INVMA 2017: Managing Invertebrates in Practice
When veterinarians are presented with an invertebrate animal, what they need most is an understanding of the husbandry needs and behaviors of that particular species.
According to Jorg Mayer, DVM, MS, DABVP (ECM), DECZM, DACZM, associate professor of zoological and exotic animal medicine at the University of Georgia College of Veterinary Medicine in Athens, invertebrates are becoming increasingly popular as pets.
Presenting at the Indiana Veterinary Medical Association’s 2018 annual meeting in Indianapolis, Dr. Mayer discussed some common problems in invertebrates and shared some basic approaches and techniques to help general practice veterinarians manage these patients.
When dealing with invertebrates in practice, he explained, veterinarians must tailor their management approach depending on whether they are presented with an individual pet animal or a problem in a collection of invertebrates. For an individual animal, the approach is similar to that for a dog or cat. “Examine the patient systematically, just as you would with a mammalian patient,” he said. “But when dealing with a collection of inver- tebrates, think herd health. You may need to sacrifice a few normal or sick animals as part of your investigation.”
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He also stressed the importance of knowing the sex of the animal because this can affect the approach to certain health problems. For example, the typical life span of a male tarantula is 2 years, whereas a female can live to age 25. If an owner requests help because several tarantulas have died between 18 months and 2 years of age, the veterinarian will need to investigate whether the deceased spiders were all female. If they were male, however, the veterinarian can explain that this merely reflects the typical life span of a male tarantula.
When investigating any health problem, veterinarians should initially examine the animal and its behavior while it is still in the container, said Dr. Mayer. If the animal needs to be handled, veterinarians should do so with care. Be aware of the dangers involved in handling invertebrates, including what weapons (stinger, fangs, etc) they have. “Be gentle and move slowly—most invertebrates that bite or sting will only do so if they feel threatened,” he said. “And avoid breathing on the animal. A tarantula, for example, sees this as a threat.” The number 1 rule is “do no harm” to either the patient or yourself, Dr. Mayer emphasized.
Many diseases of invertebrates kept as pets are related to poor husbandry, which often is associated with provision of an inappropriate substrate for the animal to live on. A substrate that is too wet may result in fungal disease, Dr. Mayer said; one that is too dry may lead to dysecdysis (abnormal shedding of the outer skin in reptiles). “Correcting the husbandry issue can often cure the presenting problem.” Inappropriate husbandry is common in the spider trade, he said, and often results in dehydration of the animals. Dr. Mayer noted that the abdomen of a healthy tarantula should be rounded. A deflated-balloon appearance indicates that the animal is dehydrated. In this case, do not offer the spider a water bowl because it may be weak and could drown in the bowl. Instead, soak a sponge in water, he advised, and place it on a dish for the spider to drink from. In severe cases of dehydration, lactated Ringer solution can be injected to replenish the spider’s fluid levels.
Dr. Mayer also reminded veterinarians to check invertebrate patients for mite infestations and to be aware of which invertebrates carry beneficial symbiotic mites. For example, centipedes do not carry beneficial mites, he said, so the presence of any mites on these animals should prompt the veterinarian to check the husbandry conditions. Disinfection of the insect’s environment, and quarantine, might be necessary.
“And don’t mess around with a tarantula that is shedding,” Dr. Mayer said. This is a vulnerable time for the animal, and its new exoskeleton is very soft. “For a few days, avoid feeding it crickets, which may eat the spider’s new soft exoskeleton. Let the new exoskeleton harden before feeding,” he stressed.
Another husbandry-related problem for many invertebrates in captivity relates to stress associated with exposure to visitors and continual handling. In such cases, an animal may flick its legs as a stress response when it feels threatened. This action results in loss of hair on the dorsal abdomen, which produces bald spots, Dr. Mayer explained.
Similarly, excessive handling often leads to animals being dropped. These traumatic incidents can present as emergencies, Dr. Mayer said, because the resulting hemolymph loss is a big problem. Hemolymph is not contained in vessels in the invertebrate body, so it just leaks from the traumatized exoskeleton.
Simple Wound Repair
Dr. Mayer discussed how to repair simple wounds on the exoskeleton of a tarantula. To anesthetize the tarantula, he advised soaking a piece of cotton wool in isoflurane and simply placing it in the container with the spider. Wait about 5 minutes, he added, until a sufficient plane of anesthesia results. Veterinarians should not be too concerned about using too much isoflurane because this is difficult to achieve in spiders, he added.
When repairing wounds, veterinarians should avoid using sutures, Dr. Mayer said. The spider’s body naturally responds to injury by producing a mold that has wound-healing properties. “Suture material can interfere with shedding of the old mold,” he explained.
Instead, when repairing wounds on insects or spiders, he advised using surgical tissue glue, bone wax, or household superglue to stop hemolymph leakage.
To deal effectively with an uncommon species, Dr. Mayer highlighted the need for veterinarians to familiarize themselves with what different invertebrates’ behaviors mean in different environments. When faced with an uncommon patient, it is important to know what normal behavior and body condition look like for that species, he said. Plenty of literature and books are available to help with this, he stressed. “Knowledge is power.”
Dr. Parry, a board-certified veterinary pathologist, graduated from the University of Liverpool in 1997. After 13 years in academia, she founded Midwest Veterinary Pathology, LLC, where she now works as a private consultant. Dr. Parry writes regularly for veterinary organizations and publications.