Cataract treatment in dogs
Cataract is a common disease in dogs affecting one, or both eyes. It occurs in all breeds and crossbreeds and at all ages. The moment of the occurrence of cataract is, in some breeds, crucial to its classification. Early occurrence may sometimes be a hereditary characteristic. Cataract is a disease that leads to a complete blindness which significantly impedes normal functioning, making a dog slow, sad and apathetic.
Symptoms of cataract
Cataract is a name given to each clouding, or loss of transparency in a lens. Changes may affect the interior of a lens or its capsule. Cataract in dogs in the early stages may affect only part of a lens, but it progressively spreads to its whole. In some cases, cataract spreads over the natural size of the capsule – so called, intumescent cataract, which leads to severe complications such as displacement of a lens, inflammation of the uvea, or glaucoma.
Fot.1 Zaćma dojrzała, twarda
Causes of cataract
Despite the kind of cataract and time of its occurrence, the mechanisms that take part in its development are similar. In normal conditions the lens consists in 2/3 of water and in 1/3 of proteins. It is bathed in aqueous humour so before it soaks, it is prevented by a special system of ion pumps, balancing its ingredients. Dysfunction of this biomechanics causes water to enter the interior of the lens, increase in the number of proteins insoluble in water and, as a consequence, loss of transparency and development of cataract.
Fot.2 Zaćma dojrzała, pęczniejąca
Dysfunction of this biomechanics causes water to enter the interior of the lens, increase in the number of proteins insoluble in water and, as a consequence, loss of transparency and development of cataract.
Nuclear sclerosis occurring physiologically in older dogs is very often mistakenly diagnosed as cataract. The symptoms may be misleading so the surgical consultation is essential. This process is connected with the compression of lens fibres which refracts the light and gives grey and blue coloration to the vision. Such cases are normal symptoms of lens ageing in dogs and do not disable sight or demand treatment.
Fot.3 Stwardnienie jądra soczewki i zaćma jądrowa
Types of cataract in dogs
Congenital cataract – usually affects both eyes, it is cataract that a dog is born with. This fact does not necessarily mean that it is hereditary. It may be caused, for example, by an infection, intoxication, or other anomalies, such as: PPM (persistent papillary membrane), PHA (persistent hyalois artery), PHTVL (persistent hyperplastic tunica vasculosa lentis), or PHPV (persistent hyberplastic primary vitreous).
Developmental (early) catarac
Developmental (early) catarac
Developmental (early) catarac – it may affect one, or both eyes and occurs early in life. It may be hereditary or acquired through some injuries, infections, intoxications, or diabetes.
Diabetic cataract – in the course of diabetes the concentration of glucose increases in the lens in which its excess is changed into insoluble in water sorbitol. It causes a sudden flow of water into the interior of the lens which injures the fibres and, as a consequence, causes cataract. In improperly treated diabetes, the development of cataract may be rapid. In regulated diabetes, the removal of cataract may be successfully performed.
Traumatic cataract – after a traffic accident, being bite, being stung with a cat’s claw, cutting with a thorn, branch, or a blade of grass – the development of cataract is very rapid. Surgical treatment is absolutely recommended.
Senile (late) cataract
Senile (late) cataract – it is an effect of usual ageing processes and statistically occurs in dogs over 6th year of life.
Hereditary cataract – frequency of its occurrence indicates specific tendencies and predispositions of a particular breed. Dogs with such cases of cataract should not be involved in breeding programs.
Treatment of cataract
The only successful method of treating cataract in dogs is surgical treatment. The newest form of surgery is phacoemulsification which uses an advanced medical apparatus which emulsifies hard nucleus with an ultrasonic handpiece which is later aspired from the eye with a special microcannula. After removing cataract, an artificial lens is implanted into the empty capsule, which restores the proper dioptric system in the eye. Aphakic eye is highly hyperopic. In order to get optimal results, a qualification test is essential. It means an ophthalmological examination to establish the cause, type and stadium of cataract. The occurrence of other eye diseases should be excluded as they could affect the results of the treatment. The examination also establishes the proper preoperative treatment in order to prepare the dog’s eyes to cataract removal. Extremely important factor having impact on the long-term positive results of the treatment, is close cooperation between the dog’s owner and an ophthalmologist.
Fot.8 Po usunięciu zaćmy dojrzałej z implantacją soczewki – pies z Fot.1
Fot.9 Po usunięciu zaćmy jądrowej z implantacją soczewki – pies z Fot.3
Fot.10 – Po usunięciu zaćmy cukrzycowej z implantacją soczewki – pies z Fot.6
Fot.11 – Po usunięciu zaćmy dojrzałej bez impantacji soczewki – Pies z Fot.2
Prognosis after the removal of cataract in dogs
Nowadays, the usage of modern, computerized apparatus to phacoemulsification of cataract helps to achieve ideal therapeutic effects. With a proper surgical qualification and lack of other eye diseases, we fully restore sight in dogs. After successful implantation of an interior lens, it is sometimes possible (through simultaneous correction of sight defects) to receive even better sight than before the development of cataract.