2016 WINTER: Color Dilute Alopecia | Marijuana | Idiopathic Trigeminal Neuritis | Pimobendan for Cats? | Canine Demodicosis | Old Cats and Dogs | Clinical Trials
Color Dilute Alopecia
Many of us know them as blue or fawn Dobermans. Other breeds such as dachshunds, Chihuahuas, Laboradors, poodles, German shepherds and great Danes are also commonly affected. Afflicted dogs demonstrate lighter hair coat coloring than typical for their breed, such as silver instead of black, or fawn instead of brown. Their unusual hair color makes them popular with pet owners, at least when first adopted. Unfortunately, many of them will develop skin and hair coat problems when they reach 6 months to 3 years of age. This condition, known as color dilute alopecia, is believed to be inherited and is the result of mutations in multiple genes.
The severity of the skin condition that develops in dogs with color dilute alopecia varies. Most dogs demonstrate a patchy alopecia over the dorsal trunk as the hair follicles become dysplastic.
Abnormal clumping of melanosomes within the hair shafts causes the shafts to fracture and break. Many dogs will also develop underlying comedones, seborrhea and secondary bacterial folliculitis. A skin biopsy of the affected areas is required to make a definitive diagnosis.
There is no cure for the cutaneous manifestations of color dilute alopecia. The goal of therapy is to minimize discomfort in the pet by controlling infection and reducing seborrhea. Oral retinoids, fatty acids and epidermal health products are typically prescribed. Antibiotics can be used to control secondary infections. Melatonin may improve hair growth. Unfortunately, treatment of color dilute alopecia can be frustrating and is lifelong. Therefore, should you have a patient with a chronic skin condition such as color dilute alopecia, consultation with one of our dermatologists, Drs. Schick and Znjada is recommended.
A Growing Toxicity
Marijuana is believed to be the most commonly used illicit drug in the United States. With its legalization for medical use in humans and its recent decriminalization in Colorado and Washington, the frequency with which pets are being exposed to marijuana or one of its derivatives is increasing.
The toxic chemical in marijuana is delta 9-tetrahydrocannabinol or THC. Dried leaves and flowers of the hemp plant Cannabis sativa contain 1-8% THC. Hashish, compressed resin produced from the flowering tops of the plants, contains 10% THC. Hash oil or butter, a concentrated form of hashish or marijuana in which the cannabinoids are extracted into the fat of oil or butter, can have a THC concentration exceeding 50%.
The most common means by which dogs and, uncommonly, cats are exposed to marijuana is by ingestion of home cooked or commercial products containing THC. THC is stored in the tissues of the brain, liver and kidneys. Being highly lipid soluble the chemical is also stored in fat deposits where it can remain for days. The majority of the THC is excreted via the biliary system and eliminated via the feces.
Signs of marijuana intoxication typically occur within 60 minutes of exposure and can last several days. The THC binds to cannabinoid receptors in the brain where it interacts with the neurotransmitters norepinephrine, dopamine, serotonin and gamma-aminobutyric acid inducing varying stimulatory and inhibitory signs involving the GI, cardiovascular and neurologic systems.
Signs of marijuana intoxication
- Depression or dysphoria
- Hyperstartle response
- Urine dribbling
Is it marijuana?
The challenge in diagnosing marijuana toxicity is getting the pet owner to confirm the pet’s potential exposure. Routine blood testing and imaging typically fail to demonstrate significant abnormalities. Furthermore, over-the-counter drug tests as well as laboratory tests for THC have not yet been proven effective in pets. Luckily the signs of THC toxicity, i.e. dysphoria, drowsiness, a hyperstartle response and especially urine dribbling are pretty recognizable.
What’s the best treatment?
Treatment after immediate exposure to marijuana could include induction of emesis and the administration of activated charcoal. Both would be contraindicated if the clinician feels the patient’s mental state predisposes the pet to the possibility of aspiration pneumonia. Interestingly, induction of emesis may not be effective as one of the marijuana’s medical uses is to inhibit nausea and vomiting in human cancer patients. The repeat administration of activated charcoal 6-8 hours after an initial administration should be considered to reduce GI absorption of the THC as it goes through eneterohepatic circulation.
Symptomatic supportive care should be individualized to the patient and would typically include IV fluids to ensure hydration and perfusion, external heating or cooling as indicated, and anti-anxiety therapy. More severely affected patients may require cardiovascular medications, oxygen supplementation or even ventilation. Intralipid therapy should be considered in more severely affected patients and those with prolonged duration of signs. Because THC is lipid soluble, it can be leached from the body with intralipid therapy. Close monitoring of these patients is important. Luckily THC has a high safety margin. To be lethal most dogs must be exposed to greater than 3 g/kg.
Could marijuana be beneficial for treating ill pets?
In humans, marijuana and its derivatives have been shown or suggested to have many potential medical uses including
- Stimulating appetite and reducing nausea in cancer patients
- Treatment of glaucoma
- Increasing lung capacity
- Controlling epilepsy
- Reducing cancer spread
- Slowing the progression of Alzheimer’s disease
- Reducing the pain of multiple sclerosis
- Relieving arthritis discomfort
- Treating inflammatory bowel disease
Reports of marijuana’s effectiveness for treating ill pets are very limited and at best anecdotal. Marijuana is a Schedule I narcotic. Even if you live in a state where medical marijuana is sanctioned, as a veterinarian it remains illegal for you to prescribe or recommend it to treat a patient.
If you feel you may be dealing with a pet who has a potential toxicity or desire closer 24 hours or after-hours monitoring of your patient, please don’t hesitate to give us a call. Our emergency and critical care services have loads of experience dealing with all types of toxicities.
Idiopathic Trigeminal Neuritis
Idiopathic trigeminal neuritis is the most common neurologic cause of acute “dropped jaw.” The disease primarily affects the mandibular branch of the trigeminal nerve, which innervates the muscles of mastication. Dysfunction of this nerve results in an inability to close the jaw. Difficulty eating and drooling are also symptoms.
The disease occurs most often in middle-aged or older dogs and occasionally in cats, but there is no gender predisposition. It is self-limiting, and the prognosis is generally good, typically completely resolving in two to six weeks with supportive care alone. Severe masticatory muscle atrophy may occur later in the course of disease and shows an unfavorable prognosis.
Because idiopathic trigeminal neuritis is a diagnosis of exclusion, careful consideration of other diagnostic differentials is key. The most important differential is rabies; any animal exhibiting mandibular paralysis is initially isolated and handled with caution. Additional possibilities include neoplasia, trauma and other infectious diseases. Complete blood count, serum chemistry profile, and urinalysis are standard diagnostics. Infectious disease titers may be normal or positive; however, a positive test does not necessarily indicate an active disease process. The following organisms are most commonly implicated in central nervous system (CNS) infections: Toxoplasma gondii, Neospora caninum, Cryptococcus neoformans, Ehrlichia canis, and Rickettsia rickettsii. Other neurologic diseases may be ruled out with CSF analysis, CT, MRI and electrodiagnostics.
There is no known specific treatment for idiopathic trigeminal neuritis. Most patients experience a gradual recovery over two to six weeks with supportive care. Physical therapy, including opening and closing the jaw, should be provided. Depending on the patient’s abilities, providing chew toys can be effective. Some animals with significant dysphagia require assistance with ingesting food and water. Firm balls of canned food should be placed on the back of the tongue to allow normal swallowing. If the animal cannot lap adequate amounts of water to maintain hydration, it may be given orally with a syringe. A water bottle meant for rodents may also provide some benefit. In severe cases, a feeding tube (esophagostomy or percutaneous endoscopic gastrostomy) may be required temporarily.
Michael Kimura, DVM, DACVIM-Neurology, is happy to take your phone consults or transfers, should you have questions or a case you believe is suffering from idiopathic trigeminal neuritis, or any other neurological condition.
Pimobendan: What About Cats?
Pimobendan is the latest and greatest cardiac medication added to our arsenal for treating mitral valve insufficiency and dilatative cardiomyopathy in dogs. Pimobendan acts as a positive inotrope in dogs, improving ventricular contractility and cardiac output. It also has balanced vasodilatory effects improving blood flow to and away from the heart. Studies have demonstrated pimobendan to improve the clinical signs and prolong the survival times of dogs with congestive heart failure.
It’s only natural to wonder whether pimobendan will work in cats. Although not presently approved for use in cats with heart disease, investigators are starting to look at whether it can achieve similar success for improving quality of life and prolonging survival in the feline species. A number of retrospective studies have been reported:
(a) In a study of 32 cats with non-taurine responsive dilatative cardiomyopathy, the 16 cats who received pimobendan demonstrated a median survival time four times longer than 16 cats who did not receive pimobendan. All cats received additional cardiac medications. No significant adverse effects were encountered. (Hambrook, JFelMedSurg)
(b) In a group of 27 cats with various forms of cardiomyopathy having ventricular systolic dysfunction, the administration of pimobendan had no significant effect on echocardiographic findings for the group evaluated pre- and then 1 to 60 days post-initiation of therapy. Adverse effects were uncommon. One cat with systolic anterior motion of the mitral valve developed severe hypotension presumably secondary to a worsening of left ventricular outflow. Pimobendan’s effect on survival time was not evaluated. (Gordon, JAVMA)
(c) A third study describes the use of pimobendan in 170 cats (164 with congestive heart failure) afflicted with a variety of cardiomyopathies. Side effects were uncommon but did include agitation, anorexia, vomiting and constipation. There was no control group so pimobendan’s effects on clinical signs and survival time could not be evaluated. (MacGregor, JVetCard)
It would not be unreasonable to suspect that cats with ventricular systolic dysfunction, similar to dogs, may benefit from the actions of pimobendan. Studies to date show, that at the doses given, the medication is typically safe. Unlike dogs, however, the cardiac changes responsible for congestive heart failure in cats can be quite varied. Pimobendan may be effective for some forms of feline cardiomyopathy, for example dilatative cardiomyopathy, but not others. Given the tremendous variation in the character of the cardiomyopathies identified in cats, it may prove more difficult to determine the combination of cardiac parameters which must be present for pimobendan to be effective. Therefore, echocardiography is an essential part of the cardiac evaluation in cats prior to the use of this medication.
If you have any questions regarding the use of pimobendan in cats, Alan Spier, DVM, DACVIM-Cardiology, and Tony Ishak, DVM, DACVIM-Cardiology, are both available for phone consults.
Canine Demodicosis: Review and Exciting News
Canine demodicosis is a cutaneous disorder that predisposes dogs to develop secondary infections of the skin. We are beginning to understand a little more about this parasite with the advent of modern microbiologic techniques, but discoveries about new treatments tend to be serendipitous, as these mites cannot be grown in vitro.
In the past, we recognized what we thought were three distinct species of mites: D. canis (the traditional mite we find in the hair follicles of dogs), D. injai (the long-tailed mite we associated with seborrheic conditions), and D. cornei (the short, stubby mite similar to D. gatoi in cats). Molecular analysis has shown that while D. injai is a separate species, but D. cornei is just a different morphologic form of D. canis.
Dobby upon presentation, after one month on Nexgard and after two months of treatment.
These products will provide not only effective treatment, but also easy maintenance for dogs with chronic demodicosis, while providing great flea and tick control! Do not forget to treat with oral antibiotic plus topical antimicrobials for as long as Demodex mites are found on skin scrapings. Dr. Znjada is available for consults and referrals at our hospital in Tampa.
We recognize localized demodicosis as a disorder than can be associated with spontaneous resolution. Generalized demodicosis in young dogs has been attributed to a genetic predisposition, and for that reason, it is recommended that these dogs be neutered. Neutering also prevents the relapse of the mange often associated with estrus in females. Adult onset demodicosis suggests the development of an underlying disorder that changes the skin biology or skin immune system in such a way that mites overgrow. We look for endocrine diseases, such as hyperadrenocorticism or hypothyroidism; any systemic disease that weakens immune function, including neoplasia; and the use of medications including steroids and possibly Apoquel®, whose use can be associated in some dogs with mite overgrowth. In the rare patient, atopic dermatitis may make a patient more susceptible to pododermodicosis.
It is important to recognize that for some dogs, we don’t find an underlying cause. We simply treat the disease and recommend maintenance therapy to prevent relapse. A perfect example is adult onset generalized demodicosis in shih tzus. These dogs often develop deep pyoderma, particularly in their feet. Any adult shih tzu that develops pyoderma of the feet, even if they have a past history of atopic dermatitis, should be evaluated for demodicosis. We find that hair plucks are very effective for this purpose as the Demodex mites adhere to the hair bulb.
The most exciting news about canine demodicosis is the discovery that the new isoxazoline flea and tick control products, afloxalaner (Nexgard®) and fluralaner (Bravecto®) appear to be very effective in treating demodicosis in dogs. When used according to the label instructions for flea and tick control, these products appear to kill demodex mites very quickly and result in rapid resolution of the disease. There is one publication available for Bravecto at this time, but I anticipate that more will be published on both medications in the foreseeable future. Treating dogs with Nexgard every 3-4 weeks plus Bravecto every 8 weeks is proving to be effective. After one dose, the mite counts are dropping from adults, juveniles, and eggs too numerous to count to 1-2 dead mites in one month! Truly amazing.
We would like to thank our colleague from our BluePearl hospitals in Texas, Valerie A. Fadok, DVM, PhD, DACVD, for allowing us to use this article in Companion. Dr. Nadine Znjada was also a contributor to the article.
Reference: Fourie et al. Efficacy of orally administered fluralaner (Bravecto) or topically applied imidacloprid/moxidectin (Advocate) against generalized demodicosis in dogs. Parasites and Vectors (2015) 8:187.
Old Cats and Dogs
As in the human population, the number of aging cats and dogs is rising. There are numerous interpretations of what constitutes old age in dogs and cats. One method equates cat and dog age with human age, but a simpler method considers the species, breed and size of the patient to estimate life expectancy. Generally speaking, small dogs and cats live longer than large breed dogs. Using the simplified approach, cats and dogs are considered to be “senior” when they approach the last 25% of their expected life span; however, preventive measures and close monitoring of clinical and laboratory data should be started during “middle age,” or when the patient has reached 50% of expected life span.
Veterinarians can work with clients to implement individualized disease prevention programs for senior patients. Senior wellness programs may increase client loyalty and improve the patient’s quality of life and longevity.
Common senior diseases
Common geriatric diseases seen in dogs and cats include chronic renal disease, diabetes, osteoarthritis, neoplasia and related paraneoplastic syndromes, hepatopathies, periodontal disease, inflammatory intestinal diseases, and idiopathic behavior changes. It is also important to note that the most common endocrinopathy in older cats is hyperthyroidism. All of these disorders are chronic and progressive, and early detection will minimize patient discomfort and slow disease progression. Senior wellness programs are based on detecting disease while it is in a subclinical state.
Common behaviors reported by owners of aging cats and dogs include excessive vocalization, wandering, disorientation, lack of social interaction, and disturbance of the wake-sleep cycle. We must first rule out all possible medical causes of behavioral changes before attributing them to senility and related cognitive dysfunction.
Care for seniors
Experts agree that middle-aged dogs and cats should have semi-annual veterinary exams. These exams should be thorough, and include obtaining a detailed history, and performing complete physical and ocular exams, as well as measuring blood pressure. In dogs, rectal exams should be performed.
If the patient is clinically normal, laboratory work should be performed annually at an outside reference lab, which allows for consistency when performing serial monitoring and more reliable results. Minimum laboratory work should include a CBC, chemistry panel and urinalysis. In cats, thyroxine should be tested. For those patients with signs of disease, laboratory work should be performed twice yearly. Additional diagnostics, such as imaging, electrocardiography or echocardiogram, should be performed when indicated.
Specialists at all of our Florida hospitals are available to take your phone consults for ages ranging from neonatal to geriatrics.
Feline Anemia Trial
Our hospitals in Tampa and Brandon are currently recruiting patients for a fully-funded trial to evaluate the safety and efficacy of an oral medication to manage anemia associated with chronic kidney disease in cats. The study consists of two phases: the efficacy phase (28 days) and the maintenance phase (8 weeks).
- Cats, > 1 year old, male or female, >0 kg
- Not pregnant, lactating or intended for breeding
- Diagnosis of chronic kidney disease
- Non-regenerative anemia with PCV < 27% at study days -7 and 0
- Stable concurrent medical conditions (i.e., heart disease, hyperthyroidism)
- Cats may be receiving SQ fluids
- Fractious cats
- Positive urine culture on study day -7
- Systolic blood pressure > 165 mmHg on study days -7 or 0
- Previous treatment with erythrocyte stimulating agents (ESA), including erythropoietin (EPO)
- Previous blood transfusion since being diagnosed with CKD
- Severe clinical signs of inflammation not attributed to CKD
- Other significant uncontrolled medical issues (i.e. lymphosarcoma, symptomatic pancreatitis etc.)
- FeLV+ or FIV+ (if not vaccinated, sponsor will cover the cost to test)
- Obvious signs of GI bleeding
The study medication, diagnostic lab work, and examinations will be provided at no cost to owners. Owners will be expected to administer the study medication at home, keep an owner diary, and comply with study protocols.
*Note that this study is not funded for diagnostic or treatment costs associated with the underlying renal disease. Those costs must still be assumed by the owner.
For more information or if you have a patient who may meet the above requirements, please contact any member of the BluePearl internal medicine team.
Canine Stage II Hemangiosarcoma Trial
This study will evaluate the effects of Yunnan Baiyao as a single agent or combined with a polysaccharopeptide on disease control and survival time in dogs with splenic hemangiosarcoma not receiving a standard chemotherapy protocol.
This study, selected for funding as a winner in a juried, national competition, is being underwritten by Frankie’s Friends charitable pet foundation.
Participants will receive the following:
- Free supply of Yunnan Baiyao during study enrollment
- Free recheck appointments every 6 weeks
- Free restaging tests (blood work, thoracic radiographs, abdominal ultrasound) every 12 weeks
The following pets may be considered for enrollment in the study:
- Postop splenectomy (within 2-3 weeks of procedure)
- Histologic diagnosis of hemangiosarcoma
- No detectable gross metastatic disease at the time of surgery based on thoracic radiographs, ultrasound, gross appearance of liver and surrounding abdominal organs at surgery, and/or liver biopsy
- No chemotherapy (i.e. doxorubicin or metronomic) was administered