ICVA NAVLE Exam Questions

Correct answer: Average number of pigs weaned per sow per year.

In North American farms, overall herd performance (not health) is evaluated by the average number of pigs weaned per sow per annum. For many farms, this number is  ≥25 to 30. Farms achieving lower than their target require evaluation to determine why this rate is low.

Pigs weaned/sow/year refers to a combination of:

1. The # of pigs weaned per litter.
2. The # of litters per sow annually.

Normal lactation is three weeks; thus, most sows can reach about 2.5 litters/sow/year. If this rate is lower than expected, it could be because conception rates are low or as a consequence of prebreeding issues. Prebreeding issues could include a longer than average (<7 days) weaning-breading interval or management-related concerns. If the number of litters/sow/year nears 2.5, but the total pigs weaned/sow/year is low, one may need to find out why low numbers of weaned pigs occurred. It could be due to smaller litter sizes or increased mortality in the preweaning piglets.

Mortality records provide the most useful parameter in identifying a health problem. Generally, swine management strives for:

• Preweaning mortality ≤10%
• Nursery mortality 3–4%
• Growing-finisher mortality of 2–3%

Herd size itself isn't a parameter that helps assess overall herd health. However, the larger the herd, the more likely one is to introduce new diseases. The larger the herd, the closer attention needs to be paid to biosecurity practices. Ultimately, the goal is to minimize the challenges provided by pathogens while maximizing herd and individual immunity.

Farrowing rates play a role in the number of pigs weaned per sow per year, but that isn't the whole picture. Suppose the sow delivers but her litters are smaller, or the litters do not survive weaning. In that case, this doesn't accurately represent the overall herd performance.

Correct answer: Granulomatous meningoencephalomyelitis

Optic neuritis, inflammation of the optic nerve, generally occurs bilaterally, resulting in vision loss without pupillary light reflexes. It manifests with a large optic disc and red areas of focal hemorrhage +- retinal detachment (peripapillary). MRI and ERG are needed for diagnosis +/- CSF taps.

Optic neuritis can be caused by various conditions, including inflammatory, of which the most common cause is granulomatous meningoencephalitis (encephalomyelitis); infectious, such as viral (e.g., canine distemper), fungal (e.g., Cryptococcus), bacterial (ehrlichiosis), or protozoal (e.g., toxoplasmosis) diseases, and cancerous processes.  

Treatment is aimed at controlling the underlying cause, if feasible. If no cause is identified, then steroids orally are used to reduce inflammation. Regardless of diagnosis and institution of appropriate therapy, a return of vision is uncommon, and as a consequence of the disease, the optic nerve often atrophies.

Correct answer: Total ammonia nitrogen (TAN), nitrate, or both may be elevated

When first-time fish hobbyists set up a fish tank, within the first six weeks of establishing a tank, animals may have die-offs or become ill — often due to overstocking and improper water balance. While parasites must always be considered in newly-acquired stock, a full water analysis should be performed. Biological filters, often used in home aquariums and outdoor ponds, help keep large volumes of fish in small aliquots of water. The filter contains nitrifying bacteria, most commonly Nitrosomonas spp. and Nitrobacter spp. Nitrosomonas spp.'s job is to denature ammonia by converting it to nitrite. Ammonia, the primary waste product of fish, and nitrite are both toxic to fish. Nitrobacter spp. then reduces nitrite to nitrate.

Filters need time to be established. Factors including oxygen levels and temperature affect the ability of the biological filter to be colonized and become a self-sufficient system.

The time needed to establish a biological filter varies and depends on the water temperature and organic load (the number of fish). Thus, when starting, ideally add only one fish at a time. Upon adding new fish, monitor ammonia, nitrite, and nitrate levels very closely, daily.

A standard rule of thumb for freshwater fish is 1 to 1.5 inches of fish per gallon of water, whereas saltwater can take 2 to 2.5 inches per gallon. More may be feasible with improved filters, but monitoring is key. Establishing a tropical fish tank can take up to 8 weeks.

In general, new tank syndrome can be avoided by setting up the tank without fish and monitoring the levels. Ammonia is then added to reach 1-5 mg/L. This initiates the process of cycling the biofilter, and monitoring continues. Once no nitrite or ammonia is detected, one can start adding fish. Alternatively, slowly adding one fish at a time over months can allow this to be done, but if not monitored properly, it can lead to toxicity and loss of life.

Correct answer: Trap and euthanize all the animals

The AVMA recognizes that multiple stakeholders have mutual goals surrounding society's numerous free-roaming and feral cats. We must humanely and ethically work together in a One Health collaborative manner with others to improve their quality of life and minimize the negative impacts on other species and other cats that these animals have. We must protect public health from infectious diseases, species loss, and ecosystem destruction.

Multiple approaches are needed to achieve these goals:

1. We need to educate the community about these animals' negative effects on the environment, wildlife, and public health. Further, we must educate owners on how to ensure their cats remain safe (properly vaccinating, sterilizing, and restricting their activities).
2. Encourage state and local ordinances.
3. Use non-lethal strategies as the focus of free-roaming abandoned or feral cat population control. Various entities need to work together to ensure their health. Trap neuter and release programs are the most commonly thought of methods. Further, while controversial, the AVMA also discusses colony management techniques for large groups of cats.
4. Encourage research to determine effective oral/parenteral contraceptive vaccines and to study the health of these free-roaming groups of animals.

The AVMA doesn't oppose euthanasia by qualified people, but only in case other avenues have been exhausted, according to the Humane Guidelines for the Euthanasia of Animals. 

Correct answer: Malt extract at 68°F–71.6°F (20°C–22°C)

Saprolegnia spp., Aphanomyces spp., and Achlya spp. are water molds (not true fungi and they can be easily cultured through the use of malt extract of Sabouraud agar, both kept at 68°F–71.6°F (20°C–22°C). The other types of agar may be used for other fungal/fungal-like organisms, but are not considered the standard for these. Verification can also be done on physical exam or by PCR but often isn't necessary. 

Water molds are more closely related to diatoms and related organisms than true molds. Saprolegnia spp. can commonly infect fish eggs and damage the external skin of live fish. Rarely, the cotton-like growths, which present on the gills, eyes, skin, or fins, can lead to deeper invasion. Those with water temperatures that drop below the fish's natural ideal range are more susceptible. 

Treatment may include formalin, hydrogen peroxide, potassium permanganate, iodophors, or sodium chloride. Stress also plays a role, so improving water quality and minimizing stress may help resolution arise faster.

Correct answer: Prazosin

You discuss with the owner that current veterinary medical evidence suggests that prazosin is not beneficial in relaxing the urethra in cats. Studies indicate that it doesn't prevent obstruction or re-obstruction. Giving medication to a cat can be challenging. Giving a cat a medication that doesn't alter the course of the disease state isn't recommended based on current medical research. You explain to the owners that you have stopped prescribing the drug and have seen no increase in obstructive disease. Those treated for obstruction had recovered as expected when you used the drug.

Assuming he is still eating well, proper management of this patient would include an injectable pain medication, fluids under his skin to provide hydration and flush out the kidneys/bladder, and oral pain meds to go home. Oral buprenorphine or gabapentin, or both, may be utilized depending on your preference, cost, and how easy the pet is to medicate. Additional recommendations include minimization of stressors (since feline interstitial cystitis is most likely secondary to an underlying stress condition, causing inflammation to go to the bladder and subsequent spasming and potential plug formation). Increasing water intake, recommending a wet food only diet, increasing the number of litterboxes in the home (and not putting them around food or water), and environmental recommendations such as toys, perches, and more. You can refer clients to The Ohio State University's Indoor Pet Initiative website, and further information may be found at the Cats Protection website.

Remind the owner of signs to look for that would be suggestive of urethral obstruction. Even though she has had a blocked cat before, it is worth reminding her how quickly they can become sick, signs suggestive of obstruction, and emergency care should be sought if signs worsen/develop/change.

Correct answer: Mandibular lymph nodes

Lymph node biopsies can be easy and low-cost. They may provide a diagnosis, help stage cancer, monitor disease, and generally has few risks. Lymph node choices are dictated in part by the type of disease process of concern. Still, sampling of the popliteal, prescapular, or inguinal lymph nodes is recommended when generalized lymphadenopathy is present. Though sampling of the mandibular and those involved in draining the GI tract may be diagnostic, their morphological appearance leaves them undesirable, as they can often be distorted secondary to reactive hyperplasia that arises secondary to constant antigenic stimulation.

In addition to fine-needle aspiration, lymph nodes can be biopsied using an incisional biopsy (wedge). However, this may be difficult depending on the nodes' size and shape. Or by lymphadenectomy, removing the entire node.

Lymphadenopathy can occur for various reasons, including infection (e.g., oral, tickborne, localized), neoplasia (metastatic disease or primary), or systemic ailments, including liver disease, pancreatitis, inflammatory bowel disease, or intestinal obstruction. The size of the node doesn't necessarily correlate to the severity of the underlying cause. Lymph node biopsies should only be undertaken if a fine needle aspirate fails to yield a sufficient diagnosis.

In healthy non-obese animals, we can usually palpate the mandibular, prescapular, superficial inguinal, and popliteal. To detect abdominal lymph node enlargement, animals generally must be severely cachectic/thin. We can also see the tonsils in some animals on oral examination.

Enlarged lymph nodes secondary to neoplasia are not generally painful, but that doesn't mean they are neoplastic just because they aren't painful.

Removal of lymph nodes can be done with pain management and local anesthetics. However, general anesthesia usually facilitates a successful, easy removal. 

Correct answer: Mortality, before recumbency develops, is low, about 10%

Jejunal hemorrhage syndrome, AKA hemorrhagic bowel syndrome, generally occurs sporadically in primarily dairy cattle. Most tend to be in the first three months of lactation. It is more common in colder months. An association but not causation has been shown with Clostridium perfringens type A (a normal bovine GI tract inhabitant) and Aspergillus fumigatus. Animals become very sick and rapidly decline within 24-48 hours.

These animals will have signs of dehydration, elevated lactate levels > 5 mmol/L, and may have signs of obstruction (Jejunal lumen becomes occluded by blood clots from severe Jejunitis). They will have a raspberry-colored stool with minimal feces. They often have sudden milk dropoff and appetite changes while passing minimal feces.

Mortality rates can range from 50-100% within 48 hours, even with appropriate therapy (medical +/- surgical management). Morbidity can reach over 10% in outbreak situations, though normal animal incidence rates are proposed to be only 1-2%.

Because of these facts, it is hard for you to provide management/prevention recommendations. But you emphasize that euthanasia isn’t a wrong decision, given the severity of the disease. 

Correct answer: Metastatic pulmonary disease

While taken as a chest view, the technicians didn’t fully collimate the image, and a good portion of the abdomen is evident. Always remember to evaluate all structures included on a radiograph, not just the area of interest (the thorax initially in this patient). For example, this radiograph shows a very obese cat with an abnormality along the ventrum of the cat not associated with the body wall that is present and seemingly hyperechoic relative to the surrounding tissue. What the owners and clinician initially presumed to be mats were several mammary masses within that vicinity. After seeing the radiographs, the clinician re-palpated the cat and evaluated the masses more closely. The soft tissue presence is evident on this radiograph.

There is pleural effusion, though scant. You cannot see the diaphragm’s proper outline and the lung lobes are slightly rounded away from the spine. There is a mixed, milliary, almost nodular, pulmonary pattern. Given the findings of the mammary masses (80–95% of feline mammary tumors are malignant), the most likely differential would be pulmonary metastatic disease, which is the primary location of metastasis for mammary carcinomas. Pulmonary metastatic lesions will be soft tissue, not mineral in opacity. (Though there does appear to be mineralization in the mammary mass area.) 

Additional differentials for a mixed pulmonary pattern include thromboembolic disease (though often radiographs are normal when animals present clinically or not this severe). Additional causes include allergic airway disease, fungal infection, fibrosis, edema, sepsis,  toxic lung injury, contusions/hemorrhage, cardiogenic edema in cats, or infectious (e.g., heartworm) disease.

Correct answer: Cryptorchidism is a sex-linked autosomal recessive genetic trait, and he should not be bred and should be neutered when he reaches skeletal maturity

Because cryptorchidism is genetic, thought to be an autosomal recessive sex-linked trait, this dog should not be bred as he risks passing it on to his progeny. Further, the retained testicle, if left in the abdomen or other abnormal position, is at a higher risk for torsion or neoplasia.

The abnormal testicle may be easy to remove and reachable from the inguinal region or found anywhere from just distal to the kidney to within the inguinal ring.

Correct answer: Immediately sedating the pet upon arrival

We want to do anything to minimize this dog’s stress before arrival and once at the clinic. Suppose we immediately jump on this dog with a comforter, pull him through a door, or physically restrain him just to sedate him before interacting. That will leave a lasting impression on the pet and likely only worsen anxiety at subsequent visits. If we can minimize this animal’s stress before and during the visit, we can hopefully teach the dog to accept minimal handling, vaccines, and more.

Cooperative Care training (a positive reinforcement training that grants dogs the ability to give consent before something happens to them) is a great way to train fearful and/or anxious dogs and, thus, act out aggressively in fearful situations. Deb Jones, Ph.D., has a very helpful book on this front. Zoos have been training wild animals for many years with this method, just not necessarily termed it that. Clicker training can be part of it as well. The key is reward based and letting the dog consent. If we were to jump on this dog and inject it immediately, that would be the exact opposite of consent.

Prior to a visit having the owner try a medication or combo of drugs such as we may find in the "Chill protocol" — Gabapentin, melatonin, and transmucosal acepromazine is one way to do so. Another is gabapentin, titrating the dose up from 10–60 mg/kg (dose ranges vary depending on the reference, but thankfully, it has a high safety margin). Just warn owners they may be sleepy/ataxic. Trazodone, a selective serotonin receptor antagonist and re-uptake inhibitor, can be a bit unpredictable when used alone. Dose ranges may vary from 3 mg/kg to 18 mg/kg, again depending on the reference. Generally, most clinicians will recommend combining it with gabapentin +/- acepromazine or other options to ensure an optimal effect.

Always have owners do trial runs at home when there is no stressor to see how the pet reacts. Are there any unexpected reactions (such as excitement or worsening aggression)? Is it enough? If it isn’t enough at home, it definitely won’t be sufficient at the vet’s office.

Have the owner muzzle-train the dog at home with positive reinforcement. There are numerous good training videos to teach a dog to accept a muzzle readily. Then the pet could come muzzled before entering, and sedation may not even be needed.

Sometimes it takes a few tries before finding the right mixture. Still, these meds, combined with positive reinforcement and cooperative care training at home, can make a difference. Happy, well visits (come in, say hello, get treats, and leave) should also be incorporated into the behavior plan for the future so that positive associations can be established.

Correct answer: Chlamydia felis

FHV-1, FCV, flu viruses, and feline pneumovirus can be identified using the above methods/sampling.

Chlamydia felis can be identified using conjunctival swabs, scrapings, or ocular biopsy.

Correct answer: Commercially slaughtered pork

Trichinella spiralis is a roundworm (nematode) in mammals, some reptiles, and birds. The organism most commonly infects swine, but it can infect many species, and all Trichinella species are zoonotic. Of high concern is the contamination of pork products, with ground pork or sausage of particular concern because one pig carcass may be used to make many sausages or to dilute beef or venison sausage.

The concern arises with animals consumed where flesh is consumed raw or the meat is incompletely cooked. This goes for horses, bears, several sea mammals, and feral pigs. Rodents and scavenged wildlife carcasses may also be of concern.

In recent years in the U.S., additional sources of concern have emerged, including eating undercooked bear meat, wild game meat, and home-slaughtered pork.

Thankfully, various control measures have kept the incidence very low at 0.1–0.3%. These measures include prohibiting pig feed from containing raw garbage, docking tails, and raising pigs in confinement. There is also a voluntary National Trichinae Certification Program in the U.S. whose goal is to eliminate trichinellosis.

Cooking pork products sufficiently and uniformly to a minimum temperature of 140°F (60°C) renders the organism non-infectious. Thus, the USDA recommends all fresh pork products be cooked to an internal temperature of at least 145°F (63°C) and that the meat rests for three minutes after cooking before cutting. This allows a safety factor that allows for various cooking modalities, from microwave ovens to conventional ovens, where the cooking may not be even throughout.

When it comes to cold, however, some species of Trichinella are cold-resistant and will not be killed. Salt curing is also ineffective at reliably killing the organism. Thus, any cured products should be thoroughly cooked before eating.

The organism encysts in muscle, and the larvae are ingested when one eats the meat with the larva present. The cyst is liberated when the muscle fibers are exposed to gastric juices. In four days, the larvae mature in the infected individual's small intestines, mate, and females enter the mucosa and emerge in the lymphatics. Some enter the gut lumen and are excreted in feces. However, feces are a minor mode of transmission. Once in the lymphatics, the larvae enter the systemic circulation, where the body's immune system destroys many of them. However, if they gain entry into a muscle fiber (one per fiber), it will create a change in that fiber where it enlarges and acts as a nurse cell. Two to three months later, the larva grows and becomes encased in a cyst-like structure. It can remain in that state for up to eleven years. Striated muscle is preferred over smooth, and active muscles such as the intercostals, diaphragm, lingual, masseter, laryngeal, and ocular muscles are common. Uncommonly, they may enter cardiac muscles. To then transmit to another species, the muscle itself must be consumed.

Swine generally become exposed by scavenging other animals' remains. Or via tail-biting and fecal exposure or, where still permitted, feeding uncooked garbage or infected meat scraps to pigs.

Pathogenicity in swine is low, primarily carriers, but can cause severe disease in people.

Trichenella-free status in the U.S. is based on ELISA (Enzyme-Linked Immunoassay) testing of the products. If an animal is identified with this organism, contact the proper public health and animal health authorities. Appropriate meat inspection practices, rodent control practices, appropriate feed consumption overweight, proper heating and freezing of products used for human consumption, and proper cooking practices aid in prevention. 

Correct answer: The owner's husband works for the drug company that is running the test

Numerous things go into conducting an effective, safe, and beneficial clinical trial. In the case of hyperthyroidism, not treating the pet at all can cause harm. So, you must ensure the study design meets your clinic's ethical and moral standards and does as minimal or no harm as feasibly possible. With a disease like hyperthyroidism, the pet must receive treatment of some kind, either as medication, methimazole, or the new food being tested.

Because all veterinary studies in the US and Canada require Institutional Animal Care and Use Committees (IACUC) oversight and investigations are designed to ensure the safety of the participants, the employment status of an owner's spouse is insignificant unless they are specifically working on the project, as that could be deemed a conflict of interest. However, if a study is well-designed, with proper blinding, random group allocation, and other factors, this shouldn't be an issue.

What is necessary, especially since our patients cannot speak for themselves, is that the owner must be provided with clear transparency and provided with all information possible. This includes risks, side effects, testing parameters, duration of the trial, access to results, and numerous other factors. Clients must know how to exit the trial if the pet is suffering, isn't eating the food, isn't doing well, or other issues arise. Clients must be able to ask questions and have them answered openly and honestly at any time.

Before enrolling a pet, owners must know what is involved to ensure transparency, provide consent, and fully comply with the trial. A household with toddlers, where owners go away on and off frequently, where there are multiple cats in the home and multiple foods fed, among other variables, may not be good candidates for a clinical trial that involves feeding a specific food because you cannot guarantee that only that food will be provided. The toddlers could give the cat people food and/or drop stuff on the floor. Or the cat could sneak and get another cat's food. So, owners have to understand the amount of involvement involved on their part and be comfortable and confident that they can do it for the study's duration. Can they pill their cat? Since both placebo and testing groups will have to pill their cats, this needs to be feasible for the owner.

Correct answer: 2–10%, higher in draft horses than lighter breeds

When the placenta isn’t expelled within the first one and a half to three hours after foaling, Retained Fetal Membranes (RFM) occur. The overall incidence is about 10%, ranging from 2–10% more common in draft breeds (e.g., Friesian) than lighter breeds. RFM occurs secondary to mid to late-term abortions but can happen anytime. When visibly protruding from the vulva, this makes diagnosis easy. However, remnants may be internally present, not visible if they have torn. If you are not sure if any portion of the membranes has been retained, lay out what has passed and grossly examine when possible.

The number one place for RFM is within the tip of the nonpregnant horn. If, when evaluating what part of the membranes have passed, you see lacerations or gaps in that area, you know that material has likely been retained.

Causes of RFM in the mare commonly include dystocias, stillbirths, abortions, endometritis/metritis, twinning, premature delivery, or induced parturition. Less commonly, we can see it as a result of a fetotomy, placentitis, medications, prolonged gestational period, C-section, fescue toxicity, hypocalcemia, entrapped placenta, or poor condition/environment/fatigue/older mares or other conditions which cause stress/debilitation.

Rectal palpation will often demonstrate improper uterine involution. If more than a few hours have passed, intrauterine fluid may be evident. Using ultrasound, RFMs manifest as hyperechoic regions in the uterine lumen. A vaginal exam may further confirm the diagnosis, as the RFMs can often be palpated directly this way.

Once diagnosed, RFM treatment should be instituted immediately to lessen the chance of common sequelae, such as metritis, laminitis, and endotoxemia, all of which can be true emergencies, as they are life-threatening. If no evidence of fetal membrane material is extruding out of the vulva, but hours after delivery, a mare shows a fever, elevated heart/respiratory rate, isn’t eating, is depressed, lethargic, has toxic/injected mucous membranes, and or lameness (potentially a sign of laminitis), this suggests systemic illness and further increases one’s suspicion for RFM.

Treatment with oxytocin is the most effective means of inducing the expulsion of the RFM. A few additional options are available if that fails. In mares who have not passed the fetal membranes within six to eight hours of foaling, they should be started on NSAIDs and broad-spectrum antibiotics. They should be monitored closely for laminitis/endotoxemia, and additional treatments should be added as warranted.

Even if the membranes pass without complications, breeding this mare on the foal heat is not recommended. Though if the RFM passes without problems, future fertility is usually good.

Correct answer: Nothing; you have tested the patient and euthanized, and your public health duty stops there

Veterinarians have a responsibility to One Health, not just public health. Our duty doesn’t stop with just an individual pet and client. If positive, this animal could have exposed numerous people and even bitten or scratched someone. A public health campaign directed towards the area where he was known to reside and the patrons of that park would provide public health education about zoonotic diseases. Further, it could alert possible exposed people to obtain necessary post-exposure prophylaxis.

Our veterinary oath requires us to use our “scientific knowledge and skills for the benefit of society through the protection of animal health and welfare, the prevention and relief of animal suffering, the conservation of animal resources, the promotion of public health, and the advancement of medical knowledge.” Thus, our duty doesn’t just stop with euthanizing and testing this pet. We are required to contact the proper authorities, which vary for each state and local jurisdiction. Still, we also have a duty to ensure the health and welfare of any person/animal exposed to this animal. If he is rabies positive, other animals in that park could also be. People should be advised not to approach strays/wild animals. They should be told not to feed them and advised to whom they should report suspicious behavior of any wild or domestic animal within the vicinity. 

This type of scenario provides a perfect example of how One Health collaboration can address a public health, environmental, and animal health threat. It provides an ideal opportunity to collaborate with health professionals, government agencies, and even community groups on public health issues, such as zoonotic diseases, like rabies. 

Correct answer: The head (and brain)

When a potentially rabid animal bites a person, rapid diagnosis is paramount to determine if that person needs to receive PEP, with the first dose ideally being administered within seven days of the bite. Exact protocols vary depending on whether an individual is already vaccinated for rabies.

Unless the animal is a small kitten or other mammals < 2 kg, most laboratories will only take the head and not the entire animal. Contact your specific official lab for their requirements for shipping, sample collection, and related protocols. The current gold standard and required testing method by the Centers for Disease Control and Prevention (CDC) is via direct fluorescent antibody testing and immunohistochemistry. Labs must be approved by local or state public health authorities to perform this service. It is not recommended to open the skull as the act of sawing can generate aerosolization of the virus. One can also submit the spinal cord if desired, but it is not required, and most labs want the head unless it is not available for testing. 

Saliva is more likely to test positive than CSF, and there isn't a valid approved diagnostic on CSF in animals. Because of the public health risk, the brain is the organ necessary to achieve a diagnosis, but for safety reasons, the head should be submitted, and the lab will separate the skull from the brain with appropriate safety precautions. 

Correct answer: Aflatoxins

Mycosis refers to a disease caused by the growth of fungal organisms and the resultant clinical illness.

Mycotoxicosis refers to adverse consequences secondary to the toxins produced by fungal organisms, most commonly obtained via ingestion.

Key mycotoxins of importance in livestock include Aflatoxins (B₁, B₂, G₁, and G₂), Deoxynivalenol (DON/Vomitoxin), Zearalenone, Fumonisins (B₁ and B₂), and Ergot alkaloids (multiple). Mycotoxicosis is likely a multi-factorial disease entity with management practices, overall herd health factors, environmental factors, feed-related factors, and more intertwined to trigger sufficient toxin exposure and trigger disease. Sometimes, feed is contaminated, and acute disease presents, making diagnosing mycotoxicosis more readily appreciable. When subacute, or chronic, exposure may contribute to clinical signs such as reproductive losses, early embryonic death, vomiting, food refusal, or decreased intake, it can be harder to attribute illness to one cause solely.

However, with Aflatoxins produced by Aspergillus flavus and A. parasiticus and obtained via corn, cottonseeds, and nuts (among other sources), severe hepatic insult or failure can occur in any species and commonly triggers general slow growth. Often considered storage mycotoxins, certain conditions can lead to their production naturally. Diseases associated with this type of toxicity are usually too costly to treat in large animals and can lead to significant economic losses. 

Correct answer: African Swine Fever

African Swine Fever (ASF) is a highly contagious, DNA virus, xotic to the U.S. Primarily in Africa, it has jumped continents sporadically to both Asia and Europe. It has a high morbidity and mortality rate. Natural hosts are both wild and domestic suids. Often subclinical in various African wild suid species, it has been known to cause disease in European wild pigs. It is not zoonotic.

The disease transmission is complex, involving wild suid species, domestic pigs, and soft (Ornithodoros) ticks. Some cycles include warthogs and bushpigs, while others require soft ticks and domestic pigs. Direct contact with infected animals is another means of transmission.

Viral shedding is high in all secretions/excretions. Viremia can be long-lasting, making carrier pigs a significant reservoir for further infections and a key area of focus to permit eradication measures. It is very stable in the environment, and survives in frozen and uncooked meats for weeks. Luckily, it is relatively easy to inactivate various products. Viral replication occurs within the monocytes and macrophages in lymph nodes, those closest to the site of initial exposure. However, it can also reproduce in endothelial cells, neutrophils, and hepatocytes. The final disease state causes significant hemorrhaging with subsequent increased vascular permeability.

ASF must be differentiated from other pig diseases, including Classical Swine Fever (hog cholera) (CSF) and Erysipelas, for example. Virulence determines disease severity. Acute, subacute, chronic, or carrier (inapparent) forms may develop. In general, ASF can cause non-specific clinical signs, including anorexia, fever, depression, and incoordination. Further, it may have skin changes, including purple discoloration and cyanotic blotching of ears, belly, snout, and limbs. The ears and flanks may also demonstrate hemorrhages. Reproductive changes from this virus also occur but seem more to manifest in the boars with sperm quality changes,

The peracute form, in never exposed areas, causes anorexia, fever, cutaneous hyperemia, and depression, with death one to four days later. 

The acute form includes anorexia, high fever (40–42 °C, 104–108 °F), lethargy, pulmonary edema, leukopenia, significant hemorrhage and necrosis of lymph tissue, ear hemorrhage and flanks, enlarged spleens, and high mortality. Additionally, vomiting and diarrhea +/- melena may be evident. Skin lesions turn pinkish, almost purple, and become severely hyperemic/cyanotic, manifesting in irregular purple marks on the extremities, chest, abdomen, perineum, and chest (exanthemas). Abortion occurs in some females and may be the first sign of disease but stillbirths, mummification, and encephalitis are not appreciated sequelae. Labored breathing and nasal discharge due to pulmonary edema precede death. 

The subacute form can have similar signs as the acute, though less severe. There may also be transitory thrombocytopenia, ascites, hydropericardium, and edema of other organs. This form can also cause abortion. In this stage, animals may actually recover after about three to four weeks, which is usually seen in already endemic areas.

The chronic form is primarily noted in Portugal and Spain with variable clinical signs.

Because this disease also resembles many of the other hemorrhagic diseases in pigs, like rysipelas, septicemic salmonellosis, and hog cholera, gross lesions alone are insufficient to diagnose it. Various diagnostic tests are available, including bone marrow testing from wild boar and standard body tissue and serum.  PCR is the most common identification mode. No vaccine is currently available. Those that survive remain protected. Restrict movements if any hemorrhagic disease is suspected and contact the proper authorities.

Any swine febrile disease with systemic, widespread hemorrhage and high mortality should put this disease high on the list.

All the remaining diseases may trigger abortions, fetal mummifications, stillbirths, and encephalitis in pigs zero to six months of age.

Classical Swine Fever (CSF), aka hog cholera, is another febrile, highly contagious disease of pigs, with virulent strains causing almost 100% morbidity and mortality. It is reportable on the national and global levels. 

CSF remains endemic in Asia, Central, and South America, and the Caribbean (posing a threat to the U.S.) and can be seen sporadically throughout Europe. The disease's origin is not understood. CSF was endemic in the U.S. but was eradicated in 1976. CSF, a Pestivirus, is related to BVD (Bovine Virus Diarrhea) and sheep’s Border Disease (B.D.). It is less resilient in the environment than ASF. Still, it can survive some curing processes and frozen products for months to years.

As with many swine diseases, signs are often non-specific but can include depression, significantly elevated temperatures, lying down, and huddling with other sick animals. Diarrhea or constipation and sometimes vomiting. CNS signs like abnormal walking and eventual hindlimb paresis or paralysis may be seen. Young growers may develop seizures; most die in three weeks or less. Less virulent strains may also demonstrate conjunctivitis and emaciation. 

Eradication, vaccination strategies, and legislation banning importations help control/prevent disease in various areas. Primary transmission occurs via oro-nasal direct or indirect contact or ingesting contaminated foods. The tonsils are the initial source of viral replication. Airborne spread is possible experimentally and potentially can occur via semen and humans as fomites.

CSF crosses the placenta, causing infection in fetuses during pregnancy. Depending on the strain, time of infection, and virulence, we can see abortions and stillbirths. If a sow is infected at 50–70 days of gestation, live births with persistent viremia seem normal initially, then develop congenital tremors, termed "late-onset CSF." They shed tons of infected virus particles and serve as significant viral reservoirs. Further, congenital CSF can lead to mummification, congenital malformations, cerebellar hypoplasia, and more.

Laboratory diagnosis is required, as it mimics other diseases, and nothing is pathognomonic. rRT-PCR is widely used with monoclonal antibodies and various other techniques. 

PPRSV (Porcine Reproductive and Respiratory Syndrome Virus) is an RNA virus in the Arteriviridae family. The disease has two clinical phases, the first causing reproductive failure and the second, respiratory disease post-weaning. If a naive herd is infected, not all will develop clinical disease, leading to a persistently infected subpopulation and carrier animal state. Since eradicating Classical Swine Fever, PRRSV is considered the most costly disease in the global swine industry.

Disease transmission occurs via direct contact and through contaminated semen.  Aerosolization and fomite transmission also contribute to disease spread. It is not zoonotic. Experimentally, insect vector transmission also occurs.

Reproductive disease phase: Stillbirths and mummies' incidence may be up to 25–35%, and over 10% may abort. Abortions may result from high fevers in the sows, fetal infection, and subsequent deaths. Anorexia and lack of milk production can lead to higher preweaning mortality rates of piglets. This form can last one to four months, depending on the health of the pigs at infection and various facility characteristics.

The Respiratory phase tends to occur in suckling piglets, with thumping respirations and conjunctivitis with histopathologic evidence of severe interstitial pneumonia. Piglets may be born viremic and serve as another source of transmission. This post-weaning phase may become chronic, causing decreased total weight gain and 10–25% mortality. Other infections may occur concurrently.

Gilts, sows, or boars may show productive issues; fever, lethargy, waxing and waning, anorexia, respiratory distress, or vomiting. Mild cyanosis of the ears, vulva, and belly can occur, as can dyspnea in nursing animals (thumping). Multiple strains may infect a single herd and are not fully cross-protective. 

Young, growing, and finishing pigs may show depression, stunted growth, fever, lethargy, and pneumonia. Sneezing and expiratory dyspnea also may occur along with stunted growth.

Control is key, but there isn’t a single control strategy that works. Ideally, establishing ‘herd immunity’ minimizes transmission and subsequent losses. But quarantine of boars for 60–90 days before introducing them to the females in a negative herd is critical. Vaccination may be utilized as a part of a control strategy, but it is not 100% effective. Modified live vaccines provide some protection and may limit shedding, but no treatment exists. Prevention is paramount.   Depopulation and appropriate cleaning measures then, obtaining all new animals PRRSV free is an option. If one doesn’t want to depopulate, they can close the herd for a minimum of 200 days, stabilizing the herd. But the risk of re-infection is high, and biosecurity protocols must be airtight.

PRV, AKA Aujesky’s disease, is a significant disease player in the swine industry but was eradicated in the U.S. in 2004. It consists of three overlapping clinical syndromes affecting either the nervous, reproductive, or respiratory systems.  It can persist in a carrier (latent state) and easily be destroyed by many disinfectants.

Transmission occurs via contact and exposure to saliva, nasal excretions, urine, and feces. The virus can survive in carrier pigs’ tonsils for several weeks and in the CNS for months. Thus, stress can precipitate recrudescence and subsequent re-shedding. It spreads through direct contact, contaminated food/water, and aerosolization.

Clinical signs vary depending on the age of the pigs affected and the immune status of the dam. Younger pigs appear more affected, while older pigs are more resistant.

Sudden death in the very young may be the only clinical sign. Nursing piglets often show neurological signs. You may see very high fevers, conjunctivitis, anorexia, tremoring, depression, vomiting, foaming at the mouth, dog-sitting, paddling, blindness, seizures, coma, and death within one to three days. The mortality in nursing pigs can reach 100%

Pigs three to nine weeks of age, already weaned, generally have respiratory signs predominate, such as nasal discharge, sneezing +/- cough, and labored breathing.  Most survive unless they develop secondary bacterial pneumonia.

Ten weeks to market weight morbidity is high and respiratory signs also predominate. They may be febrile, sneeze, cough, have nasal discharge, have depression, or be anorexic. Some will also develop CNS signs. However, most recover in seven to ten days.

Breeding animals may show respiratory illness with recovery, but reproductive failure is also possible, including mummified fetuses, stillbirths, or weak pigs. 

There is no known treatment. Swine are the natural domestic animal reservoirs. Vaccinations are highly effective, but all ages are susceptible if not vaccinated. In the commercial U.S. swine industry, the disease has been eliminated. However, a reservoir still exists in some feral populations and is prevalent in other countries. If other species, such as sheep, cattle, dogs, cats, or goats (not horses), are kept in close proximity to pigs, they are susceptible, and death usually occurs in aberrant hosts. Various wild rodents, rabbits, and fur-bearing mammals can become infected. It is not zoonotic.

Correct answer: Streptococcus canis

Canine Infectious Respiratory Disease Complex, or CIRDC, is how we now refer to "kennel cough." This isn't one entity as most owners believe it to be, namely Bordetella bronchiseptica. Still, it is instead a combination of nine different viruses or bacteria that can singularly or in combination cause upper respiratory and pneumonia in dogs. Of course, they aren't the only cause of infection but are the most commonly identified by PCR or culture. Not all dogs have a cough; they may have the classic honking cough or URI signs like conjunctivitis, sneezing, or a runny nose.

Most animals resolve without intervention in one to two weeks. However, age, appetite, size (and breed), and any underlying disease (liver shunt, kidney disease, etc.) may make it harder to fight infection and, more likely, it will progress to pneumonia.

Organisms include: 

VIRUSES:

• Canine parainfluenza virus*
• Canine adenovirus type 2*
• Canine influenza virus (subtypes H3N2 and H3N8)**
• Canine respiratory coronavirus
• Canine herpesvirus-1
• Canine distemper virus*

BACTERIA:

• Bordetella bronchiseptica**
• Mycoplasma species
• Streptococcus equis subspecies zooepidemicus, NOT Strep. canis

Those with * are vaccinated routinely, and those with ** have additional vaccination options.

Animals that get pneumonia will often have a fever, may have decreased appetite, worsening cough, dyspnea, tachypnea, and decreased energy, and may also have other signs. They may have elevated WBC counts and often require IV therapy and hospitalization to stabilize.

There is a potential zoonotic risk for S. equi subsp. zooepidemicus, but most are from contaminated milk, dairy, or equine patients. It is an organism that can be associated with rapidly fatal death because of ARDs, sepsis, or multiple organ dysfunction. Further, antibiotic resistance against this organism is prevalent.

Antibiotic therapy should use appropriate antimicrobial stewardship for organisms that are most likely contributing to clinical signs if warranted.