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2016 British Small Animal Veterinary Association Congress

Clinician's Brief (Capsule)

August 2016

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Pseudomonas aeruginosa Otitis

Patients with severe, chronic otitis externa are commonly secondarily infected with Pseudomonas aeruginosa; in those cases, the otitis externa has usually progressed and otitis media is present as well. Otitis media can be a perpetuating factor for otitis externa and can prevent its resolution. Otitis media cases require long courses of systemic antibiotics with the use of culture and susceptibility to guide therapy. Because the ear drum typically grows back when ruptured, an intact ear drum does not rule out otitis media. If the ear drum is intact, a myringotomy is required to culture the bulla and treat the condition. The bulla should be thoroughly flushed under general anesthesia using sterile saline. Topical steroids are frequently used to minimize inflammation and any neurologic signs after a deep ear flush. Oral steroids or other analgesics also may be indicated following an ear flush. 

Topical therapy for P aeruginosa should include Tris-EDTA, which binds to calcium in the cell wall of the bacteria. This weakens the cell wall and increases the effectiveness of topical antibiotic solutions. Other topical therapies may include orbifloxacin, enrofloxacin, ticarcillin/clavulanic acid, and silver sulfadiazine. Ototoxicity has not been reported from silver-based solutions in cases of otitis media with P aeruginosa.—Marsella R

Ferrets & Rabbits: Adrenal Disease

Hyperadrenocorticism is commonly seen in surgically spayed and neutered pet ferrets >3 years of age. Male and female ferrets are affected with equal frequency. Unilateral adrenal enlargement is present in 85% of ferrets with hyperadrenocorticism. Common clinical signs include symmetrical alopecia, recurrence of sexual behavior after neutering, and pruritus. Spayed jills may have vulvar swelling and, occasionally, mammary gland enlargement. Hobs may have dysuria, pollakiuria, and/or anuria secondary to periprostatic or periurethral cysts that can cause urethral obstruction. 

A tentative diagnosis can be made based on compatible clinical signs. Diagnosis is confirmed via abdominal palpation, hormonal testing, and ultrasonography. Common treatments include adrenalectomy and/or the use of long-acting gonadotrophin-releasing hormone analogues (eg, deslorelin). 

Adrenal disease is rare in rabbits but has been reported in patients >6 years of age. Return of sexual behavior with unusual aggression is the most prominent clinical sign. A doe with an adrenal tumor may present with an enlarged clitoris. Diagnosis and treatment of adrenal tumors in rabbits is similar to that in ferrets and includes surgery and/or the use of deslorelin-containing implants.—Schoemaker N

Vaccinations in Dogs & Cats

To appropriately advise clients regarding vaccinations, it is essential to understand the types of vaccines available. Live attenuated vaccines contain a live modified pathogen, which can replicate in the host without causing illness. Live genetically engineered vaccines contain a pathogen with genetically modified virulence. Live vector, genetically engineered vaccines contain a portion of a pathogen’s genome within a nonpathogenic vector virus. Killed vaccines do not contain any live organisms but still stimulate an immune response. Any vaccine may contain an adjuvant (ie, an additive that helps stimulate an immune response).

The duration of immunity from a vaccine is dependent on both the type of vaccine and host factors.

The duration of immunity from a vaccine is dependent on both the type of vaccine and host factors (eg, concurrent disease, medications, previous exposures to the pathogen, maternally derived immunity). Any immune-naïve animal requires an initial vaccine dose to prime the immune system, followed by a second booster dose to induce protective immunity. In some young animals, circulating maternally derived antibodies may block an immune response to the initial vaccination; thus, some vaccine manufacturers recommend young animals receive multiple booster vaccines, including 2 doses after the age of 12 weeks. Because clients are frequently concerned about vaccine reactions, veterinarians should be prepared to discuss risks associated with vaccination. Nonspecific immune responses, type I hypersensitivity reactions, initiation of autoimmune diseases, and vasculitis at the injection site are known adverse reactions to vaccines. All adverse reactions should be reported.—Harris B

Feline Bronchitis & Asthma

Chronic bronchial disease usually presents in cats as either chronic bronchitis or asthma. Chronic bronchitis most often causes coughing due to lower airway inflammation. Other disorders that cause coughing (eg, heart failure, pneumonia, neoplasia) must be excluded before chronic bronchitis can be diagnosed. Asthma is loosely defined as a disorder of the lower airways that causes airflow limitation; clinical signs often include wheezing or respiratory distress. Feline asthma sometimes manifests only as a daily cough. Chronic bronchitis and asthma can be difficult to differentiate when a cough is the only sign. Additionally, different combinations of clinical signs can occur, which can complicate diagnosis. Pulmonary function tests can help diagnose asthma but require significant patient compliance to complete. Although not definitive, diagnosis in general practice usually relies on clinical criteria, including thorough history, radiographic evidence of thickened bronchial walls, and a positive response to bronchodilator or corticosteroid therapy. Because small reductions in airway diameter cause large decreases in airflow, treatment does not need to be dramatic to result in significant improvement in clinical signs. Treatment of bronchial disease in cats is often multifactorial and includes environmental changes, inhaled or systemic corticosteroids and bronchodilators, and, occasionally, antibiotics.—Padrid P

Feline Chronic Diarrhea

Chronic diarrhea incidence in cats is likely underestimated because of the secretive nature of cats’ elimination behaviors. Hyperthyroidism is likely the most common cause of chronic diarrhea in older cats; measurement of a T4 level is an important initial step. Exocrine pancreatic insufficiency in cats is rare, so feline trypsin-like immunoreactivity is often a low-priority test. Because pancreatitis can cause diarrhea or may occur concurrently with feline inflammatory bowel disease, feline pancreas-specific lipase may be a worthwhile test in anorexic cats. Infection or diet may cause chronic diarrhea in young cats. Fecal samples should be evaluated for protozoal infections (eg, Tritrichomonas spp, Giardia spp). The presence of thickened bowel and/or enlarged mesenteric lymph nodes on abdominal palpation may indicate the need for ultrasonography to evaluate for inflammatory or neoplastic disease (eg, inflammatory bowel disease, lymphoma). If dietary trials are unsuccessful, intestinal biopsy may be required. Evaluation of biopsy samples is helpful to rule out large cell lymphoma or other disease processes. Diffuse intestinal disease in cats is most likely small cell lymphoma or lymphoplasmacytic enteritis; both diseases can be treated with prednisolone and chlorambucil. Cats with chronic diarrhea often have low cobalamin levels, which can magnify any intestinal pathology. Serum cobalamin levels should be measured in these cats, and, if warranted, the cat supplemented with vitamin B12.—Hall E

Nasal Disease

Feline herpesvirus 1 is a frequent cause of chronic rhinitis in cats.

Chronic rhinitis is a common finding in small animal practice. Clinical signs often include sneezing, nasal discharge, and noisy breathing. Primary causes of chronic signs include foreign bodies, masses, tooth root infections, or immune-mediated noninfectious inflammation. Commensal bacteria may cause secondary signs of green/yellow nasal discharge and congestion. Feline herpesvirus 1 is a frequent cause of chronic rhinitis in cats. Nasal radiographs with or without computed tomography, endoscopy, biopsy, and nasal flush are all components of a diagnostic workup for chronic rhinitis. Common microscopic findings include a lymphoplasmacytic, neutrophilic, segmental, moderate-to-severe rhinitis with turbinate remodeling and multifocal, intra-epithelial, intranuclear eosinophilic inclusions. Biopsy reports often resemble those seen with lymphocytic plasmacytic or inflammatory bowel disease.

Therapeutic strategies, which are more effective if instituted before turbinate destruction and remodeling, involve clearing opportunistic bacterial infections, evaluating the efficacy of steroids, and increasing patient comfort. A 3-week course of enrofloxacin and clindamycin is indicated in these cases. If the patient has previously been treated with multiple antibiotics, enrofloxacin should be replaced with marbofloxacin. If turbinate destruction is severe, chronic rotating antibiotic therapy with marbofloxacin, azithromycin, and minocycline should be instituted for weeks 1, 2, and 3, followed by a rest week. A 5-day prednisolone trial is recommended for animals with serous nasal discharge. If a response to steroid therapy is seen, fluticasone therapy should be undertaken. To improve patient comfort, sinus drainage may be facilitated by using phenylephrine nasal drops rotated with saline on a 3-day cycle (3 days decongestant, 3 days saline).—Padrid P

Managing Heart Failure on a Shoestring Budget 

It is important for veterinarians to have different diagnostic and treatment options based on varying budget amounts that still offer the possibility of acceptable clinical outcomes. When treating congestive heart failure (CHF), it is helpful to outline an optimal plan, a scaled-down plan, and a budget-restricted plan. It is essential to prioritize the cost-benefit value of each test, convey to owners the expected costs of ongoing treatment in a positive manner, and remind them that the optimum plan typically allows dogs to enjoy an excellent quality of life. It is also helpful to give owners an expected average daily cost. To limit financially and emotionally costly emergency visits, the veterinarian can instill in owners the value of careful at-home monitoring. Emphasizing the importance of routine follow-up visits can also help ensure that a budget is used optimally.—Gordon S

Spot & Manage Feline Hypertensive Retinopathy 

Cats >10 years of age appear to be at risk for systemic hypertension, which may be associated with renal insufficiency and hyperthyroidism. Less commonly, systemic hypertension may be associated with chronic anemia, diabetes mellitus, chronic corticosteroid administration, and primary aldosteronism. The eyes, brain, and kidneys are often affected by systemic hypertension because of the small vessels present in these organs; thus, routine ocular examinations are recommended for all cats >10 years of age. Blindness and hyphema, the most common presenting signs, are associated with the advanced stages of hypertension. Classic ocular signs of hypertension are retinal vessel tortuosity, nipping or kinking of vessels, and vascular spasms, followed by retinal edema, retinal detachment, and retinal hemorrhages. Iridal aneurisms and anterior segment hemorrhages may also occur. If early signs are detected and confirmed by a systolic blood pressure >160 mm Hg, treatment can be initiated before organ damage occurs. A minimum database—including CBC, serum chemistry profile, T4 level, and urinalysis with a urine protein:creatinine ratio—is recommended. Amlodipine, a calcium channel blocker, is the treatment of choice for feline hypertension. Blood pressure should be monitored starting 7 days after the start of therapy. Once hypertension is under control, it should be checked every 3 to 6 months. The amlodipine dose may be titrated to effect. Additional treatments, including benazepril, may necessary for blood pressure control and renal support, particularly in those patients with ongoing proteinuria.—Hartley C

Blood Gases  

Blood gas analysis is the measurement and interpretation of the partial pressure of oxygen (PO2) and carbon dioxide (PCO2) and of acid-base parameters (eg, blood pH, bicarbonate, base excess). Many blood gas analyzers also measure electrolytes, glucose, and lactate. Arterial PO2 (PaO2) quantifies oxygenation and can be used to calculate alveolar-arterial (A-a) gradient and PaO2:FiO2 (inspired oxygen) ratio. Additionally, PaO2 can guide oxygen supplementation and the need for mechanical ventilation. Hypoxemia is defined as PaO2 <80-90 mm Hg. Pulse oximetry measures hemoglobin saturation (SpO2). Arterial oxygen content is PaO2 (oxygen dissolved in plasma) plus oxygen bound to hemoglobin. PaO2 does not directly affect acid-base balance. PCO2 measures CO2 levels in blood. PCO2 measurements can guide need for intermittent positive-pressure ventilation in anesthetized patients or mechanical ventilation in animals with respiratory failure. End-tidal capnography (ETCO2) does not directly equate to PCO2 but can serve as a useful substitute. Blood gas analysis allows for identification of acidemia or alkalemia and interpretation regarding primary metabolic, respiratory, or mixed processes and compensatory responses. Serial lactate measurements can help assess the treatment of shock, perfusion, and tissue oxygen use. Blood gas analysis often helps complete the clinical picture and guide treatment decisions and patient monitoring.—Jasani S

Case Handover: Efficient Communication to Improve Patient Safety 

The concept of the personal continuity—in which a sole practitioner cared for a patient for the duration of any illness or hospitalization, and sometimes for its entire life—has slowly given way to system continuity. In this new model, a team of doctors, nurses, interns, and specialists provide patient care at a single facility. 

Although some may regret the changing times, others may argue that personal continuity was never actually sustainable. System continuity may allow for better work–life balance, part-time work, job sharing, larger hospitals, multi-specialty practices, and external after-hours care. With multiple caregivers collaborating on a given case, efficient and safe patient handover is paramount. In human medicine, communication breakdown is thought to result in as many as 44 000 to 98 000 deaths per year. According to a recent report on patient handover, the important components of an effective handover are: a circular chain of communication; adequate time in the schedule in which handovers can occur; sufficient quality of information highlighting the most critical patients and any concerns from previous shifts; and care plans and prioritized action items.—Niessen S

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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