Page 428 - WSAVA2018
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 25-28 September, 2018 | Singapore
E. Robertson1
1American Board Certified Diplomate Feline Practice,
Feline Vet and Endoscopy Vet Referrals, Brighton, East Sussex, United Kingdom
Indications, History and Physical Examination
Before conducting any endoscopic examination, it’s essential to first acquire a detailed clinical history and thorough patient ex- amination to accurately localize the disease process. Additional general screening tests (e.g. haematology, biochemistry, elec- trolytes and urinalysis) can also be performed to establish the general health and potential anaesthetic risk of the patient. The depth of evaluation will vary depending on the case; however, every case should receive a comprehensive history and full clin- ical examination.
The indications for rhinoscopy include: chronic and/or recurring sneezing and reverse sneezing, nasal discharge, epistaxis, ab- normal respiratory sounds such as stertor (nasopharyngeal) and/ or stridor (laryngeal). Physical examination should therefore in- clude an assessment of nasal air ow (decreased or normal, uni- lateral or bilateral change) and palpation of the palate and facial bones for pain, swelling, ipsilateral epiphora, ipsilateral exopthal- mos or evidence of bony lysis.1,2 A full oral examination should ideally include a dental assessment and oropharyngeal exam- ination. If dental disease is suspected, dental radiography may be indicated, paying special attention teeth 104, 204, 108 and 208. Neurological examination should focus on cranial nerve evaluation and also detecting signs of cerebral dysfunction such as weakness, decreased conscious proprioception, and visual deficits indicative of invasive disease. If clinically suspicious of Cryptococcosis, cytology slides of nasal secretions and Latex Cryptococcal Antigen Testing (LCAT) should be submitted, espe- cially in those patients travelling from endemic areas (e.g. Cana- da, Australia, USA). A thorough otoscopic examination should be performed of the external ear canals.
Cats with epistaxis should have a coagulation profile (e.g., plate- let count, PT/PTT and/or a mucosal bleeding time-MBT) per- formed and their blood pressure checked prior to starting as these patients may have an increased risk of bleeding. Bacterial culture and antimicrobial susceptibility testing of super- ficial nasal swabs are often unrewarding and not generally rec- ommended.3 Results typically yield normal intranasal bacterial flora and are difficult to interpret. Others suggest that results of culture and sensitivity testing may be useful in guiding antibacte- rial therapy.3 Cultures of nasal biopsy samples may be more rep- resentative for deep mucosal infections, but this has not been definitively proven.
FHV-1 or FCV virus isolation and nucleic acid amplification tech- niques are often used to implicate infection by these organisms. FHV-1 PCR assays are widely available and feline calicivirus reverse transcriptase PCR assays are also available. However, none of the PCR assays for FHV-1 have been shown to distin- guish between wild-type virus and vaccine virus. Additionally, test sensitivity (detection limits and rates) varies greatly between the tests and laboratories. These infectious agents can be de- tected in healthy cats as well as in clinically ill cats. Thus, the
positive predictive value for these assays is low and thus diag- nostic: cost value is questionable in those cats with chronic nasal disease.
For a complete evaluation of the nasal cavity, sinuses and naso- pharynx the assessment should include imaging such as (radio- graphs), CT/MRI, dental radiography, and rhinoscopy.
Introduction to Rigid Endoscopy
The novice endoscopist should strongly consider participating in hands-on wet lab courses, provided by experienced endoscopists, before attempting rigid rhinoscopy in the cat. This will ensure a level of competence that justifies the potentially high learning curve and initial investment in providing this type of service.
What is a Rigid Endoscope?
In simple terms, a rigid endoscope is a long slender stainless steel tube with a series of solid glass rod lenses which allow for the transmission of light and image.1,2 Light transmission is achieved from the use of an extracorporeal light source attached to the optical end of the endoscope. The image is then viewed via an oculus, or eye-piece, directly to the operator’s eye or a video camera which can be transmitted to a video monitor and stored in an archiving system.
Upper airway examination begins with laryngoscopy on induction. Laryngeal structure (i.e. anatomy) and function should be assessed in relation to phase of respiration. This examination should be assessed under a light plane of anaesthesia. It is vital for an assistant to ‘announce’ the phase of respiration and to not confuse normal movement to paradoxical movement found in complete laryngeal paralysis.
Caudal (Flexible) Nasopharyngoscopy:
At the beginning of the procedure, a retroflexed examination behind the soft palate should be performed in attempt to ex- clude mass lesions, nasopharyngeal stenosis or foreign bodies. A dental mirror and bright light can sometimes provide an image of this region, or a specialised instrument with light source and a flexible mirror can be obtained from commercial vendors.
A 4.0mm-5.0 mm diameter 2-way deflection endoscope with bi- opsy channel can access the nasopharynx in all but the smallest dogs or cats.
Nasal flushing, culture and cytology
Vigorous nasal flushing can be useful to dislodge mass lesions or foreign bodies. Cytology of nasal flush fluid is likely to be very superficial and of limited value in most cases. In particular, neoplastic conditions may be misdiagnosed as rhinitis following the finding of inflammatory cells only on cytology.4,5 Cytology can, however, be highly diagnostic for diseases such as nasal cryptococcosis and friable tumours (e.g. lymphoma).
Rostral (Rigid) Rhinoscopy
This procedure can be performed quite easily on most feline patients using a 1.9mm x 30 degree telescope with sheath.
This instrument has two-way stopcocks for continuous fluid in- gress and egress which removes blood, mucus or other tissue debris from the field of view. Another advantage of continuous fluid irrigation is that it can act as a superior medium and en- hance tissue magnification compared to that of air.1 The entirety of both the dorsal and ventral nasal meati can be examined ad- equately to the level of the ethmoid turbinates.

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