Respiratory Disease in Dogs, Cats, and Rabbits 2024-25 PDF

R E S P I R ATO R Y D I S E A S E I N D O G S , C AT S A N D R A B B I T S. K I R S T Y M C G I N L E Y F H E A M R C V S L E C T U R E R I N V E T E R I N A R Y C L I N I C A L S C I E N C E S LEARNING OBJECTIVES Construct a differential diagno...

R E S P I R ATO R Y D I S E A S E I N D O G S , C AT S A N D R A B B I T S. K I R S T Y M C G I N L E Y F H E A M R C V S L E C T U R E R I N V E T E R I N A R Y C L I N I C A L S C I E N C E S LEARNING OBJECTIVES Construct a differential diagnosis list based on clinical presentations and choose appropriate diagnostics. Determine appropriate medical and surgical interventions in the management and treatment of airway diseases in the dog, cat and rabbit. Determine appropriate prognosis, and the welfare implications of treatment options. Determine control measures appropriate for disease prevention. 2  CONSTRUCTION A DIFFERENTIAL DIAGNOSIS: H I S T O R Y. Signalment – age, breed predispositions. When did it start? How did it start? Has it changed? Has it happened before? Vaccinated? Recent travel, change in management, others affected? Any other signs e.g., vomiting or diarrhoea? Any pre-existing conditions? Receiving medication? Trauma, toxin ingestion? 3 CONSTRUCTION A DIFFERENTIAL DIAGNOSIS: C L I N I C A L P R E S E N TAT I O N Upper respiratory tract disease. Lower respiratory tract disease. Sneezing. Coughing. Nasal discharge. Dyspnoea or tachypnoea. Stridor/stertor. Exercise intolerance. Increase inspiratory effort. Respiratory distress/Cyanosis. Facial deformity and/or pain. Other systemic signs. Altered vocalisation or loss of voice. 4 C AT S  C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Feline Upper Respiratory Tract Infections. Usually viral-induced and common in multi-cat households and catteries. Feline Herpesvirus (FHV-1/Feline rhinotracheitis virus) often associated with: Sneezing. Ocular discharge, conjunctivitis, keratitis and corneal ulcers. Infection at a young age can result in chronic rhinitis. Feline Calicivirus (FCV): often associated with: Oral ulceration. Sneezing and nasal discharge. Chronic stomatitis and gingivitis. Can develop pneumonia in severe cases. Image from CatsCouncil.com 6 C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Feline Upper Respiratory Tract Infections. Clinical Signs: Depression. Difficulty/pain on swallowing and anorexia. Pyrexia. Ocular and nasal discharge and sneezing. Salivation. Coughing. Voice changes. Cat with viral-induced URT infection. Diagnosis: ( Bishops Stortford Vet Hospital) Clinical presentation is often suggestive. Polymerase chain reaction (PCR) from oropharyngeal or conjunctival swabs. Viral isolation (VI) from oropharyngeal or conjunctival swabs (not as widely available). 7  C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Feline Upper Respiratory Tract Infections. Treatment: Supportive care (hydration, nutrition). Antiviral therapy for FHV-1 (e.g., famciclovir). Broad-spectrum antibiotics for secondary bacterial infections. (Amoxicillin- clavulanate is often appropriate. Nebulisation (saline)and steam therapy can help ease respiratory congestion. Mucolytics. Prevention: Regular vaccination (reduce shedding and clinical signs). Stress can cause recrudescence so try to avoid. Environmental control (good hygiene, solid walls in cattery). MSD Animal Health 8 C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Chronic Rhinosinusitis. A chronic inflammatory condition, usually post-viral (secondary to FHV-1 or FCV infections). Damage to nasal turbinates reduces mucosal immunity and leads chronic secondary infection. Clinical Signs: Persistent or recurrent nasal discharge (mucopurulent). Sneezing. Nasal obstruction. Diagnosis: History, clinical signs and examination. Rule out other causes. Radiography. Rhinoscopy with biopsy for histopathology (neutrophilic and mixed inflammatory infiltrate). Advanced imaging (CT or MRI) to assess sinus involvement. 9 C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Chronic Rhinosinusitis. Treatment: Aimed at controlling severe clinical signs. Broad spectrum antibiotics (often osteomyelitis of turbinates so long courses of antibiotics (2-6 weeks) may be necessary. Ideally based on culture and sensitivity. Nebulised saline and steam treatment. NSAIDs (Care with long-term use and only if eating and well hydrated). Antivirals e.g., Famciclovir anecdotal reports that can be beneficial. Topical nasal decongestant (e.g., phenylephrine, xylometazoline) short term use only. Owners need to be aware that long-term management and recurrent courses of treatment will be required. 10 C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Allergic Rhinitis. Caused by exposure to allergens including Pollens (from trees, grasses, or weeds), dust mites, moulds, cigarette smoke or other airborne irritants, household chemicals or cleaning agents. Less common than post viral chronic rhinosinusitis but can be more responsive to treatment. Clinical Signs: Sneezing: Often intermittent but may become frequent in response to allergen exposure. Nasal Discharge: Usually serous (clear, watery), though mucopurulent discharge can occur if secondary bacterial infection develops. Cats may paw at their noses or face. Conjunctivitis: Often accompanies nasal signs in cases of allergic rhinitis. Coughing and Wheezing: In severe cases, allergic rhinitis may be associated with allergic bronchitis or feline asthma. 11 C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Diagnosis: Seasonal pattern of clinical signs. An improvement in clinical signs following anti-inflammatory or antihistamine therapy can support a diagnosis of allergic rhinitis. Exclusion of Other Causes (especially infectious causes). Eosinophilic or lymphoplasmacytic infiltrate present on biopsy. Treatment: Reduce exposure to inhaled allergens (eg, cat litter house dust, cigarette smoke, aerosol sprays). Antihistamines (eg, cetirizine), response can be unpredictable. Systemic administration of anti-inflammatory doses (e.g., prednisolone 1 mg/kg/day, then titrated down to the minimum effective dose). Inhaled corticosteroid delivered via a feline aerosol chamber once initial signs controlled. 12 C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Nasopharyngeal Foreign Bodies. Most commonly long grass blades (‘grass palate’) become lodged in the nasopharynx. Clinical Signs: Sneezing: Often sudden and severe, triggered by the irritation of the foreign body. Nasal Discharge: Usually unilateral and can be serous, mucopurulent, or hemorrhagic, depending on the duration of the foreign body's presence. Gagging, Coughing, or Reverse Sneezing: Particularly if the foreign body is lodged in the caudal nasal passages or nasopharynx. Pawing at the Face or Nose: Indicative of discomfort and irritation. Halitosis: If secondary infection develops due to the retained foreign material. Open-Mouth Breathing or Stridor: In severe cases where there is significant obstruction or inflammation causing respiratory distress. 13 C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Nasopharyngeal Foreign Bodies Diagnosis Examination of nasopharynx under general anaesthesia. May be immediately visible or require nasopharyngoscopy. Nasal flushing may be necessary if located very rostrally. Treatment Removal of foreign material May require NSAIDs and or antibiotics if more long standing. Grass blade removed from cat’s nasopharynx 14 (PDSA Nottingham).  C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Nasopharyngeal Polyps. Cause is not fully understood (possibly chronic inflammation of middle ear). These are benign pedunculated growths commonly found in young cats, arising from the middle ear or nasopharynx. Clinical Signs: Chronic nasal discharge (usually unilateral). Stertor, difficulty breathing, possible dysphagia (obstruction of nasopharynx). Otitis externa or media, possible vestibular signs or Horner’s syndrome if extending into middle ear. Diagnosis: Visual examination (otoscopy or rhinoscopy) and imaging (radiography). Histopathological examination after excision. 15  C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Treatment: Surgical removal of the polyp. Recurrence is possible, especially if the stalk is not fully excised. Temporary Horner’s syndrome is common but usually resolves. NSAID or corticosteroid can be used post-operatively to reduce secondary inflammation. Antibiotics indicated if more chronic and evidence of secondary infection on removal. Nasopharyngeal polyp after removal. (Leicester Skin Vet) 16  C O M M O N C A U S E S O F U R T D I S E A S E I N C AT S Fungal Rhinitis. Emerging disease of cats worldwide. Can be caused by Cryptococcus species (rare in UK), Aspergillus species and Penicillium species. Clinical Signs: Chronic nasal discharge +/- epistaxis. Stertor. Facial swelling Sometimes neurological signs if extension into the CNS (e.g., seizures, blindness). Cat receiving clotrimazole Diagnosis: infusion (Courtesy of A Serology (Cryptococcus spp) Ridyard) Imaging (Radiography, endoscopy, turbinate lysis frequently seen on CT Cytology and Culture of fungal plaques. Treatment: Long-term antifungal therapy (intranasal clotrimazole or oral itraconazole or posaconazole). Surgical debridement may be required in severe cases. Guarded prognosis, recurrence likely. 17 C O M M O N C A U S E S O F L R T D I S E A S E I N C AT S Feline Asthma (Feline Allergic Airway Disease): Asthma is a common lower-airway inflammatory disease in cats thought to be allergic in origin. Clinical Signs: Cough (inducible on tracheal palpation). Increased expiratory effort and expiratory wheeze. Open mouth breathing. Tachypnoea. Vomiting. Cat with open mouth breathing 18  C O M M O N C A U S E S O F L R T D I S E A S E I N C AT S Feline Asthma (Feline Allergic Airway Disease): Diagnosis: Radiograph of Rule out other diseases that can mimic clinicopathologic features of cat with asthma asthma. (Oklahoma State Radiographs: bronchial or bronchointerstitial lung pattern common. University Center for Bronchoscopy mucus, mucosal hyperemia, airway collapse, and Veterinary stenosis. Health Sciences). Eosinophilic inflammation on BAL cytology (>20% eosinophils). Thoracic CT can identify subtle lesions that may not be appreciated on radiograph. Eosinophils within BAL sample.  C O M M O N C A U S E S O F L R T D I S E A S E I N C AT S Feline Asthma (Feline Allergic Airway Disease): Management: Oral Glucocorticoids (Prednisolone 0.25-1 mg/kg PO BID. Taper to minimal effective dose for maintenance therapy). Bronchodilators (Terbutaline 0.625 mg PO BID, Theophylline 25 mg/kg PO SID). Inhaled (once initial signs controlled) Glucocorticoids (Fluticasone (110 ug q 12h, may increase up to 220 ug twice a day). Bronchodilators (Salbutamol or albuterol 1 puff/ 10 kg up to Cat receiving fluticasone therapy using a maximum of 3 puffs). a metered dose inhaler (MDI) connected to a spacer and face mask. (Credit: Glen Cousquer and Vetlexicon). 20 C O M M O N C AU S E S O F L RT D I S E A S E I N C AT S Chronic Bronchitis: Likely secondary to a previous airway insult, such as respiratory infections or inhaled irritants leading to permanent damage to the airways. Shares many historical, clinical and radiographic features of feline asthma. Clinical Signs: Chronic coughing (paroxysmal, productive, retching, gagging). Recurrent bouts of bronchopneumonia. Tachypnoea and dyspnoea. Exercise intolerance. Cachexia, debility. 21 C O M M O N C A U S E S O F L R T D I S E A S E I N C AT S Diagnosis: Radiographs showing thickened bronchial walls, Bronchoscopy showing excessive mucus roughened hyperaemic mucosa. Nondegenerate neutrophilic inflammation on BAL cytology. Hyperaemia on bronchoscopy Management: (Credit: Jonathan Dear) Glucocorticoids and bronchodilators (oral and/or inhaled). Neutrophilic Airway humidification (steam therapy). inflammation on BAL Cytology. 22  C O M M O N C AU S E S O F L RT D I S E A S E I N C AT S Bacterial Pneumonia. Less commonly identified than inflammatory disease. Pasteurella spp, Escherichia coli, Staphylococcus spp, Streptococcus spp, Pseudomonas spp, B bronchiseptica, and Radiograph Mycoplasma spp have all been reported as lower respiratory showing pathogens. Bronchial Underlying infections e.g., FIV and FeLV can enhance severity. Pattern with bronchiectasis Clinical Signs: (indicated by Cough. arrow). (Credit: Jonathan Dear). Nasal discharge. Lethargy and pyrexia. Tachypnoea and hypernoea. Dyspnoea/respiratory distress. Weight loss if more chronic. 23  C O M M O N C AU S E S O F L RT D I S E A S E I N C AT S Diagnosis: Clinical signs Radiographs diffuse and often mixed pattern. Leukocytosis on haematology (mainly neutrophilia with a left shift), Bronchoscopy (hyperemia of the epithelium, prominent mucosal vessels, rounded, thickened airway bifurcations, thick and often discoloured mucous). BAL (septic and suppurative inflammation). Management: Antibiotics ideally based on based on culture and sensitivity from BAL samples. Supportive care (oxygen, nebulization, humidification, fluids, nutritional support). 24  C O M M O N C AU S E S O F L RT D I S E A S E I N C AT S Lungworm. Aelurostrongylus abstrusus is the most prevalent. Most common in outdoor or hunting cats. Clinical Signs: Many infections not clinically significant. Lethargy and weight loss if more chronic. Severe burdens can cause coughing and dyspnoea/hypernoea. Can occasionally cause sudden death. Diagnosis: Lungworm Larvae from BAL Detection of larvae in faecal Baermann test or BAL fluid. (Credit Richard Malik and Vetlexicon). Radiographic changes variable, can be similar to those seen in feline asthma. Treatment: Fenbendazole paste. Milbemycin oxime/praziquantel Various spot-on formulations (imidacloprid/moxidectin; emodepside /praziquantel; fipronil /(S)- methoprene /eprinomectin/praziquantel ; or selamectin). 25 DOGS COMMON CAUSES OF URT DISEASE IN DOGS Infectious Tracheobronchitis /Canine infectious respiratory disease complex (Kennel Cough). A highly contagious condition caused by a number of viral and/or bacterial agents (Canine Parainfluenza virus, Canine Adenovirus, Bordetella bronchiseptica). Clinical Signs: Harsh, hacking cough (often described as "goose honk"), often with a retch Nasal discharge, submandibular lymph node enlargement. Mild lethargy and pyrexia. Diagnosis: Based on history (recent exposure to other dogs) and clinical signs. PCR testing (deep oropharyngeal swab). 27 COMMON CAUSES OF URT DISEASE IN DOGS Infectious Tracheobronchitis /Canine infectious respiratory disease complex (Kennel Cough). Treatment: Most cases are self-limiting and resolve within 3 weeks. Antitussives (e.g., butorphanol) for non-productive cough. Antibiotics if clinical signs >10 days or systemically unwell. Short-term corticosteroids (0.5 mg/kg PO BID for 3-5 days) as long as no complications. Prevention Vaccination against Bordetella and canine parainfluenza virus. Isolate affected individuals until coughing has resolved. Merck Animal Health 28  COMMON CAUSES OF URT DISEASE IN DOGS Brachycephalic Obstructive Airway Syndrome (BOAS): A group of anatomical abnormalities seen in brachycephalic breeds due to shortened skull structures. Highly prevalent in English and French bulldogs and Pugs. Components of BOAS: Stenotic nares, aberrant and hypertrophied turbinates. Nasopharyngeal narrowing and collapse. Elongated soft palate. Narrow larynx, laryngeal hypoplasia, everted laryngeal saccules. Hypoplastic trachea. Skull base malformation. French Bulldog. Ellevetsciences.com 29 COMMON CAUSES OF URT DISEASE IN DOGS Clinical Signs: Snoring, noisy breathing (stertor and stridor) Increased respiratory effort. Exercise and heat intolerance. Cyanosis and collapse. Often progress over time without intervention. Diagnosis: Based on breed predisposition and clinical examination. Endoscopic evaluation. Radiographs or CT for assessing tracheal and nasal anatomy. Treatment: Surgical management (e.g., widening of stenotic nares, soft palate resection, usually results in significant improvement. Weight management and environmental modification (e.g., avoiding heat, stress, excitement). Long-term management often required, as the condition tends to be progressive. 30 COMMON CAUSES OF URT DISEASE IN DOGS Laryngeal Paralysis. Paralysis of the arytenoid cartilages, preventing proper airway opening during inspiration. Usually affects older (> 9 years) large-breed dogs with Labrador retrievers being overrepresented. Acquired form is caused by damage to the recurrent laryngeal nerve and/or laryngeal muscles (trauma, polyneuropathy, polymyopathy, intra-or extra-thoracic masses). Many cases classed as ‘Idiopathic’ but recent evidence suggests LP may be part of a progressive generalised neuropathy. A congenital form occurs in some breeds. Clinical Signs: Inspiratory stridor. Exercise intolerance. Coughing. Dysphagia and regurgitation. Dysphonia (change in or loss of bark). Cyanosis and collapse (severe cases). 31  COMMON CAUSES OF URT DISEASE IN DOGS Diagnosis: Source: Photographs by B. Van Goethem Clinical examination. Visual inspection of the larynx under light anaesthesia (failure of arytenoid cartilages to abduct on inspiration). Thoracic radiographs (masses, aspiration pneumonia). Neurological assessment (rule out neuropathy). Biochemistry and haematology (rule out endocrinopathies). Laryngeal Paralysis Treatment: Surgical intervention (unilateral arytenoid lateralization most often used, need to monitor carefully post –op for aspiration pneumonia). Weight loss and exercise modification. Anti-inflammatory drugs to reduce laryngeal swelling. Management of concurrent conditions (e.g., concurrent hypothyroidism in around 30% of dogs with acquired LP ). Left arytenoid abduction after surgery 32 COMMON CAUSES OF URT DISEASE IN DOGS Canine nasal aspergillosis Infection occurs when Aspergillus spores are inhaled, with dogs. Fungal invasion results in local tissue destruction and inflammation. Dolichocephalic breeds predisposed. Clinical Signs: Chronic nasal discharge: Serous, mucopurulent, or hemorrhagic. Nasal pain and discomfort: Dogs may paw at their noses or show signs of facial pain. Sneezing Epistaxis Depigmentation of the nares of a dog with chronic sinonasal aspergillosis. Ulceration and/or depigmentation of the nares. (N Benitah) 33 COMMON CAUSES OF URT DISEASE IN DOGS Canine nasal aspergillosis Diagnosis: Imaging: CT or radiographs show nasal turbinate destruction and increased soft tissue density. Rhinoscopy: Visualization of fungal plaques within the nasal cavity; samples for cytology, culture, or biopsy. Serology: Aspergillus-specific antibody tests, although not always reliable. Treatment: Surgical debridement of fungal plaques and topical clotrimazole via instillation into the nasal cavity or frontal sinuses under anaesthesia every 2 weeks until negative culture/histopathology. Systemic antifungals (e.g., itraconazole or fluconazole) may be used but are less effective than topical treatment. 34 COMMON CAUSES OF LRT DISEASE IN DOGS Chronic Bronchitis: Diagnosis. Radiography: Bronchial wall thickening and distortion. Bronchiectasis. Cor pulmonale. Bronchoscopy: Tracheobronchial collapse, hyperaemia and thickening of mucosa. Increased mucous. BAL: Lots of mucous, neutrophils on cytology. Blood gas analysis: Decreased oxygen saturation (PsO2