ISSN 2398-2969

Arteriosclerosis

C lapis

Contributor(s):

Michelle Ward

Michelle Campbell-Ward

Aidan Raftery

Sarah Pellett

Introduction

Arteriosclerosis refers to thickening and hardening of arterial walls.
This condition is rare in rabbits and is even more rarely diagnosed.
Rabbits are widely used for the study of human atherosclerosis because of their unique feature of lipoprotein metabolism. Rabbits are also sensitive to cholesterol in the diet.
Cause: as a result of proliferative or degenerative changes. This leads to a loss of arterial elasticity and subsequently impaired circulation.
Lesions can occur in all major arteries, eg carotid/coronary/renal, but are most pronounced in the descending thoracic aorta and aortic arch.
Arterial wall thickening may be due to calcium deposits (usually termed spontaneous arteriosclerosis) or cholesterol/lipid deposits (referred to as atherosclerosis).
Signs: generally non-specific; referable to the organ supplied by the affected artery.
Diagnosis: radiography, serum cholesterol, serum ionized calcium, urinalysis, BP measurement, cardiac assessment.
Treatment: no specific treatment available.
Prognosis: likely to be poor.

Our understanding of this disease in the rabbit is based almost entirely on laboratory rabbit research. The incidence and clinical characteristics of arteriosclerosis in pet rabbits are largely unknown.

Presenting signs

Often an incidental finding.
When clinical signs are present, they are generally non-specific; lethargy, anorexia and weight loss.
May be referable to the organ/part of the body supplied by the affected artery.

Acute presentation

Uncommon.
Theoretically, may present acutely if circulatory function to one or more organs is disrupted.

Age predisposition

Generally incidence increases with age.
Been observed as early as 6 weeks of age.

Sex predisposition

Cholesterol concentrations show greater seasonal variation in experimental female rabbits than in males, with some sources suggesting female rabbits are less prone to diet-induced atherosclerosis because of the atheroprotective effect of 17-β-estradiol. Other sources suggest cholesterol levels are lower in pregnant and lactating female rabbits than in non-pregnant, non-lactating ones.
Male rabbits are preferable for use in atherosclerosis research because of the varying cholesterol concentrations in females, possibly affected by estrogen.
No information is available in relation to sex predisposition in pet rabbits.

Breed predisposition

Can occur in any breed and in wild rabbits but there appears to be significant breed predispositions.
Spontaneous arteriosclerosis:
- Low incidence (10%) in Dutch rabbits Dutch in the US and the Danish Country strain of albino rabbit in Europe.
- High incidence (>40%) in laboratory strains of New Zealand White rabbits New Zealand White.
Some laboratory strains of rabbits have been specifically bred as research models with a predisposition to develop atherosclerosis:
- Watanabe Heritable Hyperlipidemic Rabbit analogous to human familial hypercholesterolemia.
- St Thomas.
- Houston RT.
- Genetically modified (transgenic and knock-out) rabbits.

Public health considerations

None.

Cost considerations

Costs associated with obtaining a diagnosis are variable depending on the location and nature of the disease process. Plain radiography alone may provide a diagnosis but for complete evaluation of many patients serum biochemistry Blood biochemistry: overview and echocardiography may also be considered.
Expensive imaging techniques, eg computed tomography Computed tomography or magnetic resonance imaging Magnetic resonance imaging, are frequently used in human medicine in the diagnosis of arteriosclerosis. Their use in veterinary practice is currently limited but they may be employed for investigation of vascular disease of rabbits in the future.
Treatment costs are minimal as therapy is largely supportive.

Special risks

The cardiovascular system of rabbits with arteriosclerosis will be less able to tolerate and buffer insults, particularly if there is concurrent hypertension and/or cardiac insufficiency Heart: disease. As a result, there is a higher risk of anesthetic and surgical complications.
Thorough pre-anesthetic evaluation of the pulmonary, cardiac and renal systems is recommended.
Drug selection and dosage calculations must account for the patient's individual needs.
During anesthesia Anesthesia: overview particular care must be taken to maintain adequate ventilation and to monitor blood pressure Blood pressure measurement and tissue oxygenation .
Studies in human patients suggest that the risk of peri- and post-operative thromboembolism is higher in patients with arteriosclerosis.