester and intra-tester reliability in studies evaluating Labrador retrievers and in cats (Jaegger et al., 2020; Jaegger et al., 2007). In order to achieve reliable and repeatable results, we need to use goniometry in a reliable and repeatable way.
Patients should be placed in lateral recumbency without sedation, and the vertex, mobile and static arm should be positioned according to specific bony landmarks, as described in a recent Research Refresh (Reusing et al., 2020). Table 1 below gives the anatomical reference points for this process.
Source: Reusing et al., 2020.
Our accepted normal ranges
In the Millis and Levine textbook, the following table describes what we consider to be normal ranges of motion in our patients:
Source: Millis & Levine 2012, Gayle et al., 2002.
From this table, we can see that certain joints have a much larger range of normal values than others; the shoulder, for instance, has a 30-degree range, while many others have a 10-degree range of normal values, and others have no range at all.
Different breeds evaluated
In a study of 16 Labrador retrievers, the following goniometric measurements were taken.
Source: Millis & Levine 2012, Gayle et al., 2002.
In a study of 20 French bulldogs, the following goniometric measurements were taken:
Source: Rezende Formenton et al., 2019.
In a study comparing chondrodystrophic dogs (CD) to non-chondrodystrophic dogs (NCD) of different breeds and sizes, the following measurements were obtained:
Source: Reusing et al., 2020.
Let’s consider some of the values above and compare them to one another. The range of normal shoulder flexion is the widest, from 30-60 degrees, according to Millis and Levine, 2012.
- In Labradors, shoulder flexion is around 57 degrees.
- In French bulldogs, we see 51 degrees of shoulder flexion.
- In small CD dogs, we are in the normal range at 59 degrees, while medium CD dogs are outside that range at 73 degrees.
- NCD dogs all fall into the normal range, except for large NCD dogs who have 70 degrees of shoulder flexion.
If we consider normal shoulder extension to be between 160 and 170 degrees:
- Labradors are perfectly within that range at 165 degrees;
- French bulldogs are also within the normal range at 160 degrees of extension;
- CD dogs have far less extension, at 138 degrees;
- Many of the NCD dogs also have less extension, with the different sizes of dogs measuring 126 (large), 137 (medium), 140 (small), 151 (miniature), and 158 (giant).
In this one joint, we can see variation between normal values in healthy dogs of different breeds, types and sizes. Understanding these differences and how the joint angles are affected by these variables can help us to more accurately assess and understand the normal and pathological state of our individual patients.
Conclusion
When using goniometry, always be precise with controlling variables such as the patient’s position and mental state, and the placement of the goniometer according to specific bony landmarks. Most importantly, consider the patient in front of you as an individual as you evaluate the readings from your goniometry measurements. Taking clear note of the end feel of the joint is also an essential aspect of determining the health status of a specific joint.
References
- Jaegger, G., Marcelin-Little, D. Levine, D. 2020. Reliability of goniometry in Labrador retrievers, American Journal of Veterinary Research.
- Millis & Levine 2012, Canine Rehabilitation and Physical Therapy (2nd edition)
- Reusing M., Brocoardo, M., Weber, S. & Villanova J. Goniometric evaluation and passive range of joint motion in chondrodystrophic and non-chondrodystrophic dogs of different sizes. VCOT Open 2020;3:e66–e71.
- Rezende Formenton M, Goncalves de Lima, L., Gardilin Vassalo, F., Guilherme F.J.J., Petrocini R.L, Tabacchi Fantoni, D. 2019. Goniometric assessment in French bulldogs, Vet. Sci.
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