February 2023 NL

Strangles

Starving neglected horses.   We see the online pictures of horses at the sale and want to give them a better life.  If you are able to responsibly rescue and rehabilitate a sale or kill pen horse, precautions must be taken to protect your other horses at home from getting sick.  Most of the strangles cases seen by Dr. Hayes are sale and kill pen horses.  ALL new horses should be isolated for 4 weeks for observation.  If the rescue horse has or develops a snotty nose and fever, there is a good chance that it has strangles.  Now you have just brought it home.  Strangles is a highly contagious upper respiratory disease caused by a Strep infection of the nose, pharynx, guttural pouches and throat lymph nodes.  The Strep equi bacteria is inhaled in the nose or drank from the contaminated water trough.  It then enters the lymph nodes of the pharynx and under the jaw by the throat.  These lymph nodes enlarge sometimes impinging on the trachea causing difficulty in breathing (hence the name Strangles).  The lymph nodes fill with pus and then rupture releasing the strep filled pus out the nose or jaw and into the water trough where it can live for 30 days.  The Strep equi bacteria is also in the guttural pouches, sinuses, and throat where it can be shed nasally by the horse for 30 days with no signs of external abscesses.

Strangles Signs

1. Fever of 102 or more.  Fever is the first sign 3-4 days after exposure, and can last 7-28 days until the abscesses rupture. 
2. Snotty nose.
3. Enlarged or ruptured pus draining abscesses under the jaw, above the eye, or in the throatlatch.  The abscesses can also occur inside the top of the hind leg or internally (so called Bastard Strangles).
4. Extended head position and difficulty breathing.
5. Severity of the disease varies with age and immunity from previous infection or vaccination and with the strain of the Strep equi bacteria.

Diagnosis

Diagnosis is made from clinical signs of fever, enlarged or ruptured jaw lymph nodes.  Pus coming from the lymph node can be cultured to confirm strep equi.  When the horse has a fever of 102+, nasal swabs of the snotty nose can be sent off for a PCR test to check for Strep equi, Flu or Rhino EHV1.   A nasal wash of the throat or guttural pouch can confirm the horse has cleared or still shedding the Strep equi.  This is the best way to check for those asymptomatic carriers.

 Treatment

1. Give Banamine or Bute for the fever.
2. Dr Hayes will lance the strangles abscesses under the jaw and have you flush them with mild iodine twice a day.
3. Penicillin is only given if the horse cannot breathe or has purpura severe swelling of the legs.  Otherwise, it prolongs the abscess rupture and the disease. 
4. Four weeks after the horse has healed from the ruptured lymph nodes and snotty nose, a guttural pouch wash sample is collected and sent off for testing.  The guttural pouch can be flushed and treated at this time, especially if there is pus coming out of it as seen on the endoscope exam.  If the test is positive, we treat the guttural pouches, then test & treat again in 4 weeks until we get a negative test.

Prevention

1.  Isolation of any new horse or mini especially from a sale or rescue for 4 weeks.  Also isolate mares and babies that have returned home from the breeding farm.
2. Nasal wash PCR or do two blood test titers to check for asymptomatic carrier state of a new or isolated horse.
3. Vaccination with two intranasal or intramuscular vaccines six and three weeks before departure to the breeding farm or trainer (Do not vaccinate during an outbreak)
   
   

Strangles Outbreak Management

1. Do not move any horses.  Quarantine all horses in their pastures and barns.  (The only way that you are allowed to move a horse is to move the sick one to an isolation stall or barn if you have one)
2. Obtain history of any new horse brought in last 2 months to determine source of the infection.
3. Keep all horses in the location (pasture or barn) where the outbreak began. This is the RED zone. These horses have been exposed and will get sick with Strangles and 1 of them is your shedder the source of the outbreak
4. Identify the horses that have had nose to nose contact, share a common fence or water trough with the sick horses. This is your YELLOW zone  These horses have be exposed and can get sick.
5. Identify the horses with no contact, no common fence line or barn.  This is the GREEN zone.
6. Feed, hay and water the green zone first   Don’t go back there after you went to yellow or red
7. Take temperature of yellow zone horses am and pm to find the new sick ones.  Feed the yellow zone. Empty the water trough daily, scrub with dilute bleach and then fill.
8. Take temperatures of the RED zone horses to identify the sick ones. Give the horses with fever Banamine or Bute.  Feed the red zone.  Empty and bleach the water trough daily.  Spray Lysol on your shoes and go change your clothes and jackets.
9. Repeat the green to yellow to red zone temperature, feeding and water change in the evening.
10. PCR test the RED and Yellow horses 4 weeks after the last horse has healed from the ruptured strangles abscesses to identify the carriers.  Treat the carriers and test again in 4 weeks.

Last year Hayes Equine did a study with Merck vaccine company where we nasal swab tested 10 horses that had a snotty nose and 102+ fever.  1`/3 of the horses tested positive for strangles with no enlarged lymph nodes.  Two of the horses were rescues. One horse got it from new miniature horses that were brought in with a snotty nose and cough, and later a lymph node abscess rupture.  This year Dr Hayes’ horse at the trainer got strangles when a new weanling with a snotty nose arrived from the Kentucky sale and was put next to her horse.  Because those two horses were in a separate barn with runs, quarantined, fed last with disinfection, and handlers changed clothes, no other horses got it.  Lesson learned: ALWAYS QUARANTINE THE NEW HORSE FOR FOUR WEEKS.

 There is another Strep bacteria that can cause one enlarged lymph node called Strep Zoo.  It is not very common.  There is not any fever with it.  Sometimes it follows a snotty nose, cough, or mild upper respiratory infection.   The horse with one large jaw lymph node shows no sign of sickness, eats, rides etc.  It settles into the one lymph node below the jaw and causes a large lymph node for a month rarely rupturing.  When it gets ripe then I lance it.     Another cause of enlarged lymph nodes under the jaw is when the horse has a virus.  The lymph nodes become a little enlarged.  The difference is that the lymph nodes are soft and not painful. 

Strangles lymph nodes are always hard and painful.

Castration Signs:  February 18^th thru February 24^th