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Hypertonicity - Muscular Injury Series Part 6

Updated: Feb 21, 2023

Before I can explain what hypertonicity is and how debilitating it can be for your dog it is important to gain an understanding of what muscle tone is and the role that it plays.

Muscle tone

Muscle tone is the constant low-level contraction of skeletal muscles at rest. It is controlled by the Central Nervous System (CNS) and is essential for a dog to be able to function effectively. Muscle tone has many functions,

Posture/ balance – Your dog’s skeletal muscles have two types of sensory receptors (proprioceptors) to monitor its tension (Golgi tendon organ) and length (muscle spindle) (Refer back to Part 2B in the series for more information). Together they provide information to the CNS about the position of individual body parts. The skeletal muscles of the axial skeleton (core) function almost continuously, making tiny adjustments to maintain a standing, seated or static position, even when asleep.

Stabilisation of the joints (both statically and dynamically) – Static requires a low level of muscle tone and refers to stabilizing the joints when the body is at rest i.e. sleeping or sitting. Dynamic refers to stabilizing the joints when the body is active, therefore relatively high muscle tone will be required. The dog’s body will always rely on muscle tone to keep joints stabile as the joint capsules and the ligaments are not designed to support the joints by themselves.

Assist venous return - Venous return is the flow of blood from the extremities of the body back to the heart (right atrium) via veins.A collection of skeletal muscles called the skeletal-muscle pump supports the circulatory system and increases venous return.

Heat Production - The average temperature of a healthy dog is 38 degrees Celsius. The body must maintain this temperature regardless of the external temperature. 70% of a dog’s body heat is created by energy produced in muscles via contractions.

Safety mechanism - Muscle tone can also act as a safety mechanism keeping your dog primed and ready for action. For example, being startled by a loud bang or noise. If you palpate (feel) the muscles of your dog whilst they are asleep you will still feel a certain degree of firmness (tension).


Hypertonicity means too much resting muscle tone (tension). It is a very common condition which occurs when a muscle has been overused. Overtime the muscle becomes tightened and shortened and will remain in a constant state of mild contraction. This is not to be confused with a well-toned/ developed muscle due to strengthening and/or exercise. The muscle is sick not fit!

A hypertonic muscle is inflexible and will require more effort than is necessary to produce the movement of a healthy muscle. This causes the muscle to become fatigued and movements to become less fluid. Take the example of vacuuming the carpet. If you are hypertonic in your neck and shoulders, you will feel stiff and in some level of discomfort. You will vacuum slower and use smaller movements. However, you will feel that you have had to put in more effort to complete the job.

Symptoms of Hypertonicity

· Muscle can appear bulbous and will feel hard/solid to touch - Common areas of the dog’s body include the Iliocostalis Lumborum (lower back) and Gluteals (buttocks).

· Variations in normal posture – different stance or sitting position, altered neck or tail carriage

· Reduced range of movement/ level of performance - decreased ability for the effected muscle to lengthen and contract

· Altered gait patterns

· Increased energy demands – fatigues more quickly

· The muscle will give off a dull persistent pain and will produce a pain response when touched.

Health effects of Hypertonicity

· Higher risk of developing strains and trigger points – due to tension

· Excess pressure on the associated joints – Aggravating or causing early onset of orthopaedic conditions such as arthritis

· Nerve impingement – caused by too much pressure in the muscle can cause pain, tingling, numbness, or weakness.

· Dull chronic pain

· Increased pressure on associated arteries, veins and lymphatic vessels – This decreases circulation of blood and lymph, reduces the ability to remove metabolic waste and de-oxygenated blood (venous return, lymphatic drainage) from effected muscles and the ability to deliver fresh oxygen and nutrients to effected muscles.

Benefits of Canine Massage

If acted upon quickly hypertonic muscles respond almost immediately to clinical canine massage therapy within just a few sessions. However, there are plenty of variables which can affect how your dog will respond to treatment including the amount of time your dog has been hypertonic, their age, other existing, underlining health conditions and level of fitness.

Massage helps by!

· Reducing muscular tension – muscle is more flexible as the muscle fibres can lengthen and contract efficiently

· Reducing/ resolving lameness and stiffness resulting in improved range of motion

· Reducing muscular related joint pain

· Return to normal daily activities

· Improved balance and posture

· Increased performance in sports

· Improves circulation – removes metabolic waste and delivers fresh oxygen and nutrients to muscles. This speeds up recovery time.

It’s simple, relieve the muscles of their hypertonicity. If the pressure is released and movement is reintroduced, over time the body will deconstruct the fibrous restrictions. In many cases you will have a dog that is pain free and able to return to normal daily activities. In some cases where this cannot be achieved at the very least you will have a dog with improved comfort levels and mobility.

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