Presented from a flock of 20+ animals, with 3 having already died and one other sick. The goose had three days of neurologic episodes starting on 8/6/21 including ataxia, decreased mentation, head and neck tremors, as well as anorexia and lethargy. A physical exam revealed bradycardia, weakness, BCS 3/9, increased respiratory effort, intermittent coughing, wheezing, serous nasal discharge, and diarrhea.
The goose was emaciated with serous atrophy of fat. The lateral aspect of the right 4th digit had three well demarcated, irregular, reddish ulcers ranging from 6mm to 1.5cm in diameter. A similar lesion affected the lateral aspect of the right tarsus that was covered with a dark red crust. The subcutaneous tissue of the right inguinal and sacral areas was moderately expanded by yellowish edema The middle one-third of the trachea had petechial to ecchymotic hemorrhages.
H&E
Severe, subacute, encephalitis with lymphoplasmacytic perivascular cuffing and gliosis
West Nile flavivirus (WNV) was detetcted via PCR , no Eastern equine encephalitis alphavirus was detected, and the histologic lesions are suggestive of WNV infection. The brain was affected by perivascular infiltrates, astrogliosis and occasional spheroids within the white matter. The eye was also affected with lymphoplasmacytic pectenitis, optic neuritis and panuveitis. The sciatic and the myenteric plexus of the ileum were affected by lymphoplasmacytic lymphoplasmacytic neuritis. The skin lesion was likely secondary to trauma related to neurologic signs.
Erwood
1
91
Southcentral Division
2021
12
CAPRINE
1.5-week-old, female, goat
Presented for weakness, nasal discharge, and emaciation. Overnight, the goat died while hospitalized. 12 kids have died recently on the farm, and several others had been showing similar clinical signs.
The goat is in emaciated body condition has serous atrophy of the renal pelvic fat. The ventral portion of the right cranial lung lobe is dark pink to red, firm, and depressed. Multifocal, small, round, tan foci of caseous material are within the parenchyma. The affected section of lung sinks in formalin. The bile ducts have thickened walls and are filled with pale green mucoid material. The gallbladder is distended with similar material. The right middle ear contains a moderate amount of yellow pasty exudate.
H&E
Severe subacute multifocal suppurative cholangitis with biliary coccidia and bacilli
The cause of death in this goat was due to bronchopneumonia caused by Bibersteinia trehalose, and the biliary coccidiosis was considered an incidental finding. Biliary coccidosis is commonly recognized in rabbits (Eimeria stiedae) but rarely reported in other species such as mink, goats, chamois, hippopotami, a pig, a calf, and a dog. While the pathophysiology is uncertain, intestinal tract, blood, or lymphatic spread have all been proposed methods of infection as sporozoites and oocysts have been found in mesenteric lymph nodes. In goats, there are two reported forms of this disease: the biliary form, which is restricted to the biliary tract and gallbladder and leads to biliary hyperplasia, fibrosis, and occasionally hepatic necrosis; and the hepatobiliary form, which is additionally characterized by intrahepatic zygotes and widespread hepatic granulomas containing oocysts. This case is an example of an early stage of the biliary form as evidenced by the lack of biliary hyperplasia, fibrosis, and necrosis. It is suspected in this case that biliary coccidiosis predisposed the goat to a secondary bacterial cholangitis. A fecal floatation yielded many Eimeria spp, and no intestinal coccidia were appreciated microscopically. One report identified Eimeria caprina and Emeria alijevi from bile of a goat with hepatobiliary coccidiosis. The microscopic morphology of this biliary coccidia is most consistent with E. caprinia.
Paulson
1
92
Southcentral Division
2021
13
CANINE
10-year-old spayed female West Highland Terrier
The dog was referred for suspected nodal B-cell lymphoma based on equivocal lymph node biopsy results and generalized lymphadenopathy. Lymph node cytology was inconclusive, but the diagnosis of lymphoma was supported by flow cytometric small B-cell lymphocytosis and evidence of clonal rearrangement of the B-cell receptor via PCR. Flow cytometry, cytology, and biopsy were all suggestive of an indolent phenotype, and the patient appeared otherwise healthy with no clinical signs, so continued monitoring was elected over treatment.
A 6x7x4 cm, multilobular, well-demarcated, dark red to pale tan, firm mass effaced the cranial mediastinum and sternal lymph nodes and was firmly attached to the thoracic wall. Diffusely, there was moderate to marked enlargement of the mandibular, retropharyngeal, superficial cervical, sternal, gastric, and pancreatic lymph nodes. These lymph nodes were pale tan to dark red, semi-firm, and bulged on cut section. The spleen was diffusely enlarged with a meaty texture and was mottled pale tan to red.
H&E
Diffuse lymphoma
Although a conclusive histologic subtype was not determined, the initially diagnosed lymphoma had many characteristics suggestive of an indolent phenotype. The patient then developed acute and severe disease caused by aggressive lymphoma which was both morphologically and characteristically inconsistent with that which was previously diagnosed. Thus, this case represents a transformation of an indolent hematopoietic neoplasm to a more aggressive form. The transformation could have happened by one of three possible mechanisms: 1) a clonal subpopulation of the indolent neoplasm acquired subsequent mutations which allowed it to transform into the more aggressive form, 2) the disseminated lymphoma was not descended from the indolent neoplasm but shared a common neoplastic lymphoid precursor, or 3) the aggressive lymphoma arose de novo and had no genetic relation to the indolent lymphoma. Genetic, chromosomal, and phenotypic comparison between the two neoplastic populations is required to differentiate between these mechanisms. Unfortunately, this analysis was not performed in this case except for confirmation of consistent expression of CD20.
Dulli
1
93
Southcentral Division
2021
14
CANINE
9-year-old spayed female Labrador Retriever dog
This patient presented due to several subcutaneous masses on the left neck, left shoulder, ventral sternum, right thigh, and left thigh. Chest radiographs revealed several lung masses.
The mass on the left shoulder was firm, and it measured 10x8x6 cm.
H&E
Osteosarcoma
At the time of biopsy and cytology, the initial diagnosis for the subcutaneous masses was a sarcoma, favoring an osteosarcoma. Alkaline phosphatase stain was performed on the cytological slides from the neck, and the neoplastic cells had small, black, intracytoplasmic granules. Unfortunately, the animal developed respiratory distress after the thoracic radiograph, and due to the poor prognosis, humane euthanasia was elected. Necropsy findings supported the diagnosis of disseminated osteosarcoma, with a primary right scapular mass and metastases to the mediastinum, peritoneum, lung, skeletal muscle, kidney, lymph nodes, liver, and heart.
Faccin
1
94
Southcentral Division
2021
15
TURTLE
Adult female red-eared slider turtle
This turtle was brought to the Texas A&M Zoological service for removal of a fishhook in the cervical esophagus. When endoscopically examined, the turtle was discovered to have perforations in the esophagus and suspected in the stomach; plans were made for plastronotomy the following day. The turtle was found dead the following morning.
The esophagus was punctured by a 4 cm long fishhook with exit points 10 cm and 7.5 cm distal to the oral cavity, with associated fibrin and mucosal hemorrhage and necrosis. In addition, approximately ten 1.8 to 2 cm long, thin, white parasites with curled tails were spread throughout the proximal small intestinal mucosa. At the sites of infestation, the small intestinal mucosa was mottled yellow to bright red (enteritis).
H&E
Moderate, multifocal, chronic, ulcerative enteritis with epithelial hyperplasia and intraluminal acanthocephalans, jejunum
The cause of death in this case was likely associated with the trauma and inflammation secondary to esophageal perforation. The intestinal parasites were incidental but provide a good opportunity to review turtle parasites, particularly as the red-eared slider is a popular pet species and is also one of the IUCN’s 100 worst invasive species.
Hines
1
95
Southcentral Division
2021
16
AVIAN
Lavender Orpington pullet
Backyard flock. Owner found the bird dead and brought it to the lab that morning.
The hen was emaciated (BCS 1/9). The base of feather shafts on the neck and inguinal regions were thickly coated with lice eggs. Hundreds of living northern fowl mites were present in the feathers. The crop contained a brownish slurry with a sour odor. The pericardial sac and cranial airsacs were thickened and opaque. Multifocal, < 2 mm, slightly raised, irregular, white lesions were visible on the heart. There were variably sized (generally < 4 mm), multifocal to coalescing, white to tan, firm lesions in both lungs. The dorsal aspect of the right lung was occupied by a single firm white mass, and both sets of lungs were adhered to the body wall. The lung masses were encapsulated and comprised of concentrically layered caseous material. There was a 3 x 3 cm, solid, multilobulated to botryoidal, white to tan, slightly hemorrhagic mass adhered to the body wall, cranioventral aspect of the left lung lobe, and regionally adjacent airsacs. Smaller, similar, isolated masses were distributed on the cranial aspect of the liver capsule and were particularly numerous on the serosa of the proventriculus. The intestines were empty of digesta but contained numerous adult ascarids. The cecae were distended with firm orange cores. The ovary was immature. Ureters were distended with yellow chalky material and there were two small (< 2 mm) white masses in the right kidney.
H&E
Multifocal granulomatous disease involving airsacs, lungs, heart, and serosa
Apperson
1
96
Southcentral Division
2021
17
NHP - BABOON
26-year-old female baboon
Euthanized following decline condition due to severe bilateral stifle osteoarthritis with synovial osteochondromatosis, moderate dental tartar, and kyphosis with compression of vertebral bodies with bridging (spondylosis deformans).
The liver had a large 12x4x4 cm multilobulated mass with cavernous spaces filled with thick yellow material. Multiple yellow firm smaller masses (ranging from 2mm – 2cm) filled with yellow soft material were found along the edges.
H&E
Hepatitis, necrotizing, pyogranulomatous, lymphoplasmacytic, chronic, severe with myriad amoebic trophozoites
The family Entamoebidae is composed of diverse protists primarily found in gastrointestinal tract of humans, nonhuman primates (NHPs) and other animals. E. histolytica species complex (E. histolytica, E. dispar and E. moshkovskii) have similar morphology but have different virulence capabilities. E. dispar is primarily an enteric pathogen and E. moshkovskii is a free-living organism. E. histolytica is reported to cause typhlocolitis and extra-intestinal abscessation in humans and NHPs. Few cases of E. nuttalli has been reported in Japanese macaques and wild rhesus macaques of Nepal. The cysts or trophozoites of all species of Entamoeba are indistinguishable on histologic examination. Typical gross lesions include necrohemorrhagic and ulcerative colitis with lumen filled with blood or fibrinonecrotic debris. Abscessation may occur in liver, lungs, kidney and brain. Histologic findings in colon include necrosis of mucosa that may extend to the muscularis mucosa and flask-shaped ulcers in colon. Trophozoites of E. histolytica are spherical (10-50 um in diameter) surrounded by a thin clear halo; have a nucleus with a central dense karyosome and chromatin plaques at the periphery; light staining, granular cytoplasm with remnants of erythrocytes and glycogen (PAS positive). Differentials for colitis in NHPs include: Shigella flexneri, Shigella sonnei, Salmonella enteritidis, S. typhimurium, Campylobacter jejuni, Campylobacter coli, Yersinia enterocolitica, Yersinia pseudotuberculosis. Differentials for necrotizing and suppurative hepatitis in NHPs include: Bacterial: Francisella tularensis, Clostridium piliforme and alphaherpesviruses, tuberculosis, coccidiodomycosis, Histoplasma capsulatum var. capsulatum, Yersinia pseudotuberculosis and Streptococcus zooepidemicus. Viral: Hepatitis viruses, Yellow fever virus, Herpes B virus, Ebola and Marburg viruses.
Shivanna
1
97
Southcentral Division
2021
18
CANINE
8-year-old male American Bulldog/pitbull mix
Submitted as a legal case for “caught in the crossfire of a gunfight” with no medical history.
There were more than eighty long, slender, white nematodes consistent with Dirofilaria immitis in the right ventricle extending into and expanding the pulmonary artery, and at least five worms in the caudal vena cava. The lungs were diffusely firm and rubbery and failed to collapse, and off-white to pale beige with a brown-orange tinge and multiple hemorrhagic foci throughout all lobes. There was an 8 x 13 x 8mm nodule in the cranial aspect of the right cranial lung lobe and a second nodule measuring 2 cm in diameter in the middle of the right caudal lung lobe – on cut surface, both were purple-brown and spreadable (necrosis). There were a minimum of thirty heartworms measuring up to 29cm in length in the main artery of the right caudal lung lobe, and some extended into the area of necrosis. A minimum of five heartworms were also present in the right caudal mainstem bronchus. On cut surface of the right cranial lung lobe, two large vessels were enlarged and thrombosed, with heartworms incorporated in the thrombi. The left caudal lobe was similar to the right side, including a thrombus and the presence of heartworms; heartworm burdens were heavier in the caudal lung lobes. There were approximately ten heartworms in the accessory lung lobe.
H&E
Marked proliferative and lymphohistiocytic endarteritis, thrombosis, and mural necrosis of the pulmonary artery with intralesional nematodes consistent with Dirofilaria immitis
Due to coincidental environmental happenings, this dog was presented as a legal case. However, gross necropsy revealed a lack of penetrating wounds. Rather, there was severe dirofilariasis and pulmonary disease, with thrombosis and necrosis of the multiple large pulmonary arteries, large amounts of blood in the bronchi along with several heartworms, and a very large volume of clotted blood in the stomach. Cause of death was determined to be a combination of exsanguination, and drowning from the blood in the airways.
Vyhnal
1
98
Southcentral Division
2021
19
EQUINE
2Y, F, quarter horse, equine
This mare presented with unilateral maxillary swelling. On exam, feed packing was noted in the deciduous premolar #606. Further evaluation of the swelling via diagnostic imaging revealed an impacted and abnormally oriented maturing second premolar #206 associated with a multilocular cystic structure.
The maxillary width is expanded twice normal by an impacted and malformed tooth #206 and an associated multilocular cystic structure (not identifiable on submitted slide). Tooth #206 is approximately half the normal length, crescentic, angled approximately 45 degrees off the eruption axis, and oriented apical-palatine to occlusal-buccal with the developing pulp horns forming nonparallel structures that wrap back apical-buccal. The multilocular cystic structure around tooth #206 measures up to 3x3x1cm, unilaterally expands the maxilla, and has an empty lumen with a smooth tan surface. Tooth #606, while in the process of physiologic exfoliation, also has a loss of the infundibulum with replacement by brown-green foreign material (feed packing).
H&E
Odontodysplasia, multifocal to coalescing, severe, with marked focally extensive hypercementosis, moderate multifocal to coalescing necrotizing and histiocytic pulpitis, periodontitis, and osteomyelitis with several cocci
Odontodysplasia is rarely reported and is characterized by the disruption of normal dentinogenesis and results in abnormally shaped and often impacted teeth. There are two types of odontodysplasia - focal and regional. While focal odontodysplasia has been described in veterinary species, regional odontodysplasia refers to a human-specific entity of unknown cause where the teeth in an entire quadrant of the mouth are malformed; regional odontodysplasia has not been adequately described in any veterinary species. Focal odontodysplasia is typically trauma-induced, which alters the orientation of the enamel organ resulting in an abnormally shaped, frequently impacted or un-erupted tooth that is characterized by a dysplastic proliferation of the odontogenic germinal tissues and dental matrices (dentin, enamel, and cementum). Other causes of disruption to the enamel organ (such as infection, irritation, or other cause of inflammation) may result in a similar dysplastic proliferation.
Schwarten
1
99
Southcentral Division
2021
1
AVIAN
Adult female house sparrow
This sparrow was part of a small, wild-caught research colony. It and another male sparrow in a separate cage were found dead within 12 hours of one another with no previous clinical signs reported.
Multifocally throughout the serosal surface of the jejunum were small aggregates of fibrin and the jejunal and colonic walls were expanded by a moderate amount of edema, consistent with a fibrinous coelomitis and potentially an enteritis. A section of liver is on the submitted slide.
H&E
Moderate, multifocal to coalescing, subacute, lymphoplasmacytic and histiocytic, periportal to random necrotizing hepatitis with intracellular protozoal merozoites, macrogamonts, and microgamonts
In addition to the hepatic changes, a severe protozoal enterocolitis, splenitis, and pneumonia were appreciated, and coccidial organisms were appreciated in all tissues except the spleen. The morphology and distribution were most consistent with Atoxoplasma spp. Real-time PCR (rtPCR) was performed on the liver for Toxoplasma spp. and Chlamydia psittaci. Both were negative, while rtPCR for Atoxoplasma spp. on the liver was positive. The other affected sparrow displayed similar lesions and had identical rtPCR results. Atoxoplasma spp. are considered a junior objective synonym of Isospora, however more recent investigation has suggested it is more closely related to Eimeria spp. The syndrome of atoxoplasmosis is currently most accurately described as systemic isosporosis. Infection is considered endemic in wild birds, being found in all continents except Antarctica, and can cause acute fatal disease when birds are stressed, immunosuppressed, or have other concurrent infections, particularly in captive passerines. These parasites have a direct life cycle and are transmitted by ingestion of infective oocysts, though there is some evidence for transmission via a mite in house sparrows. The parasite undergoes asexual reproduction in the intestine and reticuloendothelial system, resulting in systemic spread, primarily to the liver, though other organs may be involved. Sexual reproduction occurs primarily in the intestinal tract, though sexual stages have been demonstrated occasionally in some species, including house sparrows. Clinical signs are nonspecific and include inappetence, weight loss, diarrhea, lethargy, and ruffled feathers. Antemortem diagnosis can be difficult because strictly enteric Isospora oocysts are indistinguishable from those which cause systemic isosporosis. Serial blood smears are required to detect the parasite within mononuclear inflammatory cells. Despite the difficulties of taxonomic classification, systemic isosporosis represents an important disease of captive passerines with the potential to cause major morbidity and mortality events in captive passerines.
Bacon
1
100
Southcentral Division
2021
2
CAPRINE
7-year-old, male castrated, domestic goat
This pet goat was apparently healthy two days prior to presentation. He became reluctant to stand and was lethargic, at which point he was taken to a local veterinary clinic. The owners believed their goat was poisoned since someone left a package of lamb chops on their porch the previous day to taunt them. Upon physical exam, the goat was non-ambulatory and slightly obtunded. CBC and chemistry revealed increased BUN and creatinine, as well as increased creatine kinase, LDH, and a slight neutrophilia. Clinical signs worsened during the hospital stay, and the patient passed away.
Transparent, yellow fluid was found in the abdomen, thorax, and pericardial sac. Systemic icterus was apparent. Multiple organs showed pallor, primarily the kidneys, heart, and brain. The liver was swollen with an enhanced reticular pattern. The rumen contained plastic bags and large roots. Lice were seen on the skin, and whipworms were found in the cecum.
H&E
Severe, multifocal, acute tubular necrosis and degeneration with abundant intratubular oxalate crystals and occasional intra-tubular granular pigment (oxalate nephrosis and pigmentary nephrosis)
Histologic changes and toxicologic testing in this case led to a diagnosis of ethylene glycol toxicosis. Ethylene glycol toxicosis is not common in ruminants, as compared with dogs and cats, although there are a few reports. The large amount of calcium oxalate crystals in this case, particularly in the brain, was a unique finding. Calcium oxalate crystals typically form following ethylene glycol ingestion. Insoluble calcium oxalate forms following gastrointestinal absorption of ethylene glycol, where it precipitates or crystalizes in vessel lumens, particularly in the kidney, and rarely in the brain. Histologically, large deposits of oxalate crystals can be seen in renal tubular lumens, tubular epithelial cells, and the interstitium of the kidney. Under polarized light, these crystal deposits characteristically appear birefringent, shaped like prisms, and arranged in sheaves.
JACOBSON
1
101
Southcentral Division
2021
3
BOVINE
6-month-old Wagyu bull calf
The calf was treated for sepsis 5 months prior to presentation. The calf was lethargic and weak for several days. On presentation, the calf was stuporous and dehydrated with injected sclera and hyperemic mucous membranes. Fecal staining was prominent on the tail and perineum, and the body condition was poor. Neurologic signs included horizontal nystagmus, decreased pupillary light reflex, and seizures. During treatment, the animal became comatose and arrested. The calf was revived with CPR, but soon became agonal and died.
Diffusely, the lungs were mildly firm and uncollapsed, while the cranioventral right lung lobe was dark red to purple. The tracheobronchial, lumbar, iliac, and mesenteric lymph nodes were mildly enlarged. The pyloric wall was mildly thickened. Multifocally, segments of the jejunum were dark purple, dilated, and thinned. The meninges were moderately congested.
H&E
Moderate, multifocal, chronic, lymphoplasmacytic and histiocytic ganglionitis with neuronal loss and intracytoplasmic viral inclusion bodies, omasum
The diagnosis of rabies was made with fluorescent antibody testing at the Texas Department of Health and immunohistochemistry. No bite wounds or trauma to the skin was noted, and the origin of the infection remains unclear. The lesions in the brain were typical for rabies, and viral inclusion bodies were numerous. Inclusions were also apparent in the adrenal gland and salivary gland. The changes in the lungs were attributed to bronchopneumonia.
Landsgaard
1
102
Southcentral Division
2021
4
EQUINE
9-yr-old Quarter Horse gelding
The horse presented with a mandibular mass that rapidly and progressively grew over the course of six weeks. On external examination, a large firm swelling was noted beneath the tongue. Radiographs revealed a large, invasive, and lytic mass that encompassed the rostral mandible to the level of both mandibular canines. A rostral mandibulectomy was performed, and the rostral mandible was submitted.
A 12x11x10 cm rostral mandible including canine teeth with an approximately 8x7x5 cm, firm to hard, round, symmetrical, tan to red mass was submitted. The mass encompassed the mandible and protruded ventrally. On cut surface, the mass was tan to yellow, firm to hard, heavily cavitated, and effaced surrounding alveolar bone.
H&E
Ameloblastoma
The location and gross appearance of this mass were highly suggestive of an odontogenic neoplasm. Other differentials included an odontogenic cyst, osteoma, ossifying fibroma, osteosarcoma, fibrosarcoma, and squamous cell carcinoma. Odontogenic neoplasms in horses are uncommon, and there is no known breed or sex predilection. Masses often present as slow growing and nonpainful swellings within the maxilla or mandible. Odontogenic neoplasms are classified by tissue of origin, and the types identified in horses include ameloblastoma, ameloblastic odontoma, ameloblastic carcinoma, odontoma, and complex odontoma. Ameloblastoma is classified based on odontogenic epithelium with absence of pulp ectomesenchyme and mineralized dental matrix. Histologically, odontogenic epithelium is classified by stellate reticulum and palisading of basilar epithelium with antibasilar nuclei and a basilar clear zone. Neoplastic cells are often arranged in plexiform ribbons, islands, anastomosing trabeculae, and “ink drop” structures. Ameloblastomas in horses are more common in the mandible than the maxilla.Odontogenic neoplasms tend to be benign, locally invasive, expansile, and cause alveolar and cortical bone lysis with displacement of teeth. The exception is the ameloblastic carcinoma, which has been shown to have a higher degree of malignancy and greater rate of metastasis. Treatment for odontogenic neoplasms include complete surgical excision, and prognosis is generally good. Local recurrence with incomplete margins has been reported.
Lui
1
103
Southcentral Division
2021
5
CANINE
Adult, male intact, mixed breed dog
The patient presented for evaluation of hyporexia and weight loss of approximately one month duration and progressive abdominal distension and labored breathing of approximately two weeks duration. Point of care abdominal and thoracic ultrasounds revealed tricavitary effusion. Cytologic examination of the peritoneal and pleural fluid were consistent with a modified transudate and transudate, respectively. A 4Dx Plus SNAP test was negative. The patient failed to respond to supportive care and continued to decline, thus the owners elected humane euthanasia.
The peritoneal cavity, pleural cavity, and pericardial sac contained marked, moderate, and mild amounts of serosanguineous to straw-yellow, clear fluid, respectively (tricavitary effusion). Multifocally, the parietal pleura lining the diaphragm and intercostal muscles, visceral pulmonary pleura, pericardial sac, and epicardium were moderately to markedly thickened, white, opaque, and firm (fibrosis). The right cranial and right middle lung lobes were adhered to the body wall by a marked amount of fibrosis. The apex of the left ventricle was adhered to the pericardial sac by a 1 cm diameter band of fibrosis. Multifocally, mesothelial hyperplasia covered the caudal lung lobes, epicardium of the right auricle, and mediastinum. There was mild endocardiosis of the mitral valve. The liver was diffusely and moderately enlarged with rounded margins (hepatomegaly) and a heterogeneously pale tan to dark red parenchyma on cut section (chronic passive congestion).
H&E
Moderate, multifocal, chronic, neutrophilic, histiocytic, and plasmacytic epicarditis with marked multifocal epicardial fibrosis and mesothelial hyperplasia, with onion skin cysts consistent with Hepatooon americanum
Canine hepatozoonosis is a tick-borne disease in the southeastern and south-central United States caused by Hepatozoon canis or Hepatozoon americanum, although infection with H. americanum is diagnosed more frequently. The vector and definitive host of H. canis and H. americanum are the brown dog tick, Rhipicephalus sanguineus, and the Gulf Coast tick, Amblyomma maculatum, respectively. Dogs are infected by ingestion of an infected tick containing mature oocysts. Sporozoites are released from oocysts in the dog’s small intestine after exposure to bile, penetrate the intestinal wall, and disseminate to target tissues by mononuclear cells where the organisms undergo merogony. The primary target tissues for H. americanum are cardiac and skeletal muscle, whereas H. canis prefers hematopoietic tissue including bone marrow, spleen, and lymph nodes. Within primary target tissues, H. americanum develops in its host cell within “onion skin cysts” eventually forming a meront that ruptures releasing numerous merozoites. Unlike H. americanum, H. canis does not form “onion skin cysts”, and instead forms distinctive “wheel-spoke” meronts containing numerous micromerozoites. In dogs infected with H. americanum, release of merozoites in the heart and skeletal muscle results in pyogranulomatous inflammation and vasculitis. In this case, the protozoal “onion skin cysts” in the cardiac and skeletal muscle are consistent with H. americanum. Although myocarditis is not evident in the examined sections, areas of cardiomyocyte loss with replacement by fibrosis and mineralization are observed, which may be secondary to historic inflammation caused by H. americanum. The findings in the pericardium and epicardium are suggestive of chronic constrictive pericarditis and epicarditis. Constrictive pericarditis is rare in dogs and cats, and causes identified include metallic foreign bodies, coccidioidomycosis, and actinomycosis. Severe cardiac dysfunction and impaired diastolic filling eventually result in congestive heart failure and death if not treated. Even though H. americanum is not identified in the pericardium and epicardium, the presence of neutrophilic and histiocytic inflammation in the epicardium, lymphoplasmacytic inflammation in the pericardium, and lack of other findings suggest H. americanum may be the cause of the chronic inflammation and fibrosis observed, leading to constrictive pericarditis and biventricular heart failure in this dog.
Milliron
1
104
Southcentral Division
2021
6
RING-TAILED LEMUR
2.4 kg, adult, neutered male ring-tailed lemur
The lemur was lethargic, inappetent, depressed, and developed a cough an hour before death. Two other lemurs in the colony exhibited similar signs and also died.
The liver was diffusely pale tan. The lungs were diffusely dark red and mildly heavy and wet (congestion and edema). Foamy fluid was within the trachea. A lymph node at the root of the mesentery was mildly enlarged, measuring 2x1.5x1 cm. The kidneys were diffusely dark purple. The abdominal cavity adipose tissue was mildly yellow.
H&E
Multifocal, mild, acute necrotizing hepatitis with intrahistiocytic and free protozoa
Toxoplasmosis is a worldwide disease cause by an apicomplexan intracellular coccidia, Toxoplasma gondii. Felids are the definitive hosts, whereas a variety of warm-blooded animals including humans, bear, deer, pigs, moose, bison, marine mammals, marsupials, birds, and small mammals serve as intermediate hosts. The presentations and mortality of this disease vary greatly depending on the immune response and susceptibility of the species affected. Marsupials (particularly macropods), New World monkeys, and lemurs are highly susceptible to fatal acute disseminated toxoplasmosis. They typically develop enteritis, necrotizing mesenteric lymphadenitis, hepatitis, interstitial pneumonia, and/ or pulmonary edema.
Neupane
1
105
Southcentral Division
2021
7
CANINE
5-year-old MN German Shepherd
The dog had a history of non-pruritic alopecia along the left pelvic limb and around the prepuce, pronounced mammary glands with hyperpigmentation around the nipples, a persistently decreased lipase, and suspected exocrine pancreatic insufficiency (EPI). He was treated with Apoquel and cephalexin by the referring veterinarian with no improvement. The dog was cryptorchid as a puppy. When he was neutered, his cryptorchid testicle was unable to be retrieved. He reportedly had two abdominal surgeries to locate the cryptorchid testicle, but the owner was unsure if it was ever retrieved.
A 6.5x6x5 cm, firm, round, smooth testicle and epididymis with twisted spermatic cord and pampiniform plexus was submitted in formalin. The testicular parenchyma was completely expanded by an encapsulated, pale tan to red, soft, cystic mass. The pampiniform plexus was expanded (edema).
H&E
Sertoli cell tumor with vascular invasion and seminoma
Testicular neoplasms are the second most common tumor in the canine, affecting mainly middle age to older dogs. The 3 most common testicular tumors are interstitial cell tumors (Leydig cell tumors) (58%), seminomas (23%), and Sertoli cell tumors (19%). They can be solitary or multiple, as in this case. These tumors are almost always benign. However, if metastasis does occur, nodules in the spermatic cord, scrotal lymph nodes, and abdominal organs may be evident. Cryptorchid testicles have a higher incidence of Sertoli cell tumors and seminomas. The right testicle seems to be predisposed to retention, which increases the risk of tumorigenesis. Castration remains the treatment of choice for these tumors and is often curative.
Zakers
1
106
Southcentral Division
2021
8
FELINE
10-year-old, female spayed Domestic Shorthair cat
The cat acutely vocalized, vomited, and began dragging his hind legs. The owner reported that the cat was making a “gurgling” noise in the car. The cat presented for euthanasia laterally recumbent with a gallop rhythm on auscultation. The cat went into respiratory arrest and was euthanized.
The heart was diffusely and moderately enlarged. The left ventricular free wall myocardium was thickened, and the left ventricular lumen was narrowed. Three thrombi were identified within the lumen of the abdominal aorta. The cranial most thrombus measured 3x0.5x0.4 cm and was directly caudal to the diaphragm. The next was 4.5 cm caudal to the first thrombus, measured 5x3x3 mm, and extended 1 mm into the left renal artery. The most distal thrombus measured 7x4x3 mm and was 4 cm caudal to the second thrombus, adjacent to the iliac arteries.
H&E
Multifocal to coalescing, severe, chronic, lymphohistiocytic and neutrophilic pancarditis with cardiomyocyte degeneration, necrosis, and loss, and moderate interstitial and endocardial fibrosis
The patient’s clinical history is consistent with the multiple emboli in the abdominal aorta, presumably secondary to blood flow turbulence. Clinical suspicion of underlying cardiac disease was confirmed with the identification of a myocarditis. Investigation for Bartonella sp. was confirmed via PCR on formalin-fixed paraffin-embedded tissue.
Barton
1
107
Southcentral Division
2021
9
CANINE
5-year-old neutered male Pit Bull Terrier
The dog presented to the referring veterinarian for acute hindlimb paraplegia bilaterally and urinary and fecal incontinence. He demonstrated pain on palpation of the thoracolumbar spine.
Multifocally throughout the cervical and lumbar spinal cord were small areas of dark red material (hemorrhage) that dissected along white matter tracts.
H&E
Severe, multifocal to coalescing, subacute, necrotizing and lymphohistiocytic meningomyelitis with lymphoplasmacytic perivascular cuffing, edema, and intraneuronal and intrahistiocytic amastigotes
Trypanosomiasis, a disease caused by numerous species of the protozoal parasite Trypanosoma, affects a wide range of mammals and can manifest in different clinical forms due to its high genetic diversity. The parasite is endemic in several Latin and South American countries, as well as Asia, Africa, the Canary Islands, and parts of the southern United States. Trypanosoma cruzi is the etiologic agent associated with Chagas disease or American trypanosomiasis, which affects an estimated 7-8 million people annually across 21 countries. The natural life cycle of the protozoan requires an arthropod vector in the family Reduviidae (Rhodnius spp., Panstrongylus spp., and Triatoma spp.), also known as kissing bugs. While feeding on a mammalian host, kissing bugs transmit infectious metacyclic trypomastigotes via defecation in or around cutaneous wounds or mucous membranes, allowing access to the host bloodstream. Once in systemic circulation, trypomastigotes can infect various host cells and form amastigotes in tissues or infect other arthropods that feed on host blood. Other routes of infection include iatrogenic transmission via contaminated needles or consumption of infected meat. Reported mammalian hosts include humans and a wide range of domestic and wildlife species including dogs, coyotes, cats, raccoons, opossums, armadillos, wood rats, skunks, capybaras, coatis, small marsupials, horses, buffaloes, camelids, cattle, and other livestock. Due to the close interaction between peridomestic dogs and humans, infected canids may serve as sentinels for surveillance of human infections since dogs are considered an important reservoir host.
Broughton
1
108
Southcentral Division
2021
20
AVIAN
Adult (unknown age) sun conure
Patient presented for difficulty breathing, anorexia, and dyschezia. Physical exam revealed a distended coelom, thin body condition, pectoral muscle atrophy, muffled heart sounds on auscultation, and dyspnea. Whole body radiographs revealed right, cranial displacement of the ventriculus, decreased serosal detail, gas within the intestines, and decreased air sac space to the paired abdominal and caudal thoracic air sacs.
The intestines were pale, thickened, severely distended, and surrounded by caseous material. Abdominal organs were adhered.
H&E
B cell lymphoma, proventriculus, ventriculus, small intestines, coelom, serosal surfaces
Lymphoma is the most common round cell neoplasm of psittacines, and is likely the most common neoplasm in this group of animals (Nemeth et al., 2016). A recent review of lymphoma in psittacines found that B cell lymphoma is the most common immunophenotype. B cell lymphomas were statistically more common in the gastrointestinal tract, similar to the case presented here (Gibson et al., 2021). This is likely due to the putative tissue of origin, gut-associated lymphoid tissue. Grading schemes for lymphoma are not available in psittacines, and mitotic counts or other factors have yet to be correlated with prognosis. Most cases present at necropsy, and it is likely that this diagnosis carries at least a poor prognosis. In this animal, lymphoma was associated with foreign body coelomitis, likely secondary to transmural infiltration of the intestines by neoplastic cells, resulting in intestinal rupture.
Gray
1
181
Southcentral Division
2021
10
AVIAN
10-month-old Rose-breasted Cockatoo
The bird presented for seizure-like activity and a 4/5 heart murmur. A CT scan revealed poor bone density, increased fat stores, and an enlarged liver indicating potential nutritional deficiencies, increased caloric intake, and a lack of exercise.
Throughout the myocardium of the right, and less severely the left, ventricles were several multifocal to coalescing, pinpoint to 5 mm diameter, firm, white, slightly raised foci. The crop was moderately dilated and contained a large amount of thick, white to tan feed material. The proventriculus was mildly dilated and flaccid.
H&E
Multisystemic lymphoplasmacytic ganglioneuritis with severe pancarditis
PCR and immunohistochemistry of the heart were both positive for avian bornavirus (ABV), the known etiologic agent for proventricular dilatation disease (PDD). In addition to the lesions described above, other findings included lymphoplasmacytic ganglioneuritis in the jejunum and colon, lymphoplasmacytic perivascular encephalitis and choroid plexitis in the cerebrum, and lymphoplasmacytic inflammation in the thymus and pancreas.
