Progressive retinal atrophy (PRA) is a group of genetic diseases seen in certain breeds of dogs and, more rarely, cats. Similar to retinitis pigmentosa in humans, it is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait, with the exception of the Siberian Husky (inherited as an X chromosome linked trait) and the Bullmastiff (inherited as an autosomal dominant trait). There is no treatment.

In general, PRAs are characterised by initial loss of rod photoreceptor cell function followed by that of the cones and for this reason night blindness is the first significant clinical sign for most dogs affected with PRA. As other retinal disorders, PRA can be divided into either dysplastic disease, where the cells develop abnormally, and degenerative, where the cells develop normally but then degenerate during the dog's lifetime.

Generalized PRA is the most common type and causes atrophy of all the neural retinal structures. Central progressive retinal atrophy (CPRA) is a different disease from PRA involving the retinal pigment epithelium (RPE), and is also known as retinal pigment epithelial dystrophy (RPED).

Unilateral primary hyperaldosteronism due to an adrenocortical adenoma or adrenocarcinoma can be potentially cured surgically. Unilateral adrenalectomy is the treatment of choice for unilateral PHA. Potential complications include hemorrhage and postoperative hypokalemia. With complete removal of the tumor, prognosis is excellent.

Bilateral primary hyperaldosteronism due to hyperplasia of the zona glomerulosa or metastasized adrenocortical adenocarcinoma should be treated medically. Medical therapy is aimed at normalizing blood pressure and plasma potassium concentration. Mineralocorticoid receptor blockers, such as spironolactone, coupled with potassium supplementation are the most commonly used treatments. Specific therapy for treating high blood pressure (e.g., amlodipine), should be added if necessary.

Most affected cats present with muscular weakness and/or ocular signs of hypertension. Signs of muscle weakness can include a plantigrade stance of the hindlimbs, cervical ventroflexion, inability to jump, lateral recumbency, or collapse. Ocular signs of arterial hypertension include mydriasis, hyphema, or blindness due to retinal detachment and/or intraocular hemorrhages. A palpable mass in the cranial abdomen is another potential finding.

Clinically induced RA has been achieved using different forms of electrical induction.

- Electroconvulsive therapy (ECT), used as a depression therapy, can cause impairments in memory. Tests show that information of days and weeks before the ECT can be permanently lost. The results of this study also show that severity of RA is more extreme in cases of bilateral ECT rather than unilateral ECT. Impairments can also be more intense if ECT is administered repetitively (sine wave simulation) as opposed to a single pulse (brief-pulse stimulation).

- Electroconvulsive shock (ECS): The research in this field has been advanced by using animals as subjects. Researchers induce RA in rats, for example, by giving daily ECS treatments. This is done to further understand RA.

When someone is suffering from RA, their memory cannot be recovered from simply being told personal experiences and their identity. This is called reminder effect or reminder treatment. The reminder effect consists of re-exposing the patient to past personal information, which cannot reverse RA. Thus, reminding the patient details of their life has no scientific bearings on recovering memory. Fortunately, memory can be and usually is recovered due to spontaneous recovery and plasticity.