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May/June 2014 Today's Veterinary Practice 59 ImagIng EssEnTIals | RaDIogRaPhy of ThE small anImal skull: TEmPoRomanDIbulaR JoInTs & TymPanIC bullaE tvpjournal.com | ImagIng EssEnTIals QUALITY CONTROL For quality control of any diagnostic image, use a simple 3-step approach. 1. Is the technique adequate, with appropriate exposure and development? 2. Is the correct anatomy present within the image? Compare the images you obtain with the images in this article. 3. Is positioning anatomically correct? Was correct ana- tomic coverage obtained? Once it is determined that the technique is adequate, make sure the appropriate anatomy is present and posi- tioning is correct, straight, and symmetric. Symmetry of the skull for VD/DV images is critical when evaluating all structures and osseous anatomy. Use the figures in this article as a guide as well as the information provided in the Ensuring Image Quality sections. SUMMARY Radiographs of the skull allow evaluation of a number of clinical signs related to the skull, TMJ, and tympanic bul- lae. The images included in this article illustrate how to produce and evaluate the quality of these radiographs. High-quality, correctly positioned and collimated radio- graphs are required in order to accurately assess the TMJ and tympanic bullae. n C1 = first cervical vertebra; DV = dorsoventral; TmJ = temporomandibular joint; VD = ventrodorsal Suggested Reading Burk rL, Feeney dA. Small Animal Radiology and Ultrasonography: A Diag- nostic Atlas and Text, 3rd ed. Philadelphia: Saunders elsevier, 2003. Kealy JK, McAllister H, Graham JP. Diagnostic Radiology and Ultrasonography of the Dog and Cat, 5th ed. Philadelphia: Saunders elsevier, 2011. Sirois M, Anthony e, Mauragis d. Handbook of Radiographic Positioning for Veterinary Technicians. Clifton Park, NY: delmar Cengage Learning, 2010. Thrall de (ed). Textbook of Veterinary Radiology, 6th ed. Philadelphia: Saun- ders elsevier, 2012. Thrall de, robertson id. Atlas of Normal Radiographic Anatomy and Anatomic Variants in the Dog and Cat. Philadelphia: elsevier Saunders, 2011. N 1 % (n=415) N 2 % (n=200) Vomiting (with and without blood) 17 4.1 25 12.5 Dry/Flaky Skin 13 3.1 2 1.0 Diarrhea (with and without blood) 13 3.1 7 3.5 Lethargy 7 1.7 4 2.0 Anorexia 5 1.2 9 4.5 Treatment Group Afoxolaner Oral active control ™NexGard and FRONTLINE VET LABS are trademarks of Merial. ©2014 Merial. All rights reserved. Body Afoxolaner Per Chewables Weight Chewable (mg) Administered 4.0 to 10.0 lbs. 11.3 One 10.1 to 24.0 lbs. 28.3 One 24.1 to 60.0 lbs. 68 One 60.1 to 121.0 lbs. 136 One Over 121.0 lbs. Administer the appropriate combination of chewables CAUTION: Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian. Description: NEXGARD™ (afoxolaner) is available in four sizes of beef-favored, soft chewables for oral administration to dogs and puppies according to their weight. Each chewable is formulated to provide a minimum afoxolaner dosage of 1.14 mg/ lb (2.5 mg/kg). Afoxolaner has the chemical composition 1-Naphthalenecarboxamide, 4-[5- [3-chloro-5-(trifuoromethyl)- phenyl]-4, 5-dihydro-5-(trifuoromethyl)-3-isoxazolyl]-N-[2-oxo-2-[(2,2,2-trifuoroethyl)amino]ethyl. Indications: NEXGARD kills adult feas and is indicated for the treatment and prevention of fea infestations (Ctenocephalides felis), and the treatment and control of American Dog tick (Dermacentor variabilis) infestations in dogs and puppies 8 weeks of age and older, weighing 4 pounds of body weight or greater, for one month. Dosage and Administration: NEXGARD is given orally once a month, at the minimum dosage of 1.14 mg/lb (2.5 mg/kg). Dosing Schedule: NEXGARD can be administered with or without food. Care should be taken that the dog consumes the complete dose, and treated animals should be observed for a few minutes to ensure that part of the dose is not lost or refused. If it is suspected that any of the dose has been lost or if vomiting occurs within two hours of administration, redose with another full dose. If a dose is missed, administer NEXGARD and resume a monthly dosing schedule. Flea Treatment and Prevention: Treatment with NEXGARD may begin at any time of the year. In areas where feas are common year-round, monthly treatment with NEXGARD should continue the entire year without interruption. To minimize the likelihood of fea reinfestation, it is important to treat all animals within a household with an approved fea control product. Tick Treatment and Control: Treatment with NEXGARD may begin at any time of the year (see Effectiveness). Contraindications: There are no known contraindications for the use of NEXGARD. Warnings: Not for use in humans. Keep this and all drugs out of the reach of children. In case of accidental ingestion, contact a physician immediately. Precautions: The safe use of NEXGARD in breeding, pregnant or lactating dogs has not been evaluated. Use with caution in dogs with a history of seizures (see Adverse Reactions). Adverse Reactions: In a well-controlled US feld study, which included a total of 333 households and 615 treated dogs (415 administered afoxolaner; 200 administered active control), no serious adverse reactions were observed with NEXGARD. Over the 90-day study period, all observations of potential adverse reactions were recorded. The most frequent reactions reported at an incidence of > 1% within any of the three months of observations are presented in the following table. The most frequently reported adverse reaction was vomiting. The occurrence of vomiting was generally self-limiting and of short duration and tended to decrease with subsequent doses in both groups. Five treated dogs experienced anorexia during the study, and two of those dogs experienced anorexia with the frst dose but not subsequent doses. Table 1: Dogs With Adverse Reactions. 1 Number of dogs in the afoxolaner treatment group with the identifed abnormality. 2 Number of dogs in the control group with the identifed abnormality. In the US feld study, one dog with a history of seizures experienced a seizure on the same day after receiving the frst dose and on the same day after receiving the second dose of NEXGARD. This dog experienced a third seizure one week after receiving the third dose. The dog remained enrolled and completed the study. Another dog with a history of seizures had a seizure 19 days after the third dose of NEXGARD. The dog remained enrolled and completed the study. A third dog with a history of seizures received NEXGARD and experienced no seizures throughout the study. To report suspected adverse events, for technical assistance or to obtain a copy of the MSDS, contact Merial at 1-888-637- 4251 or www.merial.com/nexgard. For additional information about adverse drug experience reporting for animal drugs, contact FDA at 1-888-FDA-VETS or online at http://www.fda.gov/AnimalVeterinary/SafetyHealth/ProductSafetyInformation. Mode of Action: Afoxolaner is a member of the isoxazoline family, shown to bind at a binding site to inhibit insect and acarine ligand- gated chloride channels, in particular those gated by the neurotransmitter gamma-aminobutyric acid (GABA), thereby blocking pre- and post-synaptic transfer of chloride ions across cell membranes. Prolonged afoxolaner-induced hyperexcitation results in uncontrolled activity of the central nervous system and death of insects and acarines. The selective toxicity of afoxolaner between insects and acarines and mammals may be inferred by the differential sensitivity of the insects and acarines' GABA receptors versus mammalian GABA receptors. Effectiveness: In a well-controlled laboratory study, NEXGARD demonstrated 100% effectiveness against adult feas 24 hours post- infestation for 35 days, and was ≥ 93% effective at 12 hours post-infestation through Day 21, and on Day 35. On Day 28, NEXGARD was 81.1% effective 12 hours post-infestation. Dogs in both the treated and control groups that were infested with feas on Day -1 generated fea eggs at 12- and 24-hours post-treatment (0-11 eggs and 1-17 eggs in the NEXGARD treated dogs, and 4-90 eggs and 0-118 eggs in the control dogs, at 12- and 24-hours, respectively). At subsequent evaluations post-infestation, feas from dogs in the treated group were essentially unable to produce any eggs (0-1 eggs) while feas from dogs in the control group continued to produce eggs (1-141 eggs). In a 90-day US feld study conducted in households with existing fea infestations of varying severity, the effectiveness of NEXGARD against feas on the Day 30, 60 and 90 visits compared with baseline was 98.0%, 99.7%, and 99.9%, respectively. Collectively, the data from the two studies (one laboratory and one feld) demonstrate that NEXGARD kills feas before they can lay eggs, thus preventing subsequent fea infestations after the start of treatment of existing fea infestations. In well-controlled laboratory studies, NEXGARD demonstrated >97% effectiveness against Dermacentor variabilis 48 hours post-infestation for 30 days. Animal Safety: In a margin of safety study, NEXGARD was administered orally to 8- to 9-week-old Beagle puppies at 1, 3, and 5 times the maximum exposure dose (6.3 mg/kg) for three treatments every 28 days, followed by three treatments every 14 days, for a total of six treatments. Dogs in the control group were sham-dosed. There were no clinically-relevant effects related to treatment on physical examination, body weight, food consumption, clinical pathology (hematology, clinical chemistries, or coagulation tests), gross pathology, histopathology or organ weights. Vomiting occurred throughout the study, with a similar incidence in the treated and control groups, including one dog in the 5x group that vomited four hours after treatment. In a well-controlled feld study, NEXGARD was used concomitantly with other medications, such as vaccines, anthelmintics, antibiotics (including topicals), steroids, NSAIDS, anesthetics, and antihistamines. No adverse reactions were observed from the concomitant use of NEXGARD with other medications. Storage Information: Store at or below 30°C (86°F) with excursions permitted up to 40°C (104°F). How Supplied: NEXGARD is available in four sizes of beef-favored soft chewables: 11.3, 28.3, 68 or 136 mg afoxolaner. Each chewable size is available in color-coded packages of 3 or 6 beef-favored chewables. NADA 141-406, Approved by FDA Marketed by: Frontline Vet Labs™, a Division of Merial Limited. Duluth, GA 30096-4640 USA Made in Brazil. 1050-4493-00 Rev. 7/2013 Mary Wilson, RT(R), CT, MR, CV, is a registered radiologic technologist with the American Registry of Radiologic Technologists. She manages the diagnostic imaging section at University of Florida College of Veterinary Medicine. Danielle Mauragis, CVT, is a radiology technician at University of Florida College of Veterinary Medicine where she teaches diag- nostic imaging. She coauthored the Handbook of radiographic Positioning for veterinary Technicians and received the Florida Veterinary Medical Association's 2011 Certified Veterinary Technician of the Year Award. Clifford R. Berry, DVM, Diplomate ACVR, is a professor in diagnostic imaging at University of Florida College of Veterinary Medicine. His research interests include cross-section- al imaging of the thorax, nuclear medicine, and biomedical applications of imaging. He received his DVM from University of Florida and completed a radiology residency at University of California–Davis. 2014-0506_IE_Skull2.indd 59 5/23/2014 12:59:41 PM