Practical reptile care (Proceedings)
As the popularity of reptiles has grown, so has the demand for quality veterinary care. Today, reptile medicine represents a viable subset of companion animal practice. Reptiles are stoic and have evolved to mask signs of illness, which makes them a challenge to diagnose and treat. For veterinarians and technicians who are willing to become proficient, however, reptile practice offers many rewards.
Capture and RestraintSnakes are easy to hold because there is only one dangerous part to restrain. When approaching a snake you do not know, the head may first be covered with a towel. This has the dual effect of blocking his view of the handler and providing him a sense of security. Restrain by grasping behind the head with one hand and supporting the body with the other.
Snakes do not have complete tracheal rings, so use caution that asphyxiation does not occur. Some colubrid snakes will emit a musky paste from the scent glands as a defense mechanism. Snakes that are used to being handled are much less likely to bite. Bites from non-venomous species, if they occur, are generally harmless. Use the buddy system when dealing with giant or venomous species.
Basic Exam Skills
Weigh the patient (in grams) at every opportunity. A decline in weight may be the only clue that there is a problem developing. Assess body score by examining the dorsolateral musculature. Check for mites or ticks in the gular groove between the mandibles and under the edges of scales. Examine the heat pits and eyes for mites. Look for retained skin especially on the head and spectacles. During the oral exam, look for petechiation and abscessation. Check the tongue and glottis for swelling, symmetry, and inflammation. Observe snakes for righting reflex and positional nystagmus when the head is moved side to side. Palpate the abdomen for masses and ova.
Sexing via Hemipenal Probe
Use a lubricated blunt probe (e.g. ball-tipped feeding needle, urinary catheter). Pass the probe cranially under the lateral edge of the vent flap, then flip the probe to aim it caudally. Direct the probe into a longitudinal canal that runs paramedian along the tail. If the probe passes 3 caudal scales (into the scent gland) it is female, if it passes 7-10 caudal scales (into the hemipenal canal) it is a male.
• Ventral tail vein: caudal to the cloaca with the snake in dorsal recumbency. A 5/8-1", 21-25ga needle is angled at 45° craniodorsally, between caudal scales. Apply slight negative pressure once you are under the skin. If the needle hits a vertebral body, withdraw slightly and redirect. (Best for large snakes)
Tracheal wash is the preferred method for sampling of respiratory pathogens. With the snake's head elevated, a sterile urinary catheter is placed through the glottis while the patient takes a breath. Then, 3-10 ml/kg of sterile saline is injected. The snake is quickly tilted downward, and the fluid is aspirated back into the syringe. Because of the simple anatomy of the reptile lung, samples collected in this manner may actually be lung washes. Wet mount cytology of tracheal wash samples may reveal lung worm (e.g. Rhabdias, pentastomid) larvae or ova. Anaerobic and aerobic culture and sensitivity are also performed.
Maintenance fluid rate for most reptiles is 15-25 ml/kg/day, and up to 5% of body weight may be given in a single dose if indicated. Subcutaneous or intracoelomic fluid administration is utilized in the majority of cases. In snakes, SQ fluids can be given along the lateral folds. ICe fluids are given ventrolaterally a short distance cranial to the vent, using care not to enter the caudal extent of the lungs.
IV catheters can be placed in most reptiles however a cut-down approach is usually necessary. The preferred site for snakes is the right jugular vein. A cut-down incision is made from 4-7 scutes cranial to the heart, at the junction of the ventral scutes and lateral body scales. After the vein is isolated, a catheter is placed in the usual manner and secured using tape, suture, and/or tissue adhesive.
Reptiles are slightly hypotonic when compared to birds and mammals. To prepare "Reptile Ringers Solution", mix 2 parts Dextrose 2.5%/Saline 0.45% with 1 part lactated Ringer's solution (or 1 part Dextrose 5%, 1 part Saline 0.9%, and 1 part Ringer's).
Snakes frequently present for lack of appetite. In some species (e.g. ball pythons) this can be considered a normal, seasonal occurrence. In others it may be attributed to stress or disease. Often, no abnormality can be found on physical examination or fecal testing. Force-feeding provides nutritional support for these patients while the clinician seeks to diagnose the problem and correct husbandry. In the majority of cases, force-feeding will stimulate a snake's appetite. Medications (e.g. metronidazole, fenbendazole) are frequently added to the mixture to "shotgun" the problem before resorting to further diagnostic tests.
Oxbow Carnivore Care is used for this purpose. Mix to the desired consistency. Give 2.5-5% of body weight using a catheter-tipped syringe and lubricated 14-fr. red rubber catheter. A snake's mouth can be opened with a rubber spatula or similar speculum. Its glottis will be located far cranially in the mouth and is easy to avoid. Gently massage the food caudally as it is given. After feeding, hold the snake's head elevated for several minutes. Once he is moving forwards in a serpentine fashion it is ok to release him.