1. Caseous Lymphadenitis = CLA
Corynebacterium pseudotuberculosis
gram-positive rod, produces an exotoxin ; grows on blood agar in 48 hours
can survive in environment for 2 months
penetrates the skin or mucous membranes
long incubation period (2-6 months)
chronic abscesses in local lymph nodes, lung, liver, kidney; not painful
most common location in goats = head and neck (parotid, submandibular, cervical)
most common location in sheep = nodes draining shearing wounds, lungs
dry concentric rings or creamy pus (white, gray-green)
does not interfere with health or production if only in external nodes
could confuse with congenital wattle cyst in goats
retropharyngeal abscess interferes with breathing, swallowing, difficult to treat
abscesses in lungs from inhalation or via thoracic duct
pneumonic form causes weight loss, dyspnea - could diagnose by tracheal wash, radiograph, necropsy
not economical to treat internal abscesses (rifampin with penicillin)
lance external abscesses; wear gloves, surrounding skin infectious for 1 month
formalin injected into abscess if well fixed to overlying skin
sternal abscesses are usually not CLA, often associated with CAE in goats
other organisms can cause abscesses: A. pyogenes, anaerobic Staph, Actinobacillus
surgical removal sometimes possible, but very difficult for parotid lymph node
vaccination helpful if good vaccine (Glandvac from Australia) available; colostral antibodies protect lambs
and kids until primary vaccination series begun at 3 months of age.
cull goats with abscesses or raise kids artificially to control spread

2.  Tuberculosis
Mycobacterium tuberculosis, M. bovis
often mineralized abscesses in lung, liver, spleen
acid-fast (differentiates from C. pseudotuberculosis)
reportable; kill, quarantine or kill flock

3.  Lymphosarcoma
cause in goats unknown, usually sporadic
said to be C-type oncornavirus in sheep
natural cases not caused by bovine leukemia virus though this virus will infect small ruminants
external nodes or internal organs, bone marrow
clinical course often less than 6 weeks
rather common in goats

4. Paratuberculosis, Johne´s Disease
Mycobacterium avium subsp. paratuberculosis
acid-fast
usually infects young lambs and kids
clinical signs rare before 1 to 2 years of age (first parturition)
main clinical presentation is weight loss, poor production
diarrhea terminally in 10-15% (more if internal parasites not controlled)
hypoalbuminemia and mild anemia, poor haircoat, more parasites and secondary infections
bottle jaw = submandibular edema occasionally seen
organism invades Peyers patches - no antibody response while infection contained here
fecal culture definitive in goats but difficult in sheep (different strains) - 8 to 16 weeks vs 1 year!
intestinal mucosa often not thickened
diagnose by histology of Peyers patches in distal ileum, ileocecal junction, ileocecal lymph node
granulomatous response in intestine, but sometimes paucibacillary - few acid fast organisms seen
fecal-oral transmission - "All feces are considered guilty until proven otherwise!" - C. Rossiter
do not spread infected manure on pastures
soil may remain infected for 1 year
transplacental infection possible - cull offspring of infected animals
can be in macrophages in milk or on skin of teats - remove offspring at birth if possible
shear before lambing, use adequate clean bedding
do not buy or borrow infected animal or colostrum from infected cattle
"paratuberculosis is bought and paid for"
do not leave thin animals in birthing area
cull any adult animal that cannot maintain body weight under herd management conditions
vaccine helpful in controlling clinical signs and shedding of organism (Gudair - Spain)

body condition scoring:  lumbar area of sheep, scale of 1 to 5 where 1 is skin and bones, 5 obese
    lumbar area and sternum of goats

other causes of illthrift:
 malnutrition: energy, protein, major and trace minerals
 parasites - internal and external
 bad teeth (molars)
 lame or blind
 low social hierarchy (especially goats)
 neoplasia
 gastrointestinal obstruction in goats (plastic bags)
 abomasal impaction in black-faced sheep - low BCS but full abdomen, high rumen chloride

5.  Caprine Arthritis-Encephalitis = CAE, Ovine Progressive Pneumonia = Maedi Visna
lentiviruses - sheep and goat viruses are distinct but serologically similar
reverse transcriptase, animal remains infected for life
5 main clinical manifestations:
 neurologic
 arthritic
 interstitial pneumonia
 interstitial mastitis
 cachexia

neurological form most common in 2-6 month old kids, can affect adults
posterior paresis most common but can involve any part of brain or spinal cord
lesions are grossly visible - pinkish gray, asymmetrical
cerebrospinal fluid helpful - obtain from atlanto-occipital or lumbosacral space
normal in goats < 40 mg/dl protein, < 5 cells/cmm

arthritic form in adult goats, at least > 6 months old - rarely in sheep
enlargement of carpal joints most common; stifle and hock joints also involved in some
concretions in joint capsule or bursa ("rice bodies"), thickened synovium
distension of atlanto-occipital bursa rare but distinctive
lame goat is unthrifty
radiographs show joint capsule thickening early, mineralization and bony proliferation later
differential for joint involvement includes:
 trauma
 mycoplasma
 chlamydia
 joint ill (but this is only in neonates)
sternal abscesses form in arthritic goats that lie down a lot: radiograph demonstrates bone involvement

intersititial pneumonia is most common presentation in sheep
occasional in goats (especially late pregnancy)
exercise intolerance, weight loss
bacterial pneumonia may precede activation of virus in lungs, but antibiotics give partial response only
radiograph (resembles CLA) or lung biopsy to diagnose
locally extensive consolidation of lung lobes
airways sound harsh (as in any thin sheep or goat); crackles and wheezes if bacterial pneumonia also

interstitial mastitis = hard udder (goats) or hard bag (sheep)
milk appears normal but very little available
colostrum and milk are major sources of infection to lambs and kids
accumulation of mononuclear cells around milk ducts, eventual fibrosis

transmission whenever live cells, especially macrophages, transmitted:
 colostrum and milk
 nasal secretions
 blood on instruments or reused needles, maybe lochia
 semen if bacterial infection (posthitis = pizzle rot, Brucella ovis)
clinical signs and necropsy to diagnose
most (85%) infected animals are subclinical, so positive serology does not prove virus caused signs
ELISA test more sensitive than AGID, AGID more specific

control by test and slaughter or 2 herd system
remove offspring before nursing
a few infected in utero, so test beginning at 6 months of age
may not seroconvert for months or years
"pasteurized colostrum" - one hour heat treatment at 56 °C
if buck infected, safer to breed by artificial insemination with washed semen
induction of parturition with 20 mg dexamethasone or 10 mg prostaglandin F2alpha reduces watching
 most know last possible breeding date!
 taping teats shut an alternative
 

6.  Footrot, foot scald
synergistic infection with Dichelobacter (was Bacteroides) nodosus and Fusobacterium necrophorum
anaerobes, spread under warm, wet conditions
pasture only contaminated 2 weeks
infection between toes (foot scald) may be mild strain or early infection or all that a goat with pathogenic
  strain shows
undermines sole from the heel
chronically infected animal is major source of infection
cull them!
do not buy from infected herd or use contaminated pen or truck
assume purchased animal is infected - trim feet, treat with disinfectant, give longacting tetracycline
frequent foot trimming of infected animals
frequent foot bathing in zinc sulfate (or copper sulfate)
vaccination reduces clinical cases and increases cure rate - Australian FootVax
differentials include white line abscess, laminitis, foot and mouth disease

7.  Infectious Keratoconjunctivitis, Pinkeye
mycoplasma or chlamydia
rarely is Branhamella ovis or  Moraxella bovis a secondary invader
conjunctival scrapings and special cultures
epiphora, chemosis, cloudy cornea
responds to tetracycline but recurs
carrier animals introduce to herd
differentiate from:
 entropion in lambs and kids
 exposure keratitis from listeriosis
 

Literature:
Behrens, H.: Lehrbuch der Schafkrankheiten
Smith, M.C.: Goat Medicine
Linklater, K., Smith, M.C.: Color Atlas of Diseases and Disorders of the Sheep and Goat
Martin, W.B.: Diseases of Sheep
Zettl, K., Brömel, J.: Handbuch Schafkrankheiten