Uveitis in dogs: Ocular and periocular signs of leishmaniasis
Leishmaniasis is a zoonotic disease with a broad global distribution that is also endemic to certain regions of Spain, as indicated in a study by the Ministry of Health of the Community of Madrid.1
The disease is caused by the parasite Leishmania infantum and mainly affects dogs, and while in some cases the animal is only a symptomless carrier, in others the infection can damage multiple organs constituting a life-threatening risk.
Besides the cutaneous signs, there are also ocular lesions
The most conspicuous among all the signs of leishmaniasis are cutaneous lesions. Lesions are usually located around the eyes or outer ear, although they can also be found in other parts of the body. It generally courses with alopecia, but in some cases the vet may observe ulcerative or exfoliative dermatitis.
The prevalence of eye lesions in canine leishmaniasis is relatively high, although only a few studies have analysed this relationship. After reviewing 95 cases, a study published in The Veterinary Quarterly2 revealed an incidence of 42.1% of ocular lesions, while another conducted at the University of Naples3 with a sample of 150 dogs reported a lower incidence of 16%. The main eye disorders were keratoconjunctivitis, uveitis and panophthalmitis.
A study carried out at the University of Barcelona4 assessed 105 dogs with ocular or periocular signs of leishmaniasis. The authors found that the most common sign was anterior uveitis, although they also observed signs of blepharitis and keratoconjunctivitis in which the corneal lesions had the clinical appearance of granulomatous episclerokeratitis. The subjects also had various lesions on the eyelids, such as dry dermatitis with alopecia, skin ulcerations, diffuse blepharoedema and the formation of discrete granulomas.
Uveitis in dogs secondary to leishmaniasis
The uveitis takes on a granulomatous form characterised by the formation of nodules, mainly on the surface of the iris. The cornea is less affected, but there is a significant population of amastigotes. It has a diffuse, plastic character and a greater immune-mediated component. The cornea and anterior chamber are badly affected, with a predominantly lymphoplasmacytic infiltrate.
Although the plastic form is harder to treat, it should not leave permanent sequelae if it detected in time. Nevertheless, the treatment of uveitis in dogs when secondary to leishmaniasis is more complicated and the case may progress unfavourably. The most serious complications range from synechiae to retinal detachment, glaucoma, atrophy of the iris, blindness and even eye loss, as noted in an analysis published in the AVEPA’s official journal.5
In fact, the aforementioned study conducted at the University of Barcelona demonstrated that while 79% of dogs with ocular lesions showed improvement with systemic antiprotozoan and topical anti-inflammatory treatments, many cases of anterior uveitis required long-term topical therapy.
Local anti-inflammatory drugs may improve the ocular signs and limit complications. Corticosteroids may be necessary for more severe cases, but they must be used with prudence due to the underlying parasitic infection. Aside from clinical treatment, it is important to provide a suitable diet that minimises damage, such as the ADVANCE VET DIETS Urinary Low Purine, which is specifically formulated to provide nutritional support in the medical treatment of dogs with uveitis secondary to leishmaniasis.
To facilitate diagnosis and treatment, the possibility of leishmaniasis should always be borne in mind when analysing inflammatory eye lesions of the anterior segment and adnexa, especially in regions where the disease is endemic.
