Strangles and Other Respiratory Diseases

With recent strangles outbreaks popping up on equine newsfeeds, concerns about respiratory illnesses have become prominent in almost everyone’s mind. Gallatin, Tennessee, veterinarian Andy Ligon, who holds a doctorate of veterinary medicine and offers his expertise through Cloydland Veterinary Services, weighs in on signs and treatment. Early warning signs

“The first and foremost thing that I will tell an owner is to watch their horse’s attitudes,” Ligon says. “That is the easiest thing they can look for. They know what their horse’s day-to-day routine is.”

Ligon advises observing your horses for changes in activity level, alertness, how they come in to be fed, etc., as these could be early indicators that they are starting to become lethargic, which could be a precursor to sickness.

“Before humans start to run a fever or get sick, they start to feel a little achy, joints will start to hurt and skin can start to get weird sensations,” Ligon says. “It causes us to slow down and want to sit on the couch a little more. With horses, they could potentially be slowing down, walking a little bit more stiffly, being more sluggish and not as happy as they normally would be.”

Disease progression

Ligon explains that once you get past the initial phase, the sickness will start to show itself.

“If you are dealing with a respiratory issue, typically horses are going to stand a little bit wider because they have decreased perfusion to their lungs, and it is more difficult for them to breathe,” Ligon elaborates. “The wider stance is going to open up that chest and allow them to breathe deeper than they normally would because their lungs are going to be compromised from the sickness.”

He says that owners may also be able to hear harsher breathing sounds, such as crackles and wheezes. As respiratory diseases progress, the next sign is nasal discharge.

“In the initial stage, you will have more clear mucus,” Ligon says. “Next, it is going to get a little bit thicker. After that, it is typically going to change to a white-type color. Once the sickness starts, the mucus becomes more yellow, green and sometimes gray. Sometimes, you will see blood. By then, the mucus will be thick and sticky.”

Ligon explains that the mucosal discharge will characteristically present with flared nostrils due to deeper breathing.

“In the worst-case scenarios, you can have some open-mouth breathing and drooling,” Ligon says.

Owners, he elaborates, will also note some swelling of the regional lymph nodes.

“The ones I get most commonly would be the sublingual lymph nodes below the tongue, between the lower jaw,” Ligon says.

After that, he explains, the retropharyngeal lymph nodes around the guttural pouch, located at the throatlatch, will often also be enlarged.

“They will start to get bigger to the left and right side,” Ligon says. “Potentially, you can see some of these enlargements. You may be able to feel those.”

He says these lymph nodes will usually be grape size or, at most, twice the size of a grape. However, as the condition advances, owners will be able to feel swelling that more closely resembles a silver dollar or even a golf ball in size.

“That will indicate a potential infection because those lymph nodes will drain the head,” Ligon says. “In cases of strangles, the guttural pouches are going to get enlarged. You will see some big swellings around the throatlatch. When you start touching those swellings, you will find heat and pain.”

He explains that once the condition has progressed, you will start to see some hair loss because of the focal heat response.

“After that, you will start to see a thinning of the skin and then potential rupture of the abscess,” he elaborates.

When to call the vet

Ligon says the best time to bring your veterinarian on board is when the horse has observable changes. He says that if you catch a horse in the very beginning stages, such as when they are standing a little bit wider or not exhibiting their usual first-to-the-feed pan behavior, then the condition is going to be more difficult to diagnose because the horse does not have any symptoms to go along with the changes in behavior.

“Horses are prey animals,” Ligon says. “They like to mask their symptoms well. In the small beginnings of an infection, they are going to hide that.”

To be safe, at this stage, you may instead wish to isolate the horse away from others, make note of your observations along with the date that you first began to notice the changes and take this time to determine whether or not your horse is truly sick.

The better time to call, he says, is when you start to pick up on one or two small symptoms.

“From there, we can walk the owner through whether or not it is going to be a true emergency or if it is something we need to schedule an appointment that day or maybe later on that week,” Ligon says.

If, for example, the appointment will be later that week, Ligon says there will typically be back-and-forth conversations between the owner and the veterinarian, based on symptoms and severity, and adjustments to timing and treatment can be made as necessary.

“We can almost predict when symptoms are going to start to show up,” Ligon says.

From the initial changes in behavior that an owner may note, observable symptoms of illness, if they are to come, will often appear five to 10 days later.

When respiratory diseases are present, direct touch, either horse to horse or human to horse, can lead to rapid spread. Helpful information

There are several pieces of important information that owners can relay to their veterinarians to better help them judge the timing of their appointments. The first is if the horse is not eating.

“That is a big red flag,” Ligon says. “There is something wrong somewhere. Whether it is a pain response or a true infection response, something is wrong.”

The next important piece of information is whether or not the horse has a fever. For Ligon, any resting temperature reading over 101.5 degrees Fahrenheit is a phone call. Next on the list is defecation.

“If they have not pooped at all, that is a red flag,” Ligon says.

Other changes to your horse’s defecation to note that also warrant a call to your vet are blood or mucus in the stool, straining to defecate, or small, hard fecal balls, as the last is an indicator of dehydration.

Proactively speaking

In terms of vaccinations, strangles is considered risk-based rather than a core vaccine. Core respiratory vaccines for horses are West Nile Virus, Eastern Equine Encephalomyelitis and Western Equine Encephalomyelitis. Other risk-based vaccines Ligon recommends are rhinopneumonitis and influenza. While required for competition in rated shows, Ligon recommends these not only because these diseases can spread quickly but also because they can be deadly to immunocompromised horses. Venezuelan Equine Encephalomyelitis is considered another risk-based vaccination.

Certain vaccinations are considered core because they can be transmitted not only through other horses but also through vectors such as insects. On the other hand, strangles is a bacterial infection.

“You are never going to have an amazing strangles vaccine because you are vaccinating against a bacteria,” Ligon says.

Still, he advises any of his clients who board their horses, operate an equine facility, import or export horses, or have horses going on or off property for showing or trail riding to vaccinate against the disease. He explains that horses can have physical contact with unfamiliar horses anywhere, either directly or via water tanks, buckets, etc., and should be vaccinated against strangles. This, he explains, is because strangles can rapidly spread via horse or human contact during the most routine of care, such as feeding each horse in the barn.

Prevention is critical as strangles can be more than just a common respiratory illness. Ligon explains that as the guttural pouches swell, they can cause the trachea or windpipe to collapse leading to death. He says that “bastard strangles” can also present along with strangles.

“Instead of the bacteria setting up shop in the guttural pouches, it can go in any regional lymph node,” Ligon explains.

Just a few locations in which it can be seen are in the pectoral, abdominal, and rectal lymph nodes or in lymph nodes around the legs. Ligon says that when the lymph nodes either rupture or the horse gets enough of those bacteria where its body is trying to get rid of them, the bacteria will go through the arterial or venous system.

“Then the horse gets septic, and they can potentially die from that,” Ligon says. If the lymph nodes rupture, bastard strangles are then in the body cavity. If, for example, the rupture occurs in the abdominal cavity, the horse can develop peritonitis, another potentially fatal condition.

Dr. Ligon recommends certain vaccinations for any horse who may come into contact with unfamiliar horses. Choosing the best strangles vaccine

Even though vaccination is no guarantee, there is a preferred vaccination route that can lead to improved results. The strangles vaccine can be administered intranasally or intramuscularly.

“The intranasal vaccine is significantly better,” Ligon says.

The reasoning behind this is that the horse’s body will develop an immunoglobulin E response to this type of vaccine.

“It is a focal response,” Ligon says.

He explains that the horse’s white blood cells will remember the vaccine, and when the B cells encounter strangles, they will set up the desired instant, focal response in the nasal passageways.

On the other hand, when the vaccine is administered intramuscularly, it must go through the muscle tissue to the venous or arterial system, to the regional lymphatic system, and, finally, to all of the immune system before confining itself to the respiratory tract. You still get a response, Ligon explains, but it is not as focal.

Prevent, reduce and slow

Knowing your horse can go a long way toward improved outcomes. Ligon advises that horse owners should know how to give a basic physical exam. He explains that by vaccinating, knowing the basic heart rate (28 to 46 beats per minute), respiratory rate (8 to 20 respirations per minute), and temperature (99.5-100 F) of horses, being observant for early changes in behavior and acting upon those and calling your veterinarian when the earliest symptoms of illness appear can bode well toward prevention, reduction in severity and slowing the spread of many respiratory diseases.

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