Post Hibernation Anorexia (PHA) in Testudo sp.

Anorexia is one of the most common presentations of chelonia in veterinary practice, especially after hibernation in Testudo sp. This article is focussed on hibernating Testudo species and the Russian tortoise Agrionemys horsfieldi.

We must acknowledge that not all reptiles will eat on a daily basis and that physiological anorexia may ocurr during reproductive season or before and after hibernation.

Investigation and a work up are warranted if a tortoise presents with weight loss, lethargy or any other sign of disease. If a tortoise has not eaten for a few days then daily bathing and weighing should take place, and optimal species temperatures should be checked.

Post Hibernation Anorexia (PHA)

Causes

Depletion: ocurrs when energy reserves are insuficient to compensate for an increased metabolic state. This may ocurr after years of suboptimal conditions.

Extensive hibernation: in the wild they enjoy high temperatures to prepare them for a short period of low temperatures. In captivity often this is inverted. A hibernation period should not exceed 3 months. Juveniles may hibernate for shorter periods up to one month.

Leukopaenia: ongoing suboptimal temperatures may cause a low white blood count (WBC) even pre-hibernation. White blood cell half life is limited and during the hibernation period there is no regeneration of these cells. When these animals awaken they find themselves with comprimised immune systems. Whe these tortoises are warmed up there is a rapid replication of fungus, bacteria and viruses that the WBCs cannot cope with. These animals may present with rhinitis, stomatitis or sistemic disease.

Sub optimal conditions: this is normally related to temperature. Temperatures during the active and hibernation periods should be monitored and controlled at all times

Sistemic disease: this may ocurr in ageing animals or infection, often secundary to inadequate husbandry.

Gastrintestinal infections: gastrointestinal parasitosis will rarely be the cause of anorexia but certainly a contributing factor.

Respiratory infection: upper or lower respiratory disease may ocurr.

Reproductive disease: Pre-ovulatory follicular stasis (POFS) typically ocurrs in females kept alone for many years due to the lack of male physical or pheromonal stimulusto induce ovulation. Seasonal temperature fluctuations stimulate folliculogenesis and vittelogenesis but does not progress to ovulation and subsequent egg formation.

Stress: may ocurr in recently acquired animals, active males or multispecies housing.

Rhamphoteca overgrowth: physical limitation and inability to feed.

Freezing temperatures during hibernation: if temperatures descend under 0ºC then crystals may form in the ocular lens, frontal or olfactory lobes.

An exhaustive history should be taken from tortoise owners in those that suffer PHA and a thorough clinical assessment should be made. Often animals have been deprived of food, water, heating and/or lighting. They may appear dehydrated and those that have not eaten for 7 weeks have a poor prognosis (Lawrence, 1987). It was also suggested that those tortoises that had not drunken water within 10 days recquire vetrinary intervention (Lawrence, 1987).