3.487
This Holstein cow presents with a history of poor milk yield and weight loss since calving six weeks ago; condition score 2 (scale 1-5). She stands with an arched back with the neck extended, an anxious expression and the head held lowered suggestive of thoracic pain. The cow has a gaunt appearance due to poor abdominal fill. There are bilateral purulent nasal discharges. The respiratory rate is increased with an obvious abdominal component to respiration. There are no adventitious lungs sounds. Ultrasound examination of the chest is undertaken using a 6.5 MHz microarray probe. The ultrasound probe head is at the top of the recording, dorsal is to the left, centimetre markers are shown in the right hand margin. The field depth has been set at 10 cm including chest wall. At the start of this recording the probe is positioned half way up the left chest wall where there is normal lung represented by a continuous hyperechoic white line immediately below the chest wall which is 1.5 cm thick. As the probe is moved ventrally this white line is lost and is replaced by an irregular hypoechoic area which quickly extends to the full 10 cm depth setting. This hypoechoic area represents consolidated lung/bronchiectasis. The consolidated lung has the sonographic appearance of liver (hepatoid change) and extends for more than 8 cm from the chest wall. At the end of the recording the cow is shown after six weeks’ antibiotic treatment when she is very much brighter with a good appetite. The cow now has a body condition score of 3.0—compare with her appearance at first examination.
3.488
This Holstein cow stands with an arched back with the neck extended and the head held lowered suggestive of thoracic pain. The cow is in very poor body condition with much reduced abdominal fill consistent with little/no appetite for the past several days. The respiratory rate is increased to > 40 breaths per minute with an obvious expiratory component. The cow has purulent nasal discharges. The eyes appear slightly sunken into the orbits due to loss of intra-orbital fat. There is excess salivation.
3.489
This Holstein cow is presented for low milk yield. The cow is in reasonable body condition but has reduced abdominal fill. The respiratory rate is increased. Once confined in cattle stocks, there are purulent nasal discharges. Ultrasound examination of the lungs using a 5 MHz linear scanner reveals sudden loss of the hyperechoic line representing normal aerated lung replaced by a hypoechoic area extending to the full depth of the probe field. There are several 1-2 cm diameter anechoic areas containing hyperechoic dots consistent with the sonographic appearance of abscesses. Overall, the lung pathology is consistent with bronchiectasis. To quantify prognosis summate the vertical measure of lung pathology above the point of the elbow for both sides of the chest. Where this value is >40 cm in a dairy heifer or cow (approximately 600 kg liveweight) then the prognosis is poor, where the value is <35 cm the prognosis is reasonably good. An accurate diagnosis with ultrasound demonstration of lung pathology is essential to convince a farmer that 21 consecutive days’ penicillin treatment is necessary to effect a cure.
3.490
This Holstein cow is very dull and stands with an arched back with the neck extended and the head held lowered suggestive of thoracic pain; the ears are directed caudally. The cow is in poor body condition with reduced abdominal fill consistent with little/no appetite for the past several days. The respiratory rate is increased to > 40 breaths per minute with an obvious expiratory component. Her rectal temperature is 39ºC. Ultrasound examination of the lungs using a 5MHz linear scanner reveals sudden loss of the hyperechoic line representing normal aerated lung replaced by a hypoechoic area extending to the full depth of the probe field. There are several 1-2 cm diameter anechoic areas containing hyperechoic dots consistent with the sonographic appearance of abscesses. Overall, the lung pathology is consistent with bronchiectasis. The area of lung consolidation/ bronchiectasis defined ultrasonographically indicated that the cow was unlikely to respond to antibiotic therapy. The cow was treated for 14 days with procaine penicillin but showed little clinical improvement and was euthanased for welfare reasons. Necropsy confirmed the diagnosis; it was not possible to determine whether the caudo-dorsal emphysema was present before euthanasia, but the pathologist commented that it was likely more likely to be an agonal event.
3.491
This beef cow presents with a history of weight loss since calving three months ago. The cow stands with an arched back with the neck extended and the head held lowered suggestive of thoracic pain and has an occasional muco-purulent nasal discharge. The respiratory rate is increased to >40 breaths per minute with an obvious abdominal component to respiration. Her rectal temperature is 39ºC. Ultrasound examination of the chest is undertaken using a 6.5 MHz microarray probe. The probe head is at the top of the image, dorsal is to the left, centimetre markers on the right hand margin. The field depth is initially set at 10 cm including chest wall. There is normal lung dorsally with the hyperechoic line representing normal aerated lung adjacent to the chest wall. As the probe head is moved ventrally the lung surface is displaced from the chest wall by a hypoechoic layer of inflammatory exudate (fibrinous pleurisy) about 2-3 cm thick. The lung surface appears irregular with hypoechoic columns extending into the lung representing lobular consolidation. As the probe head is moved further ventrally the pleurisy extends to 3-4 cm. At times the lung surface is smooth and appears as a hyperechoic line; at other times the lobular lung consolidation gives the lung surface a very irregular appearance. Consolidated lung represented by the hypoechoic layer underneath the visceral pleura extends for 3-4 cm and contains numerous hyperechoic areas up to 1 cm in diameter which likely represent small abscesses. The cow made a full recovery following an extended course of daily procaine penicillin injections.
3.492
This Holstein heifer stands with an arched back with the neck extended and the head held lowered suggestive of thoracic pain. The cow has a low body condition abdominal fill consistent with a much reduced appetite. The respiratory rate is increased to >40 breaths per minute with an obvious expiratory component. The heifer has a painful cough and muco-purulent nasal discharge. There is excess salivation, and the eyes appear sunken. Her rectal temperature is 38.9ºC. There is normal lung at the start of the ultrasound recording with the visceral pleura represented by the continuous hyperechoic line. As the probe head is moved down the chest wall, there is loss of this continuous hyperechoic line, instead replaced by irregular hypoechoic areas containing large hyperechoic dots representing consolidated lung/chronic suppurative pneumonia extending to a depth of 4-5 cm. The pericardial sac and beating heart are visible ventrally (lower right on the recording). This heifer failed to respond to antibiotic therapy and was euthanased for welfare reasons. Necropsy reveals a shrunken rumen with dry roughage contents consistent with a poor appetite. The liver appears fatty with rounded edges. The trachea and larger airways are inflamed containing a large amount of pus. There is sharp demarcation between normal lung dorsally and consolidation ventrally. Note that there are no obvious lung abscesses—the pathology is essentially bronchiectasis. Note the pus expressed from the airways when diseased lung is squeezed. Bronchiectasis has been defined as a dilation of a segment of a bronchus and is the result of a chronic bacterial or mycotic infection with destructive inflammation of the wall of the bronchus in chronic, undrained, purulent bronchitis with or without bronchopneumonia. Grossly dilated bronchi are filled with a viscous, purulent, yellow-green exudate comprising large collections of inflammatory cells with collapse of the surrounding parenchyma. These permanently dilated small bronchi and bronchioles, located in ventral parts of the lungs, contain a range of microorganisms including Mannheimia hemolytica, Pasteurella multocida but especially Trueperella pyogenes.
3.493
This Holstein heifer presents with a history of poor milk yield and weight loss since calving six weeks ago. The heifer has a dirty, dry staring coat. The heifer coughs frequently and has an occasional muco-purulent nasal discharge. The respiratory rate is increased to >40 breaths per minute with an obvious abdominal component to respiration. The heifer stands with an arched back with the neck extended and the head held lowered suggestive of thoracic pain. Her rectal temperature is 39ºC. The probe head is at the top of the image, dorsal is to the left, centimetre markers in the right hand margin. The field depth is initially set at 8 cm including chest wall. There is a sharp demarcation between normal lung surface represented by the hyperechoic line (dorsally, to the left) and the irregular hypoechoic area representing consolidated lung/chronic suppurative pneumonia (ventrally, to the right). The consolidated lung has the sonographic appearance of liver (hepatoid change) and extends for more than 6 cm from the chest wall. Two weeks after treatment commenced, the heifer is much brighter with a good appetite as indicated by her full rumen. The respiratory rate is still elevated, but treatment will continue for another four weeks.
3.494
This video compilation shows a Holstein cow at presentation with chronic suppurative pneumonia and two weeks later after changing the antibiotic to daily procaine penicillin injections.
3.495
This Holstein second calver presents with a history of poor milk yield and weight loss since calving six weeks ago; condition score 1.5 (scale 1-5). The udder is flabby consistent with a very poor milk (10 litres per day instead of 45-50). She stands with an arched back with the neck extended, an anxious expression and the head held lowered suggestive of thoracic pain. The cow has a gaunt appearance due to poor abdominal fill. There is a slight mucoid nasal discharge. The respiratory rate is increased to >40 breaths per minute with an obvious abdominal component to respiration. Ultrasound examination of the chest is undertaken using a 6.5 MHz microarray probe. The probe head is at the top of the image, dorsal is to the left, centimetre markers in the right hand margin. The field depth is initially set at 10 cm including chest wall. At the start of the recording, the probe is positioned half way up the left chest wall; there is no normal lung represented by the hyperechoic line at this level, and instead an irregular hypoechoic area extends to the full depth of the ultrasound machine setting. This hypoechoic area represents consolidated lung/chronic suppurative pneumonia. The consolidated lung has the sonographic appearance of liver (hepatoid change) and extends for more than 8 cm from the chest wall. The consolidated lung presents with numerous 1-2 cm diameter hypoechoic circles containing hyperechoic dots consistent with small abscesses. The ultrasound scan should not be over-interpreted; it is sufficient to determine that there is widespread pathology and that treatment involves up to six weeks’ daily penicillin injections to treat Trueperella pyogenes bronchiectasis. There was very little pathology in the right lung. After six weeks’ antibiotic treatment the cow is much brighter with a much better appetite as indicated by her full rumen. Body condition has been restored, and the cow now has a score of 2.5.
3.496
This Holstein cow presents with severe respiratory disease after failing to respond to antibiotics and NSAIDs administered by the farmer. Her rectal temperature is 39.2ºC. She stands with an arched back with the neck extended and the head held lowered suggestive of thoracic pain. The cow is mouth-breathing with flared nostrils, excess salivation and an anxious painful expression. The cow is emaciated with very poor abdominal fill consistent with little/no appetite for the past several days. There is a slight mucoid nasal discharge. The respiratory rate is increased to >40 breaths per minute with an obvious expiratory grunt. The probe head is at the top of the image, dorsal is to the left, centimetre markers in the right hand margin. The field depth is initially set at 6 cm including chest wall. At the start of the recording the probe is positioned half way up the left chest wall where there is normal lung represented by the continuous hyperechoic line. As the probe head is moved down the chest wall, the visceral pleura (lung) is displaced off the chest wall by a very narrow 1-2 mm hypoechoic band likely to represent a thin layer of pleurisy. Beneath, the lung surface is irregular. Further down the chest there is lobular consolidation seen as hypoechoic columns extending 2-3 cm into the lung surrounded by hyperechoic lines as the sound ways contact normal aerated lung. Later in the recording, the irregular hypoechoic/anechoic areas represent consolidated lung/chronic suppurative pneumonia. The ultrasound scan should not be over-interpreted; it is sufficient to determine that there is widespread pathology consistent with CSPD and that treatment involves six weeks’ daily penicillin injections to treat Trueperella pyogenes bronchiectasis. After 10 days’ antibiotic treatment the cow is much brighter with a much better appetite. Compare with the same cow at first examination.
3.497
This Charolais bull is presented three weeks after purchase. He was not quarantined on the new farm and immediately turned out with 24 cows. He is very depressed, is slow to rise and stands with its head held lowered. The rectal temperature is 41ºC. There are bilateral purulent nasal discharges. A poor appetite over several days has led to a shrunken rumen giving a very drawn-up and gaunt appearance. There were no abnormal findings on ultrasound examination of the lungs/pleurae. There are usually obvious ocular signs in IBR with purulent ocular discharges and inflamed conjunctivae; sampling is essential in this case to confirm the presumptive diagnosis of IBR and take appropriate action.
3.498
This beef cow presents at pasture during August with its head down, neck extended and ears directed caudally. There is an increased respiratory rate with an abdominal component to respiration, flared nostrils and frequent forceful coughing. The cow has poor abdominal fill due to a poor appetite. Purchased yearling cattle had been added to this group of beef cows two months earlier; there were no quarantine anthelmintic treatments. A Baermann examination is indicated, but clinical signs can be caused by prepatent lungworm infestations.
3.499
This beef cow presents during November with a history of chronic severe weight loss. There is an increased respiratory rate with an abdominal component to respiration, flared nostrils and frequent forceful coughing. The cow has poor abdominal fill due to a poor appetite. The Baermann examination was positive; necropsy confirmed the diagnosis of patent lungworm infection.
3.500
A simplified Baermann examination technique is shown. First stage larvae of D. viviparus can be demonstrated by the Baermann technique in faeces of sheep with patent infestations. Approximately 5 g of faeces are placed in an open weave gauze swab and put into a 50 ml syringe casing containing warm water. After 24-36 hours the clip on the rubber tubing at the bottom of the syringe case is released and the first few drops discarded; the next few drops are placed on a microscope slide and examined x100. When present, there are lots of lungworm larvae swimming around.
3.501
Inhalation pneumonia in dairy cows most commonly results from inhalation of rumen contents following hypocalcaemia especially when the cow becomes cast. Faulty administration of drenches may also result in inhalation of liquids. This Holstein cow presents in sternal recumbency with her head on the ground. She is very dull and depressed and is not eating. The cow has a painful expression. The respiratory rate is elevated with an obvious abdominal component. When the cow stands she has a roached back stance with the neck extended and the head held lowered and walks slowly. While this ultrasound recording is poor quality it does reveal normal lung dorsally as a bright hyperechoic (white) line replaced in the ventral lung field by an anechoic area containing multiple white dots (“snowstorm”) typical of an abscess (pyothorax). On-farm necropsy reveals extensive pyothorax of the left pleural space and necrosis of the left lung lobes. The involvement of lung tissue indicates that this is a case of inhalation pneumonia and not an abscess of the pleural space only.
3.502
A group of beef cows has been moved to lush pasture in mid-summer. One cow stands with her neck extended, has her head lowered and moves very reluctantly. The nostrils are flared and the animal mouth breathes. There is an expiratory grunt audible from 10 metres away.
3.503
A group of autumn-calving beef cows has been housed for one month in December in poorly ventilated buildings and fed very poor quality hay. One 14-year-old cow presents with frequent coughing and an increased respiratory rate and effort. Otherwise, the cow is bright and alert and eating well. There are signs of early right-sided heart failure with marked brisket oedema. Ultrasound examination shows pleural effusion to approximately 15 cm deep in the ventral chest. The cow is shown after treatment with dexamethasone for DFA when the brisket oedema has resolved (note this cow was not >3 months pregnant).
3.504
This aged beef cow presents with an increased respiratory and obvious abdominal component; the nostrils are flared during inspiration. Ultrasound examination reveals sharply demarcated areas of consolidation extending the full depth of the ventral lung field (shown on lung section at end of video recording; ventral to the right hand side). Necropsy reveals what appears grossly to be a lung tumour however this was not confirmed histologically.
3.505
During expiration (on a cold day) in this aged beef cow, breath is expelled only from the right nostril. There is exophthalmos and ocular discharge on left side and swelling in the maxillary region. A 5 cm diameter mass (tumour) is identified on endoscopic examination occluding the left nasal passage not shown).
3.506
This 9-year-old beef cow appears gaunt and in poor condition with a two weeks’ history of weight loss. There is excess salivation. The cheeks are blown out on expiration suggesting some obstruction of the nasal passages, and a connection between the nasal passages and the buccal cavity. Endoscopic examination confirms masticated food material in the nasal passages. The cow was euthanased for welfare reasons and a sagittal section through the skull confirmed the extent of bone destruction. There is metastatic spread to the retropharyngeal lymph nodes containing several 1-2 cm diameter pale yellow tumours.
3.507
This 10-day-old beef calf is dull with its ears held back and is not sucking its dam. The calf has a markedly increased respiratory rate with an obvious abdominal component. There are scant mucoid nasal discharges. The rectal temperature is 40.5°C; thoracic auscultation reveals no convincing adventitious sounds.
3.508
This week-old beef calf is dull and does not respond to people approaching it. It stands with its head lowered and ears held back. There is excess salivation. The calf has a markedly increased respiratory rate with an obvious abdominal component. The calf is slow to follow its dam and appears weak. This calf’s abnormal behaviour and demeanour are highlighted when compared to the normal calf featured at the end of the video recording.
3.509
This 6-week-old beef calf is dull and walks slowly around the field (compare with the normal calf trotting around the field later in the recording). The calf has a markedly increased respiratory rate with an obvious abdominal component. There is excess salivation and a brief period of mouth breathing. This calf requires veterinary examination; rectal temperature is the best guide to whether antibiotic treatment is needed.
3.510
This yearling beef heifer is dull, depressed and disinterested in its surroundings. The heifer stands with its neck extended and head held lowered. There is an increased respiratory rate with an abdominal component. There are bilateral muco-purulent nasal discharges and slight excess salivation. There is poor abdominal fill. There is marked jugular distension. Ultrasound examination using a 6.5 MHz microarray probe shows separation of the pleurae initially by a 2 cm wide anechoic layer dorsally progressing to around 8 cm of poorly defined hyperechoic fibrinous matrix. In some areas there are also large fibrin deposits on the visceral pleura. Necropsy confirms the extensive severe fibrinous pleurisy.
3.511
This group of spring-born beef calves has been housed for approximately two weeks. The first affected 6-month-old beef calf is very dull and stands with the head lowered and the ears drooped. There are copious mucopurulent nasal discharges and excess salivation. This calf has an increased respiratory rate and abdominal effort (shown later in the recording). The second calf is also very dull and stands with the head lowered and the ears drooped. There is a slight nasal discharge.
3.512
This recently weaned 8-month-old beef calf appears gaunt, is very dull and stands with the head lowered and the neck extended. The calf has an increased respiratory rate and a marked abdominal effort. There is a scant mucopurulent nasal discharge. Ultrasound examination of the lungs using a 6.5 MHz microarray probe reveals fibrinous pleurisy with acoustic enhancement of the lung surface where it is separated from the parietal pleura by 5-10 mm exudate. There is also fibrin separating the lung lobes extending for up to 6-8 cm from the chest wall. At necropsy, there is extensive fibrinous pleurisy and antero-ventral lung consolidation. Cut sections of lung reveal extensive interlobular oedema. There are infarcts in the liver. The clinical and necropsy findings are strongly suggestive of Pasteurella multocida infection although no further tests were undertaken for cost reasons.
3.513
This group of spring-born beef calves has been housed for approximately two weeks. This group of 5-7-month-old beef calves were weaned and housed two weeks ago. This video recording was taken at feeding time when the calves were offered 2 kg barley per head. Several calves stand at the feed barrier and do not eat. It is difficult to know whether this is because they are not accustomed to the ration or they are ill. Rectal temperature >39.6°C is the best treatment selection criterion in this situation.
3.514
This group of spring-born beef calves has been housed for approximately two weeks. This 6-month-old beef calf presents with respiratory distress with a markedly increased respiratory rate and forceful abdominal movements. The calf’s neck is extended and the head held lowered. This presentation is typical of severe BRSV infection noting that the most severely affected calves present first in the disease outbreak.
3.515
This group of spring-born beef calves has been housed for approximately two weeks. These 8-week-old dairy calves have been treated by the farmer for pneumonia on three occasions. They show an increased respiratory rate and marked abdominal effort. On ultrasound examination the hyperechoic line representing normal aerated lung surface has been replaced ventrally by an irregular heterogenous area extending 1-4 cm into the lung parenchyma representing lung consolidation. The pathology was considered to be bronchiectasis, and the calves were treated with an extended course of procaine penicillin. The calves are shown 10 days after the start of treatment and appear much brighter but still have increased respiratory rates due to the amount of consolidated lung. The sonographic findings of lung consolidation in this disease situation often remain unchanged after treatment and cannot be used as a guide to treatment efficacy.
3.516
This group of spring-born beef calves has been housed for approximately two weeks. This 8-month-old beef calf has a history of several episodes of respiratory disease treated by the farmer. The calf stands with the neck extended and the head held lowered with frequent coughing. The respiratory rate is increased to >40 breaths per minute with an obvious abdominal component to respiration. The rectal temperature is 39.0°C. There are much reduced lung sounds ventrally but no adventitious sounds. On ultrasonographic examination of the chest there is normal lung dorsally with the hyperechoic line representing normal aerated lung adjacent to the chest wall. As the probe head is moved ventrally the lung surface is replaced by an increasing hypoechoic area containing multiple hyperechoic dots which extends for up to 5-6 cm from the chest wall and represents lung consolidation consistent with CSPD/bronchiectasis. Treatment can be attempted with an extended course of procaine penicillin, but the prognosis is poor.
3.517
This 6-month-old beef calf has a history of several episodes of respiratory disease treated by the farmer with tulathromycin. The calf stands with an arched back with the neck extended and the head held lowered with frequent coughing. The calf has a muco-purulent nasal discharge. The respiratory rate is increased to >40 breaths per minute with an obvious abdominal component to respiration. The rectal temperature is 39.0°C. The probe head is at the top of the image, dorsal is to the left, centimetre markers in the right hand margin. The field depth is initially set at 8 cm including chest wall. There is normal lung dorsally with the hyperechoic line representing normal aerated lung adjacent to the chest wall. As the probe head is moved ventrally the lung surface is replaced by an increasing hypoechoic area containing multiple hyperechoic dots which extends for up to 5-6 cm from the chest wall and represents lung consolidation consistent with CSPD/bronchiectasis. The calf failed to respond to further antibiotic therapy. Necropsy reveals pleurisy on the parietal pleura. There is antero-ventral lung consolidation with fine fibrinous attachments between lung lobes and the pericardial sac. There is a large amount of pus within the trachea and bronchi originating from the lower airways consistent with a diagnosis of bronchiectasis.
3.518
These two 8-month-old weaned, recently purchased beef calves present with a history of poor appetite and occasional coughing. The calves have very slight muco-purulent nasal discharges. The respiratory rate is normal with no obvious abdominal component to respiration. There are no adventitious sounds. The ultrasound findings for both calves are now shown. The probe head is at the top of the image, dorsal is to the left, centimetre markers in the right hand margin. The field depth is initially set at 8 cm including chest wall. There is normal lung dorsally with the hyperechoic line representing normal aerated lung adjacent to the chest wall. As the probe head is moved ventrally the lung surface is replaced by an increasing hypoechoic area containing multiple hyperechoic dots which extends for up to 5-6 cm from the chest wall and represents lung consolidation consistent with CSPD/bronchiectasis. Both calves responded well to therapy with procaine penicillin.
3.519
This yearling bullock appears bright and alert but with extensive and severe peripheral oedema especially of the submandibular area, brisket and ventral body wall including the sheath/prepuce. The bullock stands with its neck extended and head held lowered. There is a markedly increased respiratory rate with an abdominal component and flaring of the nostrils. There is poor abdominal (rumen) fill dorsally. Ultrasound examination shows separation of the pleurae initially (dorsally) by a 2 cm wide anechoic layer rapidly progressing to >12 cm as the probe head is moved ventrally consistent with a pleural effusion. While there are several fine hyperechoic “threads” bridging the pleural space, there are no fibrin clots consistent with an inflammatory exudate. There is a slight increase in pericardial fluid. Necropsy confirms the extensive pleural effusion which is a component of the severe and extensive right-sided heart failure resulting from the fibrosing pneumonia. Necropsy also reveals chronic venous congestion of the liver (“nutmeg” liver).
3.520
This 6-month-old beef steer is poorly grown and in poor body condition for its age but comparison with its peer group is necessary to exclude nutritional and management factors. The calf appears to have a disproportionately large head compared to its body, and the coat is long and poor quality with considerable faecal staining round the tail and perineum. The steer has a drawn-up abdomen as a consequence of poor rumen fill/appetite. A blood sample revealed that this steer was persistently infected with BVD virus.
3.521
This yearling Limousin cross steer is in poor body condition with a markedly increased respiratory rate and effort. It had been treated on four separate occasions for respiratory disease by the farmer. Ultrasonography defines the extent of lung consolidation/bronchiectasis (only one side shown) with the diagnosis confirmed at necropsy. A blood sample revealed that this steer was persistently infected with BVD virus.
3.522
The calf is bright and alert, but there is marked inspiratory effort and stertor caused by superficial infection and associated oedema of the arytenoid cartilages of the larynx resulting in narrowing of the lumen. This calf stands with the neck extended, head held lowered with flared nostrils. The calf is then shown much improved 24 hours after dexamethasone and penicillin therapy when the inspiratory effort is very much reduced.
3.523
The calf is bright and alert, but there is marked inspiratory effort and stertor caused by superficial infection and associated oedema of the arytenoid cartilages resulting in narrowing of the lumen. This calf stands with the neck extended, head held lowered with flared nostrils.
3.524
The calf is bright and alert, but there is marked inspiratory effort and stertor caused by superficial infection and associated oedema of the arytenoid cartilages of the larynx resulting in narrowing of the lumen.