Diseases of Adult Sheep Flashcards
What are 6 general causes of ill-thrift?
Poor nutrition, parasitism, chronic respiratory disease, gastrointestinal disease, lameness, skin disease, others (mastitis, CLA, scrapie, etc.)
What is the main parasite of adult sheep in the UK?
Fluke (next is hemonchus)
How do you dx parasitism? (5)
FEC, coproantigen, FAMACHA - targeted dosing system, PM, local climate / season information
Tx for fluke and hemonchus?
Fluke:
nitroxynil, closantel, clorsulon, tricalbendazole, or double dose albendazole
Hemonchus:
nitroxynil, closantel, copper, standard nematode anthelmintics,
VACCINE (barbervax)
What are 3 most common causes of respiratory disease?
Chronic supprative pneumonia (abscessation), Jaagsietke (OPA), Maedi
5 less common causes of respiratory disease of adults?
Lungworms, pneumonic pasteurellosis, enzootic nasal tumor, inhalation pneumonia, TB
Causes of chronic suppurative pneumonia? (4)
Inhalation of bacteria, secondary bacterial infection of compromised lung tissue, hematogenous spread from septic focus, secondary to mannheimia hemolytica
CS of chronic suppurative pneumonia?
WEIGHT LOSS, depression, tachypnoea, cough
usually not pyrexic
CS of jaagsiekte?
Initial weight loss (appetite maintained), exercise intolerance, increasingly tachypnoeic, crackles over lung field
What kind of virus is jaagsiekte, and what is the incubation period?
Retrovirus
3-4 year old sheep = incubation period
Dx of Jaagsiekte?
“wheelbarrow test” - clear frothy fluid from nostrils
No detectable immune response (no blood tests)
US - sharp demarcation from normal lung tissue
PM - confirmation of diagnosis
Tx for Jaagsietke
Cull - affected sheep and offspring
Transmission of jaagsiekte?
main route of infection = respiratory (young animals mostly)
increased transmission during close contact
Maedi caused by what kind of virus?
Lentivirus (retrovirus)
How are sheep infected w/ Maedi?
infected as lambs through colostrum/milk
When (what age) would you be most likely to see clinical disease in Maedi animals?
After 3 years
CS of Maedi (ovine progressive pneumonia)
exercise intolerance
weight loss
progressive tachypnoea / dyspnoea
indurative mastitis
Dx of Maedi
Detection of antibodies to MVV -> AGIDT or ELISA
PM = firm, rubbery, heavy lungs; don’t collapse (often have concurrent pasteruellosis or jaagsiekte)
Dental problems!
I skipped writing these up because I didn’t feel like it
Cause of Johne’s
Mycobacterium avium subspecies paratuberculosis (leading to protein losing enteropathy)
Main route of infection for Johne’s
fecal - oral
CS of Johne’s
-Infected @ any age typically 2-5 years old -Weight loss / emaciation (NOT usually diarrhea) \+/- submandibular edema
Dx of Johne’s
Hypoalbuminemia and hyperglobulinemia, serology (AGIDT and ELISA),
fecal smears (acid fast bacteria - ZN stain /PCR),
PM
Serology & fecal smears have many false negatives (low sensitivity)
What do you find at PM for Johne’s
enlarged lymphatic vessels, thickening of mucosa @ terminal ileum, enlarged mesenteric LN. (color! - sometimes orange?)
Control/prevention of Johnes
Cull suspected cases (thin ewes); cull female progeny of clinical cases; separate replacement ewe lambs; reduce fecal contamination in feeding areas
- inactivated vaccine (not in UK)
- PM ill thrift cases
2 main causes of mastitis in sheep
Pasteurella multocida, Staphylococcus aureus
5 common neuro conditions in adult sheep
Listeriosis, louping-ill, polioencephalomalacia (CCN), Scrapie, pregnancy toxemia
Listeriosis - cause, and what is this infection associated with?
Listeria monocytogenes, associated w/ silage feeding
Listeriosis - seasonal incidences - when?
Most cases Feb / March
Clinical syndromes of listeriosis?
Encephalitis (most common), abortion, septicemia (usually neonate), iritis / keratoconjunctivitis
Pathogenesis of Listeriosis (2 possible routes)
1) transmission by traveling along nerve from eye or mouth lesions
2) bacteremia –> infection of the brain
CS of listeric encephalitis
Depression and anorexia, pyrexia (early), head tilt, circling, unilateral facial nerve paralysis (drooping ear & eyelid), accumulation of cud (exposure keratitis), uncoordinated gait / hemiparesis, terminal convulsions (death w/in 3-4 days)
Dx of Listeriosis
Hx, CS, histopath (though bacterial isolation from brain can be difficult), CSF may show increased protein and mononuclear cells
Tx of Literiosis
only ambulatory cases likely to respond
prolonged tx (5-14 days) - w/ abx that penetrates the BBB good nursing
Control / prevention of liseriosis
Feed good quality silage only
Louping ill - what is vector?
Ixodes ricinus tick
CS of louping ill?
ataxia -> paralysis, convulsions, coma -> death (w/in 24-48 hours)
Control of loupin ill
Vaccination (of breeding replacements and purchased stock - inactivated vaccine) - single dose @ least 28 days before tick infected pasture exposure
Reduce tick numbers
What are risk factors for polioencephalomalacia (CCN), and what causes it?
Risk factors: dietary changes (concentrates) or disruption to normal feeding in previous 2 weeks
Cause: induced thiamine (Vit B1) deficiency, occasional outbreaks associated w/ high levels of dietary sulphur
ex- overgrowth of thiaminase producing bacteria in rumen -> altered glucose metabolism -> necrosis of superficial cerebral grey matter -> generalized cerebral edema
CS of CCN
Blind, wandering, “star-gazing”, high-stepping gait, head pressing
+/- dorso-medial strabismus
Progression to recumbency, backwards flexion of neck, hyperaestheisa, convulsions
DDx for CCN
Pregnancy toxemia, listeriosis, focal symmetrical encephalomalacia, acute coenurosis
Dx of CCN
decreased erythrocyte transketolase and increased thiaminase activity in feces, rumen fluid, blood (rarely used)
usually based on CS and response to tx
PM- fluorescence of cerebral cortex under UV light; histology - bilateral laminar necrosis
Tx of CCN
early cases better prognosis
IV vitamin B1, dexamethasone
make sure adequate levels of thiamine in “multivitamin injectables”
Prognosis of CCN
usually improve w/in 24 hours; may remain blind for 2-3 weeks
earlier the case tx, the better prognosis
Scrapie - notifiable!
CS?
pruritis - “nibble reflex”
behavioral changes (nervous, aggression, sleepy/vacant)
weight loss (normal appetite),
ataxia / gait changes - hypermetria, hind limb ataxia, wide-base stance
head / neck tremor
Dx of Scrapie
PM diagnosis - histopath, IMHC and /or biochem tests for abnormal prion protein (PrPsc)
lymphoid tissue biopsy in live animals
Transmision of scrapie
vertical (placenta / milk)
lateral (direct contact and/or env contamination)
Control of scrapie
selective breeding
What is the common name for Coenurosis?
Gid
What causes gid?
tapeworm taenia multiceps - pasture contamination by dog feces
When are most cases of Gid seen?
6-24 month old sheep
CS of Gid?
depend on location of cyst:
most = one cerebral hemisphere (contralateral blindness, circling, softening of frontal bone)
cerebellum = dysmetria, ataxia, wide-based stance, bilateral proprioceptive defects
Dx of Gid
Hx and careful neuro exam
Tx of Gid
surgical removal of superficial cysts under GA
Cause of hepatic encephalopathy
Secondary to hepatic damage - cobalt deficiency, chronic Cu toxicity, ingestion of hepatotoxic plants
CS of hepatic encephalopathy
Depression, blindness, head pressing, teeth grinding
Diagnosis of hepatic encephalopathy
Liver enzymes, levels of vitamin B12 and/or Cu in blood or liver
Name 6 diseases caused by clostridia in adult sheep (and name the causative clostridia)
- Struck (perfringens type C)
- Blackleg (chauvoei)
- Black disease (novyi type B)
- Malignant edema (septicum, novyi typeA, chauvoei, sordellii)
- Botulism (botulinum types C and D)
- Abomastitis
CS of struck
Enteritis, peritonitis, sudden death
Dx of struck
PM findings (free fluid, hemorrhagic enteritis) Anaerobic culture from intestinal contents
CS of malignant edema
massive facial swelling w/ edema and gas production
Risk factors for botulism in cattle
Poultry litter, big bale silage
CS of botulism
flaccid paralysis (less evident vs. cattle) stiffness, incoordination, excitability -> salivation, difficulty swallowing, recumbency -> death w/in 24 hours
Name 4 plants that are poisonous to sheep
Bracken, Rhododendron, Brassica (kale, rape), Ragwort
When are you most likely to see bracken poisoning?
Dry years; late summer / autumn
When will you most likely see rhododendron poisoning? What are the CS?
common following heavy snowfall
CS = salivation, greenish froth around mouth and nose, severe abdominal pain; retching
ataxia -> recumbency -> convulsions -> death
Cu poisoning CS
ataxia, aimless wandering, head pressing, stupor
jaundice, hemogobinuria, anemia, death
Dx of Cu poisoning
PM findings - carcass pale / jaundiced ; liver pale tan to broze color; kidneys dark red or black ; urine dark red or black
Kidney Cu > 324 umol/kg DM confirms diagnosis
Prevention of cu poisoning
Don’t give Cu supplements to housed sheep
be wary of feeds with high Cu content (crops grown w/ use of pig or poultry manure, distillery by-products, palm oil or molassed sugarbeet pulp feeds, cattle feedstuff, red clover)
