2020-2021.Vol 36.iss1. clin path for equine practitioner Flashcards
Diseases of the equine urinary System
How is glomerular disease distinguished from injury to other areas of the urinary tract?
persistent proteinuria with or w/o azotemia
Diseases of the equine urinary System
list differentials for protienuria:
-lower urinary tract disease: cystitis
-physiologic d/t nonrenal inflamm diseases
-transient proteinuria after heavy exercise
Diseases of the equine urinary System
Diseases affecting the tubulointerstitium are clinically characterized by:
azotemia
dec urine concentration (isosthenuria)
inability to process electrolytes or maintain acid-base homeostasis
Diseases of the equine urinary System
list nephrotoxins that are causative etiologies for tubular necrosis in horses
-oak (Quercus spp) flowers, leaf buds or acrons with toxic gallotannins
-oxalate containing plants
-red maple leaves
antibiotics: amingolycosides,sulfonamides, oxytetracyclines, amphotericin B
-imidocarb diproprionate
-vitamin K3 (menadione sodium bisulfite)
-inorganic mercury & arsenic tox
Diseases of the equine urinary System
What are differentials for myconecrosis in horses?
infectious: clostridia spp & S. equi
nutritional: vit E/se def
toxic plants & drugs (ionophores)
genetic (PSSM)
exertional rhabdomyolysis
Diseases of the equine urinary System
However uncommon, leptospira interrogans serovar pomona nephritis is reliably diagnosed with what method?
Warthin Starry histochemical stain of tissues & seroology= reliable diagnostic tool
Diseases of the equine urinary System
Embolic nephritis in horses is caused by what organism?
Actinobacillus spp– in both adults & foals
Diseases of the equine urinary System
What is a sign of NSAID toxicity?
hypoproteinemia/hypoalbuminemia (GI LOSS)
azotemia
INC phosph
mild DEC Ca
Inability to concentrate urine
Diseases of the equine urinary System
What are predisposing factors to pyelonephritis?
urinary stasis
cystitis
urolithiasis
other urinary obstruction
Diseases of the equine urinary System
What congenital anomalies of the kidneys are seen in horses?
renal dysplasia
hypolasia
polycystic kidney disease
horsehoe kidney
Diseases of the equine urinary System
Primary renal neoplasia is rare in horses, what is the most common primary renal neoplasia in horses?
renal carcinoma
Diseases of the equine urinary System
What is the most common congenital lower urinary tract disease in horses?
ectopic ureters
**greater prevalence in females than males
Diseases of the equine urinary System
What is the most common urolith in horses?
calcium carbonate
Diseases of the equine urinary System
Uroliths in horses are most common in males vs females?
males
Diseases of the equine urinary System
What is the most common neopalsma of hte lower urinary tract?
squamous cell carcinoma
** reports of lymphosarcoma, transitional cell carcinoma, fibromatous polyps
Ocular pathology
What are common eyelid neoplasms in horses?
sarcoids & SCC
((others: pappiloma, melanocytoma/melanoma, lymphoma/LSA, neurofibroma, basal cell carcinoma, hemangiosarcoma fibroma/fibrosarcoma, mast cell tumor, angioma/angiosarcoma
Ocular pathology
Which breeds of horses are predisposed to developing melanocytic tumors of the eyelid?
gray or white-haired horses
Percherons
Arabians
Ocular pathology
Lists causes of conjunctivitis in horses (parasitic, fungal, bacterial , viral, etc).
Ocular pathology
What are the most common microbial isolates from conjunctival/corneal collections in healthy horses?
Gram pos: Bacillus, corynebacterium, staphylococcus, streptococcus, streptomyces
Gram neg: Acinetobacter, Enterobacter, Escherichia, Moraxella, Pseudomonas
Fungal: Aspergillus, Cladosporium
Ocular pathology
Why is keratitis caused by EHV-2 challenging to treat?
b/c recurrence is common (life-long infection)
-req antiviral therapy
-symptomatic tx of ulcers
Ocular pathology
EHV-2 keratitis definitive diagnosis
ID of the virus from an affected cornea via PCR or virus isolation
Ocular pathology
What is the most common cause of equine blindness?
equine recurrent uveitis (ERU)
**US prevalence of 25%
Ocular pathology
What are C/S of chronic stages of ERU?
hyperpigmentation
corpora nigra atrophy
posterior synechia
cataract
lens luxation
Ocular pathology
What ocular abnormalities are seen with equine motor neuron disease?
honeycomb pattern of yellow/brown pigment (ceroid/lipofuscin) within the tapetal fundus
Ocular pathology
What are nutritional causes of blindness in horses?
thiamine deficiency
equine leukoencephalomalacia
Skin Disease
What is diagnostic on biopsy for pemphigus foliaceus?
acantholytic cells within vesicles
intraepidermal clefs
**do not surgically prep the area
Skin Disease
Describe equine multisystemic eosinphilic epitheliotropic disease (MEED)
rare chronic progressive dz assoc with exfoliative dermatitis & infiltrations of eosinophils & lymphocytes in various organs
Neurologic diseases in horses
Hepatic encephalopathy
Gross lesions
Diagnosis
Gross lesions: diffuse hepatic necrosis or fibrosis
Dx: increase in serum hepatic enzymes, gross lesions in liver; microscopic: Alzheimer type II astrocytes in the brain
Neurologic diseases in horses
Leukoencephalomalacia
Gross lesions
Diagnosis
Gross lesions: edema & malacia of the white matter of the cerebrum
Diagnosis: **gross lesions in the brain
Neurologic diseases in horses
Nigropallidal encephalomalacia
Gross lesions
Diagnosis
Gross lesions: bilateral symmetric malacia focis in the globus pallidus and/or susbtantia nigra
Diagnosis: Gross lesions, evidence of ingestion of yellow tar thistle or russian knapweed
Neurologic diseases in horses
Rabies
Gross lesions
Diagnosis
Gross lesions: hemorrhagic malacia in the spinal cord
Diagnosis: floruescent ab testing of hte brain from accredited state laboratory
Neurologic diseases in horses
Equine protozoal myeloencephalitis
Diagnosis
Diagnosis: microscopic lesions: nonsuppurative to granulomatous myeloencephalitis with intralesional merezoites
Neurologic diseases in horses
What is the causative toxin of Nigropallidal encephalomalacia?
Centaurea solstitialis (yellow star thistle)
Rhaponticum repens (Russian knapweed)
Neurologic diseases in horses
Compare EDM to EMND
Neurologic diseases in horses
What clinical signs are seen with polyneuritis equi?
perineal anesthesia
urinary incontinence
urinary bladder atony with sabulous cystitis
fecal retention
tail paralysis
hind limb incoordination
+/- horners syndrome (peripheral & CN involvement)
Neurologic diseases in horses
What are clinical signs of equine grass sickness?
colic, dysphagia, ng flux with linear ulcers in the distal esophagus, gastric & SI fluid-filled dilation, colonic impaction, sweating, mm tremors death d/t gastric rupture
Chronic: bilateral ptosis with ventral deviaiton of eyelashes, rhinitis sicca, mucus- coated hard feces, weight loss, death d/t emaciation
Neurologic diseases in horses
How do you diagnose equine grass sickness antemortem?
C/S , clinical history
Exploratory celiotomy: full thickness ileal biopsy
Neurologic diseases in horses
tetanus toxins work at what sites within the CNS?
peirpheral motor end plates: SC/Brain
SNS synapses
**inhibits release of GABA causing spastic paralysis
Neurologic diseases in horses
what is the target of botulinum toxin?
blocks neurotransmitter acetycholine exocytosis vesicles in peripheral myoneural synapses causing bilat symmetric flaccid paralysis
Neurologic diseases in horses
What are the mechanisms that result in botulism intoxication?
- ingestion of preformed toxin from the environment (most common)
- elaboration of toxin from C botulinum infection in wounds
- ingestion of C botulium spores, which produce toxin w/in the GIT
Neurologic diseases in horses
On smear or culture of an infected wound, what is the characteristc appearance of tetanus?
gram positive tennis racket-shape bacteria
Toxicology for the Equine Practitioner
Toxicosis with what two toxins produces gross lesions w/in the kidney & urinary bladder
Red maple leaf tox– kidney
chronic sorghum poisoning– urinary bladder
Toxicology for the Equine Practitioner
What disease in horses resembles Parkinson disease?
Equine Nicropallidal encephalomalacia
**substania nigra compacta: loss of dopaminergic neurons & Lewy body formation
Toxicology for the Equine Practitioner
What is thought to be the toxic principle of yellow-star thistle & russian knapweed?
Repin**suspect
Toxicology for the Equine Practitioner
What is the cause of equine leukoencephalopmalacia?
ingestion of corn infected with fungus fusarium moniliforme
Toxicology for the Equine Practitioner
What is the primary toxin involved in equine leukoencephalomalacia?
fumonisin B1
Toxicology for the Equine Practitioner
What is the pathogenesis of equine leukoencephalomalacia?
sphingolipid biosynthesis by inhibiting enzyme ceramide synthase– results in accumulation of bioactive intermediates of sphingolipid metabolism– leads to cell death
Toxicology for the Equine Practitioner
Which plant species are implicated in PA toxicity?
- Senecio
- Crotalaria
- Cynoglossum
- Amsinckia
Toxicology for the Equine Practitioner
Which species of senecio– responsible for most PA poisoning in W USA
- tansy ragwort– S. jacobaea
- threadleaf or wooly groundsel– S. douglasii var longilobus
- Riddells groundsel– S. riddellii
Toxicology for the Equine Practitioner
Where is the greatest concentration of PA toxin?
flowers: Senecio spp
seeds: crotalaria, amsinckia
Toxicology for the Equine Practitioner
What is the mechanism of PA toxins in hepatotoxicity?
inhibit DNA synthesis & mitosis in the liver–> formation of megalocytes histologically
Toxicology for the Equine Practitioner
Is megalocyte formation pathognomonic for PA toxicity?
No, because also seen with alfatoxicosis
Toxicology for the Equine Practitioner
What are the primary oxidants involved in red maple leaf tox?
-gallic acid & tannic acid
-pyrogallol- may contribute
Toxicology for the Equine Practitioner
What are the differentials for the following lesions histologically:
-hemoglobinuric nephrosis, generalized icterus, splenomegaly
-Histo: renal tubular epithelial degenreatoin & necrosis w/ intratubular hemoglobin casts and heaptocyte degneration in centrilobular areas
-copper & nitrate toxicosis
equine infectious anemia
babesiosis
Toxicology for the Equine Practitioner
What clinical syndromes are seen with chronic sorghum consumption in horses (rarely cattle)?
cystitis & posterior ataxia (sorghum cystitis & ataxia syndrome)
Toxicology for the Equine Practitioner
C/S seen with chronic sorghum ingestion
posterior ataxia, progressing irreversibly to flaccid paralysis
urinary incontinence caused by overflow from a distended, atonic bladder
Toxicology for the Equine Practitioner
What is the MOA of cardiac glycosides?
inhibit the transmembrane sodium-potassium ATPase pump causing a rise in intracellular sodium & calcium
**in turn result in increased force of myocardial contraction
Toxicology for the Equine Practitioner
what is the toxic principle of white snakeroot?
tremetol
Toxicology for the Equine Practitioner
Why are c/s of toxicity caused by white snakeroot seen in young animals?
b/c toxin is rapidly excreted in milk
**nursing young can see c/s w/o maternal toxicity
Toxicology for the Equine Practitioner
Besides white snakeroot, what are other plants that can cause gross myocardial lesions in horses?
cottonseed (gossypium spp)
senna or coffee senna plant (cassia occidentalis or C obtusifolia)
Respiratory disease diagnostic approaches in the horse
what are the established reference ranges for BAL samples in horses?
macros: 50-70%
lymphs: 30-50%
neutrophils: <5%
eos: <0.1%
