Hydrotherapy for Animals-The Basics

Hydrotherapy for animals must be distinguished from aquatic therapy for animals and physical therapy rehabilitation in water for animals. While aquatic therapy for animals is technically hydrotherapy because of its use of water for therapeutic purposes, the techniques of aquatic therapy are focused on physical rehabilitation for animals through exercise in water with or without a submerged treadmill. For more information on aquatic therapy or water therapy for dogs check out the Association of Canine Water Therapy website or the Canine Hydrotherapy Association website. Generally in the veterinary medical field a well trained veterinary physical therapist would be doing the treatments with a focus on physical rehabilitation after injury or surgery. To find an animal physical therapist go to Animal Rehabilitation Special Interest Group which is a part of the APTA. At this point in time there is a lot of interest in the veterinary physical therapy field and the animal massage therapy field in working with animals in water for rehabilitation purposes. I am sure that the AVMA, the APTA and different animal massage special interest groups will be butting heads over this field soon.

The focus of this blog will be on the use of water in its three forms; solid, liquid and gas and the various applications of these three forms to treat specific pathologies that present themselves in the animal. Since this will be an ongoing topic I will start with basics. Animals have been treating themselves with hydrotherapy since the beginning of their existence. In fact without water there would be no life and dehydration in any life form leads to disease. The water hole has been the site of many a cross species truce when water supplies are low. Animals have been bathing for health forever and many roll in the mud after. Drinking water at various temperatures with various ingredients added is a form of hydrotherapy. Water is the closest thing we know to a universal solvent. Whether we are using water to treat internal conditions through infusions or applying water to the surface of the body with various degrees of temperature, mechanical pressure or friction we will cause a physiological response to the treatment and this is where we will start.

When we apply a heated pack on the surface of the body the body responds to the heat by initiating vasodilation thereby moving more blood to the area to pick up the heat. Blood is approximately 82% water and one of the major qualities of water is it’s high capacity of heat which means it has the ability to absorb and release heat. Blood coming to the surface picks up the excess heat that is being applied to the surface of the skin and redistributes the heat evenly throughout the blood stream. When we apply cold packs to the body the blood comes to the surface to heat up the area under the pack. There are primary responses and secondary responses in the systems of the body as we apply hot or cold packs to the body. We can apply hot and cold packs at varying degrees of temperature and varying lengths of time duration. In general, the higher or lower degrees of temperature that are applied to the body have a more powerful physiological effect and the shorter the time the pack is on, the more powerful the response will be. So duration of treatment and degree of temperature are critical in getting a desired therapeutic effect.

There are three phases of reactions that the body goes through with the application of hot or cold to its surface: circulatory, nervous and metabolic. The nervous system reacts to temperature changes at the surface of the body through its thermoreceptors. Thermoreceptors in the integumentary system sense changes in temperature at the bodies surface and relay this signal through the spinal cord to the area of the brain that regulates the bodies temperature. This regulatory center then responds to any temperature changes that vary from desired homeostatic norms by releasing chemicals or by triggering a motor neuron response to the stimulus. For example if cold is applied to the surface of the body a thermoreceptor under the skin in the area that the cold is applied sends a signal to the lateral spinothalmic pathway of the spinal cord which then sends this signal to the somatosensory cortex of the brain for interpretation. Once this signal is interpreted by the somatosensory cortex it then sends a signal down a motor tract to the errector pilli muscles that cause them to contract and lift the hair up on end to provide loft to the hair coat to trap heat close to the body. Another motor signal will be received by muscle cells to cause them to contract and shivering will start to take place. The shivering will generate heat as the muscle cells break down glucose into ATP for muscle energy. Simultaneously the autonomic nervous system will cause its sympathetic branch to stimulate contraction of muscles around the blood vessels to constrict the blood vessels to prevent the cold from reaching the more vital organs of the body. This last response would be a circulatory system response to the cold. Muscles contracting to promote heat build up in the area would be a metabolic response to the cold. The stronger the cold the stronger the response will be.

The size of the area of applications must be considered as well. Whole body applications of hot or cold will have different effects on the systems of the body. So we need to understand local responses to hot and cold and whole body system responses to hot or cold applications.

Definitions of water temperature are as follows:

Possibly injurious temperature is 125 degrees F. or 50 degrees C. In cases of diabetes even 110 degrees F. can be injurious.

Painfully hot temperature is between 110-120 F or 42.8-46 C

Very hot temperature is between 104-110 F or 40-42.8 C

Hot temperature is between 100-104 F or 38-40 C

Neutral temperature is between 94-97 F or 34.4-37 C

Warm temperature is between 92-100 F or 34-38 C

Tepid temperature is between 80-92 F or 27-34 C

Cool temperature is between 70-80 F or 21-27 C

Cold temperature is between 55-70 F or 13-21 C

Very Cold temperature is between 32-55 F or 0-13 C

In the next hydrotherapy for animal blog I will talk about applications of cold to very cold therapy and the physiological effects of these applications.