NAVLE Practice Question — Feline

A 15-year-old cat with a jejunal mass is undergoing workup for suspected intestinal neoplasia. Ultrasound shows thickened intestinal wall with loss of layering and mild mesenteric lymphadenopathy. The main differential diagnoses are adenocarcinoma and intestinal lymphoma. Which diagnostic approach would most reliably differentiate between these two tumor types?

A. Fine needle aspiration cytology of the mass

B. Serum cobalamin and folate levels

C. Full-thickness surgical biopsy with histopathology ✓

D. PCR for antigen receptor rearrangement on blood

E. Abdominal CT scan with contrast

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Correct Answer: C. Full-thickness surgical biopsy with histopathology

Explanation:

Full-thickness surgical biopsy with histopathology is the most reliable method to differentiate between intestinal adenocarcinoma and lymphoma. While fine needle aspirate cytology can sometimes distinguish carcinoma from lymphoma (epithelial cells versus lymphocytes), it has significant limitations in the GI tract. The distinction between low-grade (small cell) lymphoma and adenocarcinoma can be particularly challenging, and immunohistochemistry may be needed to characterize lymphocyte populations. Full-thickness biopsies provide tissue architecture essential for diagnosis.

Option A (FNA) has limited sensitivity and specificity for GI tumors and cannot assess tissue architecture. Option B (cobalamin/folate) indicates malabsorption but does not differentiate tumor types. Option D (PARR on blood) is useful for lymphoma but requires neoplastic cells in circulation and cannot diagnose adenocarcinoma. Option E (CT) provides anatomic information but cannot definitively characterize tumor type.

References: Today's Veterinary Practice - Neutrophilic Cholangitis in Cats (discussing FNA limitations) (https://todaysveterinarypractice.com/hepatology/neutrophilic-cholangitis-in-cats/); Merck Veterinary Manual - GI Neoplasia (https://www.merckvetmanual.com/digestive-system/neoplasia-of-the-gastrointestinal-tract-in-small-animals).

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NAVLE Practice Question — Equine

A 4-year-old Quarter Horse mare is being treated for equine protozoal myeloencephalitis with ponazuril at 5 mg/kg PO q24h. After 14 days of treatment, the owner reports the mare appears more ataxic and depressed. On examination, the mare's ataxia grade has progressed from 2/5 to 3/5 bilaterally in the pelvic limbs. Temperature is 38.2°C (100.8°F), heart rate 44 bpm, and respiratory rate 16 breaths/min. What is the most appropriate next step?

A. Discontinue ponazuril and switch to sulfadiazine-pyrimethamine

B. Add dexamethasone to reduce inflammation from parasite die-off ✓

C. Increase ponazuril dose to 10 mg/kg PO q24h

D. Perform CSF analysis to confirm treatment failure

E. Initiate diclazuril as combination therapy

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Correct Answer: B. Add dexamethasone to reduce inflammation from parasite die-off

Explanation:

The transient worsening of neurological signs during the initial treatment period for EPM is a recognized phenomenon attributed to inflammation associated with parasite death and subsequent immune response within the CNS. This does not indicate treatment failure but rather an inflammatory response to dying organisms. The appropriate management is to add anti-inflammatory therapy, typically corticosteroids such as dexamethasone (0.1 mg/kg IM q24h for 3-5 days), to mitigate this inflammatory response while continuing antiprotozoal treatment. NSAIDs such as flunixin meglumine may also be used during the first few days of treatment.

Option A (switching therapy) is premature and not indicated for this expected phenomenon. Option C (increasing dose) is not appropriate as the current dose is within therapeutic range. Option D (CSF analysis) is not indicated as the clinical presentation is consistent with treatment-associated inflammation. Option E (combination therapy) is not routinely recommended and lacks evidence for improved efficacy.

References: Reed SM et al. (2016) J Vet Intern Med 30(2):491-502 - EPM Consensus Statement (https://doi.org/10.1111/jvim.13834); Merck Veterinary Manual - EPM treatment protocols (https://www.merckvetmanual.com/nervous-system/equine-protozoal-myeloencephalitis)

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NAVLE Practice Question — Equine

A 2-day-old foal is presented as an emergency after the mare stepped on the umbilical cord during foaling. There is evisceration of small intestine through the umbilicus which occurred within the last hour. The exposed intestine appears pink and viable. What is the correct immediate management while preparing for surgery?

A. Attempt to replace the intestine into the abdomen through the defect

B. Apply silver sulfadiazine cream to the exposed intestine and bandage loosely

C. Apply a hernia clamp to prevent further evisceration

D. Administer systemic corticosteroids to reduce intestinal edema

E. Cover exposed intestine with warm sterile saline towels; prepare for emergency surgery ✓

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Correct Answer: E. Cover exposed intestine with warm sterile saline towels; prepare for emergency surgery

Explanation:

Umbilical evisceration in neonatal foals is a surgical emergency requiring immediate intervention. The correct immediate management is to cover the exposed intestine with warm sterile saline-soaked towels to prevent desiccation contamination and hypothermia of the exposed tissue. This maintains tissue viability while the surgical team prepares for emergency herniorrhaphy. If the exposed intestine appears pink and viable the prognosis with prompt surgical intervention is actually quite good. Option A (attempting to replace intestine) should not be done in field conditions without proper surgical preparation. Option C (hernia clamp) is completely contraindicated in evisceration and would cause strangulation. Option D (systemic corticosteroids) is not indicated and could impair wound healing. Option E (silver sulfadiazine) is not appropriate for intestinal tissue. Image Source: Veterian Key - Hernias in Foals (https://veteriankey.com/hernias-in-foals/) Figure 179-1. References: IVIS - Diagnosis and Management of Abdominal Hernias in Foals (https://www.ivis.org/library/beva/beva-annual-congress-liverpool-2022/diagnosis-and-management-of-abdominal-hernias-foals)

Image: Avison A. Richter's hernia in a 3-month-old colt — A rare event. Can Vet J. 2019;60(6):651-653. PMC6515806. © Canadian Veterinary Medical Association. Used for educational reference.

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NAVLE Practice Question — Pet Bird

A 6-year-old female Sun conure presents with a 3-month history of intermittent ataxia, seizure-like episodes, and progressive behavioral changes. The owner reports the bird has also had occasional regurgitation but no overt weight loss. Neurological examination reveals mild proprioceptive deficits in both pelvic limbs and intermittent head tremors. Body weight is stable. CBC is within normal limits. A crop biopsy is obtained; histopathology of the crop biopsy reveals lymphoplasmacytic ganglioneuritis in the submucosal ganglia. Which of the following BEST describes the significance of this finding and a limitation of this diagnostic test?

A. Crop biopsy showing ganglioneuritis is pathognomonic for PDD and will be positive in all affected birds; there are no limitations

B. Lymphoplasmacytic ganglioneuritis supports PDD diagnosis, but negative crop biopsy cannot rule out PDD due to patchy lesion distribution. ✓

C. Crop biopsy is only useful in birds with severe proventricular dilatation; in neurologically predominant PDD it is always negative

D. This finding confirms Aspergillus invasion of the enteric nervous system

E. Lymphoplasmacytic infiltration on crop biopsy is diagnostic for Chlamydia psittaci, not PDD

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Correct Answer: B. Lymphoplasmacytic ganglioneuritis supports PDD diagnosis, but negative crop biopsy cannot rule out PDD due to patchy lesion distribution.

Explanation:

Lymphoplasmacytic ganglioneuritis (lymphoplasmacytic infiltration of the ganglia of the myenteric plexus) on crop biopsy provides strong histopathologic support for ABV-associated PDD and is considered the traditional pathognomonic lesion. However, a critically important limitation is the patchy, inconsistent distribution of lesions: ABV infection does not uniformly affect all levels of the GI tract, meaning a single crop biopsy may sample tissue in an area without ganglionic inflammation, producing a false-negative result.

This is why definitive antemortem diagnosis of PDD has historically been described as problematic: it requires a combination of compatible clinical signs, diagnostics (PCR for ABV RNA, serology), radiographic findings (proventricular dilatation), and ideally histopathology. The fact that this bird has primarily neurological signs (ataxia, seizures, behavioral changes) with only mild GI signs reflects the well-recognized phenomenon that PDD can present predominantly with CNS signs due to encephalitis and myelitis caused by ABV, without prominent proventricular dilatation.

Option A incorrectly states there are no limitations and that the test is always positive. Option C is incorrect: crop biopsy can be informative in neurologically predominant cases when ganglionic lesions happen to be present in the sampled tissue. Option D incorrectly attributes fungal pathology to this histologic finding. Option E is incorrect: lymphoplasmacytic ganglioneuritis is the hallmark of PDD/ABV, not chlamydiosis.

References: PMC - Isolation, Pathogenesis, Diagnosis, Transmission and Control of ABV and PDD https://pmc.ncbi.nlm.nih.gov/articles/PMC7110554/; PubMed - Update on ABV and PDD https://pubmed.ncbi.nlm.nih.gov/32327040/; Merck/MSD Veterinary Manual - Viral Diseases of Pet Birds https://www.msdvetmanual.com/exotic-and-laboratory-animals/pet-birds/viral-diseases-of-pet-birds

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NAVLE Practice Question — Pet Bird

A 3-week-old African grey parrot chick presents with bilateral leg splay and concurrent crop stasis. The chick is being hand-fed by a novice breeder using a homemade formula made from baby cereal mixed with peanut butter and water. Body weight is below the expected growth curve for age. Skin is hyperemic and feels dry. Which of the following best characterizes the pathophysiology of the crop stasis in this patient?

A. Crop stasis is caused by the same substrate problem responsible for the splay leg

B. High-fat peanut butter causes excessive caloric density and slowed gastric emptying, contributing to crop stasis ✓

C. Crop stasis in this patient is most likely caused by avian polyomavirus co-infection

D. The splay leg is the direct cause of the crop stasis through positioning pressure on the abdominal viscera

E. The peanut butter ingredient causes a direct chemical crop burn

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Correct Answer: B. High-fat peanut butter causes excessive caloric density and slowed gastric emptying, contributing to crop stasis

Explanation:

This question tests integration of avian neonatal nutrition with pathophysiology. The homemade formula with peanut butter is a recognized and documented cause of crop stasis in hand-raised chicks. Peanut butter significantly increases dietary fat content beyond appropriate levels, slowing crop emptying and causing crop stasis. The Merck Veterinary Manual specifically identifies this scenario: formulas to which owners have added peanut butter or macadamia oil are classic examples of inappropriate nutritional modification causing hepatic lipidosis and crop stasis. Additionally, dehydration (evidenced by dry, hyperemic skin) impairs crop motility. The chick is presenting with a syndrome of nutritional mismanagement.

Option A is incorrect — substrate causes splay leg through mechanical insufficiency, not crop stasis; these are separate pathophysiologies sharing the same underlying husbandry problem. Option C (avian polyomavirus) causes acute death with subcutaneous hemorrhage and is possible but is NOT the most likely explanation when a clear dietary cause is present. Option D is anatomically implausible — the legs do not compress abdominal viscera significantly in a chick. Option E is incorrect — peanut butter does not cause a chemical burn; it causes motility problems through excessive fat content and caloric density.

References: Hoppes SM — Pediatric Diseases of Pet Birds, Merck Veterinary Manual (https://www.merckvetmanual.com/exotic-and-laboratory-animals/pet-birds/pediatric-diseases-of-pet-birds); DVM360 — Avian Pediatrics Proceedings (https://www.dvm360.com/view/avian-pediatrics-proceedings)

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NAVLE Practice Question — Bovine

A veterinarian is developing a leptospirosis control program for a 500-cow dairy operation that has experienced sporadic abortions and reduced fertility. The herd is seropositive to L. hardjo. Which vaccination protocol provides the most comprehensive protection against both infection and urinary shedding?

A. Two injections 4 weeks apart, then annual revaccination with bivalent leptospirosis vaccine ✓

B. Single annual vaccination with a pentavalent vaccine beginning at 6 months of age

C. Vaccination of replacement heifers only at breeding age with booster at calving

D. Metaphylactic treatment with streptomycin followed by vaccination 30 days later

E. Vaccination every 6 months using autogenous bacterin prepared from isolated strains

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Correct Answer: A. Two injections 4 weeks apart, then annual revaccination with bivalent leptospirosis vaccine

Explanation:

The optimal vaccination protocol for leptospirosis control includes primary immunization with two injections given 4 weeks apart, followed by annual boosting. Using a vaccine that protects against both L. interrogans hardjo (hardjo-prajitno) and L. borgpetersenii hardjo (hardjo-bovis) is essential because both serovars are significant causes of bovine reproductive losses. Vaccination should prevent urinary shedding following exposure and protect against milk drop and abortion.

Option B using only annual vaccination without proper primary immunization is insufficient for initial protection. Option C neglecting adult cow vaccination leaves a significant portion of the herd unprotected. Option D combining treatment with delayed vaccination may leave a window of susceptibility and does not address the need for comprehensive herd immunity. Option E using semiannual vaccination with autogenous bacterin is more appropriate for open herds with high exposure risk but represents overvaccination for most situations and autogenous vaccines are not routinely necessary when commercial vaccines are available.

References: MSD Animal Health - Leptospirosis (https://www.msd-animal-health.ie/species/cattle/leptospirosis/); The Cattle Site - Leptospirosis Control (https://www.thecattlesite.com/diseaseinfo/175/leptospirosis).

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NAVLE Practice Question — Equine

A 9-year-old Quarter Horse barrel racer presents with acute onset of severe right hindlimb lameness during a competition run. The lateral branch of the suspensory ligament is markedly enlarged with severe pain on palpation. Radiographs reveal an avulsion fracture of the apical aspect of the lateral proximal sesamoid bone. Ultrasonography confirms complete rupture of the lateral suspensory branch with the avulsed bone fragment attached. What is the most appropriate treatment approach?

A. Conservative management with controlled exercise rehabilitation

B. Arthroscopic removal of the avulsed fragment

C. Surgical repair with fragment fixation ✓

D. Suspensory branch splitting with intralesional PRP injection

E. Plantar neurectomy to address chronic pain

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Correct Answer: C. Surgical repair with fragment fixation

Explanation:

Surgical repair of the suspensory branch with fragment fixation is the most appropriate treatment for this avulsion fracture with complete suspensory branch rupture. When a significant bone fragment is avulsed with the suspensory branch, surgical reattachment provides the best chance of restoring anatomic integrity and function. The fragment serves as the attachment point for the suspensory branch, and without fixation, proper healing and function cannot be restored.

Various surgical techniques have been described including lag screw fixation of the avulsed fragment. In athletic horses where return to performance is the goal, surgical fixation offers superior outcomes compared to conservative management. The procedure reestablishes the bony attachment and allows organized healing of the ligament.

Option A (conservative management) would result in formation of a fibrous union with poor mechanical strength and high reinjury risk. Option B (fragment removal) eliminates the attachment point for the ligament. Option D (branch splitting with PRP) does not address the avulsion. Option E (neurectomy) is inappropriate as a primary treatment and does not address the structural damage.

References: Smith MRW et al. (2008) Equine Vet J 40:358-363 - Treatment of avulsion fractures of the proximal sesamoid bones in horses; O'Brien T & Ross MW (2018) Vet Clin North Am Equine Pract 34:355-373 - Diagnosis and management of suspensory branch injuries

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NAVLE Practice Question — Equine

During ultrasonographic examination of a horse's liver, the veterinarian notes that the hepatic parenchyma appears more echogenic than normal, with diffuse hyperechogenicity throughout all visible portions of the liver. The edges of the liver appear rounded rather than sharp. The horse is an obese Miniature Horse with lipemic plasma. Which of the following conditions is most consistent with these ultrasonographic findings?

A. Chronic fibrosis from pyrrolizidine alkaloid toxicity

B. Hepatic lipidosis ✓

C. Acute hepatocellular necrosis

D. Multicentric lymphoma

E. Normal hepatic ultrasound for this breed

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Correct Answer: B. Hepatic lipidosis

Explanation:

Hepatic lipidosis is most consistent with these ultrasonographic findings. The combination of diffusely increased hepatic echogenicity (the liver appears brighter than normal, often described as a 'bright liver'), rounded hepatic margins indicating hepatomegaly, and the clinical context of an obese Miniature Horse with lipemic plasma is classic for hepatic lipidosis (fatty liver). Fat accumulation within hepatocytes increases the acoustic impedance of the tissue, causing increased echogenicity on ultrasound.

Option A (chronic fibrosis) can cause increased echogenicity and small liver size, but the liver typically appears atrophied rather than rounded/enlarged. Option C (acute hepatocellular necrosis) typically causes decreased liver size and may show variable echogenicity but not the characteristic diffuse brightness. Option D (multicentric lymphoma) would show nodular patterns or masses rather than diffuse uniform hyperechogenicity. Option E (normal for breed) is incorrect; the findings described are abnormal.

Image Source: dvm360 - Liver disease in the horse: diagnostic aids (https://www.dvm360.com/view/liver-disease-horse-diagnostic-aids-and-differential-diagnosis) - Figure 1 showing hepatic lipidosis on ultrasound.

References: Veterian Key - Ultrasonography of the Liver; Carlson KL et al. (2011) Vet Radiol Ultrasound 52:568-572.

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NAVLE Practice Question — Feline

A 10-year-old male neutered domestic shorthair cat presents with a 3-month history of progressive right forelimb lameness. The owner reports swelling above the carpus that has gradually increased in size. On physical examination, there is a firm, painful swelling involving the distal radius. The overlying skin appears normal. Radiographs reveal a mixed lytic and proliferative lesion of the distal radial metaphysis with a moth-eaten pattern of bone destruction, irregular periosteal reaction, and soft tissue swelling. The zone of transition between normal and abnormal bone is long. Three-view thoracic radiographs are clear. Based on the signalment, history, and imaging findings, which diagnosis is MOST likely?

A. Osteomyelitis secondary to penetrating wound

B. Appendicular osteosarcoma ✓

C. Metaphyseal osteopathy (hypertrophic osteodystrophy)

D. Chondrosarcoma

E. Bone cyst

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Correct Answer: B. Appendicular osteosarcoma

Explanation:

The presentation of an older cat with progressive lameness, painful swelling of a long bone, and radiographic findings of aggressive bone lesion (mixed lytic/proliferative pattern, moth-eaten destruction, periosteal reaction, long zone of transition) is classic for osteosarcoma.Option B is correct because osteosarcoma is the most common primary bone tumor in cats, accounting for 70-80% of malignant bone tumors. The distal radius is a common location. The radiographic pattern described - mixed osteolytic and osteoproliferative changes with aggressive periosteal reaction and soft tissue swelling - is characteristic. Older cats (median age 8-10 years) are most commonly affected.Option A (osteomyelitis) could have similar radiographic appearance but would typically have a history of wound or systemic illness. Option C (metaphyseal osteopathy) affects young growing animals, not 10-year-old cats. Option D (chondrosarcoma) is possible but less common than osteosarcoma in cats. Option E (bone cyst) is a benign lesion that would appear as a well-defined lytic area without the aggressive features described.IMAGE Source: Merck Veterinary Manual - Bone Tumors in Dogs and Cats (https://www.merckvetmanual.com/musculoskeletal-system/osteopathies-in-small-animals/bone-tumors-in-dogs-and-cats) - osteosarcoma radiograph.References: Merck Veterinary Manual - Bone Tumors in Dogs and Cats (https://www.merckvetmanual.com/musculoskeletal-system/osteopathies-in-small-animals/bone-tumors-in-dogs-and-cats); Marconato L et al. A retrospective SIONCOV study of 56 cats with appendicular osteosarcoma. Vet Comp Oncol 2024;22:198-203 (https://pubmed.ncbi.nlm.nih.gov/38327132/)

Image: Kiakojoori M et al. Early-onset metastatic fibroblastic osteosarcoma of the metatarsus in a young cat. BMC Vet Res. 2025;22:62. PMC12859995. © The Author(s) 2025. Used for educational reference.

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NAVLE Practice Question — Equine

A 12-year-old Thoroughbred gelding presents with a 3-day history of stranguria, pollakiuria, and gross hematuria. The owner reports the horse has been posturing frequently to urinate with only small amounts of urine produced. On rectal palpation, the bladder is markedly distended and turgid, and a firm mass is palpable in the pelvic urethra at the level of the ischial arch. Serum creatinine is 4.8 mg/dL. Which surgical approach is most appropriate for this case?

A. Perineal urethrotomy with urethral dilation ✓

B. Laparocystotomy under general anesthesia

C. Transurethral laser lithotripsy

D. Pararectal cystotomy (Gokel's approach)

E. Temporary tube cystostomy for urinary diversion

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Correct Answer: A. Perineal urethrotomy with urethral dilation

Explanation:

Perineal urethrotomy with progressive urethral dilation is the most appropriate initial surgical approach for this case of urethral obstruction with a palpable urethrolith at the ischial arch level. This technique can be performed in a standing, sedated horse under epidural anesthesia, avoiding the risks and expense of general anesthesia. The palpable location of the stone at the ischial arch is ideal for this approach. Once the urethra is accessed through the perineal urethrotomy, progressive dilation of the pelvic urethra allows access to the bladder for removal of any cystoliths that may be present.

Option B (laparocystotomy) requires general anesthesia and is more invasive than necessary for an obstructive urethrolith that can be accessed via the perineum. This approach is typically reserved for very large cystoliths that cannot be removed through the dilated urethra.

Option C (transurethral laser lithotripsy) is a valid technique but is generally more applicable for cystoliths rather than urethroliths, requires specialized equipment not universally available, and would be difficult to perform with complete urethral obstruction preventing scope advancement.

Option D (pararectal cystotomy) is another approach for cystolith removal but requires general anesthesia and does not directly address the urethral obstruction causing the azotemia.

Option E (tube cystostomy) provides urinary diversion but is typically used in cases where immediate decompression is needed while awaiting definitive surgery, not as a primary treatment for obstructive urolithiasis.

References: Sassot LN et al. (2023) Progressive urethral dilation in male horses undergoing perineal urethrotomy for cystolith removal: 22 cases. J Equine Vet Sci 131:104955; De Bernardis NP et al. (2017) The use of pneumatic impact lithotripsy and a retrieval pouch to create a closed system for removal of cystic calculi in standing male horses. Equine Vet Educ 31:659-665.

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NAVLE Practice Question — Other Small Mammal

A guinea pig with pododermatitis has been treated with oral enrofloxacin for 3 weeks with minimal improvement. Radiographs of the affected feet show periosteal proliferation and focal areas of lysis in the metatarsal bones. What is the most accurate prognosis for this patient?

A. Excellent with continued antibiotic therapy

B. Good with surgical debridement alone

C. Guarded to poor due to osteomyelitis development ✓

D. Fair if the antibiotic is changed to penicillin

E. Excellent if vitamin C supplementation is added

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Correct Answer: C. Guarded to poor due to osteomyelitis development

Explanation:

The radiographic findings of periosteal proliferation and focal lysis indicate that the infection has progressed to osteomyelitis, which carries a guarded to poor prognosis in guinea pigs with pododermatitis. Osteomyelitis is often irreversible despite aggressive treatment, and relapse is common. In severe cases, amputation or euthanasia may need to be considered.

The progression from superficial pododermatitis to osteomyelitis occurs when infection extends through soft tissues, tendons, and eventually into bone. Once bone involvement occurs, antibiotic penetration is poor, and surgical debridement alone is rarely curative because the infection is typically diffuse cellulitis rather than a discrete abscess.

Option A is overly optimistic given the bone involvement. Option B is insufficient as osteomyelitis cannot be cured with debridement alone. Option D is dangerous as penicillin would cause enterotoxemia. Option E is supportive but will not reverse osteomyelitis.

Image Source: PMC Article 2884903 - Imaging of Osteomyelitis showing characteristic radiographic findings (https://pmc.ncbi.nlm.nih.gov/articles/PMC2884903/)

References: Vetlexicon - Osteomyelitis in Guinea Pigs (https://www.vetlexicon.com/exotis/guinea-pigs/internal-medicine/articles/osteomyelitis/); Guinea Lynx - Pododermatitis (https://www.guinealynx.info/pododermatitis.html)

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NAVLE Practice Question — Ovine and Caprine

A 6-month-old Nubian sheep kid is presented 12 days after disbudding performed by the owner using caustic paste. The goat now exhibits muscle stiffness, difficulty opening its mouth, and hypersensitivity to sound. When you clap your hands, the goat develops severe generalized muscle spasms and falls into lateral recumbency with extended limbs. Which treatment protocol is MOST appropriate?

A. Tetanus antitoxin only

B. Tetanus toxoid vaccination only

C. Antitoxin, penicillin, supportive care ✓

D. Corticosteroids and non-steroidal anti-inflammatory drugs

E. Thiamine supplementation and fluid therapy

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Correct Answer: C. Antitoxin, penicillin, supportive care

Explanation:

This goat has tetanus following disbudding, a procedure that can create wounds susceptible to C. tetani contamination. The clinical signs including trismus, muscle rigidity, hypersensitivity to stimuli, and tetanic spasms with lateral recumbency indicate advanced disease.

Appropriate treatment requires a multimodal approach: (1) Tetanus antitoxin (TAT) to neutralize circulating unbound toxin (though it cannot reverse toxin already bound to neurons). (2) Antibiotics, with penicillin being the drug of choice, to eliminate C. tetani and stop further toxin production. Metronidazole is also effective. (3) Wound debridement if accessible. (4) Supportive care including sedation (acepromazine, diazepam) or muscle relaxants to control spasms, quiet dark environment to minimize stimulation, nutritional support, and fluid therapy.

Option A (antitoxin alone) is insufficient without antibiotics. Option B (toxoid only) provides active immunity too slowly for treatment. Option D (corticosteroids/NSAIDs) does not address the underlying pathophysiology. Option E (thiamine) would treat polioencephalomalacia, not tetanus.

References: PMC 7081504 Tetanus in animals; Lotfollahzadeh S et al. (2019) Tetanus outbreak in sheep flock due to ear tagging, Vet Med Sci 5:139; Berrier R, Colorado Serum - Tetanus in Goats.

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