2016 FALL: Deciphering Bronchial Lung Patterns | Rectal Exam | Abbreviations Quiz | Xylitol Toxicity | Triage Nursing
Deciphering Bronchial Patterns
Whether you are relatively new to looking at digital radiographs or not, the amount of “background” pattern in the lungs can often be misleading. The interstitium is actually visible on a normal radiograph especially in the caudodorsal lung fields on the lateral projection because of the large size of the lobes and larger amount of superimposed structures.
The interstitium appears as the lacy soft tissue opacity between airways and vessels and is more prominent in expiratory images. This opacity, however, should not blur margins of the vessels, and as long as the pulmonary vessels are distinctly visible, you can infer that lung parenchyma is adequately aerated and normal. On top of this background opacity, the walls of the primary bronchi should be visible in a normal patient as opaque double parallel lines leaving the trachea up to the level of the second divisions.
Figure 1. Normal canine thorax (a) in which vessel margins and background interstitium are distinctly visible. In the close-up of the hilar region (b), note only the walls of the primary bronchi are visible (white arrows).
Visible bronchial walls should stay thin, linear, and distinct without blurring opacity in the immediate peribronchial parenchyma (Figure 1).
Yes, you WILL see airway walls near the hilus of the lungs in a normal dog, but you should not be able to follow these airways out into the periphery. The hallmark of a bronchial pattern is visualizing airway walls as double parallel lines (side-view, “tram tracks”) or rings (end-on-view, “doughnuts”) in the pulmonary periphery. The best places to look in the pulmonary periphery on the lateral projection are superimposed with and just cranial to the cardiac silhouette, overlying the diaphragm, and just ventral to the vertebral bodies. On the ventrodorsal projection, look lateral to the cardiac silhouette, and overlying the diaphragm caudally. Try to avoid the central hilar portions of the lung fields as these will always look “busy.” The thickening of and excess of visible airway walls in a pathologic state causes the lung fields to overall appear linear and “streaky” (Figure 2). This is a common finding in geriatric patients due to fibrosis from aging or prior disease. Bronchial patterns are typically diffuse in distribution.
Figure 2. Lateral thoracic radiograph of a 1-year-old border collie who presented for coughing, sneezing, oculonasal discharge and fever, diagnosed with infectious tracheobronchitis. Note thickened/fuzzy and prominent airway walls in the pulmonary periphery (white arrows = “tram tracks”, white circles = “doughnuts”).
One of the reasons bronchial patterns are often difficult to distinguish is that the abnormal opacity will not be as noticeable adjacent to surrounding interstitium. However, as with many things in radiology lung patterns are not always black and white (pun intended), and mixed patterns such as bronchial and interstitial or intertial and alveolar may exist with certain disease processes. Caution must be taken to ensure an artefactual change is not to blame (i.e. underexposure or an expiratory image causing the appearance of unstructured interstitial opacity).
What does it mean?
Cellular infiltrate from primary airway disease causing wall thickening is often the cause of increased conspicuity and a bronchial pattern on radiographs, but a bronchial pattern may also result from wall mineralization, luminal exudate, thickened bronchial mucosa or peribronchial cuffing (i.e peribronchial interstitial pattern). Depending on the type and stage of the particular disease process, other pulmonary patterns may be concurrently present.
Here is a list of canine/feline differentials to consider – note some of these may be disregarded due to lack of certain endemic infectious diseases here in South Texas, but travel history must be considered. Further characterization of airway disease may be obtained with airway sampling (i.e. bronchoalveolar lavage or tracheal wash) with cytology and culture, and in some cases thoracic computed tomography is helpful in better evaluating distribution and severity of disease.
Differentials for a bronchial pattern
- Allergic bronchitis – asthma
- Infectious bronchitis
- Paragonimus kellicoti (lung fluke) – dogs and cats, often with cystic lesions
- Alurostrongylus abstrusus (lungworm) – cats, often with patchy interstitial and alveolar patterns
- Heartworm – often with interstitial pattern, enlarged pulmonary arteries, and right-sided cardiomegaly
- Fungal – Histoplasmosis in cats. Other types often have pulmonary nodules and lymphadenopathy (e.g. caccidiomycosis—this occurs in neighboring states such as Arizona and California)
- Neospora caninum – dogs
- Toxoplasma gondii – cats, often with regions of patchy consolidation
- Other inflammatory bronchitis
- Toxic/inhaled irritant – i.e. smoke inhalation
- Acute lung injury/acute respiratory distress syndrome
- Cushing’s disease, hypercalcemia, hyperparathyroidism – bronchial wall mineralization mimicking a bronchial pattern
- Bronchogenic carcinoma, although often associated with mass lesions
- Pulmonary edema (an interstitial pattern that starts out as peri-bronchial with mild or early disease) – possible manifestation of cats and dogs in congestive heart failure
Article courtesy of our colleague from BluePearl in Washington, Ellie Nuth, DVM, DACVR.
The Golden Glove: The Importance of the Rectal Exam
We’ve all done it. We’re all guilty. Your canine patient is nervous and hiding behind his owners. You work to establish a sense of trust, so he’ll let you do your exam without undue stress. Maybe you give him a treat or maybe you get down on the floor and talk in a reassuring voice. After going through your exam, which he now thinks is merely a massage, you get to the end, literally. Other than nail trims, dogs dislike this particular examination procedure more than most. Ok, you think, he just went to the groomers and they didn’t find anything, I’ll let it slide this once.
Stop! The rectal exam is an essential part of the physical exam and should be done several times a year, if possible. Rectal and anal diseases are much easier to treat before clinical signs become apparent. The rectal exam provides us the opportunity to evaluate several important anatomic structures including the perianal region, sublumbar area (checking for lymph node enlargement), lumbosacral region (checking for pain), prostate gland, urethra, and colonic and rectal mucosas.
Don’t forget the anal sacs. As unpleasant as it is to express them (I usually do it in the back, away from the owners, so we don’t have to sit and talk amidst the odor), it is important. Anal sac nodules as small as 3-4mm, comprised of apocrine gland adenocarcinoma cells have been known to spread to the sublumbar nodal region, throughout the abdomen, and eventually to the lungs. Further, apocrine gland tumors can also cause hypercalcemia. If these tumors are caught early, surgical resection is much easier, and the patient’s prognosis for survival can exceed 3+ years (versus just months, if they have advanced disease).
Nearly everyone in health care – veterinary and human – uses acronyms for diseases, signs, symptoms, procedures, tests and more. How many of the following abbreviations do you know?
- HBC _________________________________
- SIDS _________________________________
- HCM _________________________________
- GDV _________________________________
- MR __________________________________
- CLL __________________________________
- MRSA ________________________________
- FIP __________________________________
- DCM _________________________________
- IBD _________________________________
- SIRS ________________________________
- MRI _________________________________
- ITP __________________________________
- PRAA ________________________________
- DKA _________________________________
- ARDS ________________________________
- CPR _________________________________
- MPL _________________________________
- BDLD ________________________________
- IMHA ________________________________
- PH __________________________________
- HOCM _______________________________
- HOD _________________________________
- TECA ________________________________
- TPLO ________________________________
- CRF _________________________________
- PPDH ________________________________
- PU/PD _______________________________
- URI _________________________________
- IVDD ________________________________
- CHF ________________________________
- SCID ________________________________
- DIB _________________________________
- NSAID _______________________________
- FCE _________________________________
- GME _________________________________
- SCC _________________________________
- PSS __________________________________
- HGE _________________________________
- DM __________________________________
- MODS ________________________________
- MCT _________________________________
- LSA __________________________________
- PLE __________________________________
- FUO _________________________________
- CT __________________________________
- CSR or CCC ____________________________
- DNR ________________________________
- MAP ________________________________
Check your answers here.
Xylitol Toxicity: Not Just Gum
The number of dogs presenting for xylitol ingestion and toxicity has increased dramatically over the past few years. Xylitol is a crystalline sugar alcohol used as a sugar substitute sweetener in many products including sugar-free gum, candy, chewable vitamins, nutritional supplements and baked goods. It is available in a granulated form for baking. Based on demonstration of anti-cariogenic properties, xylitol is added to toothpastes and other oral hygiene products. In a retrospective evaluation of 192 cases of xylitol ingestion, 96% of the dogs presented for ingestion of sugar-free gum.1
Xylitol has a wide margin of safety in people but is extremely toxic to dogs. Compared to humans, dogs experience a rapid and severe increase in blood insulin resulting in profound hypoglycemia which can last up to 24 hours. Similar effects are seen in cows, goats and rabbits. Cats and ferrets have not shown toxic effects. Ingestion of large amounts of xylitol has resulted in liver failure in dogs.
Diagnosis of xylitol toxicity is based on history of ingestion, symptoms and bloodwork. Common presenting clinical signs include vomiting, lethargy and weakness. Diarrhea, collapse and seizures may be seen. Hypoglycemia has been reported within 30 minutes of ingestion but can occur up to 12 hours post-ingestion.
Treatment recommendations are based on the amount of xylitol ingested (see table below). There is no known antidote and a narrow window for safe decontamination. Xylitol is rapidly absorbed with peak plasma concentrations at 30 minutes. Emesis is recommended in asymptomatic dogs. Activated charcoal is not likely to be beneficial as charcoal does not bind to alcohol-type compounds.
Calculating the amount of xylitol contained in products can be difficult. Products that list xylitol as the first ingredient tend to be the most toxic. The amount of xylitol in gum can range from 0.9 mg to 1000 mg/piece. While some gum products specify the xylitol content on the label, many manufactures consider this to be proprietary information. The ASPCA Animal Poison Control Center (ASPCA APCC) recommends that if xylitol is the first sugar alcohol in the ingredient list, then the estimated dose should be based on the total amount of sugar alcohols. If not the first ingredient, xylitol should be estimated to be 0.3gram/piece of gum. Granulated (baking) xylitol contains 190 grams/cup. Gabapentin liquid contains 300 mg xylitol/ml and could reach toxic levels at higher doses.
The ASPCA APCC recommends that dogs ingesting 50-100 mg/kg should receive decontamination and monitoring.2 However, hypoglycemia has been reported in a dog ingesting an estimated 30 mg/kg xylitol dose.1 Dogs ingesting >100 mg/kg are at increased risk for hypoglycemia and should be treated more aggressively. Ingestion of higher doses increases the risk of liver failure and coagulopathy. All dogs reported developing xylitol induced liver failure ingested > 500 mg/kg; however, it is not clear at this time whether the effect is dose-related or idiosyncratic. In a case report of dogs developing acute liver failure subsequent to large dose xylitol exposure, six of the eight dogs did not develop hypoglycemia prior to the onset of liver failure.3
The prognosis is very good for dogs treated promptly and for dogs with uncomplicated hypoglycemia. In a 2015 retrospective study reporting 192 cases of xylitol ingestion, 15.6 % developed hypoglycemia and 21.9 % of dogs with serum biochemistry panels performed developed mildly increased ALT or total bilirubin. No dogs developed clinical signs or biochemistry values consistent with liver failure. All dogs survived. Mild increases in liver enzymes usually resolve within a few days with supportive care.
Severe or progressive increases in liver enzyme activities (>1000), hyperbilirubinemia and coagulopathy, carry a more guarded prognosis. Mortality rate of 70-80% is reported when acute liver failure develops. Hyperphosphatemia appears to be a poor prognostic indicator. At BluePearl, we have treated several dogs with severe liver failure and coagulopathy secondary to xylitol ingestion. Although we have not been able to save all of them, we have gotten a good number home after treatment with fresh frozen plasma, fluids, GI protectants and liver protectants. In one case in which the dog ate two cups of baking xylitol, the dog developed active bleeding due to coagulopathy and ALT went up to 50,000. However, after several plasma transfusions, the dog was able to go home and bloodwork was completely normal 8 weeks later.
|Ingested Dose||Treatment recommendation|
|50-100 mg/kg||Induce vomiting if asymptomatic, observe|
|100-500 mg/kg||Induce vomiting if asymptomatic. Obtain baseline glucose, potassium, phosphorus, biliruibin and liver enzymes. Monitor blood glucose every 1-2 hours for at least 12 hours and other tests every 24 hours for at least 72 hours. If hypoglycemia develops, 1-2 ml/kg bolus of 25% dextrose and continue fluids supplemented with 2.5-5% dextrose to maintain normal glucose. Continue until glucose concentration can be maintained without supplemental dextrose.|
|>500 mg/kg||As above, except administer supplemental dextrose despite normal BG. Add liver protectants (N-acetylcysteine or Denamarin)|
A thank you for the article goes out to Linda Barton, DVM, DACVECC, our colleague from BluePearl in Washington.
- Dunayer EK. New findings on the effects of xylitol ingestion in dogs. Veterinary Medicine 2006; 791-797.
- DuHadway MR, Sharp CR, Meyes KE, et al. Retrospective evaluation of xylitol ingestion in dogs: 192 cases (2007-2012) JVECCS 25(5) 646-654.
- Dunayer EK. Gwaltney-Brant SM. Acute hepatic failure and coagulopathy associated with xylitol ingestion in eight dogs. Journal American Veterinary Medical Association 2006; 229, 1113-1117.
The term triage is derived from the French word, “trier,” which literally means to sort. It was a concept introduced by Dominique Jean Larrey during the 1800s as a method of sorting and prioritizing medical needs of soldiers. While veterinary triage is not well defined in all settings, it typically involves obtaining the chief complaint and assessing four major organ systems (circulatory, respiratory, central nervous, and urogenital). In the setting of small animal medicine, we can divide triage into two categories: telephone triage and in-hospital triage. In order to perform triage effectively and efficiently, the hospital and staff members should be prepared and cognizant of their roles. The success of triage is primarily dependent upon two factors: teamwork and preparedness.
Telephone triage is the initial contact between the client and veterinary hospital. During telephone triage, the technician should make every effort to determine the signalment, chief complaint, and nature of the problem (acute vs. chronic). Information gained prior to the arrival of a critically ill patient is crucial to optimizing patient outcomes.
In-hospital triage includes two components: primary survey of the major organ systems and a secondary, more thorough assessment of all of the organ systems. The goal of the primary survey is to identify life-threatening problems and stabilize the patient. During the primary survey, the technician should evaluate the circulatory system, respiratory system, central nervous system and urogenital system. Visual assessment and palpation are essentially all that is needed to perform a primary survey. It is of critical importance to remember that a temperature, heart rate, respiratory rate, and body weight should be obtained during the primary survey. In the event the patient is deemed unstable, airway and intravenous access should be pursued immediately. The secondary survey should be performed following stabilization of the patient and includes re-evaluation of the major organ systems in addition to addressing wounds, lameness, fractures and/or lacerations.
In order to execute triage effectively in your hospital, a specific technician should be assigned to that task. This technician should be responsible for greeting the client in the lobby and immediately taking the patient back to the treatment area for a primary survey. Once deemed stable, the patient may then be returned to the client or placed in an exam room. In the event the patient is not stable, emergency intervention should take place.
By practicing triage in your hospital, you will save lives. Telephone triage is just as important as in-hospital triage and should be stressed among all staff members. All technicians in the hospital should be trained in performing triage. Ultimately, the most important factors in performing triage include hospital preparedness and teamwork.
Answers to Abbreviations Quiz
- Hit by car
- Sudden infant death syndrome
- Hypertrophic cardiomyopathy
- Gastric dilatation and volvulus
- Mitral regurgitation
- Chronic lymphocytic leukemia
- Methicillin resistant Staphylococcus aureus
- Feline infectious peritonitis
- Dilated cardiomyopathy
- Inflammatory bowel disease
- Systemic inflammatory response syndrome
- Magnetic resonance imaging
- Immune mediated thrombocytopenia
- Persistent right aortic arch
- Diabetic ketoacidosis
- Acute respiratory distress syndrome
- Cardiopulmonary resuscitation
- Medial patellar luxation
- Big dog little dog
- Immune mediated hemolytic anemia
- Pulmonary hypertension
- Hypertrophic obstructive cardiomyopathy
- Hypertrophic osteodystrophy
- Total ear canal ablation
- Tibial plateau leveling osteotomy
- Chronic renal failure
- Peritoneal pericardial diaphragmatic hernia
- Upper respiratory infection
- Intervertebral disk disease
- Congestive heart failure
- Severe combined immunodeficiency
- Dead in bed
- Nonsteroidal anti-inflammatory drug
- Fibrocartilaginous embolic myelopathy
- Granulamatous menigioencephalitis
- Squamous cell carcinoma
- Portosystemic shunt
- Hemorrhagic gastroenteritis
- Diabetes mellitus
- Multiple organ dysfunction syndrome
- Mast cell tumor
- Protein-losing enteropathy
- Fever of unknown origin
- Computerized tomography
- Client service representative or CCC client care coordinator
- Do not resuscitate
- Mean arterial pressure