It is very important to ‘stand back’ and get a general view of the horse before carrying out a full examination. The history of the case will give you some likely clues. Don’t rush in!

You should make a mental note of the following facts from the history:

• age;

• type of horse;

• what it is used for;

• duration of clinical signs;

• coughing?

• other horses in the group affected?

• possibility of trauma?

• problems with performance?

• normal routine changed vis-à-vis housing?

You should also look at:

• general set-up;

• actual stable (particularly size and ventilation);

• bedding;

• long-fibre proportion of diet.

One should then look at the horse from a distance and note:

• type of respiration;

• frequency of respiration;

• any evidence of a ‘heave line’;

• presence of any discharge from the nose or eyes.

After an examination of the head, paying particular attention to the nostrils and the sinuses (other than for dentistry this is the only time that you stand directly in the dangerous position directly in front of a horse), then move to the left-hand side of the horse and auscultate the heart and lungs; repeat this on the right-hand side. If you suspect lower airway problems, ask the handler to cover either one nostril or the nose with a rebreathing bag (a bin liner is fine): this makes the horse breath harder, which will render chest noises easier to hear. Then move to the rear and take the rectal temperature. Move then to the larynx: palpate it to try to perceive any asymmetry. Lastly, squeeze the larynx to see whether that will initiate a cough reflex.

Strangles

Caused by the bacterium Streptococcus equi, this highly contagious disease requires no long discussion and will readily be recognized by practitioners. Laboratory confirmation by swab is always worthwhile. The debate on the merits of antibiotic treatment, which has carried on for my whole working life of 40 years, will continue. However, in the really sick young animal the use of antibiotics is justified. There is little evidence that such treatment leads to the carrier state, with the organism lingering in the guttural pouches. It is sad that a new vaccine, which was launched with such high hopes, is not available at the present time. There is a blood test available in the UK and some other countries, and this gives an indication of previous exposure and presence of disease, except during the 10 days when a horse is incubating the condition. The results of this test must be evaluated with care.

Herpes viruses in other species give confusing clinical pictures. The equine version, with its two main distinct groups, EHV-1, which is mainly responsible for abortion and myeloencephalitis, and EHV-4, which is responsible for respiratory disease, is no exception. EHV-2 is found so commonly in healthy horses that it is hard to imagine that it is a serious pathogen; separate viruses are found in the donkeys, but these do not infect the horse. Mules are infected by both equine and asinine viruses (AHV-4). However, EHV-4 and AHV-4 produce similar disease symptoms of raised temperature and nasal discharge. There is good passive immunity to the disease.

EHV-4 should always be suspected in a case of respiratory disease. The virus can be isolated from a nasopharyngeal swab or the buffy coat of a citrate blood sample taken early in the course of the disease. Paired serum samples are also diagnostic.

Equine influenza

The veterinary profession can be congratulated on the control of this contagious disease. The problems in an unvaccinated population were well illustrated in the recent serious outbreaks in South Africa and Australia. Practitioners should not hesitate to send swabs for diagnosis if they suspect the disease; paired serum samples will also be diagnostic. Infected animals show a very marked pyrexia, with depression and loss of appetite. The disease is much more serious in the donkey, mainly because the loss of appetite may lead to hyperlipaemia. Both horses and donkeys show a dry cough and swelling of the submandibular lymph nodes. Usually, horses do not require antibiotic therapy as they will recover on their own, but foals and donkeys should be treated.

Other upper respiratory viruses

Normally, these arrive in horse populations in waves, causing coughing and nasal discharges in groups of horses. Incubation periods 2–10 days are seen, so gatherings of horses are often the method of spread. The infection is self-limiting. Fresh air is beneficial, and antibiotics are justified in cases showing a persistent secondary purulent bacterial nasal discharge.

Lacerations and wounds of the nostrils

Diagnosis is straightforward, although the actual cause may not be so obvious.

Once again, diagnosis will be straightforward. The cause is likely to be damage to the facial nerve, although the actual trauma may not be apparent. The paralysis is normally permanent.

Epidermal inclusion cysts of the false nostril

Often termed atheromas, these are normally unilateral and are totally benign. They do not affect the breathing even if they grow to the size of a goose egg. Therefore, excision is purely cosmetic and is normally successful. Drainage, on the other hand, normally leads to a recurrence.

Sinusitis

There is a persistent purulent nasal discharge. If this is unilateral and malodorous it is likely to be tooth related; one of the four caudal upper cheek teeth is likely to be the cause. These should be examined very carefully with a gag, a mirror and dental picks, usually under sedation. Oblique lateral radiographs will aid diagnosis. Tooth removal is the only treatment.

If the discharge is bilateral, primary sinusitis is the likely cause. In very rare cases a fungus may be involved. Antibiotic treatment is often tried, but rarely is it effective. Surgery with copious flushing is the treatment of choice.

Ethmoid haematoma

Confusing signs accompany this haematoma: you may see a unilateral bloody nasal discharge, but often this is purulent and may well be bilateral. It is rarely true epistaxis. Confirmation of the diagnosis is normally made endoscopically and radiographically. Surgery was the previously favoured method of treatment, but nowadays laser or chemical ablation are more frequently used. Chemical ablation is achieved with 10% formaldehyde.

Guttural pouch disease

A group of syndromes that can be grouped under one heading, as they are all going to be seen as a swollen guttural pouch; whatever is causing the swelling will denominate the syndrome. Possibilities include: (i) air, as in the case of foal guttural pouch tympany; (ii) liquid pus, as in guttural pouch empyema (normally a B-haemolytic Streptococcus); and (iii) caseous, inspissated pus, as in strangles. It may also have a fungal cause, as in guttural pouch mycosis. The disease is very serious in the horse and extremely serious in the donkey.

Dorsal displacement of the soft palate

A condition normally seen intermittently at exercise, high-speed treadmill endoscopy is usually required for diagnosis as the condition occurs in the tiring horse. There are several surgical options for treatment.

Pharyngeal lymphoid hyperplasia

A condition normal in the young horse, this becomes a problem only when polyps develop. Pharyngeal sprays have been advocated, but the evidence of their effectiveness is lacking. Laser treatment is a better option.

Laryngeal hemiplegia

Normally affecting the left side, the horse is heard to make a noise on inspiration. It is relatively common in the larger horse. Unless the horse is to be used for strenuous exercise, this condition is unlikely to be a problem. Unfortunately, the well-known Hobday operation does not actually cure the condition, although it does often reduce the respiratory noise. Permanent tracheotomy – ‘tubing’ – is no longer aesthetically acceptable. The so-called tie-back operation is the treatment of choice.

Epiglottic entrapment

A rare and normally intermittent condition, it requires high-speed treadmill endoscopy for diagnosis. The horse will normally have been presented for poor performance.

Arytenoid chondritis

Another rare condition, it involves the formation of granulation tissue on one or both arytenoids, and is a disease mainly of young thoroughbreds. Historically, treatment consisted of a prolonged course of antibiotics with some steroid, but nowadays NSAIDs are used instead with the antibiotics. Diagnosis is simple with an endoscope.

Fourth brachial arch defects

Seen as congenital defects in the thoroughbred, up to 2 in 1000 may be affected. These are normally untreatable and are diagnosed on endoscopy.

May be either congenital or as the result of a kick and, provided the case is not too severe, it is best left alone. Surgery in severe cases is likely to be heroic.

Abscesses

Liable to occur in structures close to the upper respiratory tract, the signs will vary with their position. Surgeons are well advised to carry out paracentesis before lancing, as abscesses may well lie adjacent to very vital structures.

Neoplasia

Tumours are extremely rare in the respiratory system. Haemorrhage from the mouth will be seen with tumours of the pharynx, the nostrils or the upper airway. Melanomas may be seen in the guttural pouch, with the appearance of a bunch of black grapes. In this latter case, euthanasia must be advised on account of the danger of rupture of the carotid artery.

Foreign bodies

Although extremely rare in the pharynx or upper airway, these may be visualized and possibly removed with an endoscope.

Pneumonia in the foal

The foal can develop pneumonia from inhalation of bacteria, e.g. in the case of a severe cleft palate. They will also develop a stress-induced streptococcal pneumonia as a result of either overcrowding or transport. However, the normal cause is Rhodococcus equi. This organism, which produces life-threatening effects, should always be considered. Radiography and ultrasonography will aid in diagnosis rather than resorting to a transtracheal wash. Prolonged treatment by mouth with a combination of erythromycin (25 mg/kg) and rifampicin (10 mg/kg) every 12 h is required.

Pneumonia in the adult horse

Pneumonia in the adult is very rare but it is always extremely serious, particularly if associated with pleural effusion. The clinical impression is that stallions are more susceptible. The disease seems to follow either a long journey or major trauma, e.g. a bad fall. There is thoracic pain, respiratory distress and a raised rectal temperature. Aggressive antibiotic therapy with NSAIDs is required. If ultrasonography indicates pleural effusion and a fluid line, thoracic drainage is vital. The prognosis is always grave.

Chronic fibrosing interstitial pneumonia