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Diagnosing and Assessing Swellings in Horses

Diagnosing and Assessing Swellings in Horses


Swellings are a very common problem in horses. As a result we have a number of different articles on this subject: Skin bumps, hives, and nodules are discussed in their own article: Overview of Bumps, Nodules, & Tumors. Localized swellings associated with heat and pain are discussed at: Abscesses. Generalized swelling, heat and pain of the legs, which are hot and/or painful are discussed in their own article: Hot, Painful, Swellings. In this article we will address non-painful swellings in horses. Swellings of the skin can involve any tissue that underlies the skin. This would include subcutaneous swelling as in stocking up, lymph nodes, joint capsules as in bog spavin and windpuffs, bony swelling as in splints, salivary glands known as sialoceles, guttural pouches, and dozens of other structures that lie under the skin. This article discusses the localization and assessment of swellings. It will then provide links to the articles on the common causes of swellings in horses.

Why Is It Swollen

It is frequently more important to understand "why it is swollen" than know "what is swollen". Without knowing the why you cannot assess the seriousness of the condition or what the proper treatment is. Of course sometimes the what goes hand in hand with the why but there are certain characteristics of any swelling that are determined by the why. The following is a list of the swellings, characteristics, and causes.

1] Passive swelling of tissues or joint capsules

Characteristics: cool and nonpainful, soft to firm to the touch but pits with pressure then slowly refills unless it is joint distension, depending on cause may be bilaterally symmetrical and usually works its way as far ventrally as possible
Possible Causes: poor circulation, venous or lymphatic congestion, tissues that have loss their natural elasticity, heart disease, kidney or liver failure

2] Active swelling of tissues or joint capsules

Characteristics:warm and painful, firm and pits, rarely symmetrical, with time will be pulled ventrally by gravity
Possible Causes: infection, inflammation, or trauma

3] Bleeding and hematoma

Characteristics: warm but may not be painful if not causes by external trauma, if active may be enlarging rapidly
Possible Causes: ruptured blood vessel, clotting abnormalities

4] Tumors

Characteristics: firm and does not pit, usually not warm, may or may not be painful
Possible Causes: cancers, enlarged lymph nodes, thyroid gland, salivary glands

5] Hard swellings on the bone

Characteristics: firm, if caused by trauma may be accompanied by heat and soft tissue swelling
Possible Causes: splints, blunt trauma to the bone, growth plate enlargement, rapidly growing teeth, inflamed tooth roots, osteoarthritis

Specific Examples of Common Causes of Swellings in Horses

Stocking Up

In defined as a cool, nonpainful, low, bilateral swelling usually in the hind legs but possibly affecting the fronts also. Commonly the cause is the decrease circulation caused by horses standing around in stalls or paddocks not exercising. This is a form of passive edema and disappears with exercise and is not accompanied by any other clinical signs. Exacerbating factors can be past serious swellings that have distended the tissues so badly that they have loss their elasticity. Sometimes horses will stock up following exercise. Though this is probably an active edema of the tissues higher up the leg, gravity pulls this swelling into the bottom of the leg and it will feel cool. Though this is a common nonserious condition in horses if the swelling is acute or progressive, or accompanied by signs of systemic illness consider some of the other causes of passive swelling eg:

  • heart disease,

  • kidney disease,

  • liver disease

  • hypoprotienemia

  • congestion of the vasculature or lymphatics.

    Horses with very mild inflammation in the lower legs may appear to stock up. The inflammation is low grade so there is not a lot of heat. If the disease process worsens these may become hot and painful. Some of these causes maybe:

  • skin irritation from mud or early infection,

  • viral infections,

  • bruising in the feet.

    Usually nothing more than turning a horse out to pasture will cure the uncomplicated condition. Horses with moderate to severe stocking up should either not be stalled or pressure wrapped when up to prevent further loss of tissue elasticity and worsening of the condition more on bandaging. Massage or hosing with moderate pressure and warm water can help pick up the fluid (more on counter-irritation). If there is an active component, NSAID's will help. In severe cases diuretics can be administered to help decrease the swelling.

    Ventral Midline Swellings

    Many of the factors that apply to stocking up also apply to ventral midline swelling (swellings of the belly or stomach) discussed above. However, there are some special considerations with swelling of the belly.

    Pregnant Mares
    A healthy mare in the last month of pregnancy will develop VMS that is
    sometimes remarkable. Exercise is still probably the best treatment and it will resolve when the foal is born and begins nursing. If you are uncertain as to what you are looking at consult your veterinarian. There are some less common but more serious causes of ventral swelling in the late gestational mare including: inflammation of the placenta, mastitis, herniation, and prepubic tendon rupture.

    Other causes are:
    A heavy concentration of fly bites or a horse very sensitive to them may develop VMS in the warm months.
    If a slowly progressive nonresponsive swelling is found, lympatic blockage of the deep inguinal lymph nodes should be considered. Tapping the swelling will produce a serous fluid rich in lymphocytes.

    Bog Spavin and Windpuffs

    These are both examples of passive swelling of the joint capsules. Frequently they are bilateral and may represent the accumulated damage or past small traumas to the joint capsule resulting in excess fluid production and distension of the joint capsule. Windpuffs typically are distensions of the fetlock joint capsule and appear as two uniform distensions on each side of the bottom of the cannon bone just in front of the flexor tendons and just above the fetlock. Bog spavin is a large swelling on the front of the hock.
    Once established there is no treatment. While acute, rest, NSAID's, intra-articular steroids and hyaluronic acid, long term pressure wraps and/or oral chondroprotective agents may prevent them from becoming permanent.

    In a sound horse these type swellings should be considered blemishes unless proved otherwise. It should be understood swelling in the joint may also accompany degenerative joint disease and other joint pathology that may or may not be accompanied by lameness.

    Swellings in the Throatlatch Region

    The area where a horses head joins the neck is called the throatlatch. each side as been referred to as Viborgs triangle. This area is a complicted mixture of lymph nodes, salivary glands, large blood vessels and just deep to it all the guttaral pouch. Firm nodules, bilaterally enlarged are usually lymph node enlargements. Firm to flucuant swelling of one side could be an enlarged salivary gland. Generalized swelling of one side may indicate enlargment of the guttaral pouch. Proper treatment will require a diagnosis following a thorough exam and possibly further diagnostic work up. Moderate bilateral swelling of the lymph nodes in this region without fever or other signs of disease is common, usually transient, and do not require treatment. The submandibular lymph nodes may also enlarged. They are the result of mild stimulation, perhaps viral or allergic, and the lack of other signs indicate the body is handling it well. When accompanied by fever this is usually due to either viral or bacterial upper respiratory disease.

    Thyroid Gland

    A commonly found swelling found on the bottom of the neck up close to the head is the thyroid gland. Normally the thyroid sits on top of the trachea and cannot be seen or felt easily but frequently it will fall down just ventral to the trachea. It is about the size and shape of a golf ball cut in half and is not a cause of concern.

    Swellings Along or Under the Jaw

    The horse is peppered with lymph nodes all over the body and these will range in size from the size of a pea up to an several inches across. Frequently the lymph nodes under the jaw or in the throat latch area become enlarged. Usually this represents stimulation from an infection but may or may not be accompanied with signs of illness. When not accompanied by fever or other signs of illness this is usually not a cause for deep concern but should be watched. When accompanied by fever this is usually due to either viral or bacterial upper respiratory disease.
    Bilateral swellings along the bony portion of the jaw are pretty common in growing horses and are a response to active tooth growth. Unilateral swellings in adults may indicate an abcessed tooth root or even a fractured jaw. Radiographs will usually rule in or out these two problems.

    Splints, Spavin, Epiphysitis and Other Bony Enlargements

    Splints generally appear in the area from just below the knee to the tip of the splint bone, which ends about three inches above the ankle.

    These represent traumatic episodes of the bone and joints. Once allowed to heal they will be cold and nonpainful but a bony knot will remain. In time this will remodel and become smaller but will never go away completely. See Splints.

    Bony enlargements around the pastern may represent Ring Bone.

    Ring Bone

    Bony swellings around the inside lower hock may represent bony spavin.

    Both are the bony proliferation associated with degenerative joint disease. The appearance alone may be deceiving and so radiographs necessary to confirm the cause.

    Enlargements around the growth plates of growing horses may represent a pathological condition termed physitis or epiphysitis. Some enlargement may be normal during fast growth. For more information see Physeal Dysplasia.

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