Encephalitis by distemper virus in Panthera tigris

We are describing two clinical cases of ataxia and incoordination in adult tigers, a case of seizures in a tiger cub and a fourth case of severe unilateral panophtalmitis without nervous symptomology in an adult. Since the first cases wasn’t attended to by me personally, it will be reported only for the similarity of its symptoms.

All the tigers mentioned belonged to a circus and lived together in the same wagon.

The clinical condition evolved from a normal state (absence of symptoms) to a state of depression, passing through progressive ataxia with head tilting (comparable to a vestibular syndrome); and from an incipient uveitis to a manifest corneal opacity (with anisocoria). The third adult presented only severe panophtalmytis with descemetocele, but lacked encephalitis symptoms.

A four month old cub had an onset of seizures one month after the death of a second adult, during the phase of the first diagnosis in the adults.

The course of the illness was very slow, with a duration of approximately 90 days in the first case and some 150 days until the tiger was euthanatised in the second case. Although physical deterioration was very evident, all the animals conserved their appetite and aggressivity in equal measure up to the week before their death.

In two of the four cases the animal’s gait was progressively affected. It is necessary to assume that the cerebellar lesion caused an increase in the pressure of the cerebrospinal fluid, so that the animal’s indisposition, added to the condition of the primary encephalitis by the action of the distemper virus, must have caused sever pains of the encephalic origin ("headaches").

The decubitus ulcers, the irritating urine action and the incessant harassment of flies, aggravated the clinical condition even further.

The clinical diagnosis of these cases was carried out on two fronts:

1. Environmental (a diseased ecosystem)
2. Individual (The pathology in itself)

For both sections the routine exposition of any diagnostic hypothesis was practiced.

1. Environmental. A thorough study of the animal’s immediate environment is a highly important factor, for this is the place where the animal lives, except when its is doing its act. The characteristics of this immediate environment are virtually constant, apart from climatic changes, depending on the geographic area or time of year.

The fact that the possibilities of disease vary from region to region, plus the fact that circuses are often located in holiday resorts, where dogs of different population immunities are to be found, are extremely important factors, which must be thoroughly assessed. These constitute, together with the global climatic change, and habitat change in particular, the axis where these emergent viral diseases are supported.

Such factors give to a diseased ecosystem, as an overall appreciation, albeit almost inapparent, an the change in the habitat host of a devastating virus like distemper as the visible element of the pathology.

Another point to bear in mind in this sector is the importance of the cohabitation conditions between circus animals and the animals living in the areas near where the big top is pitched (stray dogs and cats).

I would also like to stress in this section the relevance of the circus’s itinerant nature.

A circus travels all over the Iberian peninsula, consequently increasing the spectrum of likely diseases. Moreover, it is often located in problematic areas, as far as disease is concerned (big cities, holiday resorts).

The characteristics of the cage paint, (Pb) and the type of desinfection carried out (phenolics, phosporates) were also taken into account.

With respect to anatomic alterations in cerebellum and in the coroideus plexus (histopathology)

Serology: direct immunofluorescence, indirect immunofluorescence, and ELISA

Its application is absolutely essential in every diagnosis

Processes of similar signology:

The emergence of viral diseases as a regulating element in wild animal populations deserves very special attention on behalf of the veterinary profession.

Morbillivirus and lentivirus are perhaps only the tip of the icebery of future viral confrontation in carnivore populations. However, we must bear in mind that perhaps this is Nature’s was of drawing our attention to the damage we are causing, offering us the change to react before it is too late. The change in habitat, added to the density of animals of different geographic regions, different climates and consequently of different immunities must concern us more then the mere fact of isolating gents, however must merit this may have.

Specialization in zoological collections could be one of the mechanisms leading to the stable population immunity, without great variations in the short term. This would permit us to establish when and how to react against the greatly feared changed in habitual host of the animal viruses known today.

Finally, veterinary surgeons as a professional body must act directly of indirectly each one according to his possibilities, to avoid the growth of uncontrolled urban animal populations (dogs, cats, etc). It isn’t my aim here to discuss the methods of carrying out this control. It is, however, necessary to stress that direct action, whether by means of surgery, pharmacology or euthanasia, if the case demands, much not be forgotten or delegated by our profession.

The replication of viruses would be limited and easily foreseeable (except in the event of disasters or imponderables) if an uncontrolled population of hosts and vectors generated by this hyperconsumer society did not exist.

• The habitual distemper host
• Maternal antibodies and vaccinations frequency in these habitual hosts
• The cold chain to which every vaccine must be adjusted
• The quality of the vaccine (quality control by a reference laboratory which isn’t related to manufacturer or distributor.)