Ovine Pathogens Flashcards
Bluetongue pathology findings
white streaks in the skeletal muscles and endothelial hemorrhage at the base of the pulmonary artery, as well as ecchymotic hemorrhages in the lymph nodes and spleen. Underlying lesions are vasculitis, and the lesions are multisystemic.
Causes abortion, fetal-mummification, stillbirth, and congenital brain malformation.
Transmitted by biting midges and vaccine available
Border Disease
“hairy-shakers”
Caused by infection of fetus in early pregnancy with a pestivirus (Flaviviridae). Related to Classical Swine Fever and BVD
Surviving lambs are persistently viremic
Abortion may occur at any stage
No effective treatment, serology on dams of affected lambs,
Problem in nieve herds
Brucella ovis in rams
Infertility and epididymitis
Champylobacter
most common cause of abortion in sheep in North America
Venereal, control with AI and vaccination
Clostridium novyi Type A
“Big head” treat with wound debridement and penicillin
Found in soil so culling and isolation unnecessary. Enters through wounds obtained during head-butting activities. Fatal if untreated.
Copper deficiency
Causes enzootic ataxia in goats and sheep. Can be primary (low intake) or secondary (factors inhibiting absorption and promoting excretion, ex. high sulfur, iron, selenium). Deficiency can cause microcytic anemia, decreased production, fading hair, heart failure, infertility, swollen joints, gastric ulcers, and diarrhea. Two neurologic diseases specific to copper deficiency are enzootic ataxia (seen in lambs 1 to 2 months old) and swayback (seen congenitally or in very young lambs and kids). Clinical signs of progressive ascending paralysis nd incoordination, muscle atrophy, and weakness. Copper deficiency leads to less myelin formation and to demyelination.
Culicoides gnat
bluetongue vector
Dermatophilus congolensis
Actinomycete that primarily affects the dorsal surface of animals. Clinically, crusting lesions will form which are easy to pull off, and many people describe them as a paintbrush lesion. In sheep, this disease may be known a strawberry footrot when the claws are affected. Remove sheep from rain.
Dichelobacter nodesus
Primary pathogen in footrot
Estrus duration
1.5-2 days, ovulations occurs about 24 hours after onset of estrus
External caseous lymphadenitis
Caseous lymphadenitis (CL) is a chronic, contagious disease caused by the bacterium Corynebacterium pseudotuberculosis.
gram-positive, facultative, intracellular coccobacillus
abscesses in the region of peripheral lymph nodes
More common form in goats
Footrot
Primary Dichelobacter nodesus Secondary Fusobacterium necrophorum
Fusobacterium necrophorum
secondary infection in footrot
Gangrenous mastitis
Caused by Mannheimia hemolytica and Staphylococcus aureus and occurs sporadically during the first 3 months of lactation. It if generally associated with poor milk supply relate to ewe undernutrition and over vigorous suckling lambs. Prognosis is grave. Control measures include ensuring ewes are well fed. Concentrated should be supplied to ewes and lambs when pasture is poor. No ewe should be expected to rear triples. Teat lesions should be identified and treated with topical antibiotics.
Gid (coenurosis)
Caused by a tapeworm Coenurus cerebralis which is the larval form of Taenia multiceps. The sheep is an intermediate host and the larvae invades the sheep’s central nervous system, forming a cyst in the brain
Grass staggers
results when plants of the genera Phalaris (Canary grasses), Lolium, Cynodon, or Paspalum are ingested. Some, like Canary grass, accumulate toxic alkaloids, while others harbor fungi with toxins. Canary grasses can cause either acute death or grass staggers. Most sheep affected by Canary grass staggers will slowly recover if removed from the offending pasture. Grass staggers is also the name of hypomagnesemia in sheep which can develop in sheep grazing lush grass pastures. It is easy to get this condition confused with the intoxication presented in this question due to the similar title of the clinical condition. Symptoms of hypomagnesemia include restlessness, staggers, an over-alert appearance, being excitable, and in some cases, aggressiveness. In severe cases, animals may fall down and go into convulsions or just die without warning.
Hydroanecephaly
in lamb - bluetongue infection in early gestation
Internal caseous lymphadenitis
thorax and abdomen - more common form in sheep
Johne’s disease (Mycobacterium avium ssp. paratuberculosis)
acid-fast rods tell tale sign of Johne’s. Typically a disease of chronic wasting, affecting animals 2 years and older.
Mannheimia haemolytica
Formerly called Pasteurella hemolytica, most common infectious bacterial disease of sheep and goats. “Blue bag” and enzoonotic pneumonia which is a hemorrhagic bronchopneumonia of young lambs and their dams. Clinical signs: fever, depression, mucopurulent nasal discharge, coughing, pulmonary crackles and wheezes, and tachypnea. Fibrinopurulent pleuropneumonia.
Melophagus ovinus
“sheep ked” one of the most widely distributed and important external parasites of sheep.
Wingless dopterans. Entire lifecycle is spent on the host.
Adult is 7mm long, brown/red, armed with stout claws.
Need to remove sheep from infected areas - only effective treatment
Mycoplasma mycoides ssp. mycoides
causes a number of conditions including pleuropneumonia, mastitis, polyarthritis, and meningitis, but is seen mainly in goats.
Mycoplasma ovipneumoniae
pneumonia in sheep
upper respiratory tract
predispose to secondary infection with Pasteurella and Mannheimia
Oestrus ovis
treat with ivermectin Adult flies deposit larvae around animals nostrils, larvae migrate up the nasal passages into the turbinates and sinuses. With time and multiplication of the larvae, hypersensitivity develops -> clinical signs of discharge and face rubbing and shaking. Secondary bacterial infection can occur. Eosinophils and mast cells seen in the discharge.
Ovine Progressive Pneumonia
Maesi-Visna - caused by a retrovirus closely related to CAEV (Caprine arthritis and encephalitis virus), with increasing wasting and respiratory distress. Secondary bacterial infections can occur, leading to coughing, bronchial exudate, depression, and fever. Indurative mastitis (hardbag) may occur. In the encephalitic form, ataxia, muscle tremors, or circling may occur and progress to paresis and eventually paralysis. Diagnosis may be confirmed in live animals via agar gel immunodiffusion of ELISA testing. No vaccine or treatment is effective, the disease is controlled by serologic testing and removal of positive animals. Re-test annually due to long incubation period and fed lambs colostrum from seronegative ewes.
Ovine/Caprine Nasal Adenocarcinoma Virus (ONAV/CNAV)
tumor is not metastatic but locally expansive and destructive.
Pasteulla multocida
pneumonia and septicemia in sheep and goats
Ulcerative Posthitis
“pizzle rot” in male sheep - corynebacterium renale in ulcers on the sheath
Veratrum californicum
Associated with the cyclops condition in sheep
