In some situations, practitioners are left trying to determine whether an animal's behavioral change reflects a medical issue or a behavioral problem.
In some situations, practitioners are left trying to determine whether an animal's behavioral change reflects a medical issue or a behavioral problem. This distinction is fuzzy and frequently artificial. An individual's genetics, behavior and physiology are so intimately entwined with each other as to make them inseparable as discreet components. The first "symptom" of any disease process is a change in the animal's behavior. Additionally, alterations in an animal's behavior, especially those that we would consider poorly adaptable (e.g. compulsive disorders) or associated with stress, produce changes in the animal's physiology and homeostasis, some of which become permanent. Humans and animals undergo changes in hypothalamic-pituitary-adrenal (HPA) axis, immune competency, and gene transcription in accordance with environmental influences that affect their behavior.
When an owner presents his/her animal to a veterinarian for medical evaluation of a behavior problem, the worst thing the clinician can do is dismiss the owner's concerns for such an evaluation. Never tell an owner such an evaluation is not necessary or appropriate. If for no other reason, these evaluations should be done so the owner has the peace of mind that he/she has addressed that step. Inappropriate behaviors are manifestations of underlying problems whether they are primarily psychological or physiological. Just as scratching is not a disease, aggression is not a behavior problem per se. Scratching is a symptom of an underlying pruritic condition just as aggression is a symptom of an underlying issue (e.g. fear, territoriality, conflict). Behavior problems should be addressed in a comprehensive manner by evaluating the animal's environment, diet, exercise routine, social relationships, and physiologic (medical) status. Although disease processes are not the direct sole cause of most behavior problems, diseases or chronic illnesses will certainly affect the expression of the behavior issue (and usually in a negative way).
There should be a high suspicion of a medical trigger 1) in very young animals, 2) in senior animals showing the onset of a new behavior, 3) when there is a sudden onset of a new behavior or a sudden change in the status of a pre-existing behavior, or 4) when the behavior truly appears unpredictable in context, frequency and/or intensity. Medical evaluations, a minimum database at the least, are also necessary if pharmacologic intervention is being considered. In some cases, a comprehensive diagnostic evaluation is beyond the owner's desire or resources; however, such evaluations should still be discussed and offered to the client. There are limitations to our knowledge and diagnostic capabilities, so while some animals may have "neurologic" or neurodevelopmental problems causing their behavior issues, we currently will be unable to diagnose them.
Aggression is affected by a variety of physiologic problems including disease and drug administration. Generally all of my aggression cases have a CBC, chemistry panel, and thyroid panel (for dogs over 1 year and middle aged to older cats). The trigger for the aggression can indicate other areas of concentration. For example, a dog that is aggressive when being handled around its head and neck may need careful otoscopic examination, oral examination and evaluation for cervical spinal pain. In young animals with aggression, other etiologies to consider include: congenital neurologic disease (e.g. lissencephaly, hydrocephalus), portosystemic shunt, storage diseases (rare), infectious disease (viral – FeLV, FIV, canine distemper; protozoal – Toxoplasmosis, Neospora; Rickettsial – RMSF, Ehrlichia, Borrelia, Bartonella), and toxins.
Middle aged to older animals should be evaluated for: osteoarthritis, endocrine disease (hyperthyroidism, hypothyroidism, hyperadrenocorticism), neoplasia, primary neurologic disease (neoplasia, GME, necrotizing encephalitis, Feline Ischemic Encephalopathy, parasitic migration, seizures [uncommon as a cause of aggression]), infectious disease (viral, protozoal, rickettsial, fungal), ocular disorders (cataracts, PRA, uveitis), hyperkinesis (also rare), and Cognitive Dysfunction. Acute or chronic pain also frequently plays a role.
Drugs that have commonly been implicated in inducing or exacerbating aggression in dogs and cats include glucocorticoids, phenylpropanolamine, theophylline, benzodiazepines, acepromazine, and excessive or unnecessary supplementation with levothyroxine.
In very young animals, serious anxiety disorders, fears and phobias are likely to be related to neurodevelopmental issues, prenatal and postnatal stress, socialization deficits, and learning events. However, congenital disorders (hydrocephalus, portosystemic shunts) and infectious disease (distemper, feline viruses, rickettsial, protozoal) can influence the animal's behavior and development (e.g. sensitizing the HPA axis to hyperrespond to stress and threat signals).
In adult animals, infectious disease, endocrine disease, chronic pain (e.g. spinal pain, intestinal cramping) and neurologic disorders can mimic or worsen anxiety states. Some episodes of spontaneous panic may represent limbic system (i.e. temporal lobe) seizures. Hyperadrenocorticism can readily mimic or worsen an anxiety disorder. Corticotrophin Releasing Factor (CRF) directly activates the anxiety centers in the brain. Although CRF is suppressed in hyperadrenocorticism, states of acute or chronic stress increase CRF levels. ACTH has been shown to increase stress grooming in rodents and glucocorticoids themselves are also anxiogenic. Pain is also a common cause of anxious behavior.
In cases of nocturnal anxiety/restlessness (including nocturnal vocalization in cats), cognitive dysfunction should be considered along with deficits in sensory perception (olfaction, audition and/or vision). Hyperthyroidism in cats is a not uncommon cause of nocturnal activity and vocalization. Other intracranial neurologic disorders will affect behavioral adaptability. Additionally, animals with osteoarthritis often become more painful at night and have difficulty finding a comfortable place to rest. Seizure disorders and sleep disorders may also cause restlessness, vocalization, and less commonly, aggressive outbursts.
In cats, by far the most common medical factor contributing to inappropriate urination is sterile cystitis and other lower urinary tract disease. Primary urinary tract disease, including urolithiasis, pyelonephritis, and incontinence can trigger or contribute to urine housesoiling, as can any disease process leading to polyuria/polydipsia. In young cats, pain (and abrupt litter changes) due to declawing surgery can trigger housesoiling. Prostatic disease in dogs can lead to increased urine marking. For fecal housesoiling, especially in cats where there are even small or intermittent changes in the cat's stool, the clinician should consider food intolerance/allergy, inflammatory bowel disease, irritable bowel syndrome, constipation/megacolon, parasitism, neoplasia (e.g. alimentary lymphosarcoma), metabolic disease (renal, hepatic, pancreatitis), endocrine (hyperthyroidism), pancreatic insufficiency, and other malabsorption syndromes. Geriatric onset housesoiling in cats is almost always associated with an identifiable disease process.
Repetitive behaviors include stereotypies and compulsive disorders including fly snapping, excessive licking (of self and/or objects), hair pulling/grooming, tail chasing, spinning, self-mutilation, shadow/light chasing, hind end checking, flank sucking, wool sucking, and pica among others. Up to 76% of cats with excessive grooming have an underlying dermatologic issue causing or contributing to the problem. A large percentage of these cats have food allergy, flea allergy, and/or atopy, although parasites such as demodex are also identified. In cats, hair pulling is sometimes associated with other symptoms of Feline Hyperesthesia Syndrome (tail chasing, vocalization, bouts of frantic running, and aggression). dogs with acral lick dermatitis (ALD) also frequently have allergic disease. ALD has also been associated with underlying arthritis (or other sources of pain) and neoplasia (soft tissue or osseous). There is mostly likely a medical etiology for any repetitive behavior that responds to steroid administration.
Dogs with tail chasing or spinning should be screened for spinal cord disease (IVDD, cauda equina, neoplasia, neuropathies), central neurologic disease (hydrocephalus, infectious, neoplasia, encephalitides, storage diseases), anal sac disease, and urogenital tract problems. Seizures are a potential differential for any form of repetitive behavior particularly tail chasing, shadow chasing, episodic excessive licking, and fly snapping. Neuropathic pain or paraesthesias are probably linked a significant number of tail chasing, spinning and self-mutilation cases; however, diagnosing these is problematic. In many cases sequential drug trials with steroids, pain medications (NSAIDs, opioids), and anticonvulsants are necessary for putative diagnosis some of these disorders.
Hyperactivity problems are typically related to management (lack of enrichment and exercise) and training (inappropriate and/or inconsistent punishment) issues. However, there are a few disease processes that can contribute or trigger hyperactive behavior. Hyperthyroidism (primarily cats but also dogs with inappropriate supplementation) and drug administration (PPA, theophylline, etc) are not uncommon causes. Hyperkinesis is a notable, although rare, cause of hyperactivity and other behavioral manifestations in dogs. Cognitive Dysfunction and general brain aging are often associated with nocturnal restlessness. Food allergies and food intolerances have been associated with hyperactive behavior as well. Central neurologic disease, including seizures, portosystemic shunts, and toxins (lead) may also be causes.