Microbiology - Veterinary Microbiology PDF

MICROBIOLOGY Veterinary microbiology deals with the study of little pathogens affecting animals. These microorganisms include bacteria, fungi, viruses, and prions. It is important to note that even small, they can cause injury to host’s cell leading to illness. Bacteria and fungi destroy cell struct...

MICROBIOLOGY Veterinary microbiology deals with the study of little pathogens affecting animals. These microorganisms include bacteria, fungi, viruses, and prions. It is important to note that even small, they can cause injury to host’s cell leading to illness. Bacteria and fungi destroy cell structures directly thru toxin production and/or indirectly by inciting inflammatory response. Virus and prions on the other hand, can make destructions during their replication process inside infected cells. Veterinarians are expected to be familiar with the most common infectious agents; their classification, mode of transmission, and the lesions they produce. It serves as the groundwork for an effective disease eradication and control. Pathogenic microorganisms Bacteria ○ Unicellular ○ Exhibit considerable morphological diversity ○ Classified either Gram (+) or Gram (-) Fungi ○ Either unicellular or multicellular (yeast or mould) ○ Capable of secreting enzymes that can digest organic matter Algae ○ Plant-like organisms ○ Can produce toxins Viruses ○ Virions are not cells but consists of nucleic acid ○ Can only multiply within living cells Prions ○ Smaller than viruses without nucleic acids ○ They are abnormally folded proteins Figure 1.Comparison of the relative sizes of RBC and Bacteria and Viruses 1|P a g e BACTERIA Staphylococcus o Gram (+) cocci in clusters resembling bunches of grapes o Commensals on mucous membranes and skin o Cause pyogenic infections o Facultative anaerobes; coagulase positive Clinical infections: 1. Bovine staphylococcal mastitis Common form of bovine mastitis worldwide caused by S. aureus Alpha-toxin production causes necrosis 2. Tick pyemia Infection of lambs caused by S. aureus Infection occurs through minor skin trauma (tick bites) Septicemia and death or localized abscess formation in many organs 3. Exudative epidermitis (Greasy Pig Disease) Occurs worldwide in young pigs up to 3 months of age Caused by S. hyicus which is present in healthy sow’s vaginal mucosa and skin Organism enter the skin through minor abrasions (bite wounds) Major virulence factor is the exfoliative toxin produced by the organism Causes widespread excessive sebaceous secretion, exfoliation on the skin surface and extensive non-pruritic dermatitis 4. Botryomycosis Infection of the stump of the spermatic cord after castration in the horse Can also occur in mammary tissues of sows Caused by S. aureus Lesion is a mass of fibrous tissue containing pus and sinus tracts 5. Bumblefoot Inflammation of the ball of the foot of birds and guinea pigs caused usually by infection with Staphylococcus spp. The organism enters the chicken's system through a cut, scratch, injury or a chafed and irritated area on its foot, followed by abscess formation (full of pus). 6. Staphylococcal infection in Dogs and Cats S. pseudintermedius causes pyoderma, otitis externa, mastitis, endometritis, cystitis, osteomyelitis, and wound infections S. aureus can also occur Streptococcus o Gram (+) cocci in chains 2|P a g e  o Catalase negative, facultative anaerobe, usually non-motile o Commensals of mucous membranes o Causes pyogenic infections Clinical infections: 1. Strangles A febrile disease involving the respiratory tract and abscessation of regional lymph nodes caused by S. equi. Metastatic infection (“Bastard Strangles”) occurs infrequently The organism has many virulent factors for protection against host’s immune response 2. Streptococcus suis infection Associated with meningitis, arthritis, septicemia and bronchopneumonia in pigs of all ages Disease outbreaks are associated to stress factors (such as overcrowding) 3. Bovine streptococcal mastitis S. agalactiae, S. dysgalactiae and S. uberis are the principal pathogens involved Actinobacteria (Actinomyces, Arcanobacterium, Actinobaculum, Nocardia and Dermatophilus) o Gram (+), many species with branching filaments o Opportunistic pathogens Clinical infections: 1. Trueperella (Arcanobacterium) pyogenes infection Common cause of suppurative lesion in many domestic species (cattle, pig, & sheep) Cases include, lymphadenitis, osteomyelitis, peritonitis, pyometra, metritis, acute mastitis in cow, and neural abscessation T. pyogenes has the ability to pit a Loeffler’s serum slope Loeffler’s coagulated serum medium - used for detection of protease production and rapid presumptive identification of Trueperella pyogenes. It is primarily used to detect Corynebacterium diphtheriae in human medicine Figure 2.Loeffler's serum slope 2. Canine actinomycosis Caused by Actinomyces viscosus 3|P a g e  Can cause subcutaneous pyogranulomatous lesions and respiratory distress 3. Bovine actinomycosis (Lumpy jaw) Caused by Actinomyces bovis Mandibular invasion following mucosal trauma from rough feed (roughage) Presence of Memory aid: Remember “MY lumpY” for fistulous tracts lumpy jaw (MYces, lumpY) discharging purulent exudate on the site of infection 4. Porcine cystitis and pyelonephritis Could be a fatal disease caused by Actinobaculum suis infection which is present in healthy boar’s prepuce Transmission through coitus Affects urinary tract of pregnant sows Signs include anorexia, arching of the back, dysuria and hematuria 5. Canine nocardiosis Cutaneous pyogranulomas or indolent ulcer (cutaneous form) Pyogranulomatous pleural lesions and pyothorax (thoracic form) Disseminated lesions (disseminated form) 6. Bovine nocardial mastitis Chronic mastitis Usually sporadic 7. Bovine farcy Chronic infection of superficial lymphatic vessels and lymph nodes Nocardia farcinica, Mycobacterium farcinogenes, and Mycobacterium senegalense are three possible etiology 8. Dermatophilosis Dermatophilus congolensis infection are usually confined to the epidermis Smear from scab material impart a “tram track” appearance (zoospores) Trauma and persistent wetting predispose to skin invasion Elevated crusty scabs and “tufted” appearance of hair on the dorsum of farm animals D. congolensis causes “Strawberry footrot” in lower limbs of sheep 9. Equine nocardioform placentitis The etiology is Crossiella equi Leads to loss of the foal 4|P a g e Corynebacterium o Gram (+) pleomorphic bacteria o Majority are commensals on mucous membrane o Cause pyogenic infections Clinical infections: 1. Caseous lymphadenitis Caused by non-nitrate- reducing C. pseudotuberculosis Enlargement and abscessation of superficial or Figure 3.Stained Corynebacterium cells. internal lymph nodes The "barred" appearance is due to the Commonly affects sheep, presence of polyphosphate inclusions goats and rarely cattle called metachromatic granules. Note Organisms can survive also the characteristic "Chinese-letter" intracellularly arrangement of cells. 2. Ulcerative lymphangitis Caused by nitrate-reducing C. pseudotuberculosis More common in horses than in cattle 3. Bovine pyelonephritis C. renale is normally present in the vulva, vagina and prepuce Stress of parturition and short urethra in the cow predispose to urinary tract infection The most severe form is caused by C. cystitidis leading to extensive renal damage 4. Ulcerative balanoposthitis (“Pizzle rot”) Characterized by ulceration around preputial orifice caused by C. renale The organism can hydrolyze urea to ammonia causing mucosal irritation High protein intake and heavy wool around the prepuce may predispose to disease development Rhodococcus equi o Gram (+) rods or cocci o Salmon-pink, mucoid, non-hemolytic colonies o Soil saprophyte o Respiratory pathogen of foals Clinical infection: 1. Suppurative bronchopneumonia in foals Affects 1-4-month-old foals Figure 4.Salmon pink Characterized by bronchopneumonia and colonies abscessation “Dusty stables” increase the likelihood of infection R. equi is an intracellular pathogen 5|P a g e Listeria o Small, Gram (+) rods o Facultative anaerobes, catalase-positive, oxidase-negative o “Tumbling” motility at 25 degrees Celsius o Environmental saprophytes Clinical infection: 1. Listeriosis in ruminants Present as encephalitis, abortion, septicemia or endophthalmitis Caused by L. monocytogenes infection Possible intracellular replication Outbreaks are often related to silage feeding during late-pregnancy (low immune system Bacillus o Large, Gram (+) rods o Produce endospores o Catalase-positive and oxidase-negative Clinical infections: 1. Infections with Bacillus licheniformis Could cause abortion in cattle and sheep Associated with feeding of silage or mouldy hay 2. Anthrax Endospores of Bacillus anthracis; Affects all mammalian species Ruminants - highly susceptible; Pigs & Horses - moderately susceptible; Carnivores - comparatively resistant; Birds - almost totally resistant Infection is via ingestion or inhalation of “spores” 3 antigenic components of the toxin: Protective antigen, edema factor and lethal factor Rapid bloating and incomplete rigor mortis Erysipelothrix rhusiopathiae o Gram (+), small rods (smooth forms) or Triple Sugar Iron agar - used to filaments (rough form) differentiate enterics based on the o Catalase-negative, coagulase-positive ability to reduce sulfur and o H2S (Hydrogen Sulfide) formed along ferment carbohydrates. stab line in triple sugar iron agar Clinical infections: 1. Swine erysipelas Can occur in four forms: septicemic, cutaneous→ACUTE; arthritis, vegetative→CHRONIC “Diamond” skin lesion 2. Erysipelas in fowl dark-coloured , swollen snoods of turkeys Post-mortem findings include enlarged friable liver and spleen 6|P a g e  Dermanyssus gallinae (red poultry mite) may serve as a reservoir and vector for the organism in chicken erysipelas 3. Infection in sheep Non-suppurative polyarthritis of lambs after navel entrance or through docking or castration wounds Clostridium o Large Gram (+) rods o Endospores produced o Anaerobic, Catalase-negative, and Oxidase-negative o Present in soil, alimentary tract, and feces Clinical infections: NEUROTOXIC CLOSTRIDIA 1. Tetanus Horses and humans - highly susceptible; Ruminants and Pigs - moderately susceptible; Carnivores - comparatively resistant Caused by introduction of C. tetani endospores into traumatized tissue The organism may reveal “drumstick” appearance on Gram-stained smears Blocks presynaptic transmission of inhibitory signals causing spastic paralysis 2. Botulism Ingestion of preformed toxin of C. botulinum causes “loin disease” in the USA Intestinal toxico-infectious form causes “shaker foal syndrome” Pigs and dogs are relatively resistant, rare in cats Acts at neuromuscular junction of cholinergic nerves blocking the release of acetylcholine resulting in flaccid paralysis HISTOTOXIC CLOSTRIDIA 1. Blackleg Activation of latent spores of C. chauvoei in muscle through traumatic injury Causes gangrenous cellulitis and myositis in both cattle and sheep Manifested by crepitation due to gas accumulation in skeletal muscle lesions 2. Malignant edema and Gas gangrene Malignant edema - C. septicum; Gas gangrene - C. perfringens type A “Big head” in rams following head wound infections 3. Braxy Abomasitis in young sheep caused by ingestion of frozen grass or feeds contaminated with C. septicum (exotoxins) 7|P a g e  Fatal; no effective treatment; lambs die within 36 hours after the onset of clinical signs 4. Infectious Necrotic Hepatitis “Black disease” of sheeps and occasionally cattle Hepatic necrosis caused by exotoxins of C. novyi type B, following tissue damage made by immature Fasciola hepatica 5. Bacillary haemoglobinuria Primarily in cattle, occasionally in sheep Endospores of C. haemolyticum present in Kupffer cells cause necrotic hepatitis and Haemoglobinuria (major clinical picture) ENTEROPATHOGENIC and ENTEROTOXEMIA-producing CLOSTRIDIA 1. Lamb dysentery Disease of young lambs, caused by C. perfringens type B Abdominal distention, pain and blood-stained feces 2. Pulpy kidney disease “overeating disease” A sheep disease caused by C. perfringens type D Affected lambs are often found dead Clinical signs include dullness, opisthotonos, convulsions and terminal coma Hyperglycemia and glycosuria are constant features Rapid kidney autolysis is a typical postmortem finding 3. Struck An acute enterotoxemia in adult sheep caused by C perfringens type C infection 4. Hemorrhagic enteritis in piglets Peracute enterotoxemia caused by C. perfringens type C Up to 80% mortality rate A less severe necrotizing enterocolitis in older piglets is caused by type A strains 5. Necrotic enteritis in chickens Primarily affects broilers up to 12 weeks of age Caused by C. perfringens type A and C (less frequent) strains 6. Clostridium difficile infections Reported in dogs with chronic diarrhea Hemorrhagic enterocolitis in newborn foals Neonatal diarrhea (mesocolonic edema) in pigs in the United States 7. Clostridium colinum infections ➔ Implicated in quail, chicken, turkey, pheasant, and grouse enteritis 8|P a g e  8. Clostridium spiroforme infections With atypical coiled morphology Implicated in antibiotic-induced rabbit enteritis 9. Tyzzer’s disease in foals Caused by C. piliforme Affects foals under 6 weeks of age May found comatose or dead Clinical signs include jaundice and diarrhea Diagnose using Warthin-Starry silver impregnation technique Memory aid: SUDDENLY DEAD YELLOW FOALS 7-40 DAYS OLD Mycobacterium o Acid-fast (ZN-positive) rods→RED Ziehl-Neelsen stain - used to identify staining rod! acid-fast microorganisms.The high o Cell walls with mycolic acid mycolic acid content of certain o Aerobic, non-motile, non-spore- Protozoa cell walls, and those of forming Mycobacteria, is responsible for the Clinical infections: staining pattern of poor absorption 1. Tuberculosis in cattle followed by high retention Caused by M. bovis Transmission is through aerosols and oral route Formation of pulmonary tubercles and occasionally induction of mammary tissues 2. Tuberculosis in avians M. avium complex infection caused nonspecific clinical signs in free range birds: dullness, emaciation and lameness M. tuberculosis occasionally infects parrots and canaries M. genavense has been isolated from pet birds 3. Feline leprosy A cutaneous disease of cats distributed worldwide Infection of M. lepraemurium through bites from infected rodents Presence of ZN-positive bacilli in smears 4. Johne’s disease Chronic, contagious fatal enteritis caused by M. avium sbsp. Paratuberculosis Two types of lesions are recognized: multibacillary (lepromatous) and paucibacillary (tuberculoid) Affected cattle are usually 2 years of age when signs are first observed Enterobacteriaceae o Gram (-) rods o Facultative anaerobes, Catalase-positive, Oxidase-negative 9|P a g e  o Enteric and Systemic pathogens, and Opportunistic pathogens Clinical infections: Escherichia coli 1. Enteric colibacillosis Affects newborn calves, lambs and piglets Hypersecretory diarrhea and interfere with fluid absorption Caused by enterotoxigenic E. coli (ETEC) that possess K88 and K99 fimbrial adhesions 2. Colisepticemia Systemic infections with septicemic strains of E. coli presents an acute fatal disease in calves, lambs and poultry Clinical signs (pyrexia, weakness, and tachycardia) are attributable to the action of endotoxin 3. Edema disease of pigs Stress-related toxemia of newly weaned pigs caused by shiga toxin- producing E. coli (STEC) 4. Post weaning diarrhea of pigs Diarrhea and purplish discoloration of the skin associated with sudden changes in feeding regimens post-weaning Caused by infection with enterotoxigenic E. coli (ETEC) strains EPEC may also be involved 5. Coliform mastitis Mammary gland infection by members of Enterobacteriaceae; E. coli occurs opportunistically Sows and cows are commonly affected Life-threatening if endotoxemia occurs 6. Urogenital tract infections Cystitis may occur in bitches following ascending infection of uropathogenic strains of E. coli Canine pyometra may occur after endometrial invasion of opportunistic E. coli Prostatitis in dogs is also associated with opportunistic E. coli invasion Salmonella serotypes 1. Enteric salmonellosis Foul-smelling diarrhea often blood-tinged Enterocolitis caused by salmonella organisms affect most mammalian species 2. Septicemic salmonellosis Commonly affects young farm animals Salmonella Choleraesuis (“hog cholera bacillus”) infection in pigs result into characteristic bluish discoloration of ears and snout 10 | P a g e  3. Salmonellosis in poultry S. Pullorum, S. Gallinarum and S. Enteritidis infects ovaries of hens and can be transmitted through eggs S. Pullorum causes Bacillary White Diarrhea in young chicks and turkey poults S. Enteritidis in undercooked egg dishes may result to human food poisoning S. Gallinarum causes “Fowl Typhoid” with similar lesion to those of pullorum disease Yersinia species 1. Enteric yersiniosis Enteritis caused by Y. pseudotuberculosis Can be seen in young farm animals 2. Septicemic yersiniosis Septicemia caused by Y. pseudotuberculosis occurs in birds kept in cages or aviaries 3. Pseudotuberculosis in laboratory animals Y. pseudotuberculosis infection in guinea pigs or rodents results into diarrhea or septicemia 4. Feline plague Three clinical forms: bubonic, septicemic, and pneumonic Acquired by cats through ingestion of Y. pestis-infected rodents Opportunistic pathogens Edwardsiella tarda: diarrhea/wound infections (rare) Enterobacter aerogenes: coliform mastitis in cow and sow Klebsiella pneumoniae: mastitis (cows), endometritis (mare), pneumonia (calves and foals) and urinary tract infection (dogs) Morganella morganii: ear and urinary tract infection (dogs and cats) Proteus mirabilis and P. vulgaris: urinary tract infection (dogs and horses), otitis externa (dogs) Serratia marcescens: mastitis (cow), septicemia (chickens) Pseudomonas and Burkholderia o Medium-sized, Gram (-) rods o Obligate aerobes, oxidase-positive and catalase positive Clinical infections: 1. Pseudomonas aeruginosa infections Causes a wide range of opportunistic infections Mink (Mustelidae) is particularly susceptible Fleece rot (sheep), Necrotic stomatitis (captive reptiles), Septicemia (mink) 11 | P a g e  Pigments produced by Pseudomonas aeruginosa: Pyocyanin (blue green), Pyoverdin (greenish yellow), Pyorubin (red), Pyomelanin (brownish black) 2. Glanders Caused by Burkholderia mallei is a contagious disease of horses Characterized by nodule and ulcer formation in the respiratory tract or on the skin Mallein test is an efficient field test for confirmation and screening 3. Malioidosis Caused by B. pseudomallei, affects many animal species including humans Endemic in tropical and subtropical regions Actinobacillus o Medium-sized, non-motile, Gram (-) rods o Facultative anaerobes o Commensals of mucous membranes Clinical infections: 1. Timber tongue (wooden tongue) Memory aid: Remember Induration of the tongue of cattle LIGNIN is what makes caused by A. lignieresii WOOD; LIGNIeresii The organism is a commensal of the oral cavity that enters tissues through erosions or lacerations in the mucosa and skin Tissue sections present “club” colonies 2. Pleuropneumonia of pigs A. pleuropneumoniae infection occurs primarily in pigs under 6 months of age Acute infection presents blood-stained froth around the snout and show cyanosis 3. Sleepy foal disease A fatal septicemia of newborn foals caused by A. equuli Foals can be infected in-utero or after birth via umbilicus since the organism is found in the reproductive tract of mares Infected foals are febrile and recumbent 4. Actinobacillus suis infection of piglets Affect pigs under 3 months of age through aerosols from the upper respiratory tract of sows Cause more invasive pleuropneumonia than A. pleuropneumoniae infection 5. Actinobacillus seminis infection in rams Common cause of epididymitis in young rams 12 | P a g e Pasteurella species, Mannheimia haemolytica, and Bibersteinia trehalosi o Small Gram (-) rods o “Bipolar” staining is prominent in smears from lesions using Giemsa method o Commensals in the upper respiratory tract (respiratory pathogens) Bipolar staining - a staining pattern that colors only the two opposite poles of the microorganism in question, leaving the rest of the bacterium unstained or of a lighter color: seen in Burkholderia, Yersinia, Klebsiella and Pasteurella Clinical infections: Figure 5. Stained P. multocida. Note 1. Haemorrhagic septicemia (“Barbone”) the characteristic bipolar staining Acute potentially fatal septicemia mainly pattern affecting buffaloes (more susceptible) and cattle in Asia caused by Pasteurella multocida serotype B:2 Overworked, poor body condition and monsoon rains are important predisposing factors Most common in animals between 6 and 24 months of age Clinical signs include respiratory distress, high fever and laryngeal edema 2. Bovine respiratory disease “Shipping fever” and “enzootic pneumonia of calves” are associated with Mannheimia haemolytica and Pasteurella multocida infection Severe stress such as transportation and close confinement may predispose to clinical infections 3. Pasteurellosis in sheep “Ovine pneumonic pasteurellosis” are usually caused by M. haemolytica and P. multocida (rare) Adverse climatic conditions or viral infections may predispose to clinical disease 4. Atrophic rhinitis of pigs Toxigenic strains of P. multocida type D or A causes a severe progressive atrophic rhinitis Coinfection with Bordetella bronchiseptica A distinct lateral deviation of the snout may develop due to damaged turbinates 5. Fowl cholera A highly contagious, often fatal septicemia of avians is caused by P. multocida types A and F 6. Snuffles in rabbits 13 | P a g e  Common, recurring, purulent rhinitis in rabbits which is caused by P. multocida or B. bronchiseptica (sometimes) Stress factors such as overcrowding, chilling, transportation, concurrent infections and poor ventilation (high ammonia levels) Purulent nasal discharge that cakes on the forelegs are common features Francisella tularensis o Gram (-) coccobacillary rods o Facultative intracellular pathogen o wildlife reservoirs and arthropods important in epidemiology Clinical infections: 1. Tularemia Chronic granulomatous lesions or subclinical infections may develop Outbreaks of tularemia have been reported in sheep but cats are the most frequently documented having clinical disease Infection is through skin abrasions or arthropod bites (Dermacentor andersoni, D. variabilis, D. occidentalis and Amblyomma americanum) In cats, infections could be acquired through predation Bordetella o Small, Gram (-) rods o Strict aerobes o Catalase-positive, Oxidase-positive o Commensals in upper respiratory tract Clinical infections: 1. Canine infectious tracheobronchitis (“Kennel cough”) B. bronchiseptica, canine parainfluenza virus 2 (CPI-2) and canine adenovirus 2 (CAV-2) are considered to be the major etiological agents Signs include coughing, gagging and mild oculonasal discharge but remain active and non-febrile 2. Atrophic rhinitis B. bronchiseptica may serve as primary colonizer and can cause turbinate hypoplasia without distortion of the snout in piglets 3. Turkey coryza Caused by B. avium infection in poults Characterized by beak-breathing, excessive lacrimation, and sneezing Histophilus somni, Haemophilus parasuis, and Avibacterium paragallinarum o Small, motile, Gram (-) rods o Facultative anaerobes o Commensals on mucous membranes Clinical infections: 14 | P a g e  1. Histophilus somni infection in cattle Normal bacterial flora of male and female bovine genital tracts Thrombotic meningoencephalitis (TME) in young cattle Severe neurologic signs 2. Histophilus somni infection in sheep Healthy sheep may carry ovine strains of H. somni in prepuce or vagina Epididymitis in young rams, vulvitis, mastitis and reduced reproductive performance in ewes, and septicemia, arthritis, meningitis, and pneumonia in lambs 3. Glasser’s disease Caused by Haemophilus parasuis, manifests as polyserositis, polyarthritis and leptomeningitis in weaned pigs (under 12 weeks) Piglets acquire the organism from sows shortly after birth either by direct contact or through aerosols 4. Infectious coryza of chickens Caused by upper respiratory tract infection of Avibacterium paragallinarum Susceptibility increases with age Characterized by serous nasal discharge and facial swelling (infraorbital sinus) Taylorella o Short, non-motile, Gram (-) rods o Optimal growth on chocolate agar Clinical infections: 1. Contagious equine metritis (CEM) Caused by T. equigenitalis which is found in the genital tract of stallions (urethral fossa), mares (clitoral fossa), and foals Characterized by copious, mucopurulent, vulvar discharge 2 to 7 days after service Moraxella o Short, Gram (-) rods, usually in pairs o Aerobic, non-motile o Found in mucous membranes Clinical infection: 1. Infectious Bovine Keratoconjunctivitis (IBK) or “Pink eye” Caused by M. bovis Features include, blepharospasm, conjunctivitis and lacrimation that may lead to corneal ulceration and permanent blindness Flies (Musca autumnalis) can act as vectors of the organism Thelazia species may exacerbate the condition 15 | P a g e Campylobacter and Helicobacter o Curved, Gram (-) rods in “gull-winged” shapes and spiral forms o Motile, microaerophilic o Commensal of the intestinal tract and sometimes of the reproductive tract (pathogens of reproductive and intestinal tracts) Clinical infections: 1. Bovine genital campylobacteriosis Helicobacter pylori – pathogen Campylobacter fetus subsp associated with gastric ulcers, venerealis is the principal cause gastric adenocarcinoma, and Transmitted during coitus mucosa-associated lymphoid Characterized by temporary tissue (MALT) lymphoma in infertility, associated with early humans embryonic death, return to estrus at irregular periods 2. Ovine genital campylobacteriosis Caused by either Campylobacter fetus subsp. Fetus or Campylobacter jejuni One of the most common cause of ovine abortion Necrotic placentitis may result to late-term abortion, stillborn or weak lambs Transmission is by feco-oral route 3. Intestinal campylobacteriosis in dogs Diarrhea caused by the presence of large numbers of Campylobacter species in the alimentary tract Usually self-limiting 4. Avian vibrionic hepatitis Birds commonly harbour C. jejuni and its principal importance is as a source of infections for humans following carcass contamination Severely affected birds are listless, loss of condition due to hepatic damage Brucella o Small, Gram (-) coccobacilli o Some species cause undulant fever in humans o Targets reproductive organs o Aerobic and capnophilic o MZN positive Clinical infections: 1. Bovine brucellosis Caused by B. abortus Low prevalence in many countries but infection has become established in wildlife (Bison and Elk) in some parts of North America Abortion (placentitis) storms may occur after fifth month of gestation (infected cows usually abort once), testicular degeneration in bulls 16 | P a g e  Ingestion of contaminated fetal tissues and fluids is the usual way of infection Venereal contact, penetration through skin abrasions, inhalation or transplacental transmission are also possible but infrequent 2. Caprine and ovine brucellosis Caused by B. melitensis Clinical disease resembles bovine brucellosis Rose-Bengal agglutination test and complement fixation test are most widely used detection methods 3. Ovine epididymitis Characterized by epididymitis in rams and placentitis in ewes caused by B. ovis infection 4. Porcine brucellosis Prolonged bacteremia and inflammatory lesions in the reproductive organs of sows and boars caused by B. suis infection Rose-Bengal plate agglutination test and the indirect ELISA are the most reliable serological diagnostic methods 5. Canine brucellosis Relatively mild asymptomatic infections but could feature decreased reproductive performances in bitches and male dogs Caused by B. canis Diagnosis: Rapid slide agglutination test kit containing 2- mercaptoethanol (screening), and tube agglutination test, ELISA, and an agar gel immunodiffusion test (confirmatory) Lawsonia intracellularis o Curved, Gram (-) rods o Obligate intracellular pathogen Clinical infection: 1. Porcine Proliferative Enteropathy (“ileitis”) L. intracellularis has an affinity for enterocytes, its site of replication Foals could also E. coli, Clostridium and Bacteroides species be affected by L. provide appropriate microenvironment for the intracellularis, colonization of L. intracellularis characterized by Commonly affects weaned pigs (6-12 weeks weight loss with of age), causing hemorrhagic diarrhea due to diarrhea and proliferative and inflammatory changes in ileum and colon colic Spirochaetes o Spiral, Motile bacteria o Although Gram (-), many stain poorly using conventional methods o Leptospira species 17 | P a g e  Found in aquatic environments Shed in urine of affected species Dark-field microscopy, silver staining, immunofluorescence and molecular technique are used for recognition o Borrelia species Transmission by arthropod vectors Culture of borrelia from infected animals is confirmatory o Brachyspira species Intestinal spirochaetes (some are important pig enteropathogens) Clinical infections: Leptospira 1. Cattle L. borgpetersenii serovar Hardjo abortion, stillbirths, agalactia 2. Horse Clinical disease is infrequent L. interrogans serovar Pomona: Equine recurrent uveitis (“moon blindness”), abortions, periodic ophthalmia) L. interrogans serovar Bratislava: Reproductive failure, abortions and stillbirths 3. Pigs L. interrogans serovar Icterohaemorrhagiae & Copenhageni Reproductive failure 4. Dogs and Cats L. interrogans serovar Canicola & Icterohaemorrhagiae Hunting, male (4-7 yrs old) dogs are more at risk Severe renal disease in pups, chronic renal disease in adults (Canicola) Peracute hemorrhagic disease, acute hepatitis with jaundice (Icterohaemorrhagiae) Clinical leptospirosis is uncommon in cats Borrelia 1. Lyme disease Caused by B. burgdorferi sensu lato Transmitted by tick vectors, Ixodes scapularis (Central and Eastern USA), Ixodes pacificus (West Coast USA) Clinical conditions include arthritic, neurological, and cardiac disease in dogs and humans and occasionally horses, cattle and sheep Rodents, birds and lizards act as reservoir hosts 2. Avian spirochaetosis Caused by B. anserina 18 | P a g e  Transmitted by soft ticks (Argas persicus) and occasionally through contact with infected material such as blood, tissue or excreta Characterized by fever, weight loss and anemia in domestic poultry Brachyspira and Treponema 1. Swine dysentery Caused by B. hyodysenteriae Feco-oral route in 6 to 12-week-old pigs Appetite is decreased and thirst may be evident, emaciated due to poor feed conversion, mucoid diarrhea 2. Porcine intestinal spirochaetosis Caused by B. pilosicoli Like swine dysentery but less severe 3. Bovine digital dermatitis/contagious ovine digital dermatitis Treponema species may be present but pathogenesis is poorly understood Pathogenic, anaerobic, non-spore-forming Gram (-) bacteria o Gram (-) anaerobic bacteria o Endospores not produced o Majority are commensal on mucosal surfaces, principally in the alimentary tract o Opportunistic pathogens Clinical infections: 1. Calf diphtheria Necrotic pharyngitis or laryngitis in calves under 3 months of age Caused by entry of Fusobacterium necrophorum in damaged pharyngeal or laryngeal mucosa 2. Bovine liver abscess Hepatic abscessation in feedlot cattle Fusobacterium necrophorum proliferates in damaged ruminal walls then reach the liver through portal vein 3. Necrotic rhinitis of pigs Chronically ill animals may have permanent facial deformity (“bull nose”) Fusobacterium necrophorum enters the snout through abrasions in the nasal mucosa 4. Thrush of the hoof Necrotic condition of equine hoof associated with poor hygiene, wet conditions, and irregular hoof cleaning, characterized by foul- smelling discharge in the sulci close to the frog of hind feet (common) Fusobacterium necrophorum infection is secondary to hoof damage 19 | P a g e  5. Black spots of bovine teats Memory aid: Fusobacterium May predispose to mastitis necrophorum is associated Invasion by F. necrophorum with anything rotten. Think footrot, quittor, necrotic Mycoplasma stomatitis, calf diphtheria, o Smallest free-living prokaryotic and necrotic rhinitis microorganisms o Lack cell walls, not stained by the Gram method o Microcolonies have “fried egg” appearance Clinical infections: 1. Contagious bovine pleuropneumonia Caused by Mycoplasma mycoides subsp. Mycoides (small colony type) Transmission is through aerosols Affected animals show expiratory grunting, coughing, and mucopurulent nasal discharge (arthritis, synovitis, and endocarditis may be present in calves) Animals adopt a characteristic stance with head and neck extended and elbows abducted Post-mortem findings include marbled lung appearance 2. Mycoplasma bovis infection Can cause severe calf pneumonia in the absence of other pathogens, and exacerbate respiratory disease caused by Pasteurella and Mannheimia species 3. Contagious agalactia of sheep and goats Caused by Mycoplasma agalactiae Characterized by mastitis, arthritis and conjunctivitis, pregnant animals may abort 4. Contagious caprine pleuropneumonia Caused by M. capricolum subsp. Capripneumoniae Signs are similar to bovine pleuropneumonia but less severe 5. Enzootic Pneumonia of pigs Caused by Mycoplasma hyopneumoniae Pigs of all ages are susceptible (intensive rearing) Characterized by coughing, poor growth and respiratory distress Confirmatory isolation and identification (gold standard), PCR- based tests (most sensitive test) 6. Other mycoplasmal diseases of pigs Mycoplasma hyorhinis causes chronic progressive polyserositis (up to 10 weeks) Mycoplasma hyosynoviae causes self-limiting arthritis and synovitis (10-30 weeks old) 20 | P a g e  7. Mycoplasmal diseases of poultry Mycoplasma gallisepticum causes chronic respiratory disease in chickens and infectious sinusitis in turkeys Transmitted through embryonic infection or aerosols Mycoplasma synoviae causes infectious synovitis in chickens and turkey Mainly transmitted by aerosols 8. Feline infectious anemia Caused by Mycoplasma haemofelis found in the surfaces of erythrocytes Common in free roaming toms (1-3 years of age) Uncertain exact mode of transmission, bite wounds, biting arthropods, perinatal transmission has been suggested 9. Infection with Mycoplasma suis One of the most common hemotropic mycoplasma infections of farm animals Signs include fever, hemolytic anemia, weakness, and jaundice Chlamydia and Chlamydophila o Spherical intracellular bacteria Elementary bodies - small, o Replicate only in living cells infectious extracellular forms of o May be found in the form of chlamydia elementary body or reticulate body Reticulate bodies - intracytoplasmic Clinical infections: form involved in the process of 1. Enzootic Abortion of Ewes (EAE) replication Caused by Chlamydophila abortus is primarily a disease of intensively managed flocks Infection occurs following ingestion of placentas and uterine discharge from infected ewes 2. Feline chlamydiosis Caused by Chlamydophila felis through direct or indirect contact with conjunctival or nasal secretions Characterized by conjunctivitis and less commonly, rhinitis 3. Sporadic bovine encephalomyelitis A bovine neurological disease caused by Chlamydophila pecorum Affected animals are usually 3 years of age, develop a high fever, and exhibit incoordination, depression, excessive salivation and diarrhea 4. Avian chlamydiosis A generalized infection affecting the digestive and respiratory tract caused by Chlamydophila psittaci Infection is acquired through inhalation or ingestion of elementary bodies from respiratory discharges and in feces 21 | P a g e Rickettsiales and Coxiella burnetti o Minute, non-motile, Gram (-) bacteria o Obligate intracellular pathogens, replicating only in cells o Demonstrated in blood smears by Romanowski stains Clinical infections: 1. Rocky mountain spotted fever in dogs Caused by R. rickettsii Transmitted by reservoir tick vectors: North America - D. variabilis & D. andersoni; Central and South America - Rhipicephalus sanguineus and Amblyomma cajennense Produces vasculitis, increase vascular permeability and hemorrhage 2. Canine monocytic ehrlichiosis Caused by Ehrlichia canis in tropical and subtropical regions Rhipicephalus sanguineus as the main tick vector A generalized disease causing fever, thrombocytopenia, leukopenia and anemia 3. Canine granulocytic ehrlichiosis Caused by E. ewingii in the USA Neutrophils are the primary target cells 4. Canine cyclic thrombocytopenia Caused by Anaplasma platys Parasitizes platelets 5. Potomac horse fever Caused by Neorickettsia risticii Needs fluke vector and an intermediate snail reservoir The organism is acquired through accidental ingestion of aquatic insects infested with infected metacercariae fever, anorexia, depression, colic, leukopenia, and laminitis may be evident Epithelial cells of crypts in the colon, monocytes, tissue macrophages and mast cells are targets 6. Bovine petechial fever (Ondiri disease) Caused by E. ondiri Limited to highland areas of Kenya and other East African countries 7. Tick-borne fever Caused by Anaplasma phagocytophilum, affects domestic and wild ruminants The main vector is the tick Ixodes ricinus The organism can survive and multiply within neutrophils, eosinophils and monocytes Severe leukopenia and impaired function of neutrophils and lymphocytes 22 | P a g e  8. Equine granulocytic ehrlichiosis Caused by A. phagocytophilum which infects horses Transmitted by Ixodes species of ticks Characterized by fever, depression, ataxia, limb edema, icterus and petechial hemorrhage on mucus membranes 9. Heartwater Caused by E. ruminantium limited to sub-Saharan Africa and some Caribbean islands Transmitted by Amblyomma species 10. Salmon poisoning Caused by Neorickettsia helminthoeca limited to Northwest Pacific Coast of North America An acute and frequently fatal infection of Canidae Dogs become infected by ingesting raw salmon containing infected fluke (Nanophyetus salmincola) metacercariae Characterized by fever, anorexia, weakness, and depression followed by persistent vomiting and bloody diarrhea 11. Elokomin fluke fever Caused by N. elokominica with same fluke vector as of salmon poisoning Milder than salmon poisoning and has a wide host range (canidae, bears, raccoons, and ferrets) 12. Bovine anaplasmosis (gall sickness) Caused by Anaplasma marginale in tropical and subtropical regions Characterized by fever, anemia and icterus Main vectors are Boophilus species 13. Aegyptianellosis in poultry Caused by Aegyptianella pullorum The vector is a tick of the genus Argus 14. Q fever Caused by Coxiella burnetii An influenza-like occupational disease of farmers, abattoir workers, and veterinarians Bacterial species of limited pathogenic significance Bartonella species (cat-scratch disease in humans) Aeromonas and Vibrio species, and Plesiomonas shigelloides Ornithobacterium rhinotracheale (respiratory disease in poultry) Riemerella anatipestifer (death in young ducks) 23 | P a g e Simonsiella o Have a large, ladder-like appearance o A gram-negative gliding bacterium considered to be a common resident in the oral cavities of dogs o Their presence during sample collection indicates contamination from the oropharynx Antibiotic-Responsive Diarrhea (ARD) in DOGS Formerly called small-intestinal bacterial overgrowth (SIBO) Cause is unknown. Diarrhea that responds to antibiotic therapy. If all antibiotics have failed, try TYLOSIN ↓Cobalamin (enteric bacteria utilizing Cobalamin) ↑Folate (bacterial production of Folate) Exocrine pancreatic insufficiency (EPI) in dogs is often complicated by SIBO Classification of bacteria based on Gram Stain Gram-positive Gram-negative Staphylococcus Escherichia Histophilus Treponema Streptococcus Salmonella Haemophilus Fusobacterium Actinomyces Yersinia Avibacterium Rickettsia Arcanobacterium Proteus Taylorella Ehrlichia Actinobaculum Klebsiella Bordetella Neorickettsia Nocardia Serratia Moraxella Anaplasma Dermatophilus Pseudomonas Brucella Aegyptianella Corynebacterium Burkholderia Campylobacter Coxiella Rhodococcus Actinobacillus Helicobacter Chlamydia Listeria Pasteurella Lawsonia Chlamydophila Erysipelothrix Mannheimia Leptospira Bacillus Bibersteinia Borrelia Clostridium Francisella Brachyspira Mycoplasma – Phylogenetically Gram-positve, but it lacks the macromolecules required in its membrane that could make it stain violet in Gram staining. Mycobacterium – does not retain any common bacteriological stain due to high lipid content in its wall, and thus is neither Gram-positive nor Gram-negative; hence Ziehl- Neelsen staining, or acid-fast staining, is used. 24 | P a g e Memory aid: Gram-positive: (No Basic List for All(3) Dermatologic Erythematous Rhods – S2C2) Nocardia, Bacillus, Listeria Arcanobacterium, Actinobaculum, Actinomyces, Dermatologic, Erysipelothrix, Rhodococcus – Staphylococcus, Streptococcus, Clostridium, Corynebacterium; Gram-negative: the rest of the herd except the two Mycos (Mycoplasma and Mycobacterium); Except Trueperella, when you hear the suffix “ella” think negative (e.g., Brucella, Francisella, Pasteurella etc.) Intracellular Aerobes Anaerobe Chlamydia Bacillus Clostridium Chlamydophila Mycobacterium Rickettsia Pseudomonas Ehrlichia Burkholderia Neorickettsia Francisella Anaplasma Bordetella Aegyptianella Moraxella Coxiella Brucella Lawsonia Francisella Other bacteria are mostly facultative anaerobes (e.g., Staphylococcus,Streptococcus, Actinomyces, Arcanobacterium, Actinobaculum, Corynebacterium, Listeria, Erysipelothrix etc.) Classification of Bacteria based on Shapes Spherical (Cocci) Coccobacilli Rods (Bacilli) (intermediate) Staphylococcus Rhodococcus Listeria Bibersteinia Streptococcus Francisella Erysipelothrix Histophilus Brucella Bacillus Haemophilus Chlamydia Clostridium Avibacterium Chlamydophila Escherichia Taylorella Salmonella Bordetella Yersinia Moraxella Pseudomonas Campylobacter Burkholderia Helicobacter Actinobacillus Lawsonia Pasteurella Mycobacterium Mannheimia 25 | P a g e  Branching: Actinomyces, Arcanobacterium, Actinobaculum, Nocardia, & Dermatophilus Spiral: Leptospira, Borrelia, Brachyspira and Treponema Pleomorphic: Corynebacterium Spore formers Pus formers Bacillus Staphylococcus Clostridium Streptococcus Corynebacterium Predilections of bacteria Eye Joints Respiratory Mucous Membranes Moraxella Histophilus Pasteurella Streptococcus (Haemophilus) Mannheimia Actinomyces Erysipelothrix Bibersteinia Trueperella Rhodococcus Actinobaculum Bordetella Histophilus Erysipelothrix (Haemophilus) (Heart) Avibacterium Actinobacillus GIT Environment/Soil Skin Reproductive Enterobacteriaceae Nocardia Dermatophilus (Scab) Brucella Clostridium Rhodococcus Staphylococcus Campylobacter Campylobacter Listeria Erysipelothrix Helicobacter Helicobacter Bacillus Clostridium 26 | P a g e Unique Bacteria to Remember When you hear of... Think... Chinese letters Corynebacterium Nitrate-reducing/ Non-nitrate- Corynebacterium, Enterobacteriaceae reducing Urease-positive Brucella Gull-winged shapes Campylobacter Chocolate agar (X and V factor) Haemophilus, Taylorella, Histophilus, Avibacterium Tram track Dermatophilus Fried egg/Umbonate/No cell wall Mycoplasma Bipolar staining Yersinia, Pasteurella, Burkholderia, Klebsiella Rods in pairs Moraxella bovis Tumbling motility/Cold enrichment Listeria Salmon-pink Rhodococcus H2S on TSI Erysipelothrix Romanowski Rickettsiales and Coxiella burnetti ZN positive/mycolic acid/acid fast Mycobacterium MZN positive Nocardia, Brucella, Chlamydia MZN negative Actinomyces, Trueperella, and Actinobaculum Pit on Loeffler’s serum slope Trueperella pyogenes 27 | P a g e FUNGI Dermatophytes o Members of the phylum Ascomycota o Affinity for keratinized structures, skin, Arthrospores (arthroconidia) – hair, and nails infectious form o Cause characteristic circular skin lesions Sabouraud dextrose agar – a termed “ringworm” type of agar used to cultivate o Zoonotic: most human infections are Dermatophytes caused by Microsporum canis contracted from infected cats Morphological features of macroconidia of some Microsporum species: 1. Microsporum canis – spindle-shaped 2. Microsporum gypseum – boat-shaped 3. Microsporum nanum – pear-shaped Morphological features of macroconidia of Trichophyton mentagrophytes and chlamydospores of T. verrucosum: 1. Trichophyton mentagrophytes – cigar-shaped 2. Trichophyton verrucosum – chlamydospores in chains; macroconidia – rare Clinical infections: 1. Dermatophytosis in small animals Cats Commonly caused by M. canis Classical ringworm lesions Persian cats appear to have heritable predisposition Dogs Caused by M. canis, M. gypseum (acquired from soil), T. mentagrophytes and T. mentagrophytes var. erinacei (acquired from hedgehogs) Presents as areas of alopecia, scaling, and broken hairs surrounded by inflammatory zones 2. Dermatophytosis in cattle Trichophyton verrucosum is the usual cause Calves are often affected 3. Dermatophytosis in horses T. equinum is the most common cause M. equinum infection occurs from time to time in young horses and is acquired from contaminated harness or grooming gear M. gypseum infection exhibits lesions usually confined to the dorsum and is acquired from rolling in soil T. mentagrophytes - rare T. verrucosum is acquired from contact with infected cattle 28 | P a g e  4. Dermatophytosis in pigs Acremonium spp. – fungi that cause Uncommon Mycetomas; also, the biological Caused by M. nanum source of Cephalosporins. 5. Favus in poultry (*Favus is the name for ringworm if it affects poultry) White patchy crusts on the comb and wattle of gallinaceous birds Caused by M. gallinae Aspergillus o Members of the phylum Ascomycota o Ubiquitous, saprophytic moulds o Respiratory pathogens, acquired by inhalation or spores Clinical infections: 1. Brooder pneumonia in young chickens Caused by A. fumigatus, affecting newly hatched chickens, resulting to formation of yellow nodules in the lungs and air sacs 2. Aspergillosis in mature birds Caused by A. fumigatus, affecting poultry, captive penguin, raptors and psittacine birds Acquired through inhalation of spore-laden from contaminated litter or feed Characterized by dyspnea and emaciation; yellowish nodules in the lungs and air sacs resembling avian tuberculosis 3. Guttural pouch mycosis in horses Caused by A. fumigatus Usually unilateral, plaque-like lesion in the pouch wall mucosa 4. Nasal aspergillosis in dogs Caused by Aspergillus species Unilateral clinical signs, common in dolichocephalic breeds of dog 5. Mycotic abortions in cows Sporadic occurrence caused by A. fumigatus proliferation in damp hay Reaches the uterus hematogenously, causes placentitis leading to abortion in late gestation Yeasts o Eukaryotic, unicellular budding cells o Asexual reproduction by blastoconidia o Candida albicans Chlamydospores are produced on corn meal agar Commensal on mucocutaneous surfaces; uncommon in the environment Opportunistic infections, related to immunosuppression o Cryptococcus neoformans 29 | P a g e  Opportunistic infection from environmental sources o Malassezia pachydermatis Bottle-shaped cells Commensal on the skin of mammals and birds Clinical infections: Candida 1. Dogs Enteritis, cutaneous lesions Mycotic stomatitis (pups) 2. Cats Cystitis, pyothorax, and ocular lesions Mycotic stomatitis (kittens) 3. Cattle Reduced fertility, abortion, and mastitis (cow) Rumenitis and gastroesophageal ulcers (calves) 4. Horse Pyometra (mare), and ocular lesions Mycotic stomatitis and gastroesophageal ulcers (foals) 5. Poultry Cloacal and vent infections (geese and turkeys) Thrush of the esophagus or crop (chickens) Cryptococcus 1. Feline cryptococcosis Nasal form: Most common form Characterized by flesh-coloured, polyp-like nasal granulomas Sometimes, presented with swollen nasal cavity (“roman nose” appearance); granulomatous rhinitis and sinusitis Cutaneous form: affects the face, head and neck Neural form: neurological signs Ocular form: chorioretinitis Malassezia pachydermatis 1. Canine seborrheic dermatitis Hypersensitivity disorders, keratinization defects, immunosuppression, and persistently moist skin folds Lesions are more frequently seen in skin folds Pruritus and erythema, accompanied by foul-smelling, greasy exudate with matting of hair 2. Canine otitis externa 30 | P a g e  Characterized by dark pungent discharge from the ear canal and intense pruritus with head shaking, scratching, and rubbing of the ears Poor ear conformation (long, pendulous ears & hairy external canal), wax retention and immunosuppression are predisposing factors Macrorhabdus ornithogaster (“Megabacteria”) Known as the avian gastric yeast Weight Loss, diarrhea, and vomiting Found in the lower portion of the proventriculus of Budgerigars Trichosporon beigelii A soil saprophyte Causes white “piedra” in humans Geotrichum candidum Soil saprophyte Associated with diarrhea of dogs and apes, and pig lymphadenitis Dimorphic fungi o Occur as moulds in the environment and as yeasts forms in animal tissues o Soil saprophytes Clinical infections: Blastomyces dermatitidis 1. Canine blastomycosis Young male sporting dog breeds Acquired through inhalation of aerosolized spores or mycelial fragments Presenting signs include coughing, exercise intolerance and dyspnea Figure 6.Chest X-ray of a dog with (pulmonary blastomycosis blastomycosis showing the typical - usual form) “snowstorm” pattern Histoplasma capsulatum much smaller than Blastomyces and Use PAS, Gomori’s Methenamine difficult to detect in H & E stain Silver or Gridley’s Fungal Stains to seen in the river valleys of the see yeast forms in macrophages and Central US, associated with bird and giant cells bat droppings 1. Canine and feline histoplasmosis Mostly asymptomatic Caused by H. capsulatum var. capsulatum Signs are related to pulmonary and intestinal (in dogs) involvements 31 | P a g e  2. Epizootic lymphangitis Caused by H. capsulatum var. farciminosum High prevalence in close contact horses Acquired from environmental sources through minor skin damage on the limbs Characterized by lymphocutaneous lesions similar to equine farcy Coccidioides immitis: limited to Mexico, and Central and South America (Think “DUSTY DESERT”: spores are carried on dust and inhaled) 1. Canine coccidioidomycosis Asymptomatic in most cases Commonly pulmonary lesions 2. Equine coccidiomycosis Clinical signs are nonspecific Related to pulmonary and musculoskeletal Sporothrix schenckii 1. Equine sporotrichosis Lymphocutaneous form (most common) Subcutaneous edema from affected limb due to lymphatic obstruction 2. Feline sporotrichosis Nodular skin lesions on limb extremities, head, and tail 3. Canine sporotrichosis Manifests as multiple ulcerated and crusted, alopecic, cutaneous lesion over the head and trunks Zygomycetes o Broad aseptate hyphae o Saprophytes, widely distributed in the environment o Mucorales and Mortierellales Lichtheimia (Absidia), Mucor, Rhizomucor, and Rhizopus, Saksenaea (Mucorales) Mortierella (Mortierella) Commonly known as “pin” or “bread” moulds o Entomophthorales Basidiobolus and Conidiobolus Produce a single conidium which forcibly discharged when mature Clinical infections: Mucorales and Mortierellales 1. Mycotic abortion Abortion in cattle in late gestation Mortierella wolfii, Lichtheimia species, Mucor species, Rhizomucor species and Rhizopus species are all implicated 32 | P a g e  2. Alimentary tract infections Mycotic rumenitis (cattle), abomasitis and ulceration (calves) Acute gastrointestinal zygomycosis has been recorded in piglets Species of the genus Lichtheimia, Absidia, and Mucor are involved 3. Mycotic pneumonia Acute fatal pneumonia of cows caused by Mortierella wolfii Entomophthorales 1. Basidiobolus infection Cause cutaneous lesions in horse and dog which resemble those associated with Pythium insidiosum 2. Conidiobolus infection Cause granulomas in horses, sheep, and llamas Cause pyogranulomatous and cutaneous lesions in dogs Fungus-like organisms o Pythium insidiosum: causes cutaneous pythiosis in horse and gastrointestinal pythiosis in dogs o Rhinosporidium seeberi: Rhinosporidiosis, which occurs in horse, dogs, and cattle, characterized by nasal polyp formation o Lacazia loboi: aquatic yeast-like organism; causes cutaneous lesions in humans and dolphins Pneumocystis carinii o Pneumonia that occurs only in immunosuppressed animals, occasionally affects horses and dogs Mycotoxins and Mycotoxicoses o Certain fungal species produce secondary metabolites (mycotoxins) in growing crops or stored feed under defined environmental conditions o Mycotoxins are diverse group of heat-stable, low molecular weight, and non- antigenic compounds that can induce characteristic disease process upon ingestion of toxic level o The effects of mycotoxins include immunosuppression, teratogenesis or carcinogenesis o Disease caused by mycotoxins are non-contagious, tend to be sporadic, seasonal, and associated with certain batches of feed Clinical mycotoxicoses: 1. Aflatoxicosis Aflatoxins produced by Aspergillus flavus and A. parasiticus, present in maize, stored grains, ground nuts, and soybeans Affect pigs, poultry, cattle, dogs, and trout worldwide Hepatotoxicity, immunosuppression mutagenesis, teratogenesis and carcinogenesis Ill-thrift, drop in milk yield, rarely death 33 | P a g e 2. Citrinin toxicosis Citrinin produced by Penicillium citrinum, P. expansum and Aspergillus terreus present in wheat, oats, maize, barley and rice Affect pigs, cattle, poultry worldwide Kidney lesions in pigs, hemorrhagic syndrome in cattle Increased water consumption in pigs, dilute urine; multiple hemorrhages on mucosal surfaces in cattle 3. Cyclopiazonic acid toxicosis Cyclopiazonic acid produced by Aspergillus species and some strains of Penicillium camemberti in stored grain meal Affect pigs and poultry worldwide Interference with ion transport across cell membranes Weakness, food refusal and anorexia in pigs; weight loss in poultry 4. Diplodiosis Unidentified neurotoxin produced by Diplodia maydis present in maize cobs Affects sheep, cattle, goats and horses in South Africa and Argentina Neurotoxicity Neurogenic signs in adults and perinatal deaths in lambs and calves 5. Ergotism ergotamine, ergometrine, and ergocristine produced by Claviceps purpurea present in the seedhead of ryegrass and other grasses and cereals Affect cattle, sheep, deer, horse, pig and poultry worldwide Neurotoxicity and vasoconstriction Convulsions, gangrene of extremities, agalactia and hyperthermia in hot climates 6. Facial eczema Sporidesmin produced by Pithomyces chartarum in the pasture litter from ryegrass and white clover Affect ruminants in New Zealand, Australia, South Africa, South America, occasionally USA and parts of Europe Hepatotoxicity, and biliary occlusion Photosensitization and jaundice 7. Fescue toxicosis Ergovaline produced by Fescue grass (Festuca Neotyphodium coenophialum arundinacea) - is a present on tall fescue grass perennial grass adapted to Affects cattle, sheep, and horse in a wide range of soil types the USA, New Zealand, Australia, and climatic conditions, and Italy commonly found in the Vasoconstriction USA 34 | P a g e  Dry gangrene in cold weather (fescue lameness); hyperthermia and low milk yield (summer fescue toxicosis) 8. Fumonisin toxicosis Fumonisins produced by Fusarium verticillioides and other Fusarium species present on standing or stored maize Affects horses and other equidae and pigs in Egypt, South Africa, USA, and Greece Mycotoxic leukoencephalomalacia in horses; porcine pulmonary edema Neurological signs include weakness, staggering, circling and depression in horses, pulmonary edema and hydrothorax in pigs 9. Mouldy sweet potato toxicity 4-ipomeanol derivative produced by Fusarium solani and Fusarium semitectum present in sweet potatoes (Ipomea batatas) Affects cattle in the USA, Australia and New Zealand Cytotoxicity producing interstitial pneumonia and pulmonary edema Respiratory distress or sudden death may occur 10. Ochratoxicosis Ochratoxins produced by Aspergillus alutaceus, other Aspergillus species, Penicillium verrucosum, and other Penicillium species present in stored barley, maize, and wheat Affects pigs and poultry worldwide Degenerative renal changes Polydipsia and polyuria in pigs; drop in egg production in birds 11. Estrogenism Zearalenone produced by Fusarium graminearum and other Fusarium species in stored maize, barley, pelleted cereal feeds and maize silage Affects pigs, cattle, and occasionally sheep worldwide Estrogenic activity Hyperemia and edema of the vulva and precocious mammary development in young gilts; anestrus and reduced litter size in mature sows; reduced fertility in cattle and sheep 12. Slaframine toxicosis Slaframine produced by Rhizoctonia leguminicola present in legumes, especially red clover, and in pasture of hay Affects sheep, cattle, and horse in the USA, Canada, Japan, France and the Netherlands Cholinergic activity Salivation, lacrimation, bloating and diarrhea; rarely death 13. Tremorgen intoxications Perennial ryegrass staggers 35 | P a g e  Lolitrem B produced by Neotyphodium lolii in perennial ryegrass (Lolium perenne) Affects cattle, pigs, poultry, sheep, horse, and deer in the USA, Australia, New Zealand, and Europe Neurotoxic: muscular tremors, incoordination, convulsive seizures and/or collapse Paspalum staggers Paspalinine and paspalitrems A, B and C produced by Claviceps paspali on the seedheads of paspalum grasses Affects cattle, sheep, and horses in the USA, South America, New Zealand, and Australia Neurotoxic: muscular tremors, incoordination, convulsive seizures and/or collapse 14. Trichothecene toxicosis Deoxynivalenol toxicosis Deoxynivalenol produced by Fusarium graminearum, F. culmorum and other Fusarium species on cereal crops Affects pigs and poultry in countries with wet seasons and temperate climates Neurotoxicity Feed refusal, vomiting and poor growth; teratogenic in rodents T-2 toxicosis T-2 toxin produced by Fusarium sporotrichioides, F. poae and other Fusarium species on mouldy wheat and other cereals Affects pigs, cattle and poultry in the USA and some other countries Cytotoxicity, immunosuppression, and hemorrhage Feed refusal in pigs; rumenitis in cattle; beak lesions and abnormal feather formation in chicken Diacetoxyscirpenol toxicosis Diacetoxyscirpenol produced by Fusarium tricinctum and other Fusarium species on cereals Affects cattle, pigs, and poultry in North America, and some other regions Necrotic lesions, mucosal hemorrhages, and vomiting ALGAE and CYANOBACTERIA Prototheca o Eukaryotic colorless algae o Widely distributed in sewage and organic matter Clinical infections: 1. Cutaneous protothecosis in cats Caused by tissue invasion of dermis by Prototheca wickerhamii Producing skin lesions 36 | P a g e  2. Disseminated protothecosis in dogs Caused by tissue invasion of intestinal mucosa by Prototheca zopfii Producing hemorrhagic colitis followed by bloody diarrhea along with signs of neurological or ocular disturbances 3. Protothecal mastitis in cows Caused by tissue invasion of bovine mammary gland by Prototheca zopfii Producing mastitis Chlorella o Eukaryotic green algae o Morphologically similar to Prototheca species but contain chloroplasts o Associated rarely with lymphadenitis in ruminants due to its characteristic tissue invasiveness Cyanobacteria o Prokaryotic photosynthetic organisms o From “algal” blooms on freshwater surfaces o Formerly known as “blue-green algae” o Produces potent hepatotoxins and neurotoxins affecting fish, birds and mammals 37 | P a g e VIRUSES Herpesviridae o Enveloped DNA viruses with icosahedral symmetry o Replicates in nucleus o Labile in the environment o Cause diseases of the respiratory, reproductive, and nervous systems Clinical infections: 1. Infectious Bovine Rhinotracheitis and pustular vulvovaginitis Caused by bovine herpesvirus 1 (BHV-1) which is usually acquired through aerosols Replication occurs in the mucous membranes of the upper respiratory tracts and vagina or prepuce Inflamed nares (“red nose”), conjunctivitis, lacrimal discharge, and corneal opacity (Respiratory form); vaginal discharge, frequent urination or lesions on preputial mucosae (vulvovaginitis) Infected animals recover within 1-2 week if not complicated with secondary bacterial infections 2. Aujeszky’s disease Caused by porcine herpesvirus 1, also referred to as Aujeszky’s disease virus (ADV), which is usually transmitted through inhalation of aerosols from infected pigs or by nose-to-nose contact The virus is shed in oronasal secretions, milk and semen Carnivores acquire infection through ingesting infected pig carcasses; sheep (highly susceptible) may be infected by direct contact with pigs Young pigs are most severely affected Neurological, respiratory, and reproductive signs are features of the disease Intense pruritus (“mad itch”) leading to mutilation is also a feature of the disease in ruminants 3. Equine Rhinopneumonitis and Equine Herpesvirus Abortion Caused by equine herpesvirus 1 (EHV-1) and equine herpesvirus 4 (EHV-4) EHV-1 infection is associated with respiratory disease, abortion, fatal generalized disease in neonatal foals and encephalomyelitis; EHV-4 is primarily associated with respiratory disease, but sporadic abortions may also be present Transmission usually occurs by the respiratory route following contact with infected nasal secretions, aborted fetuses, placentae or uterine fluids 4. Equine coital exanthema Caused by equine herpesvirus 3 (EHV-3) 38 | P a g e  It is a benign venereal disease of horses causing lesions on external genitalia and occasionally on the teats, lips, and nares; NOT associated with viremia and abortion 5. Canine herpesvirus infection Caused by canine herpesvirus 1 (CHV-1) Usually asymptomatic in adults; generalized disease with accompanying high mortality in pups Infection usually occurs by the oronasal route or possible in-utero infection Virus replicates most effectively at subnormal temperatures, that explains why pups are more vulnerable to widespread viral replication Bitches may abort; young puppies stop suckling, show signs of abdominal pain, whine endlessly and die within days 6. Feline Viral Rhinotracheitis (FVR) Caused by feline herpesvirus 1 (FHV-1) Virus is shed in oral and oculonasal secretions and require close contact for transmission Accounts for about 40% of respiratory infections in cats Young cats display signs of acute upper respiratory tract infection Fever, sneezing, inappetence, hypersalivation, conjunctivitis (eyelids stick together) and oculonasal discharge 7. Infectious laryngotracheitis Caused by gallid herpesvirus 1 (GaHV-1) Transmitted through aerosols Highly contagious respiratory disease of chickens Characterized by coughing, gasping, moist rales, oculonasal discharge, expectoration of blood-stained mucus and head shaking 8. Marek’s disease Caused by gallid herpesvirus 2 (Marek’s disease virus) Contagious lymphoproliferative disease of chickens between 12-24 weeks of age Viral replication in feather follicles, desquamated cells (“dander”) with cell-free virus are released and contaminate poultry-house dust and litter Chicks acquire infection by inhalation of viral particles present in the environment Female are more susceptible than males Clinical signs include paralysis of legs and Differentiation from lymphoid leukosis: wings and depression Based on the age of affected birds, the in conjunction with incidence of clinical signs and the peripheral nerve histopathological findings thickening 39 | P a g e  9. Malignant catarrhal fever Frequently fatal sporadic disease of ruminants Caused by alcelaphine herpesvirus 1 (AlHV-1) and ovine herpesvirus 2 (OvHV-2) OvHV-2 is carried by 95-99% of sheep in North America which shows no symptoms AlHV-1 is transmitted vertically and horizontally in wildebeest populations The pathogenesis of MCF is poorly understood (virus enters body through the upper respiratory tract) Characterized by sudden onset of fever, oculonasal discharge, enlarged lymph nodes, conjunctivitis, corneal opacity and erosive mucosal lesions in the upper respiratory tract The subfamily Alcelaphinae of the family Bovidae contains wildebeest, hartebeest, bonteboks and several similar species Figure 7.Blue wildebeest Figure 8. Coke's hartebeest Figure 9. Bontebok 40 | P a g e Papillomaviridae o Double-stranded DNA viruses o Icosahedral symmetry o Cause papillomas and fibropapillomas in domestic animals Clinical infections: 1. Bovine cutaneous papillomatosis “Rice grain” type - caused by BPV-5 (Teat fibropapilloma) “Frond” type - caused by BPV-6 (Teat papilloma) Head and neck fibropapilloma - caused by BPV-1 or 2 Cutaneous papilloma - caused by BPV-3 Self-limiting, so treatment is seldom required 2. Bovine alimentary papilloma-carcinoma complex Papillomas of the esophagus, rumen and reticulum Associated with BPV-4 infection Possible malignant transformation (squamous cell carcinoma) when animals are ingesting bracken fern Nodular fibropapillomas found in similar locations: caused by BPV-2 3. Enzootic hematuria Neoplastic lesions in the bladder wall upon BPV-2 infection with concurrent ingestion of bracken fern 4. Equine papillomatosis Papillomas on the muzzle and legs, and genital tract of 1-3 years old horses Usually regress after several months 5. Equine sarcoid caused by BPV-1 Fibroblastic skin tumors of 3-6 years old donkeys and mule; commonly arise on the head, ventral abdomen, and limbs Arbitrarily categorized as verrucous or fibroblastic Sarcoids are the most diagnosed tumor of equids, representing 20% of all equine neoplasms and 36% of all skin tumors in horses Figure 10.Verrucous (wart-like) equine sarcoid Adenoviridae o Double-stranded DNA viruses o Icosahedral symmetry o Forms intranuclear inclusion bodies o Systemic and respiratory diseases in dogs 41 | P a g e  o Systemic disease in poultry Clinical infections: 1. Infectious canine hepatitis Caused by canine adenovirus-1 (CAV-1) Affects liver and vascular endothelium Transmission occurs after ingestion of urine, feces, or saliva from infected animals Jaundice is UNCOMMON, corneal edema and anterior uveitis may develop and is attributable to immune complex deposition Basophilic intranuclear inclusion bodies in hepatocytes, Kupffer cells and endothelial cells are confirmatory Vaccination with modified live CAV-1 vaccines result in mild nephropathy with shedding of virus in urine and corneal opacity (occasionally); in contrast, modified Canine adenovirus type 2 (CAV-2) live CAV-2 vaccines infection, causes mild clinical signs similar stimulate effective to canine infectious tracheobronchitis long-lasting immunity (Kennel cough) to CAV-1 2. Egg drop syndrome Caused by an adenovirus prevalent in ducks, which affects laying hens up to 36 weeks of age Characterized by drop in egg production or by failure to reach peak production Poxviridae o DNA viruses with complex symmetry o Skin lesions are prominent feature o Replicate in cytoplasm Clinical infections: 1. Orf (contagious pustular dermatitis/contagious ecthyma) Caused by orf virus under the genus Parapoxvirus which is very stable and can survive in scab material for months Transmitted through direct or indirect contact The epitheliotropic virus produces proliferative wart-like lesions on the commissures of the lips of goats and sheep, following entry through skin abrasions 2. Sheep pox and goat pox Caused by members of the genus Capripoxvirus An OIE listed disease, endemic in Southeastern Europe, the Middle East, Africa, and Asia 3. Lumpy skin disease Caused by Neethling virus, a Capripoxvirus Endemic in subsaharan Africa and Madagascar An OIE listed disease that affects cattle 42 | P a g e  Circumscribed skin nodules on the head, neck, udder and perineum that may develop into “sit-fasts” The principal method of transmission is by mechanical transfer through biting insects 4. Swine pox Mild and often goes unrecognized skin disease caused by a member of the genus Suipoxvirus Mechanically transmitted by the pig louse (Haematopinus Suis) 5. Fowlpox Two forms: cutaneous form (dry pox) and diphtheric form (wet pox) Caused by fowl poxvirus of the genus Avipoxvirus Intracytoplasmic inclusions "Borrel bodies" are tiny virus- called “Bollinger bodies” containing granules that cluster to contain small elementary form "Bollinger bodies", are bodies (Boller bodies) may found in tissue cells of fowlpox be demonstrable histologically 6. Myxomatosis Severe generalized disease of rabbits caused by myxomavirus of the genus Leporipoxvirus An OIE listed disease characterized by gelatinous cutaneous fibromas Asfarviridae o DNA virus o Icosahedral symmetry o Replicate in cytoplasm of host cells and in soft ticks of Ornithodoros species: it is the only known DNA virus transmitted by Arthropods Clinical infections: 1. African swine fever Economically important viral disease of pigs, characterized by fever, hemorrhage in many tissues and a high mortality rate Transovarial and transstadial transmission have been described in soft ticks of the genus Ornithodoros; Oronasal route (usual), feeding of uncooked swill (spread), and contact with blood from infected animals as a result of fighting (occasionally) Circoviridae o Small, single-stranded DNA viruses with icosahedral symmetry o Replicate