Horses Flashcards
What is the primary disease affecting this horse?
A. Pneumocystis jiroveci
B. Autosomal recessive DNA-PK mutation
C. Equine adenovirus
D. Rhodococcus equi
B severe combined immunodeficiency is caused by autosomal recessive DNA-PK mutation in arabian foals. The lungs have multifocal severe disseminated pyogranulomatous pneumonia due to Rhodococcus equi and Pneumocystis jiroveci (formerly carinii) these mixed agents are common causes of death in SCID. The bloodwork confirmed severe lymphopenia (basically no lymphocytes) and profound leukopenia.
Equine adenovirus does not typically cause disease in healthy horses, is common in SCID foals! It causes bronchointerstitial pneumonia, with necrotizing bronchiolitis, epithelial intranuclear large amphophilic to basophilic inclusions
From Color Atlas of Equine Pathology, Foals and Juveniles
Foal. What is the disease name?
Epitheliogenesis imperfecta. The skin was there, but defect is in Laminin 5. Parturition causes loss of epidermis from underlying dermia. Laminin are in the hemidesmosomes which anchor epithelium to BM. Also found in the tongue.
Foal. Morph. Etiology.
Mutlifocal pyogranulomtous pneumonia. Rhodococcus equi.
If adult, consider strangles.
Tissue from a horse. Cause.
Strongylus vulgaris migration forming granulomas in the heart.
Tissue from a horse. Morph.Cause.
Hepatic hydatid cyst, focal, chronic. Have thick capsule and hydatid sand on histo (scolices). Echinococcus granulosa.
Histological lesion of Eastern equine encephalitis are in the ____________ and are ____ caudally in the brain?
A. White and gray matter; worse
B. Gray matter; less severe
C. White matter; less severe
D. Gray matter; worse
B. Gray matter; less severe
Eastern equine encephalitis (alphavirus) lesions are confined to the gray matter and are LESS severe caudally, so mostly affect the cerebral cortex (zoonotic like WNV)
This contrasts with West Nile Virus which is polioencephalomyelitis, in the gray matter, but is WORSE in the lower brainstem and spinal cord
Two clin path abnormalities.
Hyperglycemia; hyperinsulinemia; hypercortisolemia.
Name the condition and the cause.
Lethal white foal syndrome. Defect is in the endothelin B receptor which causes colonic hypoplasia with aganglionosis.
What Salmonella sp. do horses get?
Salmonella enterica subsp. Typhimurium
Tissue from a horse. Morph and cause.
Aural papillomas. Caused by Equine papillomavirus 3,4,5 and 6. Don’t regress like those on the lips.
Tissue from a horse. Morph and 3 causes.
Subendocardial mineralization. Vitamin D analog plants. Cestrum diurnum, Solanum malacoxylon, Trisetum flavescens. Also consider alfalfa. Consider lymphoma and granulomatous diseases. In cattle, consider Johne’s.
Tissue from a young horse. Morph?
Osteochondrosis. Pressure on articular cartilage leads to ischemia on epiphyseal side of vasculature from excessive growth of animal.
Mutation in endothelin receptor B in a horse results in what syndrome?What is the gross lesion?
Lethal white syndrome, common in Appaloosas carrying the roan allele. They get segmental colonic hypoplasia with aganglionosis and end up dying from colitis. Glial derived neurotrophic factor and endothelin receptor B are required for normal migration and maturation.
Tissue from a horse. Histo is a chronic and active eosinophilic dermatitis. Etiology?
Pythium spp. , oomycete. More granulomatous in canine cases. Get peripheral eosinophilia.
This schistosome trematode causes granulomatous hepatitis in horses.
Heterobilharzia americana. Also causes hypercalcemia. In dogs, look for enteric disease.
Colon from a horse. Etiology?
Small red elevated dots = small strongyle infection. Cyathostoma spp.
Tissue from a horse. Morph and etiology?
Granulomatous nephritis. Halicephalobus gingivalis. Rhabditiform nematode. Also causes eosinophilic meningoencephalitis.
Etiology? Location?
Anoplocephala perfoliata; ileocecal junction;usually no pathology.
Tissue from a foal. Etiology and histo features?
Actinobacillus equuli. Suppurative glomerulitis. Abscesses are where the glomeruli are.
Tissue from a horse. Cause?
Red maple leaf ingestion (gallotannins are the toxin) –> hemolytic anemia, methemoglobinemia and Heinz body anemia –> shock –> ischemic necrosis of renal tubular epithelium –> methemoglobin casts + acute renal tubular ischemic necrosis
Tissue from a horse. Morph and breed? Other species and breeds affected? Histo features?
Cerebellar abiotrophy (not atrophy, normal at birth, then fails to develop completely). Arabians!! Coton de Tulear, Finnish Hounds, Chinese crested Histo: loss of Purkinje cells often leaving empty baskets and a fenestrated ground layer, +/- replacement by proliferation of Bergmann astrocytes
Tissue from an adult horse. Etiology?
Cantharadin toxicosis (blister beetles); Urinary tract, esophagus, cardiac lesions.
Etiology?
EcPV-2 causes genital SCC.
A specific histological diagnostic feature of Strongylus vulgaris (the parasite that causes verminous arteritis in horses) is?
A. prominent lateral chords
B. Paired uteri
C. Calcareous corpuscles
D. Microfilaria in the uterus
A. prominent lateral chords - they are vacuolated on cross section
migrating larvae in cranial mesentery artery have thick cuticle, platymyarian musculature, body cavity/pseudocoelom, tall multinucleate intestinal cells with very prominent brush border (since they are larvae they will not have fully developed paired uteri anyhow).
Physaloptera has the BIGGEST lateral chords - big nematode, cat stomach/duodenum
calcareous corpuscles are only in cestodes - in horses Anoplocephala perfoliata and magnum is in the cecum
microfilaria in the uterus - filarids only Dirofilaria immitus (heartworm dog), Onchocerca lupi (eye conjunctiva coyote, dog), Dipetalonema
Paired uteri are seen in strongyles, filarids, oxyurids(pinworms), ascarids, spirurids, and metastrongyles so NOT specific really at all!!
Name the rhabditata nematode that can cause meningoencephalitis, nephritis, orchitis, osteomyelitis (rare), preputial cellulitis in horses?
A. Crassicauda magna
B. Crassicauda boopis
C. Trichosomoides crassicauda
D. Halicephalobus gingivalis
E. Dioctophyema renale
D. Halicephalobus gingivalis - also causes gingivitis in horses (and can migrate through the tongue and accidentally hematogenous disseminate in the horse
Crassicauda boopis and magna are in whales (C. magna in Cuvier’s beaked whales with verminous arteritis of renal veins, mesenteric arteries, aorta Vet Path 2016)
Trichosomoides crassicauda is the aphasmid bladder threadworm of rats - causes calculi > papilloma > urothelial carcinoma
Dioctophyema renale - giant kidney worm that shows up in right kidney of dogs (hydronephrosis) and peritoneum - feet long and BRIGHT RED (Robbie O’Connor had one in a flask)
Colon from a horse. Differentials?
Salmonella. Neorickettsia risticii (Potomac horse fever).
Serum hepatitis (dishrag liver) in horses is associated with what kind of virus?
equine parvovirus
A clinical indicator of PPID in horses is:
alpha - MSH
What type of metazoan parasite migrates through the muscle of horses?
Stongylus equinus.
In laminitis, what portion of P3 has inflammation?
the medulla (not seen in the dorsal or solar cortex of P3)
Infectious necrotic hepatitis in horses can be caused by what species of Clostridia?
C. novyi; liver looks cooked.
Solanum spp. is a plant that would cause what kind of lesion in a horse?
aortic mineralization; vitamin D analog
Equine cutaneous lymphoma is almost always what type?
T cell rich B cell lymphoma (also the most common in rabbits). They don’t metastasize. Progesterone-responsive, so they regress with pregnancy and then return after delivery
In rabid horses, lesions are more commonly seen in what structure?
gray matter of the spinal cord. (WNV also likes the gray matter in the spinal cord, as does post-anesthetic myelopathy). Remember, EHV-1 likes the white matter.
Equine asthma is similar to human asthma histologically in that there is extensive remodeling of what structures?
terminal bronchioles
Heterobilharzia american causes what liver lesion in horses?
granulomatous portal hepatitis with mineral. Diaphragmatic surface of the liver.
