ICVA NAVLE Exam Questions

Correct answer: Fast the animal six to eight hours prior to surgery

Diabetics can be challenging when it comes to anesthesia. Maintaining adequate perfusion is paramount to preventing damage to the pancreas (including pancreatitis). Most people underestimate the degree of dehydration in these patients, especially when obese.

We want to fast them no more than six to eight hours pre-op. Ideally, have them fed normally and given their normal insulin the day before. One to two hours prior to surgery, check their blood sugar. If it is 150–300 mg/dL, the animal should get 1/2 of its normal insulin dose subcutaneously (long-acting, not regular insulin). It is ideal to do diabetics first thing in the morning to permit them then to get back to their normal feeding/insulin schedule. However, if you have to do surgery later in the day, they should have their blood sugars checked and a small meal and dose of insulin early in the morning and still, ideally, be fasted for six to eight hours before cutting time. 

Sugars should then be checked at induction and then hourly. If the blood sugar is low, the patient should be started on a 2.5 % dextrose solution in 0.45% saline at 10–15 ml/kg for the first hour, then 5 ml/kg/hr afterward. If blood sugars are normal, lactated ringers can be used at the same fluid rates. (Again, remember that these patients are dehydrated, and usually, we underestimate this dehydration status). Frequent blood glucose checks are warranted to ensure the patient doesn't get below 66–70 or above 300. If that occurs, correction is necessary.

Correct answer: Intradermal terbutaline challenge

Testing for possible endocrine diseases or concurrent diseases that could affect an animal’s ability to sweat and expel heat or lead to exercise intolerance is important. Still, it will not confirm the diagnosis of anhidrosis.

The ACTH stimulation test is used to diagnose PPID (Pituitary Pars Intermedia Dysfunction), where 75% of horses with PPID will have an exaggerated response.

Thyroid function testing (Serums T3 and T4 assays) is beneficial to rule out hypothyroidism as it may contribute to or accompany anhidrosis. However, the true etiology and clinical course of hypothyroidism and anhidrosis are not fully elucidated, and this test, while beneficial and may provide valuable information, doesn’t definitively diagnose the condition.

We can diagnose anhidrosis by performing an intradermal sweat test. We can use terbutaline or epinephrine IM to do so.

1. An intradermal terbutaline challenge: 0.5 mg of terbutaline is injected IM with six serial dilutions (ten fold). Thus, instilling 0.1 ml in the neck or pectoral areas intradermally. Normal horses will have a local sweat response in that area at all concentrations except maybe the most dilute. The amount of sweat will be proportional to the dose. Normal horses usually start to sweat about five minutes post higher-concentration injections. If complete anhidrosis has yet to develop, we may see sweating at higher concentrations. Those with full disease will not sweat even at the highest concentration.
2. Intradermal epinephrine injection (not intravenous, as this will exacerbate the issue) may be used. Administer an injection of 1:1000 and one of 1:10,000 epinephrine intradermally. Those not affected should have local sweating within an hour, while those affected will not. 

Correct answer; Ventral interbody vertebral fusion (arthrodesis)

This colt shows classic signs of cervical stenotic myelopathy, AKA wobblers, cervical vertebral stenotic myelopathy, CVSM, CVM, cervical compressive myelopathy, and CCM. Clinical signs may start as young as six months to five years, depending on the type of lesion. Animals are ataxic secondary to developmental abnormalities in the spinal cord. Type 1 has a focal/multifocal vertebral canal stenosis, worse on flexion, between C1-6. This refers to dynamic stenosis and usually occurs in younger animals. Type II consists of C5-T1 lesions most commonly and involves soft tissue and bony spinal cord impingement with bone remodeling and stenosis.

Though they can occur acutely, signs are often slowly progressive, with weakness, ataxia, and a dysmetric gait. Animals may have changes to the cutaneous truncii reflex, paresis, and a decreased slap reflex. Usually, the hind legs are more affected than the fore. They are usually mentally appropriate with normal cranial nerve exams.

Differentials include equine protozoal myeloencephalitis, equine degenerative myelopathy, trauma, fractures, neoplasia, equine herpesvirus-1, or other malformations/congenital abnormalities.

Treatment varies with the horse's age and if it has reached its full growth potential. Treatment may consist of pain management with NSAIDs/steroids, often only providing short-term relief. Exercise and dietary restrictions, stall rest, or intra-articular injections (older animals). However, when signs are relatively acute, and the animals are young, those who present early and are young have the best chance of improving with surgical arthrodesis of the affected vertebrae via a cylindrical basket with autogenous bone pieces. For dynamic cases, it often provides relief right away. With static cases, it may take time for chronic changes to reverse and neurological improvement to become evident. Improvement ranges with surgery vary from 44% to 90% for dynamic lesions and 12–62% for static patients returning to athletic function.

Correct answer: Dermatophyte culture

Dermatophytosis or ringworm is caused by various species, is zoonotic, and is more common in cats than dogs. It is not life-threatening and usually spontaneously resolves without therapy, though it can take weeks to months. Further, in this patient, if the mother-in-law does have a ringworm species known to infect dogs, such as M. canis, and because she is immunosuppressed due to chemotherapy, treatment of this dog is warranted if the disease is confirmed. While zoonotic, most ringworm infections are more commonly associated with immunosuppressed individuals. However, always be sure to discuss the risks with owners when pets are diagnosed with ringworm, regardless of the species of ringworm and pet.

Diagnostics include:

1. Dermoscopy is a Point-of-Care (POC) tool where you use a handheld device to identify hairs for direct examination or culture. It can confirm a diagnosis when used in conjunction with a direct exam. It provides magnification of the hairs, and you can look for broken “comma” shaped ones. Select those to pluck for evaluation/culture.
2. Wood’s lamp, a POC tool, ID’s hairs for direct examination and/or culture by producing an apple green fluorescence on the hairshafts. A direct exam can confirm the diagnosis. However, Not all species fluoresce. Animals who have had some treatment will be less likely to fluoresce than those who haven’t.
3. Direct examination (cytology) POC permits one to evaluate the hair via skin scrapings, spatula, mineral oil, and/or forceps and identify disruption of the corticomedullary junction, pale hair, and arthroconidia in the cuticles may be evident.
4. Fungal culture – the gold standard and the medical-legal test to ID fungal species. This can be either in-clinic or in the lab. Plates are preferred to vials for in-house tests, permitting inoculation with a toothbrush.
5. Skin biopsy – punch biopsy or wedge/excisional biopsy from a nodule; requires special stains, so inform the pathologist what you are looking for if ringworm is suspected
6. Real-time PCR – hairs, crusts, and scales but does require large amounts of sample. A negative test suggests no ringworm, but false positives from fomites are common. Further, they aren’t yet currently used to monitor for a cure.  

Correct answer: Anatomical defects

Note that a BAR iguana with anorexia and egg retention is likely not having dystocia. Animals with dystocia are usually depressed and become rapidly unresponsive when gravid.

Causes of non-obstructive egg retention in iguanas include lack of a proper egg-laying chamber, excessively low temperatures, dehydration, poor nutrition, and poor physical condition (which may be a factor of nutrition, husbandry, or other underlying causes). An infection could contribute to this type of egg retention, but it can be hard to determine whether it caused retention or resulted in infection.

Obstructive causes of egg retention and/or dystocia may include anatomical abnormalities preventing eggs/young from passing. These may include deformed, malpositioned, too-large, or fractured eggs, and stricture or torsion of the shell gland may also trigger it. Finally, cancer, uroliths, or abnormally sized kidneys could constrict the oviducts, preventing passage. A narrow pelvic canal or spinal deformity secondary to metabolic bone disease (secondary nutritional hyperparathyroidism) can also contribute. Finally, trauma from a previously difficult egg-laying period could result in obstructive changes.

Note: Dystocia is defined by Divers and Stahl (in Mader's book) as "the inability to successfully expel term eggs or fetuses from the lower reproductive tract." Causes may include abnormal egg sizes, poor contractility, improper or lack of nesting areas, and lack of viable embryos despite mating.

Correct answer: Holstein Friesian

Umbilical hernias can happen in any species and can be of varying size and severity. They may contain just fat or omentum or, worse, GI loops. Holstein Friesian cattle are overrepresented relative to other breeds. We commonly see them in dogs and foals. Clinical signs may be associated with hernias if intestinal loops are within the body wall defect. 

Correct answer: Microscopic evaluation of the brain/spinal cord

The clinical signs described above demonstrate key signs in sheep and goats with Transmissible Spongiform Encephalopathy (TSE), known as scrapie. Sheep are the natural hosts, though goats can laterally and vertically transmit the disease as well. Susceptibility and resistance occur in various breeds. Scrapie, unlike Bovine Spongiform Encephalopathy (BSE), another prion disease, affects not only the gut-associated lymphoid or nervous system tissue but also various lymphatic tissues, the kidneys, and the placenta. Because of this, biopsy techniques for lymphoid tissue have been developed. Immunohistochemistry can be used to evaluate biopsy sections of lymphoid tissue, including tonsils, retropharyngeal lymph nodes, or nictitans. However, sensitivity is variable; classically, diagnosis is made by microscopic examination of the brain and spinal cord. The disease is not overtly zoonotic but is fatal. Eradication measures vary globally.

A complete necropsy should be performed on any sheep (+/- goat) dying without an overt cause; this includes submitting the brain +/- spinal cord for diagnosis. 

Correct answer: All-glass or all-plastic syringes and blood tubes

Red serum separator tubes are either plain or have a clot activator gel in them. These tubes can be used for serology and some infectious organism testing, but this varies with the laboratory used. Because of the rubber stopper or grommets within the tubes, these tubes are unsuitable for zinc levels.

Blue-top tubes (pastel blue) are used for coagulation-related testing, including d-dimer, PTT, and PT. The additive is sodium citrate.

Yellow-top tubes contain acid citrate dextrose and a separator gel. These tubes can evaluate chemistry panels, thyroid levels, and some immunology and serology testing. Again, it depends on the lab used.

Purple-top tubes contain EDTA (ethylenediaminetetraacetic acid), an anticoagulant to prevent clotting. This tube is generally used for CBCs and peripheral blood smears.

Finally, when testing for zinc levels, one must use all-plastic or all-glass tubing. The tube cannot have rubber of any kind, as this can jeopardize test results. Rubber stoppers or grommets on some tubes can falsely increase zinc levels. Sent in the appropriate tubes, zinc levels of > 2 ppm are positive for zinc toxicity.

Treatment includes supportive care and using a chelator such as calcium EDTA or d-penicillamine. If the pennies don't pass, surgical removal will be needed. Thankfully, zinc isn't stored in bone, so chelation therapy and resolution occur much faster than with lead toxicity.

Correct answer: Topical glucocorticoids

This cat is classic for Flea-Allergy Dermatitis (FAD). The cat is severely pruritic, has freak-out periods and severe itchiness, and, while no fleas are found, has alopecia and lesions in the expected locations. > 90% of cats with a miliary dermatitis usually have a FAD. Owners need to learn and understand a flea life cycle and realize that just because they don’t see fleas or flea dirt doesn’t mean they aren’t there. This cat is likely overgrooming and cleaning off every live flea immediately because he is so miserable.

If this client can safely bathe the cat, topical therapy may be sufficient (bathing) to treat the infection component of the condition. The use of medicated shampoos effective against bacteria and with soothing agents is often sufficient for superficial infections. However, most cats aren’t amenable to regular bathing, and thus, oral antimicrobials are likely necessary for this pet. Glucocorticoids are not usually given topically to cats as they will probably groom them off. So a short oral tapering prednisolone dose may be beneficial until the reaction calms down and he is more comfortable.

However, it isn’t just important that the owner treats and prevents fleas on the cat. The owner needs to ensure any pet in the house, whether it goes outside or not, has appropriate flea/tick prevention for three plus months and that they are diligent about daily environmental cleanup, which can also be required for three months or more, due to the life-cycle of the flea. The duration of in-home cleaning will also depend on the season, the temperature in the home, and additional factors. Failing to treat other pets and clean up the environment will permit the FAD to continue. Further, it will make diagnosis more difficult because FAD won’t be able to be ruled out unless the owner is fully compliant. 

Correct answer: Ventral coccygeal vein

In chelonians, the right jugular is notably larger than the left and can be used for catheter placement. Given this patient's degree of respiratory distress, the ventral coccygeal vein would be an unfavorable location due to the required positioning and stress for the patient.

The cephalic vein can be used in patients greater than 15 kg. For those smaller than that, an ultrasound can be used to guide placement.

The plastrocarapacial bridge can be used for IO placement, but requires a drilled pilot hole and is considered less efficacious than one of the long bones.

The humerus and femur can both be used for IO placement with similar techniques to mammals.

Correct answer: Ask, Affirm, Assess, and Act

Ask, Affirm, Assess, and Act are the 4-As to help one address moral distress. According to the American Association of Critical Care, moral stress is something that “occurs when: You know the ethically appropriate action to take but are unable to act upon it. You act in a manner contrary to your personal and professional values, which undermines your integrity and authenticity”. Blackwell’s Five-Minute Veterinary Practice Management Consult defines moral distress as “When (1) you know the ethically appropriate action to take, but you are unable to act upon it, and (2) you act in a manner contrary to your personal and professional values, which undermines your integrity and authenticity.”

Think about all the times you know what you want and need to do for your patients, but financial concerns and constraints dictate how you practice veterinary medicine rather than gold standards and appropriate standards of care.

They refer to the following: 

1. Ask yourself if you are distressed or suffering and determine if the source is work-related. Do you notice distress within your work team? This step imparts awareness of the presence of moral distress.
2. Affirm refers to acknowledging this distress and your commitment to take care of yourself and address any moral distress of your staff.
3. Assess both the overall environment (work and home) and your personal situation and evaluate the degree of distress in your practice and the readiness of the staff to take action and improve the situation. You are now ready to develop a plan of action at this stage.
4. Then, you act to improve your situation and others while preserving the authenticity and integrity of yourself and the practice as a whole. Steps may include developing a self-care plan, establishing your support network, checking for additional resources such as NOMV (Not One More Vet), and then taking action.

Acceptability, Affordability, Accessibility, and Awareness refer to the 4-As of marketing and sales.

Acknowledge, Accept, Appreciate, and Apologize refer to the 4-As of mediation/conflict resolution.

Avoid, Alter, Adapt, and Accept represent the 4-As of stress management. These may be helpful in your practice but weren’t developed by the critical care nurses specifically to improve moral distress. 

Correct answer: Pancreatitis

Cats are not small dogs. Dogs may show a wide array of clinical signs with pancreatitis, from vomiting, and diarrhea, to anorexia, lethargy, abdominal pain, icterus, and weight loss. In some studies, less than 50% of cats have overt abdominal pain. The most common clinical signs appreciated are lethargy and decreased appetite. Some cats will have vomiting, varying degrees of dehydration, belly pain, icterus, and weight loss (depending on chronicity).

Metabolic disease is possible, but patients with endocrine disease usually have additional clinical signs such as changes in drinking/urination, coat quality changes, or other abnormalities that lead you in that direction.

Cholangitis patients (depending on the form, neutrophilic, lymphocytic, or chronic) tend to have signs ranging from vomiting to diarrhea and appetite changes. They, too, may be lethargic and may also have ptyalism. However, they generally have painful abdomens more consistently than those with pancreatitis. The vomiting and diarrhea may be acute and significant or chronic and intermittent. In acute cases, patients are generally febrile. The signs tend to be a bit less generalized than lethargy and a decreased appetite, and the prevalence of pancreatitis, while not fully elucidated in cats, is presumed to be common. These patients may present with icterus but do not have to have reached that state yet. However, it cannot be ruled out as we commonly see more than one inflammatory condition in cats at a time, associated with the pancreas/liver/or GI tract.

Given the patient's age, Neoplasia has to be on the list. Still, based on your history evaluation and discussion and the patient's clinical signs, this wouldn't be the first thing we would jump to without ruling out other common causes of signs.

Correct answer: Rabies vaccinate all animals with exposure and clinical signs consistent with the virus

Rabies, an almost universally fatal disease, is best prevented before exposure. Thus, routine vaccination is considered a core vaccination for all horses. This farm's protocols and records would need to be reviewed to see where the breakdown occurred and why animals were unvaccinated or exposed. Clinical signs in horses may include sudden death or ataxia, lameness, fever, tail and anal paralysis, recumbency, colic, pharyngeal paralysis, paraplegia, hyperesthesia, pruritus, restlessness, anorexia, with hyperexcitability or irritability. Clinical signs may vary depending on the location of a bite/exposure and the progression of the disease.

The horse-wildlife interface is high-risk, and care must be taken to prevent exposure. This may require wildlife deterrents and working with the local and state public health and animal health authorities to vaccinate the local wildlife with oral bait vaccines. This has been effective in many areas. This will depend on the type of rabies variant in your area (bat, fox, raccoon, etc.), the wildlife species in the area, and the species most likely to have direct contact with the horses.

Ideally, in non-valuable, unvaccinated, exposed animals, the recommendation is humane euthanasia and rabies testing.

Horses current on their vaccination before receiving a bite from an infected animal can be boostered and monitored for 90 days for the development of clinical signs. Rabies incubation can be weeks to six months or more. However, in unvaccinated, valuable animals with a known bite of concern but without clinical signs, quarantine for at least six months may be enacted. If at any point neurological signs develop, the animal must be euthanized and the brain submitted for rabies testing. 

Correct answer: Proper cleaning of the environment and systemic therapy of the pet will help remove infective material from homes within five days of treatment initiation

An education session on ringworm for humans can talk about a lot. You can discuss possible exposures, including the soil, other animals, and key species of concern. Differences between species most commonly seen in humans vs. animals are also warranted. Further, it is crucial to discuss clinical signs in pets and humans and advise them to seek care from a medical professional when noted. Teaching people that prevention is essential and one way to do so is to minimize contact with other animals. Daycare facilities, groomers, boarding facilities, and dog parks increase an animal's exposure risk. This is not likely an issue for immunocompetent people but is something to consider for immunocompromised people. Discussing the proper treatment of pets, including topical therapy (for all) +/- systemic therapy depending on the degree of disease. Topical treatment can be done at a vet's office or at home. Topical therapy is beneficial because it shortens the time of infectivity. A recent study showed that a combination of properly cleaning the environment and topical therapy of the pet removed infective materials within the home within one week of starting therapy.

You can point out good resources for owners to obtain more detailed information and provide handouts with a list of clinical signs, appropriate means of disinfection, and other facts.

Regardless, it is paramount to mention that while uncommon, ringworm is contagious to animals and people. Thus, wearing gloves, especially if immunocompromised, and practicing proper hygiene, at all times, is appropriate. Further, suppose any new pets are brought into a home, not just for ringworm but for any infectious disease (zoonotic or otherwise). In that case, animals should be isolated from other pets. Usually, seven to ten days up to 14 days is considered a standard quarantine. After the stress of a change in environment, some diseases may take that long to manifest clinical signs and start shedding. Ensure a prompt vet visit after obtaining a new pet. Finally, do not introduce new pets to animal family members until they have the all-clear.

Correct answer: Three months; by one month of age

Angular limb deformities refer to a limb's medial or lateral deviation, named by the joint where the issue arises. The deviation's direction is based on the limb distal to the joint. Varus deformity is a medial deviation relative to the reference point, while valgus deformity is a lateral deviation. Angular limb deformities occur as a result of a:

1. Periarticular laxity
   2. Incomplete ossification of the cuboidal bones
   3. The disproportionate growth of both the epiphysis and metaphysis

When we are referring to the disproportionate growth that commonly causes carpal or tarsal valgus. If the deviation is under ten degrees, treatment is conservative. Moderate cases require surgical correction. Understanding when the growth plates close is key to knowing when intervention must be initiated. The distal metacarpal physis grows during the first three months. Thus, any changes being made need to occur by the age of one month. Compare this to the distal radius and tibia, where those plates grow through nine months of age. Any manipulation must be achieved by four to six months of age. The more severe the deformity, the earlier the intervention may be needed.

If you have a patient with limb deformities, make sure you do a complete PE (Physical Examination). Always take radiographs. If any bandaging is required, ensure daily bandage changes are performed and the limb is assessed daily to prevent wounds. 

Correct answer: 7-8 ml/kg

Ethylene glycol toxicity is common in domestic dogs and cats, but all species are susceptible. It is found in a variety of automotive products, most notably antifreeze, as well as in household products. Ultimately, toxicity leads to progressive and, if untreated, irreversible kidney failure. Signs may include GI upset, depression, cerebral edema, and metabolic acidosis. Treatment, if the problem is identified in time, is with fomepizole or ethanol.

Toxic doses in animals are as follows:

• Cats: 1.5 ml/kg
• Dogs: 4.4-6.6 ml/kg
• Poultry: 7-8 ml/kg
• Cattle: 2-10 ml/kg
• Macaques: 1.6 ml/kg
• Guinea pigs: 6.61 ml/kg

Poultry may exhibit watery feces, ataxia, lethargy, recumbency, torticollis, dyspnea, and ruffled feathers. They do not typically develop gross lesions suggestive of disease.

Toxicity is caused by the breakdown of ethylene glycol to oxalic acid. This, in turn, combines with calcium-forming calcium oxalate. The oxalate crystals then block renal tubules leading to necrosis and nephrosis.

Correct answer: Intravenous regional anesthesia (Bier block)

All of the above, including a Bier block, will provide appropriate pain management as a general injection (methadone and dexmedetomidine) or by local anesthetic actions.

A line block in the incision upon closing will help either with a short-acting or semi-short-acting local anesthetic like lidocaine or bupivacaine or off-label use of the bupivacaine liposome (Nocita®), which can persist for up to 72 hours depending on the location. It is labeled for cranial cruciate repairs, but many surgeons use it for closing any incision.

A metatarsal ring block will desensitize the superficial and deep peroneal nerves and the tibial +/- plantar and lateral nerves. This should provide numbness in the area of concern. It helps block the paw and the metatarsal regions.

An IVRA can be more effective than a ring block for major procedures. However, it is more ideal for the forelimb below the elbow than the hindlimb. It can be used for the hindlimb, but is much easier and more commonly used for the forelimbs. Further, dewclaw removal, even with firmly attached ones, is usually a short and minor procedure when done by a trained professional, and a ring block should be sufficient. Further, it requires a tourniquet which limits surgical time and is likely overkill for this patient.

Correct answer: Degenerative myelopathy

Degenerative Myelopathy (DM) affects dogs, usually over eight years of age. It is most commonly appreciated in the GSD but can be seen in other large breed dogs and the corgis. (GSDs, Boxers, Corgis, Rhodesian ridgebacks, poodles, Irish setters, and Bernese Mountain dogs are commonly noted with this condition). It is a symmetrical disease that presents with progressive weakness, an ataxic neurological disease, but one that is non-painful. MRI is usually normal with DM, ruling out spinal cord neoplasias or other causes.

Dogs with IVDD usually are painful, and while the disease can be progressive and symmetrical or asymmetrical, it doesn't usually progress in this fashion.

Dogs with spinal cord neoplasia often have asymmetrical progressive signs. They are usually painful with paraparesis. Some may have rapid onset, while others may have a slow onset. Advanced imaging would be necessary to confirm this versus DM.

Infectious meningomyelitis can be caused by various organisms, including bacteria, canine distemper virus, and fungal or protozoal diseases. These can be symmetrical or asymmetrical but usually have systemic clinical signs along with them. CNS tap and advanced imaging help differentiate.

Because DM has a genetic component and an identified gene SOD1 mutation DNA test exists. If a pet is heterozygous, their disease risk is low, but they can pass it on to their offspring. 

Correct answer: FIV infection

Negative prognostic indicators for renal lymphoma in cats include FELV infection, CNS or other organ involvement, and severe chronic kidney disease (stages 3-4). This patient is FELV + and has evidence of renal injury. If she is clinically dehydrated, IV fluid therapy may improve values, but establishing/determining her baseline would help determine her prognosis. Further, if her ataxia is secondary to CNS involvement or the pain is referred from her spine, her prognosis is much worse. If it is, in fact, due to arthritis/back pain or another cause, then that is one less mark against her.

Regardless of risk factors, you need to offer a referral to an oncology specialist who can further discuss the risks, side effects, options, and prognostic indicators.

FeLV, not FIV infections, has been associated with renal lymphoma.

Correct answer: Gallbladder wall thickening > 2 mm

Cats with cholecystitis will often have evidence on ultrasound to confirm the disease. Findings may include: 

1. Gallbladder wall thickening (> 1 mm in cats and 2–3 mm in dogs)
2. Thickening of the common bile duct's wall
3. The thickened gallbladder wall may be hyperechoic or have a hypoechoic central area stuck between two hyperechoic areas (layered appearance).

Differentials for gallbladder wall thickening include:

• Edema (hypoalbuminemic patients or those with portal hypertension)
• Cystic mucinous hyperplasia
• Acute cholecystitis
• Rarely, neoplasia

In cats with cholecystitis, we can commonly see biliary sludge, choleliths, and even sludge balls (mobile, non-shadowing, rounded, luminal structures made of bile).

One can obtain an ultrasound-guided sample of the bile for culture (cholecystocentesis).