May 2014


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When Sheba, the 10-year-old family pet German Shepherd, is unusually sluggish, walks away from her bowl of dog chow and generally looks a bit under the weather, one of the first considerations is, “Hmmm, we should take her to the vet.”

hen Peco, the pet orange-winged Amazon parrot starts looking a little puffy around the eyes and isn’t quite as chatty as usual, we think we need to take him to the vet. Even Betsy, the top milking Holstein in a small dairy herd in Carlsen Field has an urgent check-up from the vet when her udder suddenly seems strangely warm and somewhat firmer to the touch.

But what about Talbert, the blue oranda goldfish?

When he starts swimming sideways or simply lies at the bottom of his tank, do we think we should take Talbert to the vet?

What about the tilapia producers or even fishermen who go to sea and return hauling in that big catch? Can the fish they produce or catch get sick?

Can vets intervene in such cases?

With widespread concern over whether or not it’s safe to eat the fish being caught in the Gulf of Paria and the many issues and concerns regarding the health of these animals that so many of us depend on as a major protein source, it seems fitting to discuss fish health and fish health management.

So, yes, fish do get sick and yes, sick fish can be taken to or examined by a vet, provided that vet has been specifically trained in fish medicine—which can certainly be different to the dog, cat, horse, cow, sheep, goat, pig, and bird medicine, that many of us may be more familiar with. This was indeed the case when, over several weeks in March and April, hundreds of dead fish (primarily Mullets, interestingly) started washing up on beaches in southwest Trinidad, some months after the December oil spill.

As a part of the investigation, fishes were examined by a number of agencies, including the Aquatic Animal Health Diagnostic Laboratory at the Aquatic Animal Health (AAH) Unit at the UWI-School of Veterinary Medicine (UWI-SVM). Diagnostic samples from aquatic species, especially fish, are collected and handled a little differently compared with those for domestic species. As such, aquatic animal patients presented to the UWI Veterinary Hospital have their own laboratory where their samples are analysed.

The laboratory helped to clean oiled animals during the spill, and performed necropsies on aquatic species that washed ashore during and afterwards. In the March-April spate of fish mortalities in the same area, the laboratory performed necropsies daily and has worked to provide the various environmental authorities with answers to parts of this puzzle. Testing is extensive, time-consuming, and of course, aims to be thorough. Analysis of immune system responses, evidence of parasitism, microbiological analyses, determination of changes in normal tissue cellular structure, body condition scoring, analysis of gut contents, and collection and preparation of samples for submission to independent laboratories for chemical residue analysis were all done.

Now, outside of deliberately catching fish and removing them from their natural environment or an animal simply reaching the end of its natural life span, why would fish die?

Fish become stressed and may show ill health or may die when just about anything causes a severe enough deterioration of water quality. These may more commonly include proliferation of harmful algae in the body of water or the introduction of toxic or poisonous pollutants. These agents may either be directly toxic to fish, or may be indirectly toxic by disturbing water chemistry, thereby disrupting the natural balance causing the availability of an important parameter to be minimised.

Fish are also susceptible to diseases caused by a host of bacteria, viruses, fungi and parasites. Nutritional disorders, tumours, reproductive and even buoyancy disorders are all known to contribute to ill health and mortality as well. An important issue is that of some fish pathogens and diseases being passed on to humans, sometimes simply from contact and other times following consumption. Such diseases that can be transmitted from animals to humans are referred to as zoonoses. For example, have you ever heard of Fish Handler’s Disease?

There are a couple of bacterial organisms (Erysipelothrix sp. and Mycobacterium sp.) that cause Fish Handler’s disease and people who handle fish regularly, like our fishermen, should be especially aware of and be wary of these organisms. When handling fish that may be infected by either of these organisms, the bacteria may enter the body through small cuts and scrapes on the hands and result in sores that are not only unsightly, but more importantly, may be very painful and difficult to treat. Immuno-compromised persons are especially at risk. Depending on which bacterium is the offending organism, the appearance of the lesions, the diagnosis and treatment will vary. This is merely one of the many diseases that humans may be exposed to as a result of coming into contact with diseased fish. Although it does not treat or diagnose humans, the AAH Unit aids in the examination and diagnosis of these and many other fish diseases and advises owners and producers on how best to manage their stocks while ensuring that they too are not exposed to potentially harmful pathogens.

There are many contributors to deterioration of fish health. Considering our nation’s recent fish mortality event for which testing is still ongoing by several agencies, and speculation continues as to why primarily one species of fish was washing ashore in large numbers, it behoves us to continue to exercise a measure of due caution, as would be the case when deciding upon any one of our meals. After all, there are many potential contaminants that continue to be in our waters, that continue to bio-accumulate in the aquatic food chain, and that we continue to be potentially exposed to. Good water quality is vital to the growth, development and harvesting of healthy fish, be they freshwater, brackish water or marine.

Carla Phillips, DVM, MPhil, PhD is a Lecturer- Marine Mammal Medicine/Aquatic Animal Health at the UWI-SVM; Coordinator – Aquaculture/Aquatic Animal Health Unit; Coordinator – Trinidad and Tobago Marine Mammal Stranding Network.

ONE HEALTH IN THE WATER

The AAH Unit of the UWI-SVM is actively involved in spearheading aquatic environmental conservation efforts. One such effort is the hosting of an upcoming ‘One Health’ Workshop focused on Conservation of Aquatic Ecosystems. The ‘One Health’ concept is a holistic approach to addressing health-related problems, ensuring that human, animal and environmental health are all considered, so that the interrelationship among the health of all three components can be identified and effectively targeted when seeking resolutions. The Workshop will be held on June 24 and 25, 2014 at the Faculty of Medical Sciences and is especially timely in the light of ongoing human health, animal health and environmental health issues and concerns related to the oil spill and its clean-up efforts.

To access some of the many services of the Aquatic Animal Health Unit and Diagnostic Services please contact either Dr. Carla Phillips at 645-2640 x4343 or Dr. Omar Khan at 645-2640 x4305.