Rat Production, Medicine, and Diseases PDF

VMD 85:Lab Animal Med Rat Production, Medicine and Diseases Rat - Originated from Southern Russia or Northern China - There are over 130 species - Most prominent is the black and brown rat Comparison of Black and Brown Rat...

VMD 85:Lab Animal Med Rat Production, Medicine and Diseases Rat - Originated from Southern Russia or Northern China - There are over 130 species - Most prominent is the black and brown rat Comparison of Black and Brown Rat Basic biological parameters Rats as Pets  Rats can be easily handled.  Non-aggressive  Social  Easily trainable  Rarely bite General Features of Rat  Elongated body shape  Small eyes and ears  Short fur & hairless tail - Black rats have slender and longer tails  The body is covered with hair (2 types): - Guard Hair: long and coarse and protect the rest of the pelage (fur) from abrasion and frequently from moisture - Under Hair: also known as the undercoat, serves to provide insulation by trapping air close to the skin, helping to regulate body temperature and keep the rat warm - Vibrissae: or whiskers, in rats function as tactile sensors that help them navigate their environment by detecting and interpreting physical contact with objects, allowing them to sense nearby obstacles, measure spaces, and gather information about their surroundings  Bulging eyes  Well-developed eyelids  Cornea (visible structure)  One permanent set of teeth  5 digits w/ nails  Large cecum (colon-shaped), diffuse pancreas  Os penis  Brown fat (Primarily found scapulae); not diffused, more structured (difficult to scruff at neck)  No gall bladder Housing and Husbandry  Can’t vomit due to structured esophageal  Social/Single ring/muscularized - Rats preferably housed single  Coprophagic - In experiments can be housed together  No sweat glands  Adult males can be housed together - Tolerates cold better than heat  Cages should be large enough  Escape proof Reproduction and Sexing  Cage: 24”Wx 24”L x 12” H  Anogenital distance  Beddings: ¼” to 1 inch deep  Only female rats possess nipples  Temp: 18-26˚C  Males have distinct scrotum between anus & prepucial  Relative Humidity: 40% to 70% opening  Monogamous/ Polygamous kting Page 1 VMD 85:Lab Animal Med Rat Production, Medicine and Diseases Rat Space Requirement Anesthetic Agents Rat Nutrition  Pellet diet/ blocks (Fruits /vegetables) - Pellet > seed - All seed diets = increased fat = obese rats  5-10g of pellet/ 100 g BW  Ad libitum (10 mL water/100 g BW) Parasiticides for Rats Venipuncture Collection sites:  Lateral saphenous vein  Lateral tail vein  Orbital venous plexus  Cardiac puncture Hematologic Parameters Analgesics for Rats Pre-Anesthetics Diseases of Rats Routine Examination - Similar with mice - Rats are smarter than mice 1. Handling and Restraint - Use claw-type restraint/body grasp 2. History Taking - Source - Diet - environment 3. Physical Examination - From nose to tail to extremities 4. Diagnostic Procedures - Collect feces and urine 5. Preventive Medicine Atropinase in rats is an enzyme that breaks down atropine, a  Use other hand to support the lower body and hold tail compound that blocks certain nerve signals. The enzyme helps metabolize atropine, reducing its effects on the nervous system,  Do not apply too much pressure to the head or chest such as its ability to inhibit parasympathetic functions like salivation and digestion. Dermatology A. Mammary tumors - Common in 59% to 90% of adult females - 15% of adult males. - Most are benign fibroadenomas - Not deadly in rats; surgical intervention w/ good prognosis kting Page 2 VMD 85:Lab Animal Med Rat Production, Medicine and Diseases B. Fleas, Lice, and Mice (Ectoparasites) B. Mycoplasma, Streptococcus, Pseudomonas spp., - Radfordia ensifera (rat fur mite) - Mucopurulent ocular discharge o Causes ulcerative lesions due to constant pruritus C. Cataracts - Demodex nanus (demodex) - Secondary to - Polyplax spinulosa (the spined rat louse) diabetes mellitus - Fleas C. Ulcerative Dermatitis - Radfordia ensifera (rat fur mite) D. Ringtail - Due to drop in relative humidity (↓ 40%) - Fibrous bands of tissue can form around the tail - Incise the ring of tissue and apply DMSO, steroid, and antibiotics. - Keep humidity above 50%. Respiratory - No proper blood flow to tail tip A. Murine Respiratory Mycoplasmosis - Common in stillborns - Mycoplasma pulmonis - Common in rats - Due to ↑ cage ammonia - Lx: cobblestone appearance of lungs @ necropsy B. Streptococcus pneumoniae - Bacteremia with stress - Normal flora in rats C. Corynebacterium kutscheri, Pasteurella pneumotropica, and Pseudomonas aeruginosa Protozoans A. Pneumocystosis carinii - Protozoa infecting lungs. - Antonio Carini (1912) Grade 0 No rings - Signs only occur in older or immunocompromised Grade 1 1 ring at the tip rats. Grade 2 More than 1 rings on the tail - Treat with sulfas Grade 3 Necrosis and congestion; multiple rings - Diagnosis: Grade 4 Severe o PCR of lung tissue o Serology in immunocompetent animals E. Ringworms o Histopathologic survey of lung tissue. - Moderate to severe perivascular hemorrhage - Interstitial pneumonia - Filled with macrophages Cardiovascular System Lesions: A. Congestive Heart Failure - Epidermal hyperplasia - Common in older rats. - Orthokeratotic /parakeratotic hyperkeratosis - Treat supportively and give furosemide and digitalis Opthalmology A. Sialodacryoadenitis virus B. Polyarteritis nodosa - Coronavirus - Common older rats o Highly contagious - Thickening of the arteries, which predisposes them o No Tx to clot formation and aneurysms - Type 3 hypersensitivity (antibody-antigen complex) - Keratoconjunctivitis uveitis, periorbital swelling, and - Complex deposits in arterial walls = necrosis in pneumonia. arteries - No loss of activity or appetite. - Sprague Dawley Rats: commonly used for research - Treatment is usually not necessary in mild cases - No specific clinical signs - Self-limiting disease kting Page 3 VMD 85:Lab Animal Med Rat Production, Medicine and Diseases C. Radiculoneuropathy - Common in older rats - with posterior paresis progressing to paralysis. - Treat supportively - Nerve endings loss function = paralysis Gastroenterology A. Hemobartonella muris - Parasite within RBCs and - Nonpathogenic - Signs may include hemolytic anemia. - Treat with tetracyclines - Rats are carriers - Fibrinoid formation ROUTES OF ADMINISTRATION (Rats and Mice) - Mononuclear cells  Oral gavage - Maximum volume/administration: Gastroenterology - 0.20 mL A. Capillaria hepatica - 0.40 mL (mouse) - Causes no clinical signs - 3-5 mL (rats) - But yellow streaks on the liver are observed at  Subcutaneous injection: necropsy Mouse Rat - Zoonotic to humans - 2 mL - 2-5 mL - Gauge 26 to 28 - 25 to 26G - Infective stage = L3 - ½ inch length - ½ to ¾ length  Intramuscular injection: Mouse Rat - 0.10 mL - 0.10 mL - 26 to 30G;1/2 length - 26 – 28G; ½ inch  Intraperitoneal Injection: Mouse Rat - 2 mL - 3 to 5 mL - 26 to 30 G’1/2 inch - 26 to 28 G’1/2 inch B. Epizootic Diarrhea - Always tilt the animal cranially and always aspirate - Rotavirus o Yellow = urine = bladder - Rats 1 to 2 weeks of age are susceptible o Green = bile = liver - Most recover o Clear = goods Urology Anesthetic for Rodents A. Urates - Ammonium magnesium phosphate or calcium carbonate - Urinary stones are common in older rats B. Nephrocalcinosis and Progressive Nephropathy - Very common in older rats. - Treat chronic renal failure (CRF) supportively - High protein (>10 mg/kg) = Nephrocalcinosis C. Trichasomoides crassicauda - Rat Kidney Worm - Is a parasite of the rat kidney and may cause hematuria and stranguria. - Treat with methyridine Neurology A. Streptobacillus moniliformis - Rat bite fever - Many middle-ear infections and chronic pneumonias. - Head tilt is commonly seen B. Trauma or neoplasia kting Page 4 VMD 85:Lab Animal Med Rat Production, Medicine and Diseases kting Page 5