Equine Respiratory Diseases

Respiratory diseases in horses are very common and have a variety of different causes. Infectious respiratory diseases caused by bacterial and viral infections.
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The etiology is unclear, but viral respiratory infection EHV-2 , allergy, and environmental factors may play a role in the pathophysiology. Reactive airway disease heaves is triggered by exposure to organic dusts in older horses with a genetic predisposition to allergic airway disease. Small airways are obstructed by bronchoconstriction and excessive mucus production.

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The severity of clinical signs ranges from exercise intolerance to dyspnea at rest. The respiratory system is one of the most accessible body systems to test diagnostically. Endoscopic examination allows direct visualization of the upper respiratory tract, guttural pouches, trachea, and mainstem bronchi. Indications for endoscopic examination include upper airway noise, inspiratory difficulty, poor exercise performance, and unilateral or bilateral nasal discharge. Radiographs of the skull are indicated to investigate facial deformity, abnormalities of the sinus sinusitis, dental abnormalities, and sinus cyst , guttural pouch empyema, tympany , and soft-tissue structures epiglottis, soft palate.

The most important techniques for evaluation of lower respiratory tract secretions are transtracheal wash and bronchoalveolar lavage. Transtracheal wash is indicated to obtain secretions for bacterial and fungal culture of the lower respiratory tract. Bronchoalveolar lavage is indicated for cytologic evaluation of the lower respiratory tract in animals with diffuse, noninfectious pulmonary disease.

Nasal swab culture is inappropriate for investigation of pulmonary infectious disease but is indicated for horses with suspected strangles infection. Thoracic radiography and ultrasonography are valuable for assessing lower respiratory tract disease. Thoracic radiography is used to identify abnormalities of the pulmonary parenchyma, mediastinum, and diaphragm. Pulmonary consolidation pneumonia , peribronchial disease, pulmonary abscessation, interstitial disease, and mediastinal masses neoplasia, abscess, granuloma are most easily identified via thoracic radiography.

Thoracic ultrasonography is the most appropriate technique to evaluate fluid in the pleural space, peripheral pulmonary consolidation, and peripheral pulmonary abscessation. Diagnosis of strangles involves culturing, or a clinician may also use PCR polymerase chain reaction testing, which is faster than culturing but requires a culture as follow-up. Diagnosis of ongoing guttural pouch infection is best achieved by endoscopy. Treatment Treatment for strangles usually requires little more than rest, though horses having difficulty swallowing should have soft, moist food.

Immediate treatment with antibiotics in the early acute phase of the illness may get rid of the infection and prevent abscessing.

Equine respiratory disease

Veterinarians remain divided about this practice, however, because antibiotic treatment at this stage prevents a horse from developing natural immunity to the disease and thus leaves the animal vulnerable to reinfection. Natural immunity is still the best protection against repeated infection. Prevention There are two types of vaccines available for the prevention of strangles. One is an injectable IM vaccine and the other is an intranasal IN spray. Neither has proven very effective at actually preventing infection, though they may make an infection less severe. If a case of strangles is confirmed or suspected at your barn, there are a number of things you can do to help contain the outbreak.

Some of these are as follows: No horses should leave or come to the property.


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Horses with strangles and their contacts should be separated from other horses in a well-marked quarantine area. Rectal temperatures should be taken at least once daily, and horses with fever moved to the quarantine zone. New cases may be treated, if a veterinarian advises. Strict hygiene measures should be implemented, including limiting people who have contact with sick animals, changing of clothes and shoes before moving between quarantine and disease-free zones, disinfecting of hands, disinfecting of water buckets daily, disinfecting of all surfaces after removal of organic material, using separate cleaning tools, halters, brushes, etc.

Compost manure and waste feed from infectious horses in a remote area. Rest pastures used by infectious animals for 4 weeks. Thoroughly clean and disinfect anything that might have come into contact with an infectious animal at least once — twice if possible. Horses should be cultured and PCR-tested weekly for at least 3 weeks after recovery. When they consistently test negative, they can leave quarantine. If horses appear healthy but tests positive, endoscopy of the upper respiratory tract and guttural pouches should be performed.

Horses should be cultured 3 weeks after recovery before leaving quarantine.

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Pulmonary consolidation pneumonia , peribronchial disease, pulmonary abscessation, interstitial disease, and mediastinal masses neoplasia, abscess, and granuloma are most easily identified via thoracic radiography. Thoracic ultrasonography is the most appropriate technique to evaluate fluid in the pleural space, peripheral pulmonary consolidation, and peripheral pulmonary abscessation. Ultrasonography can identify the volume, location, and character of pleural fluid or air within the pleural space pneumothorax.

Additionally, it can identify fibrin tags, gas echoes anaerobic infection , masses, and fluid pockets.

Diseases | Diseases | _Horses | _Equine respiratory disease

Ultrasound guided pleurocentesis is useful to obtain a fluid samples in the case of abnormal fluid build-up in the pleural space. This fluid can then be further analysed to determine the fluid type and culture may be performed on this fluid if bacterial infection is suspected. Lung biopsy and fine needle aspiration are invasive procedures and performed only after other diagnostic procedures have been exhausted.

Pulmonary neoplasia, pulmonary fibrosis, and interstitial diseases may require lung biopsy to obtain a diagnosis. As many cases are caused or complicated by bacterial infections, antibiotic therapy may be required. If possible the choice of the antibiotic should be based on culture and sensitivity of the bacteria present. If this is not possible then a broad-spectrum antibiotic that is effective against the likely pathogens involved may be chosen. Antiparasitic drugs are indicated in the case of lungworm infection. Panacur Equine wormers are indicated for this condition. Structural abnormalities, for example laryngeal hemiplegia and epiglottic entrapment, may require surgical intervention to repair.

Regardless of the type of respiratory disease, environmental factors and supportive care are important to aid recovery. A dust and ammonia-free dry, urine free bedding stable environment prevents further damage to the protective mechanisms of the respiratory system. Highly palatable feeds are indicated to prevent weight loss during the treatment and recovery period. Adequate hydration will decrease the viscosity of respiratory secretions making the secretions easier to clear from the airways.

Rest is very important and affected horses should be kept in a dust-free environment, ideally by turning them out to pasture with no access to hay or straw. If this is not possible, then stabled horses should be bedded on shavings or shredded paper, and fed alternatives to hay, such as silage, or if hay is fed, it should be soaked prior to feeding. In addition to antibiotics, the following drugs are used to provide symptomatic relief and hasten the resolution of infection: The use of corticosteroids should be avoided in active infections due to their immunosuppressive effect and long term steroid use can lead to laminitis.

Vaccination is a crucial component in the control of respiratory disease in horses.

Vaccination does not always prevent respiratory infections in horses, but duration and severity is usually lessened in horses that have been vaccinated regularly. Your veterinary practitioner can advise on an appropriate vaccination programme for your horse based on the probability of exposure and potential disease. A variety of respiratory vaccines are available on the market either as single component vaccines like monovalent Influenza and Strep equi vaccines or as combined vaccines, for instance, combination influenza and tetanus vaccines.

MSD Animal Health markets a variety of respiratory vaccine types. It is advisable to consult the SPC of the relevant product or your veterinary practitioner for advice on correct vaccination timing and regimes. For further information on equine respiratory disease and vaccination please click here. The application of good hygiene, ventilation and management techniques is also vital to prevent respiratory disease in horses. Affected horses should be isolated until the causative agent is identified and treated appropriately. Maintain a closed yard until the infection is controlled.

Ideally no horses should enter or exit the farm until outbreak is over to avoid the spreading of disease. Disinfect areas and equipment that have been used by infected and suspect horses, including stalls and feeders and remove as much organic waste materials as possible.