Swollen Glands in Horses

Anatomy of the Horse Head and Throat Latch Area

• The horse’s head is chock full of stuff that can get swollen, like lymph nodes and salivary glands. The ones to watch out for are the mandibular lymph nodes, the retropharyngeal lymph nodes, and the parotid salivary glands. In the head and throat latch area of your horse, it’s relatively easy to notice salivary gland or lymph node swelling.

The lymphatic system in horses

• Along the circulatory system’s vessels reside the lymphatic system’s vessels, which carry lymphatic fluid. The entire system contains large organs, the thymus and the spleen, plus bone marrow, about 8000 lymph nodes (for horses, we have far less), ducts, and lymphatic vessels. This maze of structures carries lymph fluid.

Functions of the lymph system

• Pick up and drain extra fluid. Some liquids seep out of the bloodstream into surrounding tissues. The lymphatic system collects this extra fluid to prevent the accumulation of fluid in damaged areas (swelling). The lymph system returns the fluid to the bloodstream.

• This amazing network is a part of the immune system, too, and makes lymphocytes (a white blood cell) to fight infections. Bacteria and viruses are picked up by the lymphatic fluid to be destroyed by the lymphocytes.

• The lymph system also keeps the body’s fluids balanced in and around the cells.

Lymph nodes

• Your horse’s extensive network of nodes serves a few critical functions. These small, bean-shaped structures act as filtering stations for lymph fluid. As the fluid passes through a node, bacteria, fungi, and viruses are separated and obliterated by the lymphocytes.

• When nodes are actively fighting infections, they swell, which you may notice around your horse’s throat. You will notice swelling in the nodes close to the parts of the body most affected.

• The mandibular lymph nodes are located between the lower jaw bones (the mandibles) and are closer to the nose.
• The retropharyngeal lymph nodes are located near the throat latch.

Salivary glands

• These parts of the digestive system secrete saliva to help your horse chew and digest food. Saliva aids in swallowing, too. Horses have a constant stream of saliva, which helps them to clear bacteria and viruses, too.

• The parotid salivary glands are between the base of the ear and the jaw.
• The mandibular salivary glands are also along the upper jawbone.
• The sublingual salivary glands are under the tongue.

Pouches

• Only a few species have these weird pockets. Horses have two air-filled pouches in the head that hold about 12 oz. We can’t say with certainty what they are for, but it’s believed that these special pockets:

• Help cool the blood going into the brain. Major arteries, like the carotid, align with the guttural pouches, and it’s assumed that the air helps cool the blood going into the brain.

• They may also help balance air pressure.

• The location also surrounds nerves that control swallowing, blinking, and other life-dependent functions, and it’s thought that the pouches help protect that area and functions.

• It’s basically an air-filled pocket that branches off from the horse’s Eustachian tube (the tube that connects the middle ear to the throat). Horses have two guttural pouches—one on each side of the head—located just behind the jaw and below the ears. Each pouch can hold about 300–500 milliliters (about the size of a soda can).

• The guttural pouches branch off from the Eustachian tube that runs from the inner ear to the throat. They are behind the jaw and below the ears.

This article has a cursory image of the major glands in the head and neck area.

Why a Horse’s Glands or Lymph Nodes Swell

• You may notice that something around your horse’s throat/ear/neck area is puffy. The many structures in the area can swell for many reasons, including:

• Local infection. The mandibular lymph nodes might swell if a tooth (or something else) is abscessed or otherwise infected. Of course, an infection is painful and needs the vet’s attention. Many broken teeth and abscessed teeth create painful chewing, food dropping, and a foul smell coming from your horse’s nose and/or mouth.

• Grass! Yes, grass. Some horses react to a toxic fungus on weeds or clover in the grass that causes the parotid salivary glands to go into overdrive. This is known as the clove slobbers. Removal from the grass for a day usually clears things up.

• Grass glands or grass mumps is the term for an allergic reaction, in the grass or otherwise, that causes the parotid glands to swell.

• Something worse, like strangles. This highly contagious condition involves all sorts of swollen glands that can actually rupture. A fever and nasal discharge accompany it. I can’t stress this enough – it’s highly contagious and definitely needs a vet – pronto! Daily temperature checks and vital sign observations are key to catching all sorts of things early – including strangles.

• Guttural pouch empyema. You may also see swelling when pus and infection fill the guttural pouch.

• There may also be a fracture of a tooth, or part of the jaw or skull.

More on the clover slobbers can be found here.

You can read more about grass mumps here.

Strangles and Swollen Glands in Horses

• Strangles is a wildly contagious bacterial infection. The Streptococcus equi bacteria typically infect the upper respiratory tract, causing symptoms such as fever, nasal discharge, lethargy, and swollen lymph nodes around the throat latch area.

• The lymph nodes can become infected abscesses, which may rupture and drain. Breathing may become difficult, hence the name strangles. Horses may also cough, lose their appetite, and exhibit signs of depression and lethargy.

• Not only is strangles highly contagious through direct contact, but it can also be transmitted via shared buckets, water, or feeders. Horses can also pick it up from your hands and any contaminated surfaces.

Bastard strangles

• Bastard strangles happen when the bacteria spreads to other parts of the body via the bloodstream or the lymphatic system.

• It’s as bad as you think, and can be fatal. Horses will have your typical signs of strangles, plus they may have abdominal pain (colic), swollen legs, bleeding under the skin, and abscesses in organs like the lungs, kidneys, and liver.

This article has some photos of active strangles cases.

Abscesses

• Swollen glands in horses may be the result of an abscess, which is a closed collection of white blood cells and bacteria. Like a pimple, but anywhere, and of any size. They are often hot and accompany a fever.

• Any abscess in the head area should be treated as Strangles until otherwise confirmed. These infections may be related to a fractured tooth, a dental infection, a foreign body like a fox tail, or a wound. Puncture wounds are notorious for scabbing over and leaving a deep pocket to collect pus and make an abscess.

• This is definitely a time to call your vet and have them investigate. Veterinary protocol may include taking a biopsy of the area to test for bacteria, an ultrasound to look for underlying causes, or scoping to examine the guttural pouches.

• The specific treatment will align with the cause.

Read more about dental trouble in horses here.

Parotiditis

• Swollen parotid glands create parotiditis, also known as grass mumps. It’s thought that this inflammation is pasture-related, with some pollen, mold, or grass triggering allergies. And yes, it can resemble strangles, but without any other symptoms like fever or nasal discharge.

• Usually, the parotid glands swell without pain and are more noticeable in spring or fall. The swelling may subside quickly after they are removed from grass pasture. It may also be an injury triggering the swelling.

• It may also be linked to sialoadentis, a bacteria infection of the salivary glands. Often this is painful and may lead to abscesses. If your horse grows stones in the salivary gland, it’s sialolithiasis.

Fractures

• Horses can fracture their teeth, jaw, orbits, and other parts of their bodies. Swelling is a definite sign of disease and injury, and your horse will need X-rays or other diagnostic imaging to see the extent of damage.

• Aside from swelling, you will most likely notice your horse drooling or having trouble eating. They may also become head shy, and show colic-like signs or have an elevated heart rate as related to pain. One side of their face may droop. You may be able to feel or see dents, bumps, or other changes to the bone.

• Dental issues like broken teeth often show up as quidding, dropping feed, a funny mouth odor, or decreased appetite.

Guttural Pouch Empyema

• Empyema of the guttural pouch occurs when the air spaces fill with infection. Sometimes, the pus will harden into balls called chondroids. You will see nasal discharge, swelling, and fever, and your horse will have trouble swallowing. And yes, this looks like strangles. Your vet will need to use endoscopy to see inside the pouch, and likely flush the area (lavage).

• This condition is usually caused by a secondary infection after strangles. You may also see a stiff head carriage, and your horse’s breathing may change.

Course of Action for Swollen Glands in Horses

• First, don’t panic. A quick assessment of your horse’s vital signs, especially their temperature, gives you more information as to how your horse is actually feeling.

• Then, back up and look at the big picture. Is your horse acting off or strange? How are the nose and eyes? Are they eating, drinking, peeing, and pooping as usual? 

• How are they eating and drinking? Swollen glands in horses may impact their chewing ability.

• Take a quick peek at the other horses in the area. Do they have swollen throat latches? Do any of them have a fever?

• Has your horse recently changed paddocks or pastures, exposing them to new weeds to chew on? Have you been to a horse show lately?

• It’s always worth a call to your vet for guidance. The primary reason for early veterinary intervention is to prevent the spread of any infectious diseases and to get your horse some relief, pronto.

Diagnostic Procedures and the Physical Examination

• Your vet will examine your horse and take their vital signs during a physical exam. A fever is a strong indicator of an infection, as is nasal discharge.

Depending on what your vet finds on the initial exam, they may need to:

• Send a sample for a bacterial culture to identify the type of bacteria and the appropriate antibiotic, if needed. This step is vital for confirming strangles.

• Do a PCR test to detect Strep. equi. This polymerase chain reaction test is much faster than a culture and looks for specific bacterial DNA.

• Your vet may need to lance and drain abscesses and take X-rays to look for dental issues. In some cases, if they suspect the guttural pouch has a problem, your horse can have endoscopy to visualize the area.

• Prescribe pain medications or other treatments, which may need repeating.

• Monitor the other horses in the barn for similar clinical signs and swellings.

You might find swelling along the throat latch area, or in between the jawbones.

Treatments for Lumps and Swellings Beyond Antibiotics

• Antibiotics are usually part of the protocol for infections, like strangles or abscesses caused by other things, like dental issues.

• Your horse may need more than that, including flushing of the wound, compresses, hosing, bandaging, and anti-inflammatory medications (NSAIDs) or other pain medications.

• You may need to reduce or eliminate pasture grazing if grass mumps becomes a considerable problem. If you can isolate potential allergens, it will be easier to manage, too.

• Because of the highly contagious nature of strangles, which causes swollen glands in horses, it’s always best to isolate any suspected horse from the rest of the herd and follow strict protocols for isolation to reduce the risk of spreading this disease to other horses.

• Taking the vital signs of every horse on the property is best to ensure you have isolated any contagious diseases. Twice a day, even, to be on the safe side.

One last point to hammer home – knowing what’s normal, using your hands to inspect your horse’s whole body, and taking your horse’s temp daily will alert you to things before they go sideways badly.