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Rat Diseases

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Title: Rat Diseases Author: Alberto Mendoza Last modified by: alberto Created Date: 10/28/2008 1:52:17 AM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Rat Diseases


1
Rat Diseases
2
Murine Respiratory Mycoplasmosis
  • Mycoplasma pulmonis
  • Very common and important!
  • Transmission intrauterine and aerosol
  • Chronic subclinical carrier state disease
    precipitated by stress and airway damage
  • Same as mice

3
Nasal Discharge Porphyrin Staining
4
Murine Respiratory Mycoplasmosis- Cobblestone
lung
5
Streptococcosis
  • Streptococcus pneumoniae
  • Humans are primary reservoir
  • Transmission by aerosol and contact
  • Incidence of infection is low

6
Streptococcosis
  • Clinical signs
  • URT infection that spreads to LRT
  • Especially effects young rats
  • Dyspnea, snuffling, abdominal breathing
  • Weight loss, hunched posture

7
Streptococcosis
  • Pathologic findings
  • Fibrinopurulent pleuritis
  • Pericarditis
  • Otitis media

8
Fibrinopurulent pleuritis
9
Streptococcosis
  • Diagnosis and treatment
  • Histology and culture
  • Oxytetracycline in water will control mortality
    but will not eliminate carrier state

10
Rat Bite (Haverhill) Fever
  • Streptobacillus moniliformis
  • Commensal in nasopharynx of wild and some
    laboratory rats
  • Transmission (rat bites, aerosol, contaminated
    bedding, fomites)
  • Zoonotic (endocarditis/DJD)

11
Rat Bite Fever
  • Diagnosis
  • Very difficult to culture
  • Treatment
  • Penicillin (no procaine use Pen G benzathine or
    Streptomycin if used in rats)

12
Tyzzers Disease
  • Etiology 
  • Clostridium piliforme is a gram-negative,
    obligate intracellular rod that produces spores
  • See mice.

13
Clinical Signs
  •   Subclinical infection is the most common form
    of infection in the rat. Clinical manifestations
    of Tyzzer's disease include anorexia, hunched
    posture, distended abdomen, rough hair coat and
    death.  Diarrhea has not been reported in the
    rat. 

14
Gross Pathology
  •   A "fat rat" syndrome with a flaccid segmental
    dilatation of the intestine (especially of the
    ileum) has been described.  The liver typically
    has multiple pale foci throughout. Circumscribed,
    greyish foci may sometimes be observed in the
    myocardium. Multiple necrotic foci in sections
    of  liver and myocardium are often surrounded by
    a pyogranulomatous cellular infiltrate

15
Staphylococcal Dermatitis
  • A syndrome of ulcerated to scabby skin lesions on
    the dorsal cervical or cranial regions occur
    frequently in some rat colonies .  This syndrome
    appears to be seasonal with most cases occurring
    in the spring and occasionally the fall.  Trauma
    to the skin from fighting, scratching, etc. is
    thought to be an inciting factor. 
  • In many cases, Staphylococcus sp., including S.
    aureus and S. epidermidis, have been isolated
    from the wounds.

16
Staphylococcal Dermatitis
  • Combination therapy of oral benadryl (10 mg/kg)
    and chloramphenicol (50 mg/kg) has resulted in
    resolution of ulcerative lesions.   
  • Clipping  toenails of the hind foot has allowed
    healing of the wounds without antibiotic therapy
  • Clean with Nolvasan

17
Sialodacryoadenitis virus (SDAV)
  • Very common coronavirus
  • Highly contagious via aerosol, contact, fomites
  • Tropism for salivary, lacrimal, Harderian gland,
    and lung
  • Usually mild disease (strain dependent)

18
Sialodacryoadenitis virus (SDAV)
  • Clinical signs (transient)
  • Oculonasal porphyrin staining
  • Enlarged submaxillary salivary gland
  • Exophthalmus and blepharospasm (keratitis/corneal
    ulcers)
  • Photophobia
  • Sniffling, nasal crackles

19
SDAV- Exopthalmia
20
(No Transcript)
21
Swollen edematous salivary glands Cervical
lymph node enlargement
22
interstitial pneumonia
23
SDAV- Pathology Diagnosis
  • Coagulative necrosis squamous metaplasia of
    gland types above
  • Rhinitis, tracheitis, focal bronchitis,
    bronchiolitis w/ neutrophil infiltrate
  • ELISA

24
SDAV- Treatment
  • No treatment available
  • No carrier state
  • Spread contamination throughout large colony so
    that every rat gets infected or separate out
    clinical cases in small colony
  • Cease breeding for 2 months

25
Parvoviruses (RV, H-1, RMV, and RPV-1a)
  • Etiology
  • Parvoviruses are single stranded DNA viruses.
    Multiple species of parvoviruses in rats include
    Rat Virus (RV or Kilham rat virus), H-1 (Toolan's
    H-1 virus), Rat Minute Virus (RMV 1a, 1b and 1c)
    and Rat Parvovirus 1 (RPV-1a).  Of these, RV is
    the only virus species reported to cause clinical
    disease in rats

26
Parvovirus cont..
  • Transmission is primarily by direct contact or
    contact with fomites.
  • Clinical Signs Parvovirus infections are usually
    subclinical.
  • In newly infected breeding colonies, RV causes
    decreased fertility, fetal resorption, small
    litters, and runting of pups.

27
Parvovirus cont..
  • Diagnosis Serologic assays are used for virus
    identification
  • Control Eliminate seropositive rats and replace
    with parvovirus-free animals. Since parvoviruses
    can survive for weeks in the environment,
    environmental clean-up with parvovirocidal
    disinfectants is critical to prevent re-infection
    of clean rats

28
Parasites
29
Radfordia ensifera Rat Fur Mite
  • Relatively common
  • Transmission by direct contact
  • May be subclinical, or cause
  • Scruffiness, pruritus, patchy alopecia,
    self-trauma, skin ulcerations, pyoderma,
    secondary bacterial infections

30
Radfordia ensifera Rat Fur Mite
  • Diagnosis collection and examination of mites

31
Treatment
  • Ivermectin at 0.2 mg/kg SQ may be effective when
    administered every 2 to 3 weeks for a total of 3
    treatments

32
Flagellated Protozoa
  • Spironucleus muris and Giardia muris are protozoa
    that colonize the upper small intestine
    Spironucelus muris dwells in the mucosal crypts
    of the small intestine and in the pylorus, and
    Giardia muris resides along the villous
    enterocytes in the anterior small intestine.

33
Syphacia muris (Rat Pinworm)
  •  Transmission  Syphacia muris deposits eggs in
    the perianal region.  Transmission of infection
    occurs via ova ingestion.  The eggs are very
    light and have been shown to aerosolize,
    resulting in widespread exposure.  The incidence
    of infection is high.

34
Clinical Signs 
  • No signs are usually seen.  It has been reported
    that heavy parasite loads may lead to catarrhal
    enteritis, or perianal irritation causing hair to
    be chewed off the tail base

35
Diagnosis
  •  Direct exam of cecal contents, fecal flotation,
    and tape test of the perianal region will
    identify adults and eggs, respectively.  The eggs
    are slightly smaller and more symmetrical than
    those of Syphacia obvelata.

36
  • This image shows adult pinworms found in the
    cecum and large intestine

37
Treatment
  • If treatment is desired, piperazine (4 to 7 mg/ml
    water) for 3 to 10 days is effective.  Karo syrup
    can be added to the solution if the rats refuse
    to drink it. 
  • Fenbendazole medicated feed provided every other
    week for 5 weeks has been an effective treatment
    method.
  • Ivermectin at 0.2 mg/kg subQ weekly for 2 to 3
    weeks or in drinking water (25 mg/liter) for 4 to
    5 daily treatments 3 days apart.

38
Control
  • Rigid sanitary procedures, use of filtered cage
    tops to prevent aerosol transmission, and regular
    ova examinations with treatment may control the
    parasitism.

39
NEOPLASTIC DISEASES
40
Mammary Fibroadenoma
  • Most common rat tumor
  • Almost always benign
  • Rare in males
  • Fast growing
  • Will make you a hero (easy to fix)
  • Surgical excision (be quick, look for feeder
    vessel, keep rat warm and well hydrated)

41
Mammary Fibroadenoma
  • Because of the extensive mammary tissue present
    in rats, tumors may be found practically
    anywhere--behind the shoulder blades, at the base
    of the tail, etc.

Look mom, I can Carry my tumor!
42
Mammary Fibroadenoma
With surgical removal, the prognosis is good,
although recurrence in another location is
common. 
43
Pituitary Chromophobe Adenoma
  •  This is an extremely common tumor of rats,
    although incidence varies with strain.  Grossly,
    tumors are soft with an irregular surface and may
    have prominent hemorrhagic areas.  They are
    generally well circumscribed and compress
    adjacent brain tissue, occasionally causing
    hydrocephalus resulting in depression or head
    tilt.  The tumors commonly secrete prolactin

44
MISCELLANEOUS  DISEASES
45
Malocclusion
  • Autosomal recessive trait
  • Incisors overgrown poorly aligned
  • Inanition, oral trauma, ptyalism (slobbers),
    starvation
  • Diagnosis- just look
  • Do not breed these rats
  • Clip w/sharp human nail clippers but avoid
    scissoring action. Dremmel-type dental disc every
    2 to 3 months

46
Malocclusion
47
Heat Exhaustion
  • Rats have a limited ability to regulate body
    temperature with the primary thermoregulatory
    mechanism being tail vein dilation or
    constriction. 
  • Males also use scrotal vasculature for same
    purpose
  • Hyperemic scrotum (pathognomonic)

48
Heat Exhaustion
  • Predisposing factors to heat exhaustion are
    ambient temperatures above 28oC (85oF), high
    humidity (about 80), poor ventilation and
    overcrowding
  • The rats salivate profusely to wet the hair coat
    for cooling, and water consumption increases (see
    photo). 
  • Death from heat exhaustion can be diagnosed from
    history of high temperature, lack of water (or
    empty water bottles), saliva soaked chins
  • Treatment of affected rats includes cool water
    baths, forced-feeding water, and subcutaneous
    saline or 5 dextrose administration

49
Ringtail
  • Low environmental humidity (lt40)
  • Annular constriction of the base of the tail
  • More common in weanlings and rats in wire-bottom
    cages
  • Tail may slough
  • Increase humidity and provide bedding

50
Ringtail
  • Tail stumps usually heal without complication.
    Prevention of ringtail is accomplished by
    providing sufficient environmental humidity,
    reducing drafts, and maintaining room
    temperatures between 70oF to 74oF. 

51
Urinary calculi
Clinical signs may be absent but obstruction
within the pelvis may cause hydronephrosis. 
Occlusion of the neck of the bladder will cause
acute dilatation, uremia and death.
52
ZOONOTIC DISEASES 
53
Salmonella
  • Rats are reservoirs for bacterial diseases that
    are pathogenic to man. Salmonellosis, especially
    Salmonella enterica serovars Enteritidis and
    Typhimurium have been diagnosed in research and
    pet rats.
  • Salmonellae are Gram-negative toxin-producing
    enteric bacteria that are transmitted through
    contact with infected feces. Rats are frequently
    asymptomatically infected, and rarely exhibit
    systemic infection.
  • Definitive diagnosis of infection is provided by
    culture
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