by Heather Bjornebo, DVM, DABVP(Reptile-Amphibian Practice), CertAqV
Many clients with rabbits are unaware of the important health benefits of spaying rabbits. Spaying refers to the surgical sterilization of a veterinary patient by removing their ovaries and, at least in the United States, their uterus. There are many benefits to having your rabbit spayed that go beyond preventing unwanted litters.
The biggest benefit is the elimination of the potential to get uterine cancer. Uterine tumors are extremely common in rabbits as they age. Some studies have shown as many as 44% of rabbits developing some form of uterine abnormality in their lifetime. Another important benefit of spaying your rabbit is spayed rabbits are also significantly less likely to get mammary tumors (breast cancer).
Beyond the medical benefits of spaying your rabbit, there are also benefits that will help her make a better pet for your family. Spayed rabbits are better at using their litterbox and tend to be less aggressive. Spay rabbits are easier going and oftentimes more affectionate.
So what should you consider when looking for a veterinarian to have your rabbit spayed? Rabbits in general are considered a higher anesthetic risk than dogs and cats so it is very important to find a veterinary hospital where not only is the veterinarian very familiar with your rabbit’s medical needs, but their staff is trained well so your rabbit receives the best care and monitoring during the procedure. While cheaper prices can be found at spay/neuter only practices, often time this lower cost comes with less one-on-one care, decreased monitoring during and after the procedure, and less supportive care such as skimping on IV fluids. Given the special needs of rabbit patients, we recommend rabbits be spayed at a full service exotics practice. To find an exotic veterinarian in your area visit aemv.org and use their find-a-vet search tool.
By Heather Bjornebo, DVM, DABVP(Reptile-Amphibian Practice), CertAqV
One of the things I love about exotic pet medicine is how rapidly things are advancing and progressing. It seems every year we are getting new advanced treatment options for our patients which is so exciting. One medication that I am excited about is Capromorelin.
Recent studies on capromorelin, sold by the trade names Entyce® (dogs) and Elura® (cats), have shown promise as a medication to help stimulate appetite in sick exotic pets. Classified as a ghrelin agonist mimics the hunger hormone ghrelin where in the brain it acts on the hypothalamus resulting increased growth hormone release by the pituitary gland causing increased hunger and food intake. In addition, capromorelin also increases insulin-like growth factor-1, which increases lean muscle mass.
One recent promising study published in the Journal of Exotic Pet Medicine and Surgery on hedgehogs showed significant increases in food intake when the medication was administered. Seventy percent of the hedgehogs in this study administered this medication showed an increase over those recieving the placebo consuming on average 11% more food.1
A study showed capromorelin decreased stress induced weight loss in laboratory mice. The only study group where no benefit was seen with this medication was when patients were receiving the long acting opioid pain medication Buprenorphine-XR.2
Another recent study in rabbits compared the efficacy of capromorelin versus Mirtazapine on improving appetite. Mirtazapine is another meidcation often used in veterianry medicine to increase appetite in sick animals. It is available as a topical gel that can be applied to the ear lobe. While previous studies in rabbits showed mirtazapine increases fecal output, it did not improve appetite. In this study it showed a positive effect on appetite with healthy rabbits increasing their intake after 2 days. Normal patients given capromorelin also showed significant increase in appetite, though not as profound as those given mirtazapine. Conversely, patients recovering from neuter surgery didn’t demonstrate any significant improvement in appetite on either medication. The overall take home was both medications help appetite, with mirtazapine being more effective and less stressful for the patient due to being topical and not oral. However, both did show promise in treatment of GI stasis.2
Capromorelin has also been studied in birds. In a study in chickens the medication not only biochemically increased their blood insulin levels, it increased their appetite demonstrated by increased pecks per hour.4
Definitely, more studies are needed to fully evaluate the use of this medication in exotic pets. So far the initial studies show a lot of promise, even if the results in rabbits suggest topcial Mirtazapine may be the medication of choice in this species. While less effective, it still gives practitioners another tool to treat GI stasis in this species. Hopefully, in the years to come more studies covering its efficacy and use in many other types of exotic pets, including reptiles.
If you have questions about Capromorelin, contact your family veterinarian.
References:
Huckins, G.L., Mans, C. and Doss, G.A., 2025. Effects of oral capromorelin on food intake and body weight in healthy, four-toed hedgehogs (Atelerix albiventris). Journal of Exotic Pet Medicine, 52, pp.1-3.
Punger, E.M., Norris, S.L., Stevens, S.C., Santos, K.H. and Christy, A.C., 2024. Investigating the Effect of Enterally Administered Capromorelin on Body Weight in Mice (Mus musculus). Comparative Medicine, 74(5), pp.327-335.
Draper, J.M., Savson, D.J., Lavin, E.S., Feldman, E.R., Singh, B., Martin-Flores, M. and Daugherity, E.K., 2022. Comparison of effects of capromorelin and mirtazapine on appetite in New Zealand white rabbits (Oryctolagus cuniculus). Journal of the American Association for Laboratory Animal Science, 61(5), pp.495-505.
Ceron-Romero, N., Taofeek, N., Thomas, A., Vroonland, E., Sanmartin, K., Verghese, M., Heinen, E. and Vizcarra, J.A., 2021. Capromorelin, a ghrelin receptor agonist, increases feed intake and body weight gain in broiler chickens (Gallus gallus domesticus). Poultry science, 100(8), p.101204.
Rabbit hemorrhagic disease (RHDV2) is endemic in southern Arizona, meaning it can’t be eradicated. The disease is highly contagious and can be spread through direct contact with infected rabbits, their feces, urine, and contaminated materials. It can also be transmitted by insects, such as flies, which can carry the virus.
Here are some things you can do to protect your pet rabbit and prevent the spread of RHDV2:
Not using any equipment, clothing, or boots for field work that you use with your pet rabbit
Vaccinate your pet: Get your pet rabbit vaccinated twice as soon as possible. You can get your pet vaccinated at select private exotic animal clinics.
Keep your pet indoors: Ideally, all pet rabbits should be housed indoors.
Take precautions when handling wild rabbits: If you work with or hunt wild rabbits, take special care to prevent your pet rabbit from coming into contact with them. You can do this by:
Removing any field clothing and showering after handling wild rabbits .
Did you know that respiratory infections are come of the most common medical conditions seen in pet rats. Both acute respiratory illness and chronic have been well documented. Acute bacterial pneumonia is characterized by sudden onset of symptoms and is often caused by Corynebacterium kutscheri or Streptococcus pneumonia. Corynebacterium kutscheri is often referred to as pseudotuberculosis (a.k.a. false tuberculosis) and is more often seen in older rats. On the other hand, Streptococcus pneumonia is more commonly diagnosed in younger rats and is actually contagious to people. Chronic disease, commonly referred to as murine respiratory mycoplasmosis, is caused by Mycoplasma pulmonis. Co-infections with cilia-associated respiratory bacillus, Sendai virus, or Sialodacryoadenitis virus are common.
Symptoms of respiratory illness in rats include difficulty breathing, rapid respirations, blue gums, sneezing, ocular/nasal discharge, red pigment staining around the nose, eyes, and front paws, lethargy, head tilt to rolling, muffled heart sounds on veterinary examination, and acute death in severe cases.
Following a thorough physical examination, your veterinarian may recommend chest x-rays. X-rays of the skull may also be recommended to evaluate the inner ear. Blood testing may also be recommended to evaluate the body’s response to infection through a while blood cell count and metabolic state through a serum biochemistry panel. Your veterinarian may also recommend microbial culture and a DNA probe (a.k.a. PCR) test for Mycoplasma especially if the patient isn’t responding as expected to treatment.
Initial therapy involves stabilizing the patient. Hospitalization for oxygen therapy is necessary for patients struggling to breathe. Patients should remain hospitalized until stable on oral medications. Your vet will prescribe appropriate antibiotics and anti-inflammatory medications based on the patient’s illness and needs. Additional treatment with bronchodilators, fluid therapy, and assist feeding. Patients with chronic illness may require long term or pulse therapy as well as may be prescribed medications to treat secondary chronic pulmonary hypertension.
Learn more about respiratory disease in rats by visiting our Educational Guide here.
UV light or Ultraviolet light is high energy light than violet but lower energy than X-rays on the electromagnetic spectrum. Ten percent of the light energy produced by the sun is UV light. UV light is invisible to most humans. Small birds, on the other hand, have a forth color receptor in their retinas that gives them “true” UV vision.
UV light is further broken up into UV-A, UV-B, and UV-C.
UV-A is low wave UV. It easily penetrates the ozone layer. This is the light we find in black lights and is known as “soft” UV. Reptiles utilize this light to help regulate behaviors (a.k.a. their circadian rhythm) such as feeding, daytime movement, mating, and similar activities.
UV-B is medium-wave UV or “intermediate” UV and most of this light frequency is absorbed by our ozone layer. Biologically, it is utilized by non-fish vertebrates like reptiles, amphibians, birds, mammals, and even humans for vitamin D synthesis.
UV-C is short-wave UV or “hard” UV. It is ionizing radiation and used in germicidal UV sterilizers. Luckily, the UV-C produced by our sun is completely absorbed by the ozone layer and our atmosphere.
Why do reptiles need UVB light?
Reptiles, like many vertebrates, utilize UV-B light in the synthesis of vitamin D. When UV-B light interacts with the skin it interacts with 7-dihydrocholesterol activating it into cholecalciferol, or vitamin D3. From there it undergoes further transformation within the liver and kidneys to become 1,25-dihydroxyvitamin D3 used for maintenance of calcium balanced within the body. So without UV-B light that first step in producing this vital chemical regulator within the body never happens. 1,25-dihydroxyvitamin D3 is important as it increases absorption of calcium from the diet, decreases loss of calcium in the urine from the kidneys, prevents overproduction of parathyroid hormone, and modulates the activity if the cells of the skeletal system.
Do all reptiles need UVB light?
Diurnal reptiles, such as iguanas, bearded dragons, turtles, tortoises, water dragons, day geckos, etc. all require UV-B for production of active vitamin D3. Crepuscular reptiles, those active at dawn and dusk, have been found to also be able to utilize UV-B to activate vitamin D3. However, they can also utilize dietary vitamin D3 and have been raised in captivity for generations without UVB lighting. Studies in nocturnal reptiles (i.e. pythons, boas) have shown they cannot utilize UV-B for vitamin D3 activation. However, there may be additional benefits that UV-B lighting provides that have yet to be discovered.
What sources of UVB lighting are available to pet owners?
UV-B light for your reptile can be naturally provided from the sun or artificially by using specially designed light bulbs that produce UV-B. Natural sun can only be used by reptiles housed outside. This is because UV-B cannot penetrate glass so placing your pet near a window will not work. UV-B is only able to penetrate the glass of UV-B bulbs because the glass has been specially treated to allow UV-B to penetrate the glass. This coating wears off over 6-12 months of use causing these bulbs to stop producing UV-B light long before they burn out. This is why manufacturers recommend replacing these bulbs regularly. Artificial UV-B is available in 4 different types of reptile bulbs: fluorescent, mercury vapor, metal halide, and LED.
The first is fluorescent which produces light using a low-pressure mercury-vapor gas-exchange lamp that fluoresces to produce visible light. These bulbs produce minimal heat and come in 3 types. The first are the T8 bulbs, this is a second generation fluorescent straight tube bulb (first generation being T12 bulbs and are no longer produced as UV-B bulbs). The second are the compact fluorescent bulbs where the fluorescent tube is formed into a coil or loop and then set into a normal light bulb socket. Both T8 and compact fluorescent bulbs produce similar amounts UV-B. The third and newest type are the T5 or third generation straight tube fluorescent bulbs. These emit stronger light and have more UV-B production than both T8 and compact fluorescent bulbs.
Most UV-B fluorescent bulbs are sold in various strengths, which vary in their labeling depending on the manufacturer. For example, Zoo Med sells them as 2.0, 5.0, and 10.0 bulbs corresponding to 2%, 5% and 10% UV-B production respectively. While Arcadia sells 2%, 7%, 10%, 12% and 14% bulbs. Exo-Terra takes a completely different aproach utilizing a more complex system to help keepers choose the correct bulb based on species and basking distance with bulbs labeled as 100, 150, or 200.
The second type of UV-B bulb available to reptile owners are Mercury Vapor bulbs. A mercury-vapor lamp is a gas-discharge lamp that uses an electric arc through vaporized mercury to produce light. They procude both head and UV-B light. These bulbs are ballasted, when they turn off they need to cool down before they will turn back on, so they cannot be regulated with a thermostat like standard heat lamps. They have a higher UV penetration and UV index than fluorescent bulbs making them ideal for larger enclosures (40 gallons or larger).
Metal Halide bulbs are the third type available on the market. A metal-halide lamp is an electrical lamp that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides. This bubl also produces both heat and light, but less heat at a lower wattage than mercury vapor bulbs. These high intensity UV-B bulbs also work well for larger habitats. It should be noted that special fixures are required for these and standard heat domes will not work.
The final type available are LED or light-emitting diode lamps. These are a semiconductor light source that emits light when current flows through it. Relatively new to the market, more research is needed to really gauge how they compare to other bulbs on the market. While expensive, these bulbs are energy efficient and produce little to no heat.
What is UV penetration and why is understanding this important to choosing the right lighting for your pet?
UV penetration is the concept that the farther you get from the UV-B source, the lower the UV-B index is. Different bulbs are going to give you different depths of penetration into the cage. It is important to take this into account when choosing the lighting for your pet. In general, mercury vapor and metal halide bulbs have the highest (or deepest) penetration while fluorescents the penetration is lower. Below are some examples of UV penetration diagrams for a variety of different UV-B bulbs.
What is UV index?
The last area that needs to be touched on is UV index. UV index is an international standard measurement of the strength of sunburn-producing ultraviolet radiation at a particular place and time. It’s an open-ended linear scale, directly proportional to the intensity of UV radiation that causes sunburn on human skin. It was invented to help people effectively protect themselves from UV radiation, which has health benefits in moderation but in excess causes negative effects. We borrow this in reptiles just as a measure of the amount of UVB reaching our pets.
Summary
UV-B lighting is essential for the health of many pet reptiles. Most reptiles require UVB lighting to properly absorb and utilize dietary calcium. Without UVB many reptiles will develop Nutritional Secondary Hyperparathyroidism a.k.a. “Metabolic Bone Disease.” It is important to understand that artificial UVB lights need to be changed every 6-12 months as they will stop giving off UVB light. Both species and cage setup should be considered when choosing the right UVB source.
Reptiles are often referred to being “cold-blooded”, which can be misleading. More appropriately they should be considered poikilothermic or ectothermic, which means that unlike mammals and birds reptiles are unable to regulate their body temperatures internally and change their body temperature in adaptation to their environmental temperature. Because reptiles do not need to expend as much energy heating their bodies, they have a much lower metabolic rate than that of mammals. Each reptile species has what is referred to as its preferred optimal temperature zone which is a narrow temperature range at which they are active and undergo typical functions such as feeding, digestion and reproduction. Outside of this range these functions may be hindered or cease altogether. Some species will hibernate during colder months and during this time their metabolic rate will decrease.
Reptiles belong to the Class Reptilia, which can be broken further down into 4 Orders: Squamata, Chelonia, Crocodilia, and Tuatara.
Tuatara
The Tuatara is an ancient type of reptile only found in New Zealand and is a protected species only rarely seen in captivity in zoos or very special private collections.
Crocodilia
Crocodilians include crocodiles, alligators, and caiman. Members of Crocodilia are illegal to own as pets in Arizona.
Squamata
The order squamata can be broken down into 2 suborders: Serpentes (snakes) and Sauria (lizards).
There are over 2,700 species of snakes worldwide and snakes can be found on every continent besides Antarctica . While the obvious answer to how snakes differ from lizards might appear to be that they lack limbs, it gets confusing when you consider legless lizards. Thus, to be more precise, snakes differ from lizards by lacking external ears and lacking remnants of forelimbs. That said, some snakes do have vestigial hind limbs, which can be seen externally as a pair of spurs on either side of their cloaca. Snakes also lack eyelids. Instead their eyes are protected by a clear scale known as a spectacle, which is shed at the same time as the snake sheds its skin.
All snakes are carnivorous, most feed on rodents, lizards, birds, and even eggs. Since snakes are unable to chew or take bites of their meals, they must swallow their food whole. To do this they have a very flexible skull and jawbones. Snakes can easily consume an animal as big as they are wide. The majority of snakes are non-venomous and kill their prey by constriction. Those that are venomous produce venom in glands located behind the eyes and inject it via fangs by biting. Venomous snakes should be discouraged as pets due to the risk of injury to humans.
Most snakes lay eggs (oviparous), with the exceptions of nearly all boas and some vipers such as rattlesnakes who give live birth (viviparous). Snake eggs are oval shaped and have flexible, leathery shells.
Snakes are largely non-social and live solitary lives, rarely seeking out company outside of the breeding season.
Lizards far outnumber snakes with nearly 5,000 different species worldwide. And like snakes, lizards can be found on every continent except Antarctica. Lizards have well developed color vision and communicate via body language and pheromones. Most lizards are solitary animals and keep a loose territory. Most lay eggs (oviparous) but some do give live birth (viviparous). There are two species of venomous lizard, the Gila monster and the beaded lizard.
Some lizards have unusual adaptations. Many species of gecko have adhesive lamina on their toes to enable them to climb on sheer surfaces. Many geckos also lack eyelids and, similar to snakes, have a spectacle.
Many species of lizard have the ability to drop their tails, an adaptation referred to as autonomy. Most lizards will regrow their tails with the exception of Rhacodactylus geckos. Lizards that do not practice autonomy will not regrow a lost tail, however.
Both snakes and lizards shed their skin as they grow. Snakes shed their skin in one large piece, while lizards often do so in multiple smaller pieces. Proper shedding is very important to their health.
Chelonians
This suborder includes turtles, terrapins and tortoises. Turtles most accurately should be used to describe sea turtles, which are not kept as pets due to their size and care requirements. Terrapins are the freshwater and land dwelling species that are what we commonly refer to as turtles. Terrapins are omnivorous to carnivorous. Tortoises are strictly land dwelling and predominantly herbivorous. Often, the confusion arises when trying to distinguish a box turtle from a tortoise. While they are primarily land animals, box turtles are terrapins. They are omnivores and have limbs more similar to that of a terrapin.
All Chelonians have a protective shell, however some may be more protective than others. Soft shelled turtles, for instance, have a shell covered with leathery skin that does very little for protection. Other than soft shells, a chelonian’s shell is comprised of living bone covered with plates of keratin, similar to scales, called scutes. It is normal for terrapins to shed their scutes as they grow, but not for tortoises.
One of the most well known characteristics of chelonians is that they are very long lived; even the shortest-lived aquatic terrapins routinely live 20-30 years. Tortoises can live 60-100 years, depending on species. Chelonians are very social animals and establish loose territories. Males can be very territorial and will fight over resources and females. All chelonians lay eggs (oviparous); they produce eggs with a hard shell similar to a bird’s egg and are usually spherical.
Basic Anatomy
Most reptiles have a 3-chambered heart as well as a renal portal system where blood passes through the kidneys both as it leaves the heart and as it returns to the heart after traveling through the back end of the body.
Reptile lungs are simple and sac-like and often have a vascular epithelium towards the front and non-respiratory epithelium towards the back. They do not have aleoli like mammals, but instead their pulmonary functional unit is called faveoli, small air spaces in the lungs that resemble honeycomb cells.
Reptile gonads are internal and the right and left gonads are located at different levels of the snake between the pancreas and the kidneys. Male snakes and lizards have paired copulatory organs called hemipenes while male chelonians and crocodilians have a single phallus. These are not associated with the urination and only function for mating, thus if diseased these may be amputated.
Snakes
Snakes possess very elastic to allow for ingestion of prey. Periodically shed whole, usually between 2 to 4 times per year depending on growth rate. They also are very delicately built compared to other reptiles. They have two rows of teeth on the top (maxillary and pterygoids) and one on the bottom (mandibular). Their teeth are recurved and are periodically shed throughout life. Their tongue is long, deeply forked and lies in sheath under the glottis and is used in olfaction (smell) together with the Jacobson’s organ found on the palate. They have no external ears and no tympanic membrane or middle ear, yet they are able to hear low frequency sound using the inner ear. Their vision geared for movement and they have no eyelids, instead their eyes are covered with a spectacle. Heat-pits are present on the heads of boas, pythons, and pit vipers allowing them to find prey in complete darkness.
The right lung is larger than the left in snakes, with the left lung completely non-functional (vestigial) in colubrids like corn snakes and kingsnakes. Like all reptiles, snakes lack of diaphragm.
Venom glands in snakes are modified salivary glands and located behind the eyes on the head.
Like all reptiles, the snake ureter empties into part of the cloaca called the urodeum. Snakes lack a urinary bladder. Male snakes have a sexual portion of the kidney that enlarges during the breeding season and produces seminal fluid.
Lizards
Unlike snakes, most lizards shed their skin in pieces. Their skin is usually fairly thick and scaled, with the exception of geckos who possess very thin skin. Many practice tail autonomy, meaning they can drop their tails as a defence mechanism. While most species will regrow their tails, not all can do this, i.e. crested geckos. Bearded dragons do not drop their tails and their tails cannot regenerate if lost.
Their ear drum, or tympanic membrane, is visible and there is no external or ear lobe.
Most lizards have eyelids, with the exception of some species of geckos, and have well developed color vision. Many also possess a degenerate 3rd eye or parietal eye located on the top of the head. It contains a retina and lens and is used to stimulate hormone production as well as moderate behavior associated with thermoregulation and basking times.
The heart is 3-chambered and located between the shoulders in most lizards, with the exception of monitor lizards where it is located low in the chest.
Lizard tongue morphology varies based on function.
Chelonians
Probably the most promanent part of chelonian anatomy is their shell witha dorsal carapace and ventral plastron. Their pectoral and pelvic girdles are uniquely located within their rib cage. Comprised of living bone covered with protectie keratin, their shells are well innervated and can feel touch and pain.
Their eyes are similar to birds and they possess scleral ossicles, small circular bones embedded in the whites of the eyes.
The chelonian ear is hidden behind a large scale or several smaller scales that overlies their tympanic membrane (ear drum).
Chelonians have large lungs that extend the length of the shell. Like all reptiles, they lack a diaphragm. Their shell prevents movement of the rib cage so respiration requires movement of the head and forelimbs.
While chelonians have a relatively simple stomach, the large intestines of many tortoises is extensive and used for microbial digestion of fiber.
Measures all bivalent cations, majority is dissolved magnesium and calcium
Measured in “dH” aka degree hardness— 1 dH=17.8ppm CaCO3
Hardness of the water plays into the buffering ability of the water
Hard water >300 mg/L, soft water <150 mg/L
Used for skeletal and scale growth, and in mollusks and crustaceans for shells
High levels can affect drugs administered in the water and require higher concentrations of drug be added
Too high: zinc deficiency cataracts due to competition for absorption with calcium, nephrocalcinosis
Too low—decreased buffering capacity causing acid pH in environment (see KH and pH information on each parameter), slow or stunted growth (due to not enough calcium for growth)
Carbonate Hardness (KH)
Should be > 4.5 dH (degree of hardness), 7-9.8 dH in coral or invertebrate tanks
Other terms used “buffering capacity”, “alkalinity”
Measure of the carbonates and bicarbonates within the system
Carbonates provide buffering capacity and an energy source for use by the bacteria involved with biofiltration and the plants in the tank when CO2 levels fall
The higher the KH, the more buffering capacity of the water, the larger ability to bind H+ ions and resist pH drop in the water
Important for corals and invertebrate skeleton
If the buffering capacity is used up and not replaced or Hardness level <4.5 dH the everyday processes that occur in the tank with continue to drop the pH = biofilter will stop working, fish will become stress and undergo changes due to acidic irritation
Treatment: Water changes with help replace the buffer, Limestone or baking soda can be added to provide buffer
Phosphate
Phosphate levels <0.1 mg/L
In high levels will cause algal over growth
Naturally occur due to breakdown of plants, animals, waste products, and fertilizers
High levels can occur at the water source or from nutrient build up and breakdown in the water (over stocking, algae die-off, lack of water changes, fertilizer application nearby)
Treatment: Water change to decrease, clean the tank/pond of extra plant or algae and debris that you can. if large scale you can place a phosphate binding filter or phosphate binding chemicals into the water.
Copper
Aim for zero ppm, no more than 2.0 mg/L during copper baths
Higher in soft water
Cause- high levels from water source, treatment with bath, algae treatment
Toxicity: osmoregulation dysfunction causing high levels of blood potassium from kidney failure/toxicity, immunosuppression, damage to lateral line organ, generalized multi-organ
Cerenia, generically known as Maropitant, is a neurokinin-1 receptor antagonist. It mediates effects of central and peripheral substance P, an excitatory neurotransmitter and is in a class of peptides known as neurokinins. Substance P binds neurokinin-1 receptors which are G protein coupled receptors. As an antagonist, maropitant and others like it, blocks the action of substance P.
Where are neurokin-1 receptors located?
They are located in the central nervous system, heart and blood vessels, genitourinary system, immune system , and gastrointestinal tract.
What are the effects of Cerenia in the body?
These neurokin-1 receptors are involved in blood cell production, wound healing, neurogenic inflammation, cell survival, cell proliferation, pain transmission, endocrine and paracrine secretions, dilation of blood vessels. They are involved with neuronal transmission associated with depression, stress. Cerenia antagonizes the affects in these areas as well as acts on two areas in the central nervous system to stop vomiting: area postrema and nucleus tractus solitaries.
So if rabbits and rodents cannot vomit, why is it often used in exotic companion mammals?
While the anti-vomiting effects in rabbits and rodents not seem as important since they cannot vomit, it does not necessarily mean they cannot feel nausea. Efficacy of maropitant for preventing vomiting is also associated with pmotion sickness in dogs where it blocks final common pathway in the vomiting center of the brain. Studies showed it was very effective in preventing vomiting in dogs premedicated with hydromorphone, an opioid drug often associated with nausea and vomiting in patients. There are reports on Veterinary Information Network as well about its use with rabbits during head tilt and it is thought to maybe be helpful to reduce nausea from vestibular disease. It is also used in ferrets and birds as an anti-regurgitation drug.
What about its use in pain control?
As a neurokinin-1 receptor antagonist, Maropitant has shown to reduce anesthetic requirements of dogs undergoing surgery and can be used to reduce visceral pain. In rabbits, Maropitant reduced the viscerosensory response caused by colorectal distention and it is often in rabbits and guinea pigs as pain control for gastrointestinal stasis.
It also has anti-itch effects!
Since neurokinin-1 receptors are involved in mediating some itch pathways. Substance P is found in nerve fibers in the skin and it plays a significant role in the nerve pathways that are involved in inchiness. antagonizing, or blocking these pathways, can be helpful to reduce itch. Studies have shown similar drugs reducing itch in humans and Maropitant signficantly reduced the itchiness of ulcerative dermtitis lesions in mice.
It can also reduce the creation of abdominal adhesions forming after surgery!
Antagonizing neurokinin 1 receptors decreases postoperative adhesion formation and increases peritoneal fibrinolytic activity. Research in a rat model with the use of a neurokinin-1 receptor antagonist (NK-1RA) was found to decrease postoperative peritoneal adhesion formation by up to 53% at higher doses studied compared to saline controls. This research indicated that the antagonist used blocked the binding of substance P to neurokinin receptors. Left unblocked, substance P is proinflammatory and results proliferation of scar tissue and stimulates excessive blood vessel formation. Furthermore, antagonism appears to increase expression of tissue-type plasminogen activator an important enzyme in the production of plasmin, a protein that breaks down fibrin and scar tissue production. Research in rabbits has shown that intestinal adhesions can be reduced compared to controls when tissue-type plasminogen activator is given intraperitoneally.
But wait… there’s more… how about in respiratory disease
Maropitant has been used to treat canine chronic bronchitis. Substance P acts on the neurokinin-1 receptor in airway inflammation and the cough reflex. Antagonizing substance P showed a significant decrease in cough frequency and severity but no change in inflammation.
So are their side effects for Maropitant we should consider?
Some recommend not giving for more than 5 days in a row since the enzyme responsible for its metabolism, CYP2D15, becomes saturated. It should also be used with caution with highly protein bound drugs as these drugs compete with Maropitant for protein binding and there can be increases in unbound Maropitant in the blood. Also it should be used with caution with calcium channel antagonists as maropitant has an affinity for Ca and K channels. Excessive use may also decrease intestinal motility and it induced intestinal motility disorder in mice.
