Table 2.
‘Common’ signs of ageing in mice, grouped by organ/system.
| Organ/system | Possible clinical signs/pathology |
|---|---|
| Skin and hair | Hair thinning, hair loss, greying Loss of vibrissae Dry, flaky skin; unkempt coat Delayed wound healing, greater propensity to postoperative infections/abscessation Increased risk/incidence of cutaneous or subcutaneous tumours |
| Special senses | Ocular opacities, loss of vision, ocular or periocular infections Dry, sunken eye/s Hearing loss Loss of vibrissae |
| Cardiovascular | General slowing down; exercise intolerance Increased risk/incidence of: Strokes (neurological signs; sudden death) Heart attacks/fatal arrhythmias (extreme collapse; sudden death) Poorer post-anaesthetic recovery/anaesthetic-related death |
| Respiratory | Nasal discharge, sneezing, coughing/chattering, rapid/shallow breathing, dyspnoea, aerophagia Increased risk/incidence of tumours |
| Digestive | Malocclusions, dental abscesses Gastrointestinal dysfunction (diarrhoea; constipation; changed Body Condition Score39 (BCS)) Rectal prolapse Increased risk/incidence of tumours |
| Musculoskeletal | Arthritis/arthrosis/loss of muscle tone (swollen/painful joints; reluctance to move; general slowing down; exercise intolerance; gait abnormalities; decreased grip strength) Hunched posture Increased risk/incidence of bone fractures/dislocations (pain) |
| Metabolic/endocrine | Less able to thermoregulate (shivering; cold stress; piloerection; heat intolerance; decreased core body temperature) Less able to keep energy balance (weight loss; weight gain) Less able to process/clear drugs (increased risk of toxicity) Increased risk/incidence of tumours |
| Urinary | Bladder dysfunction (urinary retention; incontinence) Renal degenerative pathology (excess drinking; excess urination; weight loss) Urethral blockages Increased risk/incidence of tumours |
| Reproductive | Hormonal dysfunction (abnormal oestrus cycles; permanent anoestrus; infertility) Prolapses (penis; vagina) Abscessation or impaction of accessory sex glands Increased risk/incidence of dystocia Increased risk/incidence of tumours Vaginal discharges (may be related to benign uterine polyps) Scrotal hernias |
| Neurological/behavioural | Stereotypic behaviour; self-mutilation; altered consciousness or ‘temperament’ Fits/seizures (rigid tail, open-mouth, salivation) Head tilt Limb weakness (paresis), paralysis, ataxia; tremors; hunching Increased risk/incidence of tumours |
Clinical signs in italics denote those considered by the authors as most commonly encountered in aged mice.