NTCA medicine - small mammals (rodents) Flashcards
(96 cards)
1
Q
How are ‘rodentia subgrouped?
A
- The Caviomorpha
→ guinea pig, chinchilla,
and degu - The Myomorpha
→ “rat like” or “mouse
-
like” rodents. - The Sciuromorpha
→“squirrel
-like”
rodents.
2
Q
Who is in the Muroidea ?
A
Muridae -> gerbils, old world rats and micr
Cricetidae -> true hamsters
3
Q
What different Rats are there?
A
- Brown rat -> rattus norvegicus
- ## Giant Gambian Pouched Rat
4
Q
Mice ?
A
Mus musculus from the wild mouse
- Nocturnal
- Omnivorous
- Male -> strong odour
5
Q
Key features of Mice?
A
6
Q
Common hamsters?
A
Golden or Syrian hamster (Mesocricetus auratus), the Russian hamsters
(Djungarian - Phodopus sungorus
7
Q
Gerbil species?
A
Mongolian gerbils → Meriones unguiculatus.
8
Q
Info about gerbils?
A
- Originate from dry sandy grasslands → adapted to a desert environment → produce most of their water
requirement from metabolic processes - Burrowing diurnal rodents and are active at dusk and dawn.
- Highly sociable
9
Q
Key features of gerbils?
A
10
Q
Guinea pigs main info ?
A
● Average longevity 4–8 years
● Respiratory rate 40–120 bpm
● Heart rate 226–300 bpm
● Body temperature 38–39.5°C
● Maintenance fluid therapy →100–150 ml/kg/day
● Sexual maturity → 4–6 weeks female, 9–10 weeks male
● Gestation 59–72 days
11
Q
Assessing pain?
A
● Absence of normal behaviour
● Porphyrin staining (‘red tears’
– rats)
● Hunched?
● Hiding?
● Rubbing at affected area? Belly pressing?
● Contractions of abdominal muscles?
● Loss of appetite?
● Change to HR, RR and depth
12
Q
SC injecitons?
A
→ between
the scapulae, back or abdomen.
- Hamsters→ care not to inject into the
cheek pouches - Large volumes → painful
13
Q
IM injections?
A
- Challenging due to the small
muscle mass. - Painful
- Quadriceps
- Gluteal muscles
14
Q
Vasculature / venipuncture?
A
● Circulating blood volumes in rodents is
approximately 5-8% of bodyweight.
○ Keep sample volumes to the minimum
○ Consider potential blood loss
○ Consider haematoma formation.
15
Q
What blood sampling sites?
A
○ Lateral saphenous vein
○ Cephalic vein – My vein of choice in g pig!
○ Jugular vein
also lateral tail vein in rats, mice and gerbils (care degloving!)
16
Q
Describe tail venipuncure
A
- The tail has lateral veins in the 3 o’clock and 9 o’clock positions
- Can be visualised at the base of the tail.
- In the rat, may be carried out conscious
- Apply EMLA (local anaesthetic cream)
- Warm the tail → may aid in vasodilation.
17
Q
Gingival vein sampling?
A
- Gingival vein sampling → described as an easily accessible site for blood collection.
- Hamsters, guinea pigs, rats and mice → collect under a brief general anaesthetic
- In a recent paper, it described that even repeated sampling had no effect on food intake,
bruising or haematoma formation.
18
Q
Cranial VC sampling?
A
- Caution with this site
- Cardiac tamponade
- Laceration of the cranial vena cava
- Puncturing the heart
- Performed under a general anaesthetic
- Insulin syringe
- Sample at the thoracic inlet
- Direct the needle caudally at a 30-degree angle off
midline and toward the opposite hind leg - Needle very close to the heart!
19
Q
Anatomical features of rodent dentition?
A
- Large, continuously growing, paired, mandibular and
maxillary incisors. - Chisel-shaped occlusal surface.
- Labial surface is composed of hard wearing ename
20
Q
Incisors have …?
A
open apical pulp cavities → are constantly
growing → elodont (elongating, continuously growing, teeth)
21
Q
Incisors are..
A
aradicular (no roots)
22
Q
T/F rodents have canines
A
False
23
Q
Rodents are monophyodont & simplicidentata - what does this mean ?
A
Monophyodont -> develop nly one set of teeth through life
Simplicidentata -> 1 pair of maxillary incisors (no peg teeth)
24
Q
What feature of rats mandibular symphysis ?
A
MOBILE & visible at the lower incisor teeth -> significant separation of the lower incisor teeth at tip
25
How rapidly do incisors grow?
2-4 mm a week
26
Rodent incisors?
longer than the maxillary incisor crowns
→ crown to length ratio for the upper to lower incisors is approximately 1:3 in rats and hamsters.
Fractures common
27
What teeth do myomorphs not have?
premolars
28
Dental formula of myomorphs?
2 * [ I1/1, C0/0, P0/0, M3/3] = 16 teeth
29
Features of myomorph teeth?
* Anelodont molar teeth →they are truly rooted, with a limited growth period.
* They are brachydont → short crowned.
* Cusps on the occlusal surface (hamster and rat, not the gerbil).
* The molar teeth are also referred to as cheek teeth.
30
How do the teeth interact when eating?
* Each mandibular cheek tooth is in occlusion with the corresponding maxillary cheek
tooth when chewing.
* When gnawing with the incisors, the mandible is pulled forward and the maxillary and mandibular molars are not in occlusion.
31
Hystricomorphs dental formula?
2 * [ I1/1, C0/0, P1/1, M3/3] = 20 teeth
32
Hystricomorph dental features ?
* Hypsodont → long crowned teeth
* Elodont → continuously growing cheek teeth as well as
incisor teeth
* Aradicular → no anatomical roots
* Anisognatism → wider mandible
* Cheek teeth normally at 30° occlusal plane
33
What client concerns may indicate dental dx?
● Reduced appetite, to anorexia ● Dysphagia ● Ptyalism/hypersalivation ● Droppings smaller and less
frequent
→ none produced
● Incisor malocclusion ● Facial swellings ● Overgrown or changes to
incisor teeth
34
Diagnostics of dental dx?
● Clinical exam →palpate the mandible &
ventral neck carefully. Look for
oculonasal discharge, check for facial
asymmetry, check for exophthalmos
● Conscious oral exam → otoscope →
challenging → we may miss up to 50%
of cases! Perform last.
● Oral examination under
sedation/anaesthesia
● Stomatoscopy
● Radiography
● Advanced imaging
○ CT
○ MRI
35
KEY POINT
Osteoarthritis of the temporomandibular joints will cause secondary dental
disease due to pain caused by chewing.
● Osteoarthritis of any joints may cause secondary dental disease due to a decrease in
appetite → dental disease seen in an older guinea pig is often SECONDARY to underlying
issues. MULTIMODAL ANALGESIA IS ESSENTIAL.
36
GI hypomotility happens when?
a primary condition or secondary
to virtually any other disease process causing pain.
37
Bloat ?
may occur secondary to GI hypomotility or as a primary
issue post-ingestion of fermented food or an excess of leaves
from the brassica family.
38
CLS of bloat?
abdominal distension, dehydration, reluctance to move.
39
What to distinguish bloat from in Guinea Pigs?
GDV!
40
How would u manage bloat?
Fluids, analgesia, maropitant, encourage to move, GI motility
meds if not obstructed and no GDV.
41
GDV signs ?
hypovolaemic shock: tachycardia, weak
pulses, pale or cyanotic mucous membranes, and hypothermia.
42
What are the two common types of enteritis we see in rodents & small mammals?
- Proliferative ileitis (Lawsonia intraC) -> hamsters
- AB-associated dysbiosis (DON'T GIVE THESE ABs)
43
Describe 'Wet tail' (Lawsonia)
- Affects 3-8 wk old hamsters
- Dehydration, lethargfy, foul-smelling D+ , abdo pain
- Guarded - poor pg, fatal w/in 24-48h
44
WHO NOT TO GIVE AMs ?
- Hamsters
- GPs
- Chinchillas/ degus
45
What common DDX for resp dx?
● Infectious
○ Bacterial
○ Viral
○ Fungal
● Non-infectious
○ Environmental
○ Heat stress – guinea pigs/chinchillas
○ Diaphragmatic hernia
○ Pregnancy toxaemia
○ Gastric dilatation
○ Cardiovascular disease
○ Pulmonary neoplasia
46
What important respiratory dx HISTORY?
* Diet – any changes? Nutritional deficiency – vit C?
* Substrate/bedding – dusty? Ammonia build-up?
* Design of enclosure – temp, humidity & ventilation
* Cleaning regime
* Conspecifics
* Recent changes to husbandry or routine
* Neutering status (e.g., g pigs – large ovarian cysts
causing pain)
47
Investigating resp dx pt 1?
Clinical exam )> ausc over trachea, whole thorax, HR & rythm, oculoN disC
48
If suspect upper resp?
○ Culture and sensitivity from a deep nasal swab
○ Opportunistic/environmental bacteria if just swab nares
49
Chlamydia suspected?
-> PCR - Chlamydia caviae (guinea pigs)
○ Conjunctival scrapings → intracytoplasmic, coccoid, basophilic organisms (elementary and reticulate
bodies)
50
Tracheal lavage ?
○ Aerobic, anaerobic and fungal culture
○ Cytology → heavy growth of a single species and a corresponding cytological response = more likely to
be significant.
○ Normal flora MAY be opportunistic pathogens in immunocompromised animals
51
What Lower Respiratory diagnostics?
- Thoracic Xray
- Bacterial pneumonia -> interstital pattern , air bronchograms
- Solitary mass -> neoP, abscess, ...
52
Bloods for RESPIRATORY diagnostics?
○ Total white blood cell count may or may not be
increased
○ May see a relative neutrophilia and/or lymphopenia
○ May see leucopenia → overwhelming infection
(bacterial or viral) or inflammation
53
PME ?
Lung congestion, fibrin adhesions, fibrosis,
suppurative lesions, pulmonary abscesses.
Granulomas, lung consolidation, myocarditis,
tracheitis, bronchitis, otitis media/interna,
septicaemia
54
What MAJOR RAT RESPIRATORY PATHOGENS
○ Mycoplasma pulmonis – very common. ○ Streptococcus pneumoniae ○ Corynebacterium kutscheri
55
What two things act synergistically in resp dx?
○ Chronic respiratory disease
○ Bacterial pneumonia
56
Guinea Pigs Resp?
- Pneumonia significant
- subclin infection comes otu when stress
- Opportunistic bact (bordatella, strep, pasteurella...)
57
TX in GPS resp dx?
58
Urinary features of rodents?
separate urinary and
vaginal openings → can determine
if discharge is from urinary or
reproductive system.
59
Who has OSpenis?
Do not confuse os-penis on
radiographs for urolithiasis
○ Chinchilla, guinea pig, rats,
mice, hamsters, gerbils
60
Signs of acute renal failure?
○ Non specific (anorexia, lethargy)
○ Pain (bruxism – pain scoring recommended)
○ Other signs, e.g., GI ileus/stasis
61
Signs of chronic renal failure?
○ Weight loss
○ PUPD
○ Poor body condition
○ Occasionally haematuria
○ Reduced appetite
○ GI stasis
62
Signs of cystitis/urolithiasis?
○ Pain (hunched posture)
○ Urine scald
○ Vocalisation when passing urine
○ Haematuria
○ Urinary incontinence
○ Urine dribbling
○ Dysuria = Pain or burning sensation while passing urine.
○ Stranguria = Slow, painful discharge of small volumes of urine expelled only by straining despite a feeling of urgency
○ Pollakiuria = frequent, abnormal urination during the day.
63
History relevant to urinary dx?
* Diet
* Bottle vs bowl
* Design of enclosure
* Exercise – sedentary animals more prone to sludge
* Conspecifics
* Recent changes to husbandry or routine
64
Is urinary obstruction possible in male mice?
YEs infection of preputial and bulbourethral glands
65
Differences relative to environmnt?
Gerbils -> loop of henle longer -> concentrate urine more effectively for water conservation
66
What urinary issue in GP sows?
Cystitis -> chronic with acute flare ups
Ascending infection -> E.Coli, strp spp
67
Many GPs with cystitis will have ->
Full painful bladder
68
Urinalysis for ystitis?
a sediment exam (normal guinea pig urine
will contain calcium carbonate, calcium oxalate, and/or struvite crystals). Check for RBCS, WBCS with
associated inflammatory cells → may see (normally) porphyrin in urine which may visually mimic blood.
69
What diagnostics to do with cystitis other than urinalysis ?
● Urine culture
● Imaging to rule out urolithiasis and OA
70
Tx for cystitis?
Treatment → reduce stressors, analgesia (meloxicam +/- multimodal depending on severity, e.g.,
gabapentin, buprenorphine), encourage water intake.
● Antibiotics if clinically justified and ideally based on C+S
○ Trimethoprim sulfamethoxazole is a sensible first line choice of antibiotic while waiting on culture
results & antibiotics is warranted
71
Urolithiasis in GPs & hamsters ?
common
72
What cls depending on stones?
○ Non-specific → weight loss, anorexia, lethargy ○ Abdominal pain → hunched posture, bruxism ○ Haematuria ○ Stranguria ○ Dysuria
73
Diagnostics for urolithiasis?
Diagnostics → radiography allows identification of radiodense stones anywhere in the urinary tract (or seminal vesicles in males).
When performing
lateral abdominal radiographs ensure that the hind legs are pulled away from the body for visualisation of any calculi within the distal urethra.
Ultrasonography for calculi and hydronephrosis or hydroureter secondary to
urolithiasis
74
What reproductive issue in guinea pigs?
OVARIAN CYSTS
75
Classifiation of ovarian cysts?
* Physiologic, infectious and neoplastic → according to their cause)
* Cysts of the rete ovarii (serous cysts), follicular cysts or paraovarian cysts →
according to their anatomical origin in relation to the ovary
76
When do GPs get ovarian cysts?
s between 3 months and 5 years.
77
What are serous cysts?
→ intraovarian --> appear to be non functional
* Correlation between age, prevalence and size of cysts, NOT correlated with
reproduction history.
78
Follicular cysts ?
→ functional
* Clinical signs → lethargy, abdominal distension, bilateral symmetrical alopecia (nonpruritic), crusting of nipples/changes to mammary gland, depression, occasionally vaginal
discharge.
79
What TX for Ovarian cysts in GPs ?
- Surgery
- Percutaneous drainage of cysts
- HcG - off license
- Leuprolide acetate -
- Deslorelin implant -> no reduction in cyst size
80
What main causes of derm dx can we see?
- barbering (esp mice)
- EctoPs
- Endorine
- Fungal
- Neoplasitc
81
Barbering?
Overcrowding, lack of bedding, lack of dietary fibre, conflict,
stress/illness
82
What main ectoP?
MITES -> CS: self trauma, alopecia, hyperkeratosis, 2ary bact infections
Dx -> CLS & deep skin scrapes
Tx : based on species and ectoP often ivermectin/selamectin
83
Endocrine derm dx?
cystic ovaries
– guinea pig; hyperadrenocorticism
–hamster/guinea pig
84
What causes dermatophytosis?
Trichophyton mentagrophytes or Microsporum canis.
! can be asymptomatic
85
CS & DX Dermatophytosis?
○ CS - hair loss, crusting lesions around the eyes, nose, and extremities. White scaling and
scabbing. Pruritus (occasionally), secondary bacterial infection is not uncommon.
○ Diagnostics - microscopic examination, fungal culture. Trichophyton mentagrophytes does not
fluoresce under a Woods Lamp.
86
Tx of Dermatophytosis?
Systemic therapy with either itraconazole 5–10 mg/kg q24hrs or terbinafine 20
mg/kg q24hrs (continue until two negative fungal cultures are obtained 1 month apart). Topical
treatment, analgesia, antibiotics if secondary bacterial infection, disinfection of the environment.
87
What neoplasia causes derm dx?
cutaneous endotheliotropic lymphoma (hamsters) → mycosis fungoides
○ Progressive alopecia, scaly flaky skin leading to nodules & plaques. Secondary bacterial infection
common. Painful
88
What derm dx specific to gerbils?
Nasal dermatitis -> 'stress overcrowding' -> →hypersecretion of Harderian glands &
accumulation of porphyrin → self trauma/irritation/secondary infection.
89
What to do for nasal dermatitis?
Correct husbandry, address humidity, topical cleaning, analgesia (meloxicam), systemic
antibiotics if clinically warranted – TMPS 30mg/kg PO BID, provide sand bath
90
What GP specific derm dx?
Chelitis -> inflammation and crusting on the lipds - due to abrasive foodstuffs or acidic foods
91
What nutritional deficiencies can we see in GPs?
Hypovit C -> Scurvy
● Unable to produce own vitamin C (L-ascorbic acid)
● Lack the gene that controls the production of L-gulonolactone oxidase → this is necessary to convert Lgulonolactone to ascorbic acid
92
CLS for Scurvy?
○ HL weakness
○ Stiff gait
○ Anorexia
○ Unkempt fur
○ Bleeding in joints
○ Haemorrhage under skin
○ Hypersalivation
○ Vocalising due to pain
○ Swellings of costochondral junctions
93
Endocrine / Neoplasia in GP?
- HyperAC
- HyperT
- Lymphoma
94
Rats endocrine & neoplastic?
○ Pituitary adenomas are very common in aged rats with female rats being
overrepresented.
○ Mammary tumours
○ Zymbal gland neoplasia
95
Mice endocrine & neoplastic?
mammary tumours - rapidly metastasize
96
Dwarf hamsters & gerbils neoplasia?
ventral sebaceous gland neoplasia
