Bovine Infectious Diseases Flashcards
- Growth medium: Hayflick’s agar (microaerophilic environmental)
- Common cause of otitis media-externa (usually caused result of consuming contaminated milk); head tilt, unilateral ear droop, ptosis, apiphora.
- Lameness, fever, respiratory signs (cough, tachypnea, and nasal discharge), death, swollen joints, and tenosynovitis.
- Post mortem: lungs with multiple abscesses full of pus and caseated material
- Treatment: Tulathromycin. ________ lack a cell wall drugs that act on cell wall (penicillin, cephalosporins) never good choice. Other good choices are tetracyclines or tilmicosin(resistance)
Mycoplasma bovis
- Rickettsial organism transmitted by ticks.
- Obligate intracellular bacterium
- Decreased milk production
- Fever
- Blood smear: organism at the margin of the red blood cells
- Low mortality rate in calves; adult cattle 20-50% mortality.
- Treatment: Oxytetracycline. Single injection of long acting tetracycline (20mg/kg)
- PCV below 12% blood transfusion needed.
- Cattle weak, depressed, staring into space. Pale, icteric, and febrile, no hemoglobinuria.
- No hemoglobinuria due to extravascular hemolysis
- Large destruction of red blood cells, fever, weight loss, respiratory distress, abortion and death
- Sometimes lifetime carriers.
Anaplasmosis
Anaplasma marginale
- G (-) obligate anaerobe, normal rumen micrflora.
- Hepatic abscesses, gastroenteritis in ruminants
- Foot rot
- Metritis
- Bacteremic spread -> liver -> release of toxins leading to damage and potential abscess formation
- Lesions: yellow and spherical with irregular outlines
- Calf diphtheria (necrotic laryngitis / laryngeal necrobacillosis): caused by Histphilus somni and _____
- Can result in death or a premanently misshapen larynx
- Inspiratory dyspnea, loud respiratory noises, open mouth breathing, extended head and neck, moist painful cough, febrile, anorectic and depressed
- 3-18 months of age. Acute signs. Die within the week if no treated. Respiratory distress 1 day duration.
- Moist painful cough and loud inspiratory stridor
- Head nd neck extended.
- Swelling around larynx.
- Episcleral injection.
Fusobacterium necrophorum
- Blackleg (Clostridium sordelli (called malignant edema) can also be a cause)
- Vaccines containing up to 8 different Clostridia are often used.
- Start vaccination at younger age in high risk farms to maintain high colostral levels of antibody, give booster 4-8 weeks. Annual revaccination
- Calves under one year are most susceptible
- Post-mortem black leg
- Vaccinate all calves 4-6 months age with killed vaccine containing Clostridium septics and several other common clostridial organisms
Clostridium chauvoei
- Black leg can also be seen (often called malignant edema)
Clostridium Septicum / Sordellii
- Woody or wooden tongue
- Introduced by breaks in the mucosa allowing the normal rumen inhabitant causing painful granulomas
- Treated with IV sodium iodide.
- Other systemic antibiotics (tetracyclines) can be used
- Inability to pretend, excessive salivation, visibly enlarged tongue rot rides.
- Enlarged submandibular area.
- Tongue hard, painful and nodular.
- Treatment: Sodium iodide IV as a 10-20% solution, repeat after 7 day interval (70mg/kg IV)
Actinobacillus lignieresii
- Gram (+), obligate pathogen of the mammary gland
- Usually causes subclinical mastitis, sometimes high somatic cell counts and clinical signs
- Diagnosis: CAMP reaction (plate S. aureus and _____ act together to lose red blood cells (clearing on culture plate)
Streptococcus agalactiae
- To eliminate: treat and vaccine.
- Vaccine will not eliminate existing carriers
- Long acting tetracycline
- Mid- to late-gestation abortions
Leptospira interrogans
Serovar Hardjo (type Hardjo-Bovis) is carried by cattle.
Cattle maintenance host of Hardjo
- Most common CNS infection in adult ruminants
- Associated with feeding silage
- Microabscesses in the brain resulting in unilateral cranial nerve signs: facial nerve paralysis, vestibular signs (circling), head tilt, and dysphagia.
- CN V-XII may be involved.
- Head pressing.
- Abortions
- Treatment: Tetracyclines or high levels of penicillin
- CSF: monocytosis
Listeria monocytogenes
- Respiratory disease and septicemia
- TEME (Thromboembolic meningencephalitis) or otitis media / interna young feedlot animals: head tilt, nystagmus, circling and stumbling. Ipsilateral facial paralysis.
- Affects the cerebellum and brain stem
- Systemic diseases such as pneumonia, laryngeal disorders, joint infections, metritis, orcHitis and conjunctivitis
- History of pneumonia that resolves with antibiotic.
- Swelling carpi, tarsi and stifles. Distension of associated tendon sheaths.
- Stiff gait.
- Postmortem: Fibrinous pleuritis and papillary muscle necrosis.
Histophilus somni
- Worst pathogen in Bovine Pulmonary Disease
- Severe fever, dyspnea, cough and respiratory distress
- Necropsy: Fibrinopurulent bronchopneumonia
- Most common primary cause of shipping fever (multifactorial etology (bacterial and viral) - Histophilus somni, Pasteurella multocida, and Mycoplasma)
- Most cattle carry it as commensal.
- Stress proliferate and infect lungs
Mannheimia hemolytica
Formerly called Pasteurella hemolytica
- Abortions (last half of pregnancy), retained placenta, metritis, lack of signs in younger animals.
- Relatively normal appearance of the examined fetuses.
- Late abortion (6-7 months), weak or stillborn calves.
- Placenta retention and/or metritis
- Younger - pre-pubescent heifers no affected
- Necropsy fetus: lung consolidation
- Diagnosis: Serologic testing
Brucella
- Abortion - first half of gestation.
- Placentitis + pneumonia fetus
- Commonly associated with pos-coital pyometra + Early embryonic death
Tritrichomonas fetus
- Manifests as sores and abscesses in cattle, common on the lateral thorax, neck, flank or head
- An injury can result in inoculation of the organism.
- Cows are relatively unaffected systemically and the lesions will resolve on their own 2-4 weeks
- Flush the wound and let it heal
Corynebacterium pseudotuberculosis
- Recent uterine infection.
- Cattle less common that horses, sheep and goats (they are less sensitive to the toxin)
- Toxins moves retrograde up the peripheral neuron into the spinal cord, where it prevents release of inhibitory neurotransmitters (GABA) - causing spastic paralysis
Tetanus
- Tends to cause Septicemia in dairy calves 4-8 weeks of age
- Transmitted from carriers to neonate at birth via milk
- Cull carriers. Vaccine calves modified live vaccine
- Lesions: serosal and subcutaneous petechial hemorrhages and heavy wet red lungs
Salmonella dublin
- Deltaproteobcterium.
- Transmitted by ground-dwelling soft tick Ornithodoros coriaceus.
- Abortion 3-4 month after exposure.
- Prevention: Raise heifers in the foothills and put pregnant heifers in the hills only when 6 months or more pregnant (provide premonition immunity)
- Control tick by irrigated pastures
-No vaccine available
Epizootic Bovine Abortion
- Forage poisoning.
- Occurs in groups of animal fed improperly stored or contaminated animal carcass
- Down, unable to get up, weak, staggering.
- Normal TPR, profoundly weak, tongue stays out, masseter muscle strength, pupillary light response poor.
Botulism
- Black bloody discharge from all orifices
- Incomplete rigor mortis despite being dead for a day
- Acute death
- Lesions occur in the reticuloendothelial system and vasculture
- Do not perform necropsy
- Reportable
Anthrax
Bacillus anthracis
- Paratuberculosis (Johne’s disease)
- Granulomatous ileitis and colitis.
- Diarrhea results: dumps albumin into the lumen (rapid lose weight)
- ELISA
- Suddenly lose of weight.
- Watery green diarrhea.
Mycobacterium avium
- Early embryonic death but does not result in pyometra.
Campylobacter fetus
- Sawhorse stance, lockjaw, and elevated tail.
- Sensitive to tactile and auditory stimuli.
- Infection from inoculation of a wound.
- Can via ingestion
Clostridium tetani
- Bacillary hemoglobinuria
- Resides in the liver until anaerobic conditions develop - replication - producing toxins.
- Red urine.
- Necropsy: urine dark red and all body fluids are icteric and hemorrhagic. Hemorrhage in the abomasum and reticulum. Liver anemic infarct near the portal vein.
- Liver flukes are associated (anaerobic tracts for organism to bloom) - marshy areas with snails are part if the fluke live cycle
Clostridium hemolyticum
Clostridium novyi type D.
- Laryngeal abscesses.
- No febrile and septic.
Trueperella pyogenes
- Lumpy jaw
- Often from eating hard scabrous feeds.
- Part of the normal oral and rumen flora
- Hard non-painful swelling of the mandible or maxilla along with productive and destructive bony changes
Actinomycosis
*Actinomyces bovis**
- Pink eye
- Flies are main vector: Lyperosia irritans, Stomoxys clcitrans, Musca autumnalis.
Moreaxella bovis
- Protozoan parasite
- Definitive host: Dog (coyote or other canidae) which acquire the disease eating infected meat and spreads to cow by shedding Oocysts in pasture or feeds
- Abortion (mid-term)
- Diagnosis: IFA
- Abortions usually 4-6months, but can occur throughout gestation.
Neospora caninum
- Roundworm
- Type I occurs in winter and spring, large numbers of L3 larvae from heavily contaminated pastures (or on irrigated summer pasture). Egg counts higher. Clinical disease most common in younger animals after weaning. Older animals after invading the abomasal mucosa, develop L4 stage, wait for favorable climate conditions and cause Type II.
- Type II outbreaks autumn into winter with hot dry summer and cool wet fall and winter. Fecal egg counts are low, thousands of inhibited early L4 stage larvae ready to exit abomasal glands. Many larvae emerge causing dysfunction of abomasum leading to severe albumin loss, diarrhea and death.
- Treatment benzimidazoles (fenbendazole) and ivermectin
- Levamisole less effective
- TII: weight loss, diarrhea, thickened mucosal folds in abomasum (less shiny mucous than normal)
- TI: found in naive calves and not associated with large numbers of larvae
Ostertagia ostertagi
- Reportable disease
- Pruritus leg lesions: papules, erythema, scaling, crusting, alopecia.
- Diagnosis: skin scraping
- Treatment Ivermectin
Chorioptes bovis
- Not shed in milk
- Obligate parasite of the genital tract
- Abortion.
- Temporary infertility or early embryonic death
Bovine campylobacteriosis
Campylobacter fetus ssp venerealis
- First half of gestation, no placentitis or pneumonia in fetus
- Associated with a post-coital pyometra in addition to causing early embryonic death.
Tritrichomonas foetus
- Prevention: Lasalocid, monensin, amprolium, decoquinate, diclazuril and toltrazuril
- No vaccine
- Less than 1 year - nervous coccidiosis in cattle.
- Enteric infection (production of a neurotoxin thought)
Coccidiosis
Eimeria spp
- L1 larvae migrate to the esophagus
- L2 migrated mooted to L3 larvae where they drill an air hole, grow, falling out on the ground, pupating for 1-3 months before becoming a short-lived fly
- L3 larvae are on the subcutaneous tissue of the back
Hypoderma lineatum
- L1 larvae migrate to the epidural fat of the spinal cord
- L3 larvae are on the subcutaneous tissue of the back
Hypoderma bovis
- Red cell parasite.
- Transmitted Boophilus ticks.
- Hemolytic anemia, hemoglobinuria (differentiates from anaplasmosis), icterus and death
- Piroplasmosis, red water, Texas fever, tick fever.
Babesiosis
Babesia bigemina
- Bovine lungworm - verminous bronchitis
- Cooler moist summers
- Young cattle more severely, cough, frequent tachypnea.
- Diagnosis: fecal examination (Baermann)
- Altihelmintic program 3, 8 and 13 weeks post-turnout.
Dictyocaulus viviparus
- Fly also known as screwworm
- Females lay eggs at the edge of fresh wounds.
- Larvae hatch in 24 hours.
- As larvae eat living tissue creates huge wound.
- Larvae fall off and pupate completing life cycle in 21 days
- Reportable
Cochliomyia hominivorax
- Reportable
- Economically devastating
Sarcoptes scabei
- Congenital abnormality associated: cerebellar hypoplasia
- Microphthalmia and hydrancephaly also observed, not as common.
- Type 1 and Type 2. virus classified as being cytopathic or noncytopthic.
- Diarrhea, reproductive problems, occasional cerebellar hypoplasia.
- Persistently-infected carrier cattle infect fetuses.
- A susceptible non-immune cow carrying a fetus between 60-150 days, if infected by a non-cytopathic biotype can pass the virus to the fetus and may become persistently infected. The calf can spread the virus during its life.
- Mucosal disease is a severe form. Occur when animal born infected with non-CPE (non cytopathic effect) form super infected with CPE biotype, or the virus transforms to the CPE byotipe. Severe ulcerations throughout GI tract resulting in death.
Bovine Viral Diarrhea
Occurs in cattle when A 5-month (50-150 days) old calf which was persistently infected as a fetus with a non cytopathic (nonCPE) biotype of BVD virus is superinfected with a cytopathic (CPE) biotype of BVD due to rearranging of the parent non-CPE viral RNA (pathogenesis of mucosal disease and chronic BVD)
- Subtypes: BHV-1.1 Responsible of Respiratory Infections.
- BHV-1.2: genital infections and respiratory disease.
- BHV-1.3: reclassified as BHV 5), neurologic infections.
- No interdigital lesions
- BHV-1 responsable of ophthalmic lesions. Infect the trigeminal ganglia and becomes latent.
- When the animal is immunosuppressed the virus replicates an causes disease
- BHV-II Bovine Ulverative Mammilitis.
- BHV-III: acelaphine herpesvirus (African Mlignant Catharrhal Fever)
- Anorexia, serous nasal and ocular discharge, short explosive cough and hyperemia of nasal mucosa.
Infectious Bovine Rhinotracheitis
Interdigital legions differentials
- Foot-and-mouth disease
- Interdigital necrobacillosis
- Bovine Viral Diarrhea
- Malignant Catarrhal fever
- Poor milk production and weight loss.
- Normal TPR, poor body condition, multiple enlarged lymph nodes at widely scattered locations
- Can cause clinical lymphoma
- Most definitive diagnosis ELISA for antibodies,reveals that the cow has ntibodies, but not that she has clinical lymphoma
- Aspiration of lymph nodes can lead to false positives as many inflamed reactive nodes in cattle can have cells that look neoplastic
Bovine Leukosis Virus
- Winter dysentery
- Epidemic disorder of housed cattle in cold months affecting 10-90% of adult cows.
- Colon affected.
- Course weeks, the herd becomes immune and recovers (milk production may not recover to previous levels)
- Brownish fetid liquid feces full ofbubbls.
- Clots of blood.
- Normal temperature.
- Slightly dehydrated.
- Drop in appetite and milk production
Coronavirus
- “Mad Itch”
- Introduction new pigs.
- Pruritus with alopecia
- Pigs are the primary host, usually asymptomatic.
- Several cows with acute onset of ataxia, nystagmus, circling, strabismus, and depression, strange behavior, vocalization, convulsions, and death.
- Intense pruritus and alopecia.
- No treatment.
- Control: remove pigs.
Pseudorabies
- Herpesvirus (Carried by sheep in North America) called Ovine Herpesvirus Type 2
- Affects lymphocytes and allows the animal’s own killer cels to attack blood vessels resulting in arteritis
- High fever, and enlarged lymph nodes
- Severe form usually fatal: cloudy eyes, mucoid nasal discharge, thickened and cracked skin and diarrhea, corneal opacity, thick white nasal discharge, enlarged prescapular lymph nodes and diarrhea with blood, oral erosions
Malignant Catarrhal Fever
Ringworm
Trichophyton mentagrophytes
- Cattle and horses
- In calves can be severe, in cold weather and decreased UV light
- Zoonotic
A 2-year-old feedlot steer presents with high fever, anorexia, serous nasal discharge progressing to mucopurulent, excessive salivation, and conjunctivitis with lacrimal discharge. Nasal mucosa appears inflamed, and the animal exhibits coughing. What is the most likely diagnosis?
A. Bovine Viral Diarrhea
B. Infectious Bovine Rhinotracheitis
C. Parainfluenza-3 Virus Infection
D. Bovine Respiratory Syncytial Virus Infection
Answer: B. Infectious Bovine Rhinotracheitis
Explanation:
Infectious Bovine Rhinotracheitis (IBR), caused by Bovine Herpesvirus-1 (BHV-1), commonly presents with high fever, anorexia, serous nasal discharge that may become mucopurulent, excessive salivation, conjunctivitis with lacrimal discharge, inflamed nasal mucosa (“red nose”), and coughing. These clinical signs are indicative of the respiratory form of BHV-1 infection.
Viral Infections Associated with Bovine Respiratory Disease Complex in Cattle
Which of the following best describes the pathophysiological mechanism of latency and reactivation in Bovine Herpesvirus-1 (BHV-1) infections?
A. BHV-1 integrates into the host genome, leading to persistent infection.
B. BHV-1 establishes latency in sensory ganglia and can reactivate under stress.
C. BHV-1 remains in the bloodstream, causing chronic viremia.
D. BHV-1 persists in lymphoid tissues, leading to continuous shedding.
Answer: B. BHV-1 establishes latency in sensory ganglia and can reactivate under stress.
Explanation:
BHV-1, an alphaherpesvirus, establishes latent infections in sensory ganglia or pharyngeal tonsils after the initial infection. Reactivation of the virus can occur due to various stressors, such as inclement weather, poor husbandry, or management events like calving or mixing. Reactivated latent carriers may not exhibit clinical signs but can shed the virus, serving as a source of infection for susceptible animals.
Which diagnostic method is most appropriate for confirming a suspected outbreak of Infectious Bovine Rhinotracheitis in a herd?
A. Clinical signs observation alone
B. Virus isolation or PCR from nasal swabs
C. Serological testing for antibodies
D. Histopathological examination of lung tissue
Answer: B. Virus isolation or PCR from nasal swabs
Explanation:
While clinical signs can suggest IBR, definitive diagnosis requires laboratory confirmation. Virus isolation or PCR assays performed on nasal swabs are reliable methods for detecting BHV-1 during active infection. Serological testing can indicate exposure but may not distinguish between past and current infections. Histopathological examination is more invasive and typically reserved for post-mortem analysis.
Viral Infections Associated with Bovine Respiratory Disease Complex in Cattle
A 2-year-old feedlot steer presents with high fever, anorexia, excessive salivation, serous nasal discharge progressing to mucopurulent, and conjunctivitis with lacrimal discharge. On physical examination, inflamed nares (“red nose”) and dyspnea due to laryngeal occlusion with purulent material are noted. What is the most likely diagnosis, and which pathogen is responsible?
• A) Bovine Viral Diarrhea Virus (BVDV) • B) Bovine Respiratory Syncytial Virus (BRSV) • C) Bovine Herpesvirus 1 (BHV-1) • D) Parainfluenza-3 Virus (PI-3)
Answer: C) Bovine Herpesvirus 1 (BHV-1)
Explanation: The clinical presentation described is characteristic of Infectious Bovine Rhinotracheitis (IBR), a disease caused by Bovine Herpesvirus 1 (BHV-1). IBR primarily affects the upper respiratory tract and is common in feedlot cattle. Clinical signs include high fever, anorexia, coughing, excessive salivation, nasal discharge that progresses from serous to mucopurulent, conjunctivitis with lacrimal discharge, inflamed nares (“red nose”), and dyspnea if the larynx becomes occluded with purulent material. BHV-1 can also cause conjunctivitis with corneal opacity as the only clinical sign. In the absence of bacterial pneumonia, recovery generally occurs 4–5 days after the onset of clinical signs.
Which subtype of Bovine Herpesvirus 1 (BHV-1) is primarily associated with genital infections in cattle, and what are the typical clinical manifestations in affected cows and bulls?
• A) BHV-1.1; respiratory infections • B) BHV-1.2; genital infections • C) BHV-1.3; neurologic infections • D) BHV-1.4; enteric infections
Answer: B) BHV-1.2; genital infections
Explanation: Bovine Herpesvirus 1 (BHV-1) has been classified into subtypes based on clinical manifestations. BHV-1.2 is primarily associated with genital infections in cattle. In cows, this manifests as infectious pustular vulvovaginitis, characterized by frequent urination, elevation of the tailhead, mild vaginal discharge, swollen vulva, and small papules followed by erosions and ulcers on the mucosal surface. In bulls, the condition presents as infectious pustular balanoposthitis, with similar lesions occurring on the penis and prepuce. Transmission can occur in the absence of visible lesions and via artificial insemination with semen from subclinically infected bulls.
What are the recommended vaccination strategies for controlling Infectious Bovine Rhinotracheitis (IBR) in breeding and feeder cattle, and what precautions should be taken regarding vaccine administration in pregnant cows?
• A) Use only inactivated vaccines in all cattle; avoid vaccination during pregnancy • B) Administer modified live virus (MLV) vaccines to all cattle; safe for use in pregnant cows • C) Immunize breeding and replacement heifers and bulls at 6–8 months old, before breeding, and yearly thereafter; feeder calves should be immunized 2–3 weeks before entry into the feedlot; use intranasal MLV vaccines in pregnant cows • D) Vaccination is not recommended for IBR control
Answer: C) Immunize breeding and replacement heifers and bulls at 6–8 months old, before breeding, and yearly thereafter; feeder calves should be immunized 2–3 weeks before entry into the feedlot; use intranasal MLV vaccines in pregnant cows
Explanation: Effective control of Infectious Bovine Rhinotracheitis (IBR) involves strategic vaccination protocols. Breeding and replacement heifers and bulls should be immunized at 6–8 months old, before breeding, and yearly thereafter. Feeder calves should be vaccinated 2–3 weeks before entry into the feedlot. Both parenteral and intranasal modified live virus (MLV) vaccines are available; however, parenteral MLV vaccines may cause abortion in naive pregnant cattle. Therefore, intranasal MLV vaccines are recommended for use in pregnant cows, as they can be used safely in all pregnant cattle.
A 4-month-old calf presents with unilateral ear droop, head tilt, ptosis, and epiphora. A history reveals it was fed unpasteurized milk. What is the most likely causative agent, and what condition does it cause?
• A) Pasteurella multocida; Otitis media • B) Mycoplasma bovis; Otitis media • C) Mannheimia haemolytica; Otitis externa • D) Histophilus somni; Otitis interna
Answer: B) Mycoplasma bovis; Otitis media
Explanation:
Mycoplasma bovis is a common cause of otitis media and otitis externa, often linked to the consumption of contaminated unpasteurized milk. Clinical signs include unilateral ear droop, head tilt, ptosis, and epiphora. Mycoplasma bovis, a wall-less bacterium, thrives in microaerophilic environments and grows on Hayflick’s agar. Early identification and treatment are crucial to avoid complications. Tulathromycin or tetracyclines are effective treatments, as Mycoplasma lacks a cell wall, rendering antibiotics like penicillin and cephalosporins ineffective.
During a postmortem examination of a beef steer with a history of lameness, fever, and respiratory signs, the lungs are found to contain multiple abscesses filled with pus and caseated material. Which pathogen is the most likely cause, and which antibiotic class is ineffective for treatment?
• A) Mycoplasma bovis; Beta-lactams • B) Mannheimia haemolytica; Macrolides • C) Histophilus somni; Fluoroquinolones • D) Pasteurella multocida; Tetracyclines
Answer: A) Mycoplasma bovis; Beta-lactams
Explanation:
Mycoplasma bovis commonly causes severe chronic respiratory disease in cattle, characterized by abscesses in the lungs filled with purulent and caseated material. This pathogen lacks a cell wall, making it resistant to beta-lactam antibiotics such as penicillins and cephalosporins, which target cell wall synthesis. Effective treatments include tulathromycin, tetracyclines, or tilmicosin (though resistance to tilmicosin is observed in some cases). Prompt treatment is essential to minimize morbidity and mortality.
Which medium is required to culture Mycoplasma bovis, and why are beta-lactam antibiotics ineffective against this pathogen?
• A) Hayflick’s agar; Lacks cell wall • B) MacConkey agar; Beta-lactam resistance genes • C) Blood agar; Lacks membrane-bound enzymes • D) Sabouraud’s agar; Biofilm formation
Answer: A) Hayflick’s agar; Lacks cell wall
Explanation:
Mycoplasma bovis requires specialized culture conditions, growing on Hayflick’s agar in a microaerophilic environment. It lacks a cell wall, which makes beta-lactam antibiotics, such as penicillins and cephalosporins, ineffective, as these drugs target bacterial cell wall synthesis. Instead, tulathromycin or tetracyclines are recommended treatments. Mycoplasma species are known for their small genome and dependence on host cells for nutrients, which complicates culture and treatment strategies.
A 1-year-old heifer presents with fever, depression, and decreased milk production. Upon examination, the animal exhibits diarrhea and erosive lesions in the oral cavity. The farmer reports that several other young cattle in the herd have shown similar signs, with some cases resulting in death. What is the most likely diagnosis, and which diagnostic tests would confirm this condition?
A. Bovine Viral Diarrhea (BVD); confirm with virus isolation and PCR.
B. Malignant Catarrhal Fever; confirm with serology and PCR.
C. Bluetongue; confirm with virus isolation and ELISA.
D. Rinderpest; confirm with virus neutralization test and PCR.
Answer: A. Bovine Viral Diarrhea (BVD); confirm with virus isolation and PCR.
Explanation: The clinical signs of fever, depression, decreased milk production, diarrhea, and oral erosions in young cattle are indicative of Bovine Viral Diarrhea (BVD). BVD is caused by the Bovine Viral Diarrhea Virus (BVDV), a pestivirus that leads to immunosuppression and can affect multiple body systems. Diagnosis is confirmed through virus isolation and PCR testing to detect the presence of BVDV.
A cattle herd experiences multiple abortions, and some calves are born weak or with congenital defects. Additionally, a few young calves exhibit persistent diarrhea and fail to thrive despite adequate nutrition. Considering the reproductive and neonatal issues observed, which disease should be suspected, and what is the pathogenesis leading to persistently infected (PI) calves?
A. Bovine Viral Diarrhea (BVD); infection of the dam between days 30 and 120 of gestation leads to immunotolerance and birth of PI calves.
B. Infectious Bovine Rhinotracheitis; infection during late gestation causes fetal infection and weak calves.
C. Leptospirosis; transplacental infection results in abortion and stillbirths.
D. Neosporosis; vertical transmission leads to abortion and congenital defects.
Answer: A. Bovine Viral Diarrhea (BVD); infection of the dam between days 30 and 120 of gestation leads to immunotolerance and birth of PI calves.
Explanation:
BVDV infection during early gestation (approximately days 30 to 120) can result in the fetus becoming immunotolerant to the virus, leading to the birth of persistently infected (PI) calves. These PI animals shed the virus throughout their lives, serving as reservoirs for BVDV transmission. Clinical manifestations in PI calves include persistent diarrhea, poor growth, and increased susceptibility to other diseases.
infected (PI) cow with Bovine Viral Diarrhea Virus (BVDV) suddenly develops severe diarrhea, high fever, and erosive lesions in the gastrointestinal tract. Despite supportive care, the cow’s condition deteriorates rapidly, leading to death within a few days. What is the most likely explanation for the acute worsening of the cow’s condition, and what is the underlying mechanism?
A. Development of Mucosal Disease; superinfection with a cytopathic strain of BVDV.
B. Secondary bacterial infection; immunosuppression due to BVDV.
C. Acute BVDV infection; exposure to a high-virulence noncytopathic strain.
D. Parasitic infestation; compromised immunity from persistent BVDV infection.
Answer: A. Development of Mucosal Disease; superinfection with a cytopathic strain of BVDV.
Explanation:
Mucosal Disease (MD) is a fatal condition that occurs in cattle persistently infected with a noncytopathic strain of BVDV when they become superinfected with a cytopathic strain of the virus. This superinfection can result from mutation of the resident noncytopathic virus to a cytopathic form or from external sources such as modified-live vaccines. MD is characterized by severe enteritis, mucosal erosions, and rapid deterioration, often leading to death.
Abortion in Cattle
- Abortion: Premature expulsion of the fetus, typically defined as occurring before the fetus is viable.
- Genetic Factors: Often cause early embryonic death.
- Nutritional Deficiencies: Vitamins A, E, selenium, and iron.
- Toxins: Ponderosa pine needles (isocupressic acid), locoweed (indolizidine alkaloid), broomweed, coumarins, mycotoxins, nitrates/nitrites.
- Physical Trauma: Rarely causes abortion.
-
Bluetongue:
- Causative Agent: Orbivirus.
- Symptoms: Abortion, mummification, stillbirth, CNS malformations.
- Diagnosis: PCR, precolostral antibodies.
- Prevention: Vaccination, vector control.
-
Bovine Viral Diarrhea (BVD):
- Causative Agent: Pestivirus.
- Symptoms: Embryonic death, congenital malformations, abortion.
- Diagnosis: Virus isolation, PCR, precolostral antibodies.
- Prevention: Vaccination, remove persistently infected animals.
-
Brucellosis:
- Causative Agent: Brucella abortus.
- Symptoms: Abortion in late gestation, placentitis.
- Diagnosis: Serology, fluorescent antibody staining.
- Prevention: Calfhood vaccination, test-and-slaughter.
-
Campylobacteriosis:
- Causative Agent: Campylobacter fetus venerealis.
- Symptoms: Infertility, early embryonic death, abortion.
- Diagnosis: Darkfield examination, culture.
- Prevention: Artificial insemination, vaccination.
-
Chlamydiosis:
- Causative Agent: Chlamydophila abortus.
- Symptoms: Abortion in late gestation, placentitis.
- Diagnosis: Stained smears, ELISA, PCR.
- Prevention: No vaccine for cattle.
-
Epizootic Bovine Abortion:
- Causative Agent: Pajaroellobacter abortibovis.
- Symptoms: Late-term abortion, hepatomegaly, splenomegaly.
- Diagnosis: Histopathology, fetal IgG.
- Prevention: Exposure to endemic areas before breeding.
-
Infectious Bovine Rhinotracheitis (IBR):
- Causative Agent: Bovine herpesvirus 1.
- Symptoms: Abortion at any stage, placentitis.
- Diagnosis: Immunologic staining, virus isolation.
- Prevention: Vaccination.
-
Leptospirosis:
- Causative Agent: Leptospira spp.
- Symptoms: Late-term abortion, icterus in fetuses.
- Diagnosis: Fluorescent antibody staining, PCR.
- Prevention: Vaccination, elimination of contamination sources.
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Listeriosis:
- Causative Agent: Listeria monocytogenes.
- Symptoms: Abortion at any stage, placentitis, fetal septicemia.
- Diagnosis: Culture from fetus or placenta.
- Prevention: Avoiding contaminated feed.
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Mycotic Abortion:
- Causative Agents: Aspergillus, Mucor, Absidia.
- Symptoms: Abortion from 4 months to term, placentitis.
- Diagnosis: Presence of fungal hyphae in tissues.
- Prevention: Avoid moldy feed.
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Neosporosis:
- Causative Agent: Neospora caninum.
- Symptoms: Abortion at 3-6 months, fetal autolysis.
- Diagnosis: Immunohistochemistry, PCR.
- Prevention: Hygiene, vaccination.
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Trichomoniasis:
- Causative Agent: Tritrichomonas foetus.
- Symptoms: Early embryonic death, placentitis.
- Diagnosis: Culture from abomasal contents.
- Prevention: Artificial insemination, vaccination.
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Trueperella pyogenes:
- Symptoms: Sporadic abortion, endometritis, placentitis.
- Diagnosis: Culture from placenta or abomasal contents.
- Prevention: No effective bacterin available.
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Ureaplasma diversum:
- Symptoms: Sporadic abortion, placentitis, stillbirths.
- Diagnosis: Isolation from placenta, lungs, abomasal contents.
- Prevention: No specific vaccine available.
- Akabane Virus, Parainfluenza-3 Virus, Salmonella spp, Mycoplasma spp, Histophilus somni: Causes sporadic abortions, requiring specific diagnostic and preventive measures.
For detailed information, visit the Merck Veterinary Manual - Abortion in Cattle.
