Canine Persistent Pupillary Membranes (PPMs) are common congenital ocular anomalies of dogs. The condition is associated with the the pupillary membrane remnants, a tissue that normally disappears during fetal development. PPMs can be unilateral or bilateral, and can involve one or both eyes. They have been reported in many breeds, particularly those with a higher prevalence of inherited ocular disease, such as the Collie, Shetland Sheepdog, and Chow Chow.
Clinically, PPMs can appear as strings or strands of tissue extending from the iris to the cornea. The strands can vary in length and width and might be translucent or pigmented; they can also be associated with defects in iris development and formation (e.
PPMs can cause varying degrees of visual impairment, depending on their size and location. They could lead to corneal scarring, which can result in cloudiness or opacity of the cornea. The strands can also interfere with the normal pupillary light reflex, causing irregular dilation or constriction. In some cases, PPMs can cause photophobia, tearing, and even glaucoma.
Although the exact cause of PPMs is not yet known, a genetic component is suspected. The condition is often seen in litters with multiple affected puppies, and are inherited as an autosomal dominant trait. Breeding animals with PPMs should be done with caution, since the condition can have serious implications for vision.
Symptoms of Canine Persistent Pupillary Membranes
- Strands of tissue extending from the iris to the cornea
- Corneal scarring or cloudiness
- Irregular pupillary light reflex, causing dilation/constriction
- Photophobia, tearing, and glaucoma
Diagnosing Canine Persistent Pupillary Membranes
Diagnosing Persistent Pupillary Membranes (PPMs) is usually based on the observation of signs and symptoms. Ophthalmic examination should be conducted to identify any strains or strands of tissue extending from the iris to the cornea. The veterinarian can use various instruments, such as a slit lamp, ophthalmoscope, or gonioscopy to assess the condition and its severity. A fluorescein dye test could also be used to detect any corneal scars or cloudiness that can be associated with PPMs.
Stages of Canine Persistent Pupillary Membranes
Persistent Pupillary Membranes (PPMs) can be split into three stages, depending on the severity of their condition.
PPMs are characterized by mild impairment or absence of pupillary light reflex and minimal corneal involvement.
PPMs are characterized by moderate impairment or absence of pupillary light reflex and corneal involvement, with some strands extending into the anterior chamber.
PPMs are characterized by severe impairment or absence of pupillary light reflex and extensive corneal involvement, with strands extending into the posterior chamber.
Treating Canine Persistent Pupillary Membranes
Treating Persistent Pupillary Membranes (PPMs) is typically aimed at relieving symptoms and improving vision. Depending on the severity of their condition, treatment can include medical management or surgically removing the strands.
Medical management involves controlling inflammation and minimizing scarring with topical medications, such as corticosteroids or non-steroidal anti-inflammatory
For medical management, the veterinarian will usually use topical medications, such as corticosteroids or non-steroidal anti-inflammatory drugs, to control inflammation and minimize scarring. Surgically removing the strands could also be necessary depending on the severity of their condition.
Preventing Canine Persistent Pupillary Membranes
The best way to prevent Persistent Pupillary Membranes (PPMs) is to practice responsible breeding. Breeding animals with a known history of the condition should be avoided, as it can cause serious effects on vision in affected puppies. It’s also important to ensure that puppies are regularly examined by a veterinarian prior to sale or adoption. This will help identify any potential issues that could affect a puppy’s vision.