Facts About Equine Respiratory Disease
A horse's respiratory tract consists of two sections, the upper respiratory
tract including the nose, throat (pharynx and larynx) and windpipe (trachea), and the lower
respiratory tract including the lower portion of the windpipe and the lungs (bronchi, alveoli).
Several mechanisms protect a healthy horse from respiratory disease.
- The respiratory tract is lined with mucus-coated cells that trap airborne particles.
- Tiny fingerlike projections (cilia) on the cells' surfaces also work to keep the airway clear.
- Coughing can dislodge inhaled irritants or accumulated secretions.
Despite these natural defense mechanisms, infections frequently develop.
The Equine Athlete
Training and competition place additional demands on a horse's respiratory
system. Increased pressure on the nasal passages often irritates the turbinates
(spiral, spongy bones in the nostril). Likewise, pressure caused by coughing can injure the
turbinates and nasal passages, causing bleeding and making the horse vulnerable to infection.
Incidence of Infection
In a clinical trial conducted by Jonathan H. Foreman, DVM, MS, Diplomate,
ACV/M, 70 percent of the horses transported 320 miles developed a respiratory infection within
10 days of delivery.
Consequences
Respiratory infections in horses can be responsible for:
- diminished performance
- additional cost of re-training after recuperation
- increased animal care and medical costs
- abscesses in the abdomen or chest
- death
Clinical Signs
Clinical signs (objective evidence) of respiratory disease include:
- Depression or malaise
- Anorexia or inappetence
- Nasal discharge
- Cough
- Fever greater than 102.5 degrees F (normal rectal body temperature for the horse
is 100.5 degrees plus or minus 1 degree F)
- Respiration rate of greater than 24/minute
Of course, some of these signs are also associated with other diseases. Your veterinarian
will differentiate the specific cause of the horse's clinical condition from other possible causes.
What Your Veterinarian Needs to Know
Making a differential diagnosis is the process of determining the specific
cause of a horse's respiratory disease in preparation for treatment. The initial evaluation
should include questions about the horse's history.
- How old is the horse and what is its origin?
- Has the horse traveled recently?
- Has the horse been exposed to other horses at racetracks, training stables or breeding farms?
- What is the horse's vaccination record?
- When were the horse's symptoms first noticed?
- What has happened since then?
- Has the horse been treated for respiratory disease before? When and how?
- Has the horse suffered any recent stress, such as overexertion, illness, surgery or transport?
Physical Examination
Your veterinarian will examine the horse carefully, giving special attention
to the respiratory and cardiovascular systems.
- Respiratory rate, heart rate and rectal temperature will be determined.
- The kind and amount of discharge from the nose or eyes will be noted.
- Careful listening to the respiratory tract with a stethoscope in a quiet setting will be performed.
Bacterial Culture
Streptococcus zooepidemicus, a normal resident of the upper respiratory
tract, is the most common bacterial species isolated in equine respiratory disease. In field
trials with NAXCEL® (ceftiofur sodium) Sterile Powder, S. zooepidemicus
was isolated from 80 percent of the horses that developed respiratory disease. Streptococcus equi
is also frequently implicated.
Most bacterial infections in horses are caused by normal inhabitants of the upper respiratory
tract that are inhaled (aspirated) into the lower respiratory tract (bronchi and lungs). These
common bacteria cause disease when the clearance and defense mechanisms of the respiratory tract
are impaired. That is only one reason that bacterial infections often appear in a host already
weakened by a viral infection.
As with all drugs, NAXCEL should not be used in animals found to be hypersensitive to the product.
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