Page 1283 - Problem-Based Feline Medicine

61 – THE CAT WITH A CLOUDY EYE 1275

Other signs suggestive of renal and/or thyroid disease, Cats with renal disease should be placed on appropriate
such as progressive weight loss, polydipsia, polyuria medical and dietary management. For more details see the
and azotemia may be present. main reference on page 337 (The Thin, Inappetent Cat).

Diagnosis FELINE IMMUNODEFICIENCY VIRUS*

Clinicians should suspect this problem in any old cat
Classical signs
that has suddenly gone blind.
● Show signs of mild uveitis.
Ophthalmoscopy will demonstrate vitreal hemorrhage.
● “Snowbank” inflammation of the pars
The retina will appear out of focus, and hemorrhage
plana seen through dilated pupil. Appears
adjacent to the major retinal blood vessels is visible.
as cloudy outer vitreous in this area.
Blood pressure is most commonly measured in the ● May be other systemic signs such as loss
cat using Doppler technology. Arterial blood pressure of weight, inappetence and fever.
greater than 160 mmHg confirms a diagnosis of hyper-
tensive retinopathy. Most cats with clinical signs have a
Pathogenesis
blood pressure of greater than 200 mmHg.
BUN, creatinine and urine protein:creatinine ratios are use- Infection with the virus usually occurs as a result of a
ful clinical pathology parameters to check renal function. bite from another FIV-positive cat. Transmission in
saliva by grooming is thought possible, but rare.
Thyroid function should be checked by measuring
plasma thyroxine (T4) concentration. After infection a viremic phase occurs, which may be
associated with a transient fever, generalized lympha-
Further useful procedures include cardiac ultrasound, denopathy and neutropenia. An asymptomatic carrier
and in some cases, imaging of the thyroid with radio- state or chronic disease then follows.
isotopes.
Clinical signs
Treatment
Cats that develop signs of FIV may have evidence of
Amlodipine (Norvasc, Pfizer) is a calcium channel
generalized systemic disease such as weight loss, and
blocker, which has a greater effect on vascular smooth
poor body and coat condition. Pyrexia, lymphadeno-
muscle cells than on cardiac muscle cells. The dose is
pathy and infections of the oral cavity, respiratory tract,
approximately 0.625 mg/cat/day, i.e. 1/4 of a 2.5 mg
skin and other sites may occur.
tablet (USA) or 1/8 of a 5 mg tablet (Australia).
In the eye, pars planitis or “snow bank” inflamma-
The use of corticosteroids is controversial.
tion of the pars plana resulting in vitreous cloudiness
If hypertension is associated with hypertrophic car- is thought to be almost pathognomonic for FIV infec-
diomyopathy, then calcium channel blockers such as tion. Other signs of uveitis can also be seen, such as
diltiazem may be used. For more detail see main refer- cloudy aqueous and iris inflammation.
ence on page 162 for details (The Cat With
Tachycardia, Bradycardia or an Irregular Rhythm).
Diagnosis
b-blockers such as propranolol (Inderal) can also be
A tentative diagnosis is based on the clinical signs of
used in the management of the cardiac disease at 1/4 of
vitreous cloudiness described as “snow bank” inflam-
a 10 mg tablet q 8 h.
mation, in a FIV-positive cat.
Hyperthyroidism when present, should be treated using
surgery, radioactive iodine (131-I) or anti-thyroid drugs
Treatment
such as carbimazole or methimazole. For more detail
see main reference on page 305 (The Cat With Weight Supportive treatment is indicated, and depends on the
Loss and a Good Appetite). organ system affected.