Diseases of the larynx.

The procedure for examining the patient with laryngeal disease depends largely upon the degree to which its respiration is impaired. Laryngoscopy and electromyography are the principal diagnostic tools. Common laryngeal diseases, diagnoses, and treatments are discussed.     

Disorders of the pharynx.

Pharyngeal disorders are complex and difficult to treat. Disorders that lead to anatomic derangement, such as trauma and neoplasia, can significantly affect the function of this organ. Pharyngeal dysfunction can manifest as dysphagia, persistent palatal displacement, or exercise intolerance. Secondary complications are serious and life threatening and include aspiration pneumonia, weight loss, and death. Pharyngeal disorders that are only recognizable during strenuous exercise are difficult to diagnose and are treated with limited success, even though they are responsible for significant economic losses with performance animals.     

Disorders of the canine penis.

Function and anatomy of the canine penis are reviewed. Functional abnormalities of the penis described include lack of erection and lack of ejaculation. Physical abnormalities of the penis also are described, including paraphimosis. Diagnosis and treatment options are described.     

Disorders of the avian integument.

The avian integument consists of highly specialized structures that show extreme variations between species. Feathers are the most obvious part of the integument, and their color and beauty forms an important basis for the attraction of birds to humans. Any disorder in the feathers can be distressing for a client and frustrating for the avian practitioner. The cause of some disorders may be apparent, but others have a complex pathogenesis involving management, human-bird interaction, malnutrition, psychologic factors, disease, or hormone imbalances.     

Xeroradiographic evaluation of the equine larynx

The normal radiographic anatomy of the equine larynx was determine by use of xeroradiography and dissection. The body and laminae of the thyroid cartilage, the muscular process of the arytenoid cartilages, and the dorsal lamina and arch of the cricoid cartilage had radiographic evidence of mineralization (calcification) and/or ossification in clinically normal horses. There was a significant (P less than 0.01) increase in the degree of mineralization of the thyroid and arytenoid cartilages with advancing age. Horses with diagnosis of arytenoid chondrosis (arytenoid chondral dysplasia, arytenoid chondropathy) by use of endoscopy had radiographic changes that included: enlargement with increased density of the arytenoid cartilage region, abnormal patterns of mineralization (dystrophic mineralization or osseous metaplasia), abnormal contour of the corniculate process(es) and laryngeal masses, sometimes obliterating part or all of the lateral laryngeal ventricles.     

The larynx of the Basenji dog

In two aged Basenji bitches, the lateral laryngeal saccules were absent or reduced and the laryngeal recesses (ventricles of Morgagni) were shallow compared with those of other dogs. No other significant differences were discovered. It is not yet established whether or not these anatomical features are directly related to barklessness in these dogs. The terminology used for these anatomical features is discussed.     

Surgery of the canine pharynx and larynx

Brief reference is made to the main clinical features of the surgical conditions (congenital and acquired) of the canine pharynx and larynx; the techniques of surgical treatment are described and assessed.     

Solitary extramedullary plasmacytoma of the canine larynx

An 11-year-old, female, spayed cocker spaniel was presented with dysphonia caused by a solitary laryngeal mass. Excisional biopsy was performed, and a diagnosis of plasmacytoma was made on the basis of histological examination. Further investigations showed no signs of systemic involvement. Coarse fractionated radiation therapy failed to control the tumour. Therapy was successfully instituted with a conventional combination chemotherapy protocol over a period of 14 months. The dog remains disease free 30 months after diagnosis. Most solitary, extramedullary plasmacytomas in dogs arise in the gastrointestinal tract, with fewer reports in other sites. The larynx is an uncommon sight of involvement in any species, and to the authors' knowledge, this is the first report of this tumour type in the canine larynx. In contrast to the therapeutic benefits reported in humans, the combination of surgery and radiation therapy was unsuccessful in this case, although sustained remission was gained following chemotherapy.     

Problems of the equine larynx and pharynx

Extract

The major research effort of the Surgery Department at Massey has been directed for some time towards the problems of the equine upper respiratory tract. A considerable part of our work is concerned with the examination and treatment of horses exhibiting abnormal respiratory noises. These noises are oftenassociated with impaired performance. Two of the most common conditions are left laryngeal hemplegia, and “soft palate paresis”.     

Preferential denervation of the adductor muscles of the equine larynx. II: Nerve pathology

The terminal branches of the recurrent laryngeal nerve (RLN) of three normal ponies and six horses with sub-clinical laryngeal disease were examined qualitatively and quantitatively in an attempt to explain the preferential denervation of the laryngeal adductor muscles in the neuropathy of idiopathic laryngeal hemiplegia (ILH). The myelinated fibre spectra of all the motor nerve fibres in the left and right abductor and adductor branches of the RLN in three normal ponies were measured. The density of myelinated fibres was also calculated. There was no significant difference between the larger group of myelinated fibres in the adductor or abductor branches. In the six horses with laryngeal hemiparesis, however, there was a marked preferential loss of the medium/large size myelinated fibres in the left adductor branch, although nerve fibre densities were not significantly different. While no simple morphometrical feature was found to explain the selective muscle denervation, the greater loss of large diameter myelinated fibres in the adductor branches confirms the earlier observation of adductor muscle susceptibility in the neuropathy of ILH.     

Preferential denervation of the adductor muscles of the equine larynx. I: Muscle pathology

The laryngeal muscles of 18 horses were examined histologically. The neurogenic changes found in each muscle were scored by four reviewers and the results evaluated statistically. Fifteen of these horses had endoscopic evidence of abnormal laryngeal function, three of which were defined as having adductor paralysis. Measurement of muscle fibre area in two horses with idiopathic laryngeal hemiplegia (ILH) was performed. In the quantitative study of neurogenic change, the adductor muscles were more significantly affected than the abductor muscle. This was also true in the clinical cases of ILH where measurement of muscle fibre area demonstrated that the lateral cricoarytenoid (adductor) muscles showed a wider range of pathological changes than the dorsal cricoarytenoid muscle (abductor). Those horses with the most severe muscle pathology also had the most abnormal endoscopic findings. The propensity for denervation of the adductor muscles should provide clues as to the pathogenesis and natural history of horses with sub-clinical laryngeal disease and ILH.     

Malignant melanoma of the larynx in a dog

Laryngeal dysfunction due to neoplastic disease is rare. Consequently, little is known about the behaviour or treatment of these tumours (Crow 1980). Clinical signs common to most laryngeal tumours include hoarseness and sometimes complete loss of voice (Wheeldon and others 1982). The signs develop over many months and later include stertorous breathing and dyspnoea (Harvey 1981). This case report was a malignant melanoma of the larynx and perilaryngeal tissues.