Surgical management of recurrent laryngeal neuropathy

Recurrent laryngeal neuropathy (RLN, laryngeal hemiplegia, laryngeal paralysis, ‘roaring’) is common in the equine industry with a prevalence ranging from 2.6–11% in light breeds ( Raphel 1982 ; Lane 1987 ; Morris and Seeherman 1990 ) up to 38% in draught breeds ( Brakenhoff et al. 2006 ; Perkins et al. 2009 ). There are a number of different surgical treatments currently available and more being developed. This article aims to discuss factors affecting choice of treatment and then provide an evidence‐based approach to describe surgical approaches, success rates and morbidity. Specific details of surgical methods are not given as they are readily available in surgical textbooks ( Stick 2006 ; McGorum et al. 2007 ).     

Treatment of oromaxillary fistulae in nine standing horses (2002–2006)

Reasons for performing study: There is minimal published information on equine oromaxillary fistulae that are unrelated to cheek teeth (CT) repulsion or on the conservative treatment of these atypical fistulae. Objectives: To report equine oromaxillary fistulae unrelated to CT extraction and describe their management in standing horses. Methods: Case details of oromaxillary fistulae of atypical aetiology occurring at 2 referral centres between 2002–2006, including their treatment and response to treatment were examined. Results: Nine cases of oromaxillary fistula were recorded, mainly in aged horses (median 22 years). Fistulae were associated with CT diastemata in 7 cases, fractured CT in one and a central defect in a worn CT in another. After removing food and exudate from the sinuses, 6 cases were treated successfully by filling the diastema or dental defect with polymethylmethacrylate (PMMA). Following dental extraction, the other 3 cases were treated successfully by use of PMMA alveolar packing. Conclusion: Older horses can spontaneously develop oromaxillary fistulae, usually secondary to CT diastemata. In the absence of apical infection, this disorder can usually be treated successfully in standing horses by treating the sinusitis and sealing the oral aspect of the diastema with PMMA. Potential relevance: Older horses with sinusitis should be assessed for the presence of CT diastemata and oromaxillary fistulae. If detected, these disorders can be treated successfully in the standing horse.     

Challenges in the treatment of equine periocular squamous cell carcinoma

Management of periocular squamous cell carcinoma is challenging because of the need for adjunctive therapy, the adverse effects of therapies and the frequent recurrence of SCC. Appropriate treatment of equine ocular SCC usually involves surgical excision combined with adjunctive therapy selected as appropriate for the anatomic site of the lesion. Metastasis of periocular SCC has been reported to occur in approximately 6–15% of cases. The horse owner should be carefully educated to understand that for best long‐term results from the treatment of periocular SCC, they must be diligent in observing signs of recurrence or metastasis and be willing to have the horse examined as soon as adverse signs are observed. Furthermore, external beam radiation may be effective in the treatment of metastatic SCC and further clinical studies of this treatment modality are needed.     

A promising surgical approach to equine glaucoma

The preceding case report by Wilson et al. (2015) describes the surgical placement of a Baerveldt glaucoma shunt in a glaucomatous equine eye that had been refractory to aggressive medical and repeated surgical therapies yet maintained functional vision. Shunt placement surgery successfully maintained vision and intraocular pressure in the normal range in the affected eye. This is the first report of long‐term successful glaucoma filtration surgery in a horse. Glaucoma shunt placement shows promise for maintaining vision and comfort in equine eyes affected with glaucoma. There is much to be learned in terms of the most appropriate implant type for the equine eye, the risk of complications such as ocular hypotony or tube fibrosis, and the utility of combination therapy with transcleral cyclophotocoagulation and implant placement, but with the report of one case in which gonioimplant placement has been associated with intraocular pressure control for over one year, further investigations appear warranted. This case provides a glimmer of hope for long‐term treatment of a painful, blinding disease that has traditionally carried a poor prognosis in horses.     

Photodynamic therapy for the treatment of periocular squamous cell carcinoma in horses: a pilot study

Objective  Local photodynamic therapy (PDT) is a novel cancer therapy in veterinary ophthalmology. A prospective pilot study seeking to demonstrate proof of principle and safety for the treatment of equine periocular squamous cell carcinoma (PSCC) was therefore conducted. We hypothesized that surgical excision with adjunctive local PDT is an effective and safe treatment for equine PSCC.
Procedures  Nine horses (10 eyes) with PSCC were treated with surgical resection, local infiltration of resulting wound beds with 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH) and irradiation with 665-nm wavelength diode laser. Regular follow-up ophthalmic examinations were performed.
Results  Surgical resection and PDT yielded disease-free intervals of 25–68 months in our study horses as of January, 2008. These results were obtained following a single treatment in seven horses and two treatments in one horse. In one horse, carcinoma in situ developed 2.5 months after partial surgical excision and PDT, requiring local excision under standing sedation.
Conclusions  Preliminary results suggest that surgical resection and adjunctive local PDT is a safe and effective novel treatment for PSCC in horses. More research is needed before PDT for the treatment of equine PSCC can be adequately compared with other current modalities. Important to future investigations regarding PDT, tumor recurrence rate, length of hospitalization, number of treatment episodes required to effect tumor remission, and total treatment costs should be examined in a controlled manner. Our present results and experiences suggest that this treatment may be useful in the treatment of equine PSCC.     

Carbon dioxide laser photoablation adjunctive therapy following superficial lamellar keratectomy and bulbar conjunctivectomy for the treatment of corneolimbal squamous cell carcinoma in horses: a review of 24 cases

Objective To determine the complications and nonrecurrence rates following superficial lamellar keratectomy, bulbar conjunctivectomy, and adjunctive carbon dioxide (CO₂) photoablation for corneolimbal squamous cell carcinoma (SCC) in the horse. Study design Retrospective study. Sample population Twenty‐four horses with corneolimbal SCC. Procedure Medical records of horses diagnosed with corneolimbal SCC that was surgically excised and where CO₂ photoablation was used as an adjunctive therapy from 2000 to 2007 were reviewed. Signalment, prior therapy, tumor location and size, complications, and recurrence of SCC were recorded. Results The Thoroughbred was the most commonly (25%) represented breed. Lesions were >10 mm in diameter in 70.8% of cases. Eight horses (33.3%) had neoplastic cells extending to the deep margin of the keratectomy. All horses were available for follow‐up for an average ± standard deviation of 40.7 ± 25 months. Four horses (16.7%) developed a recurrence of SCC. Three of these four horses underwent repeat keratectomy and CO₂ photoablation, one each, at 4 months, 1, and 2 years following the initial procedure. One horse underwent enucleation 8 months following the initial procedure. Conclusions and clinical relevance As an adjunctive therapy, CO₂ photoablation was successful in 87.5% of the horses following a single procedure and in a total of 91.7% following a second therapeutic application. CO₂ photoablation appears to be effective as an adjunctive therapy following removal of large corneolimbal SCC in the horse and in cases in which all tumor cells were not excised.     

Technical set‐up and radiation exposure for standing computed tomography of the equine head

The recent adaptation of human computed tomography (CT) machines to enable scanning of the equine head via standing sedation has revolutionised our ability to acquire images of this complex anatomical region. There are a small number of CT systems installed worldwide and it is to be expected that this will increase in the next few years; however, currently, there is no publication that describes the technical set‐up required to permit CT scanning of the equine head. This paper describes the technical set‐up, technique and exposures necessary to accomplish CT scanning of the horse under standing sedation to diagnose disorders of the equine head.     

Extraction of cheek teeth using a lateral buccotomy approach in 114 horses (1999-2009)

Reason for performing the study: There are few published data regarding the success rates of cheek tooth (CT) removal by lateral buccotomy in the horse. Objectives: A retrospective study of 114 horses admitted to 2 private equine referral hospitals over a 10 year period (1999–2009), which underwent CT removal via a lateral buccotomy. Methods: Hospital records were analysed and details including case details, presenting complaint and results of all diagnostic tests and surgical reports were documented. Information obtained during post operative reassessment was also available for analysis. Long‐term follow‐up information (>2 months) was obtained for 112 horses. Results: Short‐term complications (<2 months) occurred in 24/77 horses (31%) undergoing exodontia of the maxillary CT and 10/37 horses (27%) involving mandibular CT, with the majority arising from partial wound dehiscence and infection following 16 extractions (47%). All healed well by second intention. Other complications included both temporary (n = 6) and permanent (n = 3) facial nerve paralysis, myositis (n = 4) and the inadvertent establishment of an oroantral fistula (n = 4). One myositis case was subjected to euthanasia 24 h post operatively. Five horses had persistent sinusitis following surgery due to dental remnants (n = 2) and excessive packing material (n = 1) found in the sinuses. No inciting cause could be found in the remaining 2 horses. One further horse suffered a fatal cardiac arrest at induction of anaesthesia. Of all horses, 92% operated on had returned to their previous level of work after >2 months with no complications. Conclusion: Horses with CT removal by a lateral buccotomy have a reasonable prognosis for long‐term outcome. Potential relevance: Performing a lateral buccotomy is a justified treatment alternative for the surgical removal of equine CT following unsuccessful attempts by standing oral extraction, offering advantages over alternatives such as retropulsion, endodontic therapy and periapical curettage.     

Pulmonary fibrosis and gammaherpesvirus infection in horses

Pulmonary fibrosis is a devastating and often progressive condition leading to exercise intolerance and frequently the demise of the animal. Although uncommonly encountered in horses, the condition is intensely researched both in human medicine and animal models. Viral infections have long been suspected to play a part in the development of pulmonary fibrosis and neoplastic conditions in other species. In 2007, an association between equine herpesvirus 5 (EHV‐5) infection and nodular pulmonary fibrosis in horses was suggested and the name equine multinodular pulmonary fibrosis (EMPF) was introduced. Recently, the presence of EHV‐5 in equine lymphoma has also emerged. The case report by Schwarz et al. in this issue describes a horse suffering from concurrent T cell leukaemia and EMPF in association with EHV‐5. This article summarises current knowledge about EMPF and EHV‐5 infections in horses, recent developments in the understanding of pulmonary fibrosis in man and the proposed contribution of viral infections to pulmonary fibrosis and neoplastic conditions.     

A technique for computed tomography (CT) of the foot in the standing horse

Computed tomography (CT) in equine orthopaedics is currently limited because of the price, availability, impossibility to transport the scanner into surgical theatre, and the contraindications of general anaesthesia in some patients. A pQCT (peripheral quantitative computerised tomography) scanner was designed by the authors to image the limbs of the horse, both in standing or recumbent position. Standing computed tomography of the foot with a pQCT scanner is feasible and well tolerated by the horse. It enables good visualisation of bony structures but is not suitable to evaluate soft tissues. The technique can also assist surgery by assessing the 3D configuration of bone lesions.     

Injection of the insertion of the deep digital flexor tendon in horses using radiographic guidance

Insertional tendinopathies of the DDFT have been reported both as the sole lesion and as part of a multifocal lesion (Dyson et al. 2003). Computed tomography (CT) and magnetic resonance imaging allow specific diagnosis of deep digital flexor tendon lesions within the hoof capsule; however, direct intralesional treatment of such lesions is difficult because of the hoof's rigid structure. A technique designed to mimic intralesional injection of insertional tendinopathies of the DDFT in the standing horse using radiographic guidance was assessed. Radiographic and contrast CT imaging and sectioning of the limbs confirmed accurate injection in all cases although inadvertant administration of injectate into adjacent structures was also evident.     

Infraspinatus and intertubercular (bicipital) bursae sepsis

The case report by O'Sullivan et al. in this month's issue of EVE describes an unusual case of synovial sepsis raising interesting points on synovial infection in general and more specifically the implication of haematogenous spread of bacteria from a remote site in the mature horse. The identification of synovial sepsis in this location is challenging due to the complex and unfamiliar anatomy in the shoulder region. This clinical commentary reviews the anatomy in this region and discusses the unusual presentation of synovial sepsis secondary to haematogenous spread.     

Parotid salivary gland carcinoma in a geriatric horse

This case report describes a geriatric gelding with a 2 month history of fast‐growing masses within the parotid and submandibular regions. The horse was dyspnoeic on presentation and upper airway endoscopy revealed partial airway obstruction at the level of the pharynx, secondary to a space‐occupying mass. Cytological evaluation of multiple fine‐needle aspirates obtained from the masses were suggestive of salivary gland neoplasia, therefore the horse was subjected to humane euthanasia. A computed tomographical scan was obtained post mortem and revealed a large multi‐lobulated mass involving both guttural pouches, resulting in 80% occlusion of the naso‐ and oropharynx. Histopathology confirmed a parotid salivary gland carcinoma (papillary‐cystic type). Salivary gland tumours are extremely rare in horses, with only a few cases reported in the literature. Treatment of these malignancies proves to be challenging, requiring complete parotidectomy or surgical debulkment, in combination with adjunctive therapy.     

Portosystemic shunts: A diagnostic challenge

The case report in this issue by Woodford et al. (2017) describes the surgical management of an extrahepatic portosystemic shunt in a 5‐week old miniature foal. Only a handful of reports exist in the literature describing surgical procedures for repair of these congenital abnormalities in foals. One of the important aspects of the accompanying case report was the multidisciplinary approach taken in handling, imaging and surgical repair of the extrahepatic shunt. Small animal internal medicine specialists and surgeons diagnose portosystemic shunts much more frequently than equine veterinarians, regardless of whether they are general practitioners or specialists. It is therefore important to work as a team with small and large animal practitioners. The case described by Woodford et al. (2017) had a positive outcome.     

Aggressive surgery in the management of oral neoplasia

Aggressive surgical techniques such as mandibulectomy and maxillectomy have become the standard surgical treatment for oral neoplasia. The development of these procedures has provided some hope for a cure or at least extended life span in animals with oral tumors. Although large segments of bone and soft tissue are usually removed, function and cosmesis are acceptable. Postoperative complications are common but are usually treatable. Best prognosis for long-term survival is for patients with benign tumors or early SCC. Less favorable results have been found with fibrosarcoma and MM. Continued research in adjunctive treatment of these tumors may further improve the results of combined surgical and medical management.     

Two‐ and three‐dimensional computed tomographic anatomy of the enamel,infundibulae and pulp of 126 equine cheek teeth. Part 2: Findings in teeth with macroscopic occlusal or computed tomographic lesions

Reasons for performing study: Dental disease often presents a diagnostic challenge in the horse. Computed tomography (CT) is increasingly used in the evaluation of head related disease in the horse, but the CT appearance of the most common dental diseases of horses has not yet been fully described. Objective: To describe the CT appearance of the peripheral enamel, pulp, infundibular enamel and cement in equine cheek teeth with macroscopic occlusal or CT lesions. Methods: In this study, 126 cadaveric cheek teeth with eruption ages of between 0.5 and 19 years were evaluated for lesions of their infundibulae, pulp and enamel using occlusal surface morphology, 2‐ (2D) and 3‐dimensional (3D) CT and anatomical sectioning. Variations in teeth with no macroscopic lesions have been described in a previous study. The infundibular lesions were categorised further into one of 6 classifications. Results: Infundibular lesions were identified on CT in 90% (115/128) of infundibulae. Of these, 65% (83/128) had infundibular lesions on occlusal surface examination. The extent of infundibular lesions observed varied with age group. All infundibulae over 6 years post eruption had detectable lesions. Peripheral enamel hypoplasia and enamel prolapses, were observed in 10% (12/126) and 1.6% (2/126) of teeth, respectively. The CT appearance of teeth with pulp infections was seen to vary with differing pathologies. Conclusions and potential relevance: The high prevalence of infundibular lesions should encourage consideration of their clinical significance, in addition to the role of infundibulae in dental disease of the horse. Two‐dimensional and 3D CT proved to be highly valuable imaging modalities for dental disease, enabling lesions within the enamel, infundibulae and pulp of equine cheek teeth to be easily detected. The results of this study will facilitate the use of 2D and 3D CT as clinical diagnostic tools for dental disease and aid in the selection of the most appropriate treatment protocol.     

Suspected case of hypersplenism as a cause of anaemia,thrombocytopenia and leucopenia in a Miniature Horse gelding

A 23-year-old Miniature Horse gelding was presented to the Lloyd Veterinary Medical Center with a 3-week history of decreased appetite, lethargy and mild intermittent colic. A complete blood count revealed leucopenia, characterised by neutropenia and lymphopenia, as well as anaemia, thrombocytopenia and hyperproteinaemia whereas hypertriglyceridaemia was noted on serum biochemistry profile. Bone marrow evaluation was nondiagnostic and the horse was negative for antiplatelet antibody testing, Coombs test, equine infectious anaemia virus and Anaplasma phagocytophilum. The horse was hospitalised for 36 days and received supportive care, antibiotics, corticosteroids, dextrose-containing fluids and a whole blood transfusion. Following initial improvement and stabilisation, the horse became severely anaemic and acutely recumbent on Day 36 and was subjected to euthanasia. Post-mortem examination provided a diagnosis of hypersplenism with a markedly enlarged spleen along with histiocytic phagocytosis of erythrocytes and platelets. Examination of bone marrow showed appropriate erythroid hyperplasia and no evidence of myelopthisis or neoplasia. This report describes the first presumptive case of primary hypersplenism in an equid as a cause of pancytopenia.     

Two horses with thoracic lymphoma diagnosed using thoracoscopic biopsy

This report describes the use of thoracoscopy in 2 horses to obtain an antemortem diagnosis of thoracic lymphoma. The first horse in this report presented for assessment of weight loss and fever of unknown origin. The second presented with a history of upper respiratory tract noise and coughing during exercise. Although a strong clinical suspicion of neoplasia existed, a definitive antemortem diagnosis of thoracic lymphoma was not made in either case until biopsy samples obtained during standing thoracoscopy were examined.     

Standing surgery and procedures of the head

Although most surgical procedures of the head are technically easier to perform with the horse under general anesthesia, other factors will influence whether a surgical procedure is performed with the horse standing or recumbent under the influence of general anesthesia. The accessibility of the head lends itself to many standing surgical procedures if the proper combination of analgesia and physical and chemical restraint is used. Traumatic injuries of the head (lacerations, facial bone fractures, and oral fractures) may involve vital structures, and a thorough examination is indicated. Failure to treat a traumatic injury may result in facial deformity, bony sequestra, paranasal sinusitis, salivary-cutaneous fistula, cutaneous fistulas into a nasal passage or paranasal sinus, nasal septal deformities, and ocular dysfunction. Proper management of these injuries typically results in a cosmetic outcome because of the head's abundant blood supply. Other surgical procedures that can be performed in the standing horse include centesis and trephination of the paranasal sinuses, certain dental procedures, alar fold stabilization, and extirpation of epidermal inclusion cysts of the nasal diverticulum.     

Anatomy of the dura mater venous sinus of Alouatta belzebul

The anatomy of the dura mater's venous sinuses is important in the veterinary clinical and surgical area, for cranial procedures and interventions of wild animals, in addition to assisting in the management of neurological diseases, which can prevent serious complications. The macroscopic anatomy of the venous sinuses of the dura mater of Alouatta belzebul was studied. Five adult specimens, males and females, were dissected and fixed in 10% formaldehyde solution. In the dura mater of the Alouatta belzebul, nine venous sinuses were observed, being them dorsal sagittal sinus, ventral sagittal sinus, transverse sinus, straight sinus, sigmoid sinus, temporal sinus, parietal sinus, basilar sinus and cavernous sinus, with morphological similarities in origin, path and destination of blood flow to the internal jugular vein, assisting in the venous drainage function of the brain in this species. These data are similar to those found in other species of non-human and human primates such as Saimiri sciureus, Sapajus libidinosus and Homo sapiens. Of the venous sinuses observed, the cavernous sinus was of considerable clinical and surgical importance in Alouatta belzebul due to its topographic arrangement next to the internal carotid artery and pituitary gland, data that corroborate Sapajus libidinosus, Macaca fascicularis, Macaca mulatta, Papio ursinus, Cercopithecus pygerithrus and Galago senegalensis. In this context, the knowledge of the macroscopic anatomy of the venous sinuses of the dura mater may contribute to the role of veterinarians in less invasive surgical procedures in non-human primates such as Alouatta belzebul and other mammals.